WO2022187050A1

WO2022187050A1 - Anti-cd117 agents and compositions and methods for making and using the same

Info

Publication number: WO2022187050A1
Application number: PCT/US2022/017478
Authority: WO
Inventors: Cheng-rui LI; Chien-Chung Chen; Takatoku Oida; Weihao CHEN; David Soper; Xifeng Yang
Original assignee: Biolegend Inc
Current assignee: Biolegend Inc
Priority date: 2021-03-01
Filing date: 2022-02-23
Publication date: 2022-09-09
Anticipated expiration: 2023-09-01

Abstract

Compositions and methods for making and using anti-CD117 agents, for example, monoclonal antibodies, CD117-binding antibody fragments, and derivatives are described, as are kits, nucleic acids encoding such molecules, diagnostic reagents and kits that include anti-CD117 agents, and methods of making and using the same.

Description

ANTI-CD117 AGENTS AND COMPOSITIONS AND METHODS FOR MAKING AND

USING THE SAME

Cross-Reference To Related Application

This application claims priority to U.S. Provisional Application No. 63/155,287, filed March 1, 2021 , entitled "ANTI-CD117 AGENTS AND COMPOSITIONS AND METHODS FOR MAKING AND USING THE SAME ", the contents of which are hereby incorporated by reference in their entirety for all purposes.

Incorporation by Reference of Sequence Listing

The present application is being filed along with a Sequence Listing in electronic format. The Sequence Listing is provided as a file entitled "BLD016PCT", created on Feb. 18, 2022, which is 83,726 bytes in size. The information in the electronic format of the Sequence Listing is incorporated herein by reference in its entirety.

Field

The technology relates in part to agents that bind cluster of differentiation 117, i.e. , CD117, and its variants, particularly to monoclonal antibodies, antibody fragments, and antibody derivatives specifically reactive to CD117 under physiological and/or in vitro conditions. Such agents can be useful for laboratory/research purposes (e.g., flow cytometry), and may be used in the treatment and/or prevention of various diseases or disorders through the delivery of pharmaceutical or other compositions that contain such agents.

Background

The following description includes information that may be useful in understanding the present technology. It is not an admission that any of the information provided herein, or any publication specifically or implicitly referenced herein, is prior art, or even particularly relevant, to the presently claimed technology.

Tyrosine-protein kinase KIT, cluster of differentiation 117 (CD117) or mast/stem cell growth factor receptor (SCFR), is encoded by proto-oncogene c-KIT. c-KIT is a type III receptor tyrosine kinase that is typically expressed on the surface of hematopoietic stem cells. c-KIT binds stem cell factor to form a dimer that activates its intrinsic tyrosine kinase activity, which in turn phosphorylates and activates some signal transduction molecules in the cell. Signaling through c-KIT plays a role in cell survival, proliferation, and differentiation.

While mutations in c-KIT alone have not been shown to be sufficient for tumorigenesis, c-KIT has been found to play a significant role in cancer occurrence. Deregulation of c-KIT, including gain-of-function mutations, has been detected in several human cancers, with leukemia being the first cancer to be linked to a c-KIT activating mutation. Currently, the kinase inhibitor drug imatinib is used to inhibit c-KIT. c-KIT, however, is expressed in normal tissues such as breast epithelial, vascular endothelial, sweat glands, and retinal astrocytes. There exists a need for reagents to better study c-KIT, as well as therapeutics to discriminately target c-KIT in cancer cells.

Described herein are particular monoclonal antibodies to c-KIT (CD117) that provide superior target specificity, signal-to-noise ratios, and the like as compared to other reported anti-CD117 antibodies, as well as antigen-binding fragments of such antibodies that also bind CD117.

Summary

Provided herein, in some aspects, are anti-CD117 agents that bind cluster of differentiation 117 (CD117), including anti-CD117 antibodies, CD117-binding antibody fragments, derivatives, and variants of such antibodies and antibody fragments or antigen-binding fragments thereof (including immunoconjugates, labeled antibodies and antigen-binding antibody fragments, and the like), diagnostic reagents that comprise such agents, containers and kits that include an anti-CD117 agent provided herein, and methods of making and using the same.

Provided herein, in certain aspects is an anti-CD117 agent that binds under laboratory or physiological conditions, where the agent comprises at least one immunoglobulin heavy chain variable domain and at least one immunoglobulin light chain variable domain, where a) each immunoglobulin heavy chain variable domain of the anti-CD117 agent comprises first, second, and third heavy chain complementarity determining regions (CDRs), where the first heavy chain CDR (CDRH1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅ (SEQ ID NO: 100), where X₁ is S, T, N, E, or D, X₂ is Y or H, X₃ is G, T, W, D, Y, or N, X₄ is M, I, or V, and X₅ is S, H, N, V, or A; the second heavy chain CDR (CDRH2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁ X₂ X₃X₄ X₅ X₆ X₇ X₈ X₉X₁₀X₁₁X₁₂X₁₃X₁₄ X₁₅X₁₆X₁₇X₁₈X₁₉ (SEQ ID NO: 101), where X₁ is T, Y, M, G, E, R, A, or D, X₂ is I or M, X₃ is S, R, N, H, K, or no amino acid, X₄ is L, T, W, Y, or no amino acid, X₅ is K, G, S, D, or no amino acid, X₆ is G, P, S, or T, X₇ is G, S, N, I, or R, X₈ is G, S, D, or N, X₉ is T, S, G, D, Y, or R, X₁₀ is Y, F, E, S, G, L, K, D, or N,X₁₁ is T, I, F, or Y, X₁₂ is Y, H, R, F, S, N, or V, X₁₃ is Y, L, E, S, P, or D, X₁₄ is P, N, A, G, or S, X₁₅ is D, Q, E, F, L, or V, X₁₆ is S, K, or Y, X₁₇ is L, V, F, M, G, S, or N, X₁₈ is R or K, andX₁₉ is G, D, or R; and the third heavy chain CDR (CDRH3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂ X₁₃Y (SEQ ID NO: 102), where X₁ is D, E, L, G, I, or H, X₂ is W, R, D, G, E, L, or no amino acid, X₃ is D, W, Y, A, R, F, or no amino acid, X₄ is D, R, A, Y, I, or no amino acid, X₅ is S, G, P, I, Y, or no amino acid, X₆ is Y, A, W, T, S, D, or no amino acid, X₇ is F, M, P, Y, G, or no amino acid, X₈ is D, A, F, E, R, or no amino acid, X₉ is Y, D, F, A, I, or S, X₁₀ is Y, H, N, or S, X₁₁ is T, W, Y, or P, X₁₂ is M or F, and X₁₃ is A, T, or D; and b) each immunoglobulin light chain variable domain of the anti-CD117 agent comprises first, second, and third light chain CDRs, where the first light chain CDR (CDRL1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂SX₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆ X₁₇ (SEQ ID NO: 103), where X₁ is S, K, or R, X₂ is A, S, or R, X₄ is Q, S, T, or E, X₅ is S, G, D, or no amino acid, X₆ is L, D, I, N, or no amino acid, X₇ is L, V, I, H, or no amino acid, X₈ is N, H, G, S, or no amino acid, X₉ is S, G, or no amino acid, X₉ is S, G, or no amino acid, X₁₀ is G, S, or no amino acid, X₁₁ is D, N, S, or no amino acid, X₁₂ is I, Q, L, G, or no amino acid, X₁₃ is S, K, I, R, N, or no amino acid, X₁₄ is N, T, or no amino acid, X₁₅ is Y, F, or no amino acid, X₁₆ is L, M, or V, and X₁₇ is N, T, H, S, A, or Y; the second light chain CDR (CDRL2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇ (SEQ ID NO: 104), where X₁ is Y, W, S, F, K, R, or N, X₂ is T, A, V, or D, X₃ is S, D, or I, X₄ is S, T, N, R, K, or P, X₅ is L or R, X₆ is H, Q, E, A, F, or P, and X₇ is S or D; the third light chain CDR (CDRL3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉ (SEQ ID NO: 105), where X₁ is Q, H, S, or L, X₂ is Q, N, H, or S, X₃ is Y, D, W, G, H, T, or S, X₄ is S, Y, or T, X₅ is K, G, T, S, H, H, D, or no amino acid, X₆ is V, Y, L, T, F, G, S, or no amino acid, X₇ is P, S, or I, X₈ is W, L, Y, P, T, or S, and X₉ is T, V, or A.

Also provided in certain aspects is a first anti-CD117 agent that binds CD117 under laboratory or physiological conditions, where the first agent competitively binds with a second anti-CD117 agent, which the second agent comprises at least one immunoglobulin heavy chain variable domain and at least one immunoglobulin light chain variable domain, where a) each immunoglobulin heavy chain variable domain of the second agent comprises first, second, and third heavy chain variable domain of the second agent comprises first, second, and third heavy chain complementarity determining regions (CDRs), where a) each immunoglobulin heavy chain variable domain of the second agent comprises first, second, and third heavy chain complementarity determining regions (CDRs), where the first heavy chain CDR (CDRH1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅ (SEQ ID NO: 100), where X₁ is S, T, N, E, or D, X₂ is Y or H, X₃ is G, T, W, D, Y, or N, X₄ is M, I, or V, and X₅ is S, H, N, V, or A; the second heavy chain CDR (CDRH2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇X₁₈X₁₉ (SEQ ID NO: 101), where X₁ is T, Y, M, G, E, R, A, or D, X₂ is I or M, X₃ is S, R, N, H, K, or no amino acid, X₄ is L, T, W, Y, or no amino acid, X₅ is K, G, S, D, or no amino acid, X₆ is G, P, S, or T, X₇ is G, S, N, I, or R, X₈ is G, S, D, or N, X₉ is T, S, G, D, Y, or R, X₁₀ is Y, F, E, S, G, L, K, D, or N, X₁₁ is T, I, F, or Y, X₁₂ is Y, H, R, F, S, N, or V, X₁₃ is Y, L, E, S, P, or D, X₁₄ is P, N, A, G, or S, X₁₅ is D, Q, E, F, L, or V, X₁₆ is S, K, or Y, X₁₇ is L, V, F, M, G, S, or N, X₁₈ is R or K, and X₁9 is G, D, or R; and the third heavy chain CDR (CDRH3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃Y (SEQ ID NO: 102), where X₁ is D, E, L, G, I, or H, X₂ is W, R, D, G, E, L, or no amino acid, X₃ is D, W, Y , A, R, F, or no amino acid, X₄ is D, R, A, Y, I, or no amino acid, X₅ is S, G, P, I, Y, or no amino acid, X₃ is Y, A, W, T, S, D, or no amino acid, X₇ is F, M, P, Y, G, or no amino acid, X₈ is D, A, F, E, R, or no amino acid, X₉ is Y, D, F, A, I, or S, X₁₀ is Y, H, N, or S, X₁₁ is T, W, Y, or P, X₁₂ is M or F, and X₁₃ is A, T, or D; and b) each immunoglobulin light chain variable domain of the anti-CD117 agent comprises first, second, and third light chain CDRs, where the first light chain CDR (CDRL1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂SX₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃ X₁₄X₁₅X₁₆X₁₇ (SEQ ID NO: 103), where X₁ is S, K, or R, X₂ is A, S, or R, X₄ is Q, S, T, or E, X₅ is S, G, D, or no amino acid, X₃ is L, D, I, N, or no amino acid, X₇ is L, V, I, H, or no amino acid, X₈ is N, H, G, S, or no amino acid, X₉ is S, G, or no amino acid, X₉ is S, G, or no amino acid, X₁₀ is G, S, or no amino acid, X₁₁ is D, N, S, or no amino acid, X₁₂ is I, Q, L, G, or no amino acid, X₁₃ is S,

K, I, R, N, or no amino acid, X₁₄ is N, T, or no amino acid, X₁₅ is Y, F, or no amino acid, X₁₆ is

L, M, or V, and X₁₇ is N, T, H, S, A, or Y; the second light chain CDR (CDRL2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇ (SEQ ID NO: 104), where X₁ is Y, W, S, F, K, R, or N, X₂ is T, A, V, or D, X₃ is S, D, or I, X₄ is S, T, N, R, K, or P, X₅ is L or R, X₆ is H, Q, E, A, F, or P, and X₇ is S or D; the third light chain CDR (CDRL3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₃X₇X₈X₉ (SEQ ID NO: 105), where X₁ is Q, H, S, or L, X₂ is Q, N, H, or S, X₃ is Y, D, W, G, H, T, or S, X₄ is S, Y, or T, X₅ is K, G, T, S, H, H, D, or no amino acid, X₆ is V, Y, L, T, F, G, S, or no amino acid, X₇ is P, S, or I, X₈ is W, L, Y, P, T, or S, and X₉ is T, V, or A.

Also provided in certain aspects is a first anti-CD117 agent that binds CD117 under laboratory or physiological conditions, where the first agent binds to the same epitope as a second anti- CD117 agent, which the second agent comprises at least one immunoglobulin heavy chain variable domain and at least one immunoglobulin light chain variable domain, where a) each immunoglobulin heavy chain variable domain of the second agent comprises first, second, and third heavy chain complementarity determining regions (CDRs), where the first heavy chain CDR (CDRH1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅ (SEQ ID NO: 100), where X₁ is S, T, N, E, or D, X₂ is Y or H, X₃ is G, T, W, D, Y, or N, X₄ is M, I, or V, and X₅ is S, H, N, V, or A; the second heavy chain CDR (CDRH2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇X₁₈X₁₉ (SEQ ID NO: 101), where X₁ is T, Y, M, G, E, R, A, or D, X₂ is I or M, X₃ is S, R, N, H, K, or no amino acid, X₄ is L, T, W, Y, or no amino acid, X₅ is K, G, S, D, or no amino acid, X₆ is G, P, S, or T, X₇ is G, S, N, I, or R, X₈ is G, S, D, or N, X₉ is T, S, G, D, Y, or R, X₁₀ is Y, F, E, S, G, L, K, D, or N, X₁₁ is T, I, F, or Y, X₁₂ is Y, H, R, F, S, N, or V, X₁₃ is Y, L, E, S, P, or D, X₁₄ is P, N, A, G, or S, X₁5 is D, Q, E, F, L, or V, X₁₆ is S, K, or Y, X₁₇ is L, V, F, M, G, S, or N, X₁₈ is R or K, and X₁₉ is G, D, or R; and the third heavy chain CDR (CDRH3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃Y (SEQ ID NO: 102), where X₁ is D, E, L, G, I, or H, X₂ is W, R, D, G, E, L, or no amino acid, X₃ is D, W, Y , A, R, F, or no amino acid, X₄ is D, R, A, Y, I, or no amino acid, X₅ is S, G, P, I, Y, or no amino acid, X₆ is Y, A, W, T, S, D, or no amino acid, X₇ is F, M, P, Y, G, or no amino acid, X₈ is D, A, F, E, R, or no amino acid, X₉ is Y, D, F, A, I, or S, X₁₀ is Y, H, N, or S, X₁₁ is T, W, Y, or P, X₁₂ is M or F, and X₁₃ is A, T, or D; and b) each immunoglobulin light chain variable domain of the anti-CD117 agent comprises first, second, and third light chain CDRs, where the first light chain CDR (CDRL1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂SX₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇ (SEQ ID NO: 103), where X₁ is S, K, or R, X₂ is A, S, or R, X₄ is Q, S, T, or E, X₅ is S, G, D, or no amino acid, X₆ is L, D, I, N, or no amino acid, X₇ is L, V, I, H, or no amino acid, X₈ is N, H, G, S, or no amino acid, X₉ is S, G, or no amino acid, X₉ is S, G, or no amino acid, X₁₀ is G, S, or no amino acid, X₁₁ is D, N, S, or no amino acid, X₁₂ is I, Q, L, G, or no amino acid, X₁₃ is S, K, I, R, N, or no amino acid, X₁₄ is N, T, or no amino acid, X₁₅ is Y, F, or no amino acid, X₁₆ is L, M, or V, and X₁₇ is N, T, H, S, A, or Y; the second light chain CDR (CDRL2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence to the amino acid sequence X₁X₂X₃X₄X₅X₃X₇ (SEQ ID NO: 104), where X₁ is Y, W, S, F, K, R, or N, X₂ is T, A, V, or D, X₃ is S, D, or I, X₄ is S, T, N, R, K, or P, X₅ is L or R, X₆ is H, Q, E, A, F, or P, and X₇ is S or D; the third light chain CDR (CDRL3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉ (SEQ ID NO: 105), where X₁ is Q, H, S, or L, X₂ is Q, N, H, or S, X₃ is Y, D, W, G, H, T, or S, X₄ is S, Y, or T, X₅ is K, G, T, S, H, H, D, or no amino acid, X₆ is V, Y, L, T, F, G, S, or no amino acid, X₇ is P, S, or I, X₈ is W, L, Y, P, T, or S, and X₉ is T, V, or A.

Also provided in certain aspects are anti-CD117 agents for detecting CD117 in a heterogeneous population of cells, where CD117 is detected at a significant level in hematopoietic stem cells and mast cells in the population, and CD117 is not significantly detected in other cells in the population.

Also provided in certain aspects are methods of detecting CD117 in a heterogeneous population of cells, comprising contacting the population with an anti-CD117 agent provided herein, wherein CD117 is not significantly detected in other cells in the population.

In one aspect, provided herein are isolated, non-naturally occurring anti-CD117 agents, particularly antibodies, or antigen-binding fragments or derivatives thereof, that bind CD117 under physiological conditions. In the context of anti-CD117 antibodies or antigen-binding fragments, such molecules generally comprise two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains. In such molecules, each of the immunoglobulin heavy and light chain variable domains comprise first, second, and third chain complementarity determining regions (CDRs) arrayed as follows: FR1-CDR1-FR2- CDR2-FR3-CDR3-FR4.

In the heavy chain variable domain portions, the first heavy chain CDR (CDRH1) comprises an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with the amino acid sequence SYGMS, TYTIH, NYGMS, SYWMN, NYDMS, EHYMV, NYWMN, SYYIS, SYGVS, DYWMS, or DYNMA (SEQ ID NOs: 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, respectively), the second heavy chain CDR (CDRH2) comprises an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with the amino acid sequence TISGGGTYTYYPDSLRG, TIRGGGSFTYYPDSVKG, YINPSSGYTHYNQKFKD, TISGGGDFTYYPDSMRR,

MIHPSDSEIRLNQKFKD, YISSGGGSFFYPDTVKG, GINPNNGGTSYNQKFKG,

EIRLKSNNYLTHYAESVKG, RIHPSDSEIRLNQKFKD, YINTGTISTKYNENFKG, AMWSGGSTDYNSGLKS, DIKYDGSDTNYVPSLKN, TISYDGRSIYYRDSVKG, or AIWSGGSTDYNSALKS (SEQ ID NOs: 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, respectively), and the third heavy chain CDR (CDRH3) comprises an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with the amino acid sequence DWDDSYFDY, DRWRD, EDYAGAMDF, LGDYPWFAY, GEAIITPFAY, IRRDYSMDY, EIHTMAY, GDYEYNWFTY, EDGRSYYFDY, HLFYYDGRSYPFAY, or GDYEYSWFTY (SEQ ID NOs: 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65, 66, respectively).

In the light chain variable domain portions, the first light chain CDR (CDRL1) comprises an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with amino acid sequence SASQDISNYLN, KSSQSLLNSGNQKNYLT, SASSSLIYMH, RASQDIRNYLS, KSSQSLLNSSNQKNYLA, RSSQSLVHSDGNTYLH, RSSQSLVHSDGSTYLH,

KRSTGDIGSNYVY, RASEDIHNGLA, KSSQSLLSSGNQKNFLA, or KRSTGNIGSNYVH (SEQ ID NOs: 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, and 77, respectively), the second light chain CDR (CDRL2) comprises an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with the amino acid sequence YTSSLHS, YTSSLQS, WASTRES, STSNLAS, YTSRLQS, FASTRES, KVSNRFS, RVSNRFS, RDDKRPD, NAISLHS, WASPRQS (SEQ ID NOs: 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, and 88, respectively), and the third light chain CDR (CDRL3) comprises an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with the amino acid sequence QQYSKVPWT, QNDYGYPLT, HHWSSYT, QQGYTLPWT, QQHYSTPPT, SQTTHVPLT, LQSTHFPWT, QSYSSGITV, QQYYNYPWT, QQYYDSPLA, or QSYSSGISV (SEQ ID NOs: 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, and 99, respectively).

In some embodiments, the isolated, non-naturally occurring anti-CD117 antibodies, or CD117 binding fragments thereof, including a first heavy chain CDR having the amino acid sequence NYDMS (SEQ ID NO: 35), the second heavy chain CDR having the amino acid sequence YISSGGGSFFYPDTVKG (SEQ ID NO: 47), the third heavy chain CDR having the amino acid sequence LGDYPWFAY (SEQ ID NO: 59), the first light chain CDR having the amino acid sequence RASQDIRNYLS (SEQ ID NO: 70), the second heavy chain CDR having the amino acid sequence YTSRLQS (SEQ ID NO: 82), and the third light chain CDR having the amino acid sequence QQGYTLPWT (SEQ ID NO: 92).

In other embodiments, the isolated, non-naturally occurring anti-CD117 antibodies, or CD117 binding fragments thereof, including a first heavy chain CDR having the amino acid sequence DYWMS (SEQ ID NO: 40), the second heavy chain CDR having the amino acid sequence DIKYDGSDTNYVPSLKN (SEQ ID NO: 53), the third heavy chain CDR having the amino acid sequence EDGRSYYFDY (SEQ ID NO: 64), the first light chain CDR having the amino acid sequence RASEDIHNGLA (SEQ ID NO: 75), the second light chain CDR having the amino acid sequence NAISLHS (SEQ ID NO: 87), and the third light chain CDR having the amino acid sequence QQYYNYPWT (SEQ ID NO: 97).

In some embodiments, the isolated anti-CD117 agent comprises a non-naturally occurring anti-CD117 antibody (mAb) comprising two immunoglobulin heavy chain variable domains comprising first, second, and third heavy chain complementarity determining regions (CDRH1- 3, respectively) and two immunoglobulin light chain variable domains comprising first, second, and third light chain complementarity determining regions (CDRL1-3, respectively), where the antibody comprises immunoglobulin heavy chain variable domains and immunoglobulin light chain variable domains having sets of CDRH1-3 and CDRL1-3 selected from the groups consisting of:

Table 1. CDR Sequences of anti-CD117 antibodies (Kabat numbering scheme)

In some embodiments, the isolated anti-CD117 agent comprises a non-naturally occurring anti-CD117 antibody (mAb) comprising two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains, where the immunoglobulin heavy chain variable domains have an amino acid sequence selected from amongst SEQ ID NOs: 1-15 or an amino acid sequence having at least 65%-95% or more sequence identity with any such heavy chain variable domain sequence and the immunoglobulin light chain variable domains are selected from amongst SEQ ID NOs: 16-30 or an amino acid sequence having at least 65%-95% or more sequence identity with any such light chain variable domain sequence. In some embodiments, where anti-CD117 agents are antibodies, or antigen-binding antibody fragments thereof, the antibodies (or fragments thereof) are monoclonal antibodies, and may be camel, human, humanized, mouse, rabbit, or other mammalian antibodies or antigenbinding antibody fragments. In some embodiments, the antibody (antigen-binding antibody fragment) is an IgG. In other embodiments, the IgG is an lgG1 , lgG2a or lgG2b, or lgG3, or lgG4.

In certain embodiments of anti-CD117 antibodies and antigen-binding antibody fragments that are other than fully human antibodies (i.e. , antibodies produced or derived from a mammal capable of producing all or a portion of the human antibody repertoire), the molecules are chimeric or humanized anti-CD117 antibodies and antigen-binding antibody fragments.

In some embodiments, the anti-CD117 antibody, antigen-binding antibody fragment, or derivative or variant thereof includes a detectable label.

In some embodiments, the anti-CD117 agent, for example, an anti-CD117 antibody, antigenbinding antibody fragment, or derivative or variant thereof, is part of an immunoconjugate that further includes a cytotoxic agent, for example, a nucleic acid, a peptide, a polypeptide, a small molecule, or an aptamer.

A related aspect of the technology described herein concerns compositions that include an anti-CD117 agent that is an isolated, non-naturally occurring anti-CD117 antibody or antigenbinding antibody fragment according to the technology described herein. In addition to containing an anti-CD117 antibody or an antigen-binding antibody fragment described herein, such compositions typically also include a carrier, for example, a pharmaceutically acceptable carrier. Such compositions may be packaged in containers, which in some embodiments, are further packaged into kits that also include instructions for use. In the context of pharmaceutical compositions, such kits instructions are a package insert containing not only instructions or use but also information about the pharmaceutically active ingredient (e.g., the anti-CD117 antibody, antigen-binding antibody fragment, or derivative or variant thereof).

Another related aspect concerns diagnostics configured to detect CD117 in a biological sample, often a biological sample taken from a subject. Such kits include a diagnostic reagent that include an anti-CD117 agent described herein, for example, an anti-CD117 antibody, antigen-binding antibody fragment, or derivative or variant thereof conjugated with detectable reagents such as fluorophores or enzyme substrates and/or immobilized on a solid support.

Still other aspects of the technology provided herein concern the manufacture of an anti- CD117 agent described herein. In the context of anti-CD117 antibodies (or antigen-binding antibody fragments or derivatives or variants thereof), one such aspect concerns isolated nucleic acid molecules that encode polypeptides provided herein. In some embodiments, such nucleic acids encode an immunoglobulin heavy chain variable domain having a first heavy chain CDR (CDRH1) that includes an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with the amino acid sequence SYGMS, TYTIH, NYGMS, SYWMN, NYDMS, EHYMV, NYWMN, SYYIS, SYGVS, DYWMS, or DYNMA (SEQ ID NOs: 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, respectively), the second heavy chain CDR (CDRH2) comprises an amino acid sequence that has a sequence identity of at least 65 %, optionally a sequence identity of at least 80 %, at least 90 %, at least 95 %, and 100 % identity with the amino acid sequence TISGGGTYTYYPDSLRG, TIRGGGSFTYYPDSVKG, YINPSSGYTHYNQKFKD, TISGGGDFTYYPDSMRR, MIHPSDSEIRLNQKFKD, YISSGGGSFFYPDTVKG, GINPNNGGTSYNQKFKG, EIRLKSNNYLTHYAESVKG, RIHPSDSEIRLNQKFKD,

YINTGTISTKYNENFKG, AMWSGGSTDYNSGLKS, DIKYDGSDTNYVPSLKN,

TISYDGRSIYYRDSVKG, or AIWSGGSTDYNSALKS (SEQ ID NOs: 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, 55, respectively), and the third heavy chain CDR (CDRH3) comprises an amino acid sequence that has a sequence identity of at least 65 %, optionally a sequence identity of at least 80 %, at least 90 %, at least 95 %, and 100 % identity with the amino acid sequence DWDDSYFDY, DRWRD, EDYAGAMDF, LGDYPWFAY, GEAIITPFAY, IRRDYSMDY, EIHTMAY, GDYEYNWFTY, EDGRSYYFDY, HLFYYDGRSYPFAY, or GDYEYSWFTY (SEQ ID NOs: 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65, 66, respectively). Such nucleic acids may also encode an immunoglobulin light chain variable domain where a first light chain CDR (CDRL1) that includes an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with amino acid sequence SASQDISNYLN, KSSQSLLNSGNQKNYLT, SASSSLIYMH, RASQDIRNYLS, KSSQSLLNSSNQKNYLA, RSSQSLVHSDGNTYLH, RSSQSLVHSDGSTYLH, KRSTGDIGSNYVY, RASEDIHNGLA, KSSQSLLSSGNQKNFLA, or KRSTGNIGSNYVH (SEQ ID NOs: 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, and 77, respectively), the second light chain CDR (CDRL2) comprises an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with the amino acid sequence YTSSLHS, YTSSLQS, WASTRES, STSNLAS, YTSRLQS, FASTRES, KVSNRFS, RVSNRFS, RDDKRPD, NAISLHS, WASPRQS (SEQ ID NOs: 78, 79, 80, 81 , 82, 83, 84, 85, 86, 87, and 88, respectively), and the third light chain CDR (CDRL3) comprises an amino acid sequence that has a sequence identity of at least 65%, optionally a sequence identity of at least 80%, at least 90%, at least 95%, and 100% identity with the amino acid sequence QQYSKVPWT, QNDYGYPLT, HHWSSYT, QQGYTLPWT, QQHYSTPPT, SQTTHVPLT, LQSTHFPWT, QSYSSGITV, QQYYNYPWT, QQYYDSPLA, or QSYSSGISV (SEQ ID NOs: 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, and 99, respectively).

In certain embodiments, nucleic acid molecules provided herein encode an immunoglobulin heavy chain variable domain having an amino acid sequence selected from among SEQ ID NOs: 1-15 or an amino acid sequence having at least 65%-95% or more sequence identity with any such heavy chain variable domain sequence and an immunoglobulin light chain variable domain having an amino acid sequence selected from among SEQ ID NOs: 16-30 or an amino acid sequence having at least 65%-95% or more sequence identity with any such light chain variable domain sequence.

Related aspects concern plasmids, and expression cassettes and vectors, that carry nucleic acids provided herein, as well as recombinant host cells transfected with such nucleic acid molecules.

Still other aspects of the technology provided herein concern methods of treating or preventing a disease or disorder associated with aberrant levels of CD117. Such methods include administering to a subject in need of such treatment an anti-CD117 agent provided herein (e.g., an anti-CD117 antibody or antigen-binding fragment, derivative, or variant thereof) in an amount sufficient to effect treatment, thereby treating or preventing the disease or disorder. In certain instances, an anti-CD117 agent provided herein (e.g., an anti-CD117 antibody or antigen-binding fragment, derivative, or variant thereof) may be used as an adjuvant or in conjunction with an adjuvant (e.g., for vaccines).

Further aspects of the technology provided herein concern diagnostic methods of using an anti-CD117 agent provided herein, for example, in vitro or in vivo diagnostic assays to detect the presence of CD117.

In yet another aspect, an anti-CD117 antibody or antigen-binding fragment thereof comprising one or more of: a) an immunoglobulin heavy chain variable domain comprising:

(i) a heavy chain complementary determining region 1 (CDRH1) comprising the sequence X₁X₂X₃X₄X₅ (SEQ ID NO: 100), wherein X₁ is S, T, N, E, or D ; X₂ is Y or H; X₃ is G, T, W, D, Y, or N; X₄ is M, I, or V; and X₅ is S, H, N, V, or A;

(ii) a heavy chain complementary determining region 2 (CDRH2) comprising the sequence X₁X₂X₃X₄X₅X₃X₇X₈X₉X₁₀X₁₁X₁₂ X₁₃X₁₄X₁₅X₁₆X₁₁ X₁sX₁₉ (SEQ ID NO: 101), wherein X₁ is T, Y, M, G, E, R, A, or D; X₂ is I or M; X₃ is S, R, N, H, K, or no amino acid; X₄ is L, T, W, Y, or no amino acid; X₅ is K, G, S, D, or no amino acid; X₆ is G, P, S, or T; X₇ is G, S, N, I, or R; X₈ is G, S, D, or N; X₉ is T, S, G, D, Y, or R; X₁₀ is Y, F, E, S, G, L, K, D, or N; X₁₁ is T, I, F, or Y; X₁₂ is Y, H, R, F, S, N, or V; X₁₃ is Y, L, E, S, P, or D; X₁₄ is P, N, A, G, or S; X₁₅ is D, Q, E, F, L, or V; X₁₆ is S, K, or Y; X₁₇ is L, V, F, M, G, S, or N; X₁₈ is R or K; and X₁₉ is G, D, or R;

(iii) a heavy chain complementary determining region 3 (CDRH3) comprising the sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃ Y (SEQ ID NO: 102), wherein X₁ is D, E, L, G, I, or H; X₂ is W, R, D, G, E, L, or no amino acid; X₃ is D, W, Y, A, R, F, or no amino acid; X₄ is D, R, A, Y, I, or no amino acid; X₅ is S, G, P, I, Y, or no amino acid; X₆ is Y, A, W, T, S, D, or no amino acid; X₇ is F, M, P, Y, G, or no amino acid; X₈ is D, A, F, E, R, or no amino acid; X₉ is Y, D, F, A, I, or S ; X₁₀ is Y, H, N, or S; X₁₁ is T, W, Y, or P; X₁₂ is M or F; and X₁₃ is A, T, or D; b) an immunoglobulin light chain variable domain comprising:

(i) a light chain complementary determining region 1 (CDRL1) comprising the sequence X₁X₂SX₄X₅X₃X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁7 (SEQ ID NO: 103), wherein X₁ is S, K, or R; X₂ is A, S, or R; X₄ is Q, S, T, or E; X₅ is S, G, D, or no amino acid; X₆ is L, D, I, N, or no amino acid; X₇ is L, V, I, H, or no amino acid; X₈ is N, H, G, S, or no amino acid; X₉ is S, G, or no amino acid; X₁₀ is G, S, or no amino acid; X₁₁ is D, N, S, or no amino acid; X₁₂ is I, Q, L, G, or no amino acid; X₁₃ is S, K, I, R, N, or no amino acid; X₁₄ is N, T, or no amino acid; X₁₅ is Y, F, or no amino acid; X₁₆ is L, M, or V; and X₁₇ is N, T, H, S, A, or Y;

(ii) a light chain complementary determining region 2 (CDRL2) comprising the sequence X₁X₂X₃X₄X₅X₆X₇ (SEQ ID NO: 104), wherein X₁ is Y, W, S, F, K, R, or N; X₂ is T, A, V, or D; X₃ is S, D, or I; X₄ is S, T, N, R, K, or P; X₅ is L or R; X₆ is H, Q, E, A, F, or P; and X₇ is S or D; and

(iii) a light chain complementary determining region 3 (CDRL3) comprising the sequence X₁X₂X₃X₄X₅X₃X₇X₈X₉ (SEQ ID NO: 105), wherein X₁ is Q, H, S, or L; X₂ is Q, N, H, or S; X₃ is Y, D, W, G, H, T, or S; X₄ is S, Y, or T; X₅ is K, G, T, S, H, H, D, or no amino acid; X₆ is V, Y, L, T, F, G, S, or no amino acid; X₇ is P, S, or I; Xe is W, L, Y, P, T, or S; and X₉ is T, V, or A.

In some embodiments of this aspect, the immunoglobulin heavy chain variable domain comprises a CDRH1 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, and 41 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, and 41; a CDRH2 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 and 55 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 and 55; and a CDRH3 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65 and 66 or a sequence of amino acids that exhibits at least 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65 and 66.

In some embodiments, the immunoglobulin light chain variable domain comprises a CDRL1 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, and 77, or a sequence of amino acids that exhibits at least 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, and 77; a CDRL2 comprising the sequence of amino acids set forth in any of SEQ ID NO: 78, 79, 80, 81, 82, 83, 84, 85, 86, 87 and 88 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 78, 79, 80, 81 , 82, 83, 84, 85, 86, 87 and 88; and a CDRL3 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 89, 90, 91 , 92, 93, 94, 95, 96, 97, 98 and 99, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 89, 90, 91 , 92, 93, 94, 95, 96, 97, 98 and 99.

In some embodiments of this aspect, the CDRH1 comprises the sequence of amino acids set forth in any of SEQ ID NOs: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, and 41, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, and 41; the CDRH2 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 and 55, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 and 55; the CDRH3 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65 and 66, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 56, 57, 58, 59, 60, 61, 62, 63, 64, 65 and 66; the CDRL1 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 67, 68, 69, 70, 71 , 72, 73, 74, 75, 76, and 77, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 67, 68, 69, 70, 71 , 72, 73, 74, 75, 76, and 77; the CDRL2 comprises a sequence of amino acids set forth in any of SEQ I D NOs: 78, 79, 80, 81 , 82, 83, 84, 85, 86, 87 and 88 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 78, 79, 80, 81, 82, 83, 84, 85, 86, 87 and 88; and the CDRL3 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 and 99, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 and 99.

In some embodiments, the immunoglobulin heavy chain variable domain comprises the amino acid sequence set forth in any of SEQ ID NOs: 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 or a sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to any of SEQ ID NOs: 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15.

In some embodiments, the immunoglobulin light chain variable domain comprises the amino acid sequence set forth in any of SEQ ID NOs: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30 or a sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to any of SEQ ID NOs: 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29 and 30.

In some embodiments of this aspect, the immunoglobulin heavy chain variable domain comprises the amino acid sequence set forth in any of SEQ ID NOs: 1 , 2, 3, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, and 15 or a sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to any of SEQ ID NOs: 1, 2, 3, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, and 15 and the immunoglobulin light chain variable domain comprises the amino acid sequence set forth in any of SEQ ID NOs: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30, or a sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to any of SEQ ID NOs: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30. In some embodiments, the antibody or antigen-binding fragment thereof comprises one immunoglobulin heavy chain variable domain and one immunoglobulin light chain variable domain.

In some embodiments, the antibody or antigen-binding fragment thereof comprises two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains.

In some embodiments, the antibody or antigen-binding fragment thereof is isolated. In some embodiments, the antibody or antigen-binding fragment thereof is humanized.

In some embodiments of this aspect, the antibody or antigen-binding fragment thereof is conjugated to a detectable marker or label. In particular embodiments, the detectable marker or label comprises a detectable moiety or oligonucleotide label. In some embodiments, the antibody or antigen-binding fragment thereof is non-diffusively immobilized on a solid support.

In some embodiments, the antibody or antigen-binding fragment thereof is a single chain fragment. In certain embodiments, the single chain fragment is a single chain variable fragment (scFv).

In some embodiments of this aspect, the antibody or antigen-binding fragment thereof specifically binds to CD117. In particular embodiments, the antibody or antigen-binding fragment thereof induces or inhibits phosphorylation of CD117.

In another aspect, the disclosure features an antibody or antigen-binding fragment thereof described herein for use in the detection of CD117 in a sample. In some embodiments, the sample comprises a cell (e.g., a cancer cell or a non-cancer cell). In certain embodiments, the detection is performed in vitro. In certain embodiments, the detection is performed in vivo.

In another aspect, the disclosure features a diagnostic reagent comprising the antibody or antigen-binding fragment thereof described herein.

In another aspect, the disclosure features a kit comprising the antibody or antigen-binding fragment thereof described herein or the diagnostic reagent described herein.

In another aspect, the disclosure features a composition comprising the antibody or antigenbinding fragment thereof described herein and a pharmaceutically acceptable excipient.

In another aspect, the disclosure features an isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin heavy chain variable domain of the antibody or antigen-binding fragment thereof described herein. In particular embodiments, the immunoglobulin heavy chain variable domain comprises the sequence of nucleotides set forth in any of SEQ ID NOs: 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 , and 122.

In another aspect, the disclosure features an isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin light chain variable domain of the antibody or antigen-binding fragment thereof described herein. In particular embodiments, the immunoglobulin light chain variable domain comprises the sequence of nucleotides set forth in any of SEQ ID NOs: 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, and 137.

In yet another aspect, the disclosure features an isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin heavy chain variable domain and the immunoglobulin light chain variable domain of the antibody or antigen-binding fragment thereof described herein.

In another aspect, the disclosure features the nucleotide sequence that encodes the immunoglobulin heavy chain variable domain comprises the sequence set forth in any of SEQ ID NOs: 108, 109, 110, 111 , 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 , and 122; and the immunoglobulin light chain variable domain comprises the sequence of amino acids set forth in any of SEQ ID NOs: 123, 124, 125, 126, 127, 128, 129, 130, 131 , 132, 133, 134, 135, 136, and 137.

In another aspect, the disclosure features a recombinant expression vector comprising a first expression cassette and a second expression cassette, wherein the first expression cassette comprises a nucleic acid molecule comprising a nucleotide sequence that encodes the immunoglobulin heavy chain variable domain of the antibody or antigen-binding fragment thereof described herein, and the second expression cassette comprises a nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin light chain variable domain of the antibody or antigen-binding fragment thereof described herein. In particular embodiments, the first and second expression cassettes comprise a promoter.

In another aspect, the disclosure features a host cell transfected with the recombinant expression vector described herein.

In another aspect, the disclosure features a method of detecting CD117 in a sample, comprising: a) contacting a sample with the antibody or antigen-binding fragment thereof described herein, under conditions to bind said antibody or antigen binding fragment thereof to a CD117 receptor on said sample, wherein the binding generates the production of one or more receptor/antibody or antigen binding fragment thereof complexes; and b) detecting the presence of the complexes, wherein the detecting comprises the presence or absence of the CD117 receptor on said sample.

In another aspect, the disclosure features a method of treating or preventing a disease or disorder associated with CD117 in a subject, comprising: a) contacting a sample known or suspected to contain a CD117 receptor with the antibody or antigen-binding fragment thereof described herein; b) detecting the presence of complexes comprising CD117 and the antibody or antigen-binding fragment thereof, wherein the presence of the complexes indicates the presence of a disease or disorder; and c) administering to the subject the antibody or antigenbinding fragment thereof described herein.

In another aspect, the disclosure features a method of diagnosing a disease or disorder, comprising: a) isolating a sample from a subject; b) incubating the sample with the antibody or antigen binding fragment thereof described herein, for a period of time sufficient to generate complexes comprising CD117 and the antibody or antigen-binding fragment thereof; and c) detecting the presence or absence of the complexes. In certain embodiments, the method further comprises: d) associating presence or abundance of CD117 with the prognosis of a disease or disorder. In certain embodiments, the method further comprises: d) associating presence or abundance of CD117 with a location of interest of a tissue sample.

In another aspect, the disclosure features an antibody or antigen binding fragment thereof described herein for use in a method of detecting CD117 in a tissue sample.

In yet another aspect, the disclosure features an antibody or antigen binding fragment thereof described herein for use in the construction of a protein library. In particular embodiments, the construction of a protein library comprises sequencing or flow cytometry.

Certain embodiments are described further in the following description, examples, claims and drawings.

Brief Description of the Drawings

The drawings illustrate certain embodiments of the technology and are not limiting. For clarity and ease of illustration, the drawings are not made to scale and, in some instances, various aspects may be shown exaggerated or enlarged to facilitate an understanding of particular embodiments.

FIG. 1 shows the amino acid sequence of a representative full-length human CD117 precursor (SEQ ID NO: 106). In the sequence, the amino acid residues that make up the signal peptide (residues 1-25) are underlined. Residues 26-976 comprise the mature, processed form of the protein. See, e.g., NCBI Reference Sequence: NP_000213.1. FIGS. 2A and 2B show the amino acid sequences of the variable domains of the immunoglobulin heavy (SEQ ID NOs: 1-15) and light (SEQ ID NOs: 16-30) chains of 15 different anti-CD117 antibodies (AB 1-15) provided herein. The CDR regions of each of the heavy and light chains are shown in bold and are underlined. In each of the alignments, three characters and ",") are used: "*" indicates positions that have a single, fully conserved residue; indicates that one of the following "strong" residue groups is fully conserved: STA; NEQK; NHQK; NDEQ; QHRK; MILV; MILF; HY; and FYW; and indicates that one of the following "weaker" residue groups is fully conserved: CSA; ATV; SAG; STNK; STPA; SGND; SNDEQK; NDEQHK; NEQHRK; FVLIM; and HFY. These are all the positively scoring residue groups that occur in the Gonnet Pam250 matrix. The "strong" and "weak" residue groups are defined as "strong" score > 0.5 and "weak" score < 0.5, respectively.

FIG. 3 lists information for anti-CD117 antibodies used in the experiments described in the Examples, below.

FIGS. 4A-4F are scatter plots showing the results of the gating strategy used for the flow cytometry experiments described in Example 3, below. Staining: FIGS. 4A and 4B (isotype control); FIGS. 4C and 4D (AB7), and FIGS. 4E and 4F (AB11).

FIGS. 5A-5P show histograms of Kasumi-3 cells stained with anti-CD117 antibodies.

FIGS. 6A-6C are scatter plots showing the gating strategy used for the flow cytometry experiments described in Example 3, below.

FIGS. 7A-7P show scatter plots of PBMCs stained with anti-CD117 antibodies.

FIG. 8 shows downstream signaling through CD117 was activated by SCF at 5 minutes. Phosphorylation of RPS6 through PI3K and MAPK pathways was used as the readout. Cells and samples were analyzed and relative MFI signaling was compared to isotype control.

Detailed Description

Provided herein are agents that bind CD117. In some aspects, antibodies, and fragments thereof, that bind to CD117 are provided herein. For example, particular monoclonal antibodies to CD117 that provide superior target specificity, signal-to-noise ratios, and the like as compared to other reported anti-CD117 antibodies, as well as antigen-binding fragments of such antibodies that bind CD117, are described herein. Also provided herein are methods for producing anti-CD117 agents, particularly anti-CD117 antibodies, with desirable properties including affinity and/or specificity for CD117 and/or its variants. Antibody Generation and Characterization

Anti-CD117 agents (e.g., anti-CD117 antibodies) provided herein may have a strong binding affinity and/or specificity for CD117. In some embodiments, anti-CD117 agents may be chimeric antibodies. In some embodiments, anti-CD117 agents may be humanized antibodies. In some embodiments, anti-CD117 agents may be variant antibodies. Antibodies, for example, may have beneficial properties from a therapeutic perspective. Assays for determining the activity of anti-CD117 antibodies provided herein include, for example, cell- based ELISA (e.g., to measure relative avidity of the antibody for the target on cells), flow cytometry (e.g., to measure cell specificity of the antibody), and cytotoxicity (e.g., to measure potential to mediate direct or indirect killing of CD117-expressing target cells). In certain instances, a humanized or variant antibody fails to elicit an immunogenic response upon administration of a therapeutically effective amount of the antibody to a human patient. In certain instances, if an immunogenic response is elicited, the response may be such that the antibody still provides a therapeutic benefit to the patient treated therewith.

In some embodiments, anti-CD117 agents (e.g., anti-CD117 antibodies, humanized anti- CD117 antibodies) herein bind the same epitope. To screen for antibodies that bind to an epitope on CD117 bound by an antibody of interest (e.g., those that block binding of the antibody to CD117), a cross-blocking assay such as that described in Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory, Ed Harlow and David Lane (1988), can be performed. In certain instances, epitope mapping, e.g., as described in Champe et al. , J. Biol. Chem. 270:1388-1394 (1995), in Cunningham and Wells, Science 244:1081 - 1085 (1989), or in Davidson and Doranz, Immunology 143: 13 - 20 (2014), can be performed to determine whether the antibody binds an epitope of interest.

Antibodies herein generally have a heavy chain variable domain comprising an amino acid sequence represented by the formula: FRH1-CDRH1-FRH2-CDRH2-FRH3-CDRH3-FRH4, where "FRH1-4" represents the four heavy chain framework regions and "CDRH1-3" represents the three hypervariable regions of an anti-CD117 antibody variable heavy domain. FRH1-4 may be derived from a consensus sequence (for example the most common amino acids of a class, subclass or subgroup of heavy or light chains of human immunoglobulins) or may be derived from an individual human antibody framework region or from a combination of different framework region sequences. Many human antibody framework region or from a combination of different framework region sequences. Many human antibody framework region sequences are compiled in Kabat et al. (1992) SEQUENCES OF PROTEINS OF IMMUNOLOGICAL INTEREST, National Institutes of Health Publication No. 91-3242, for example. In one embodiment, the variable heavy FR is provided by a consensus sequence of a human immunoglobulin subgroup as compiled by Kabat et al., supra. The human variable heavy FR sequence may have substitutions therein, e.g., where the human FR residue is replaced by a corresponding nonhuman residue (by "corresponding nonhuman residue" is meant the nonhuman residue with the same Kabat positional numbering as the human residue of interest when the human and nonhuman sequences are aligned), but replacement with the nonhuman residue is not necessary. For example, a replacement FR residue other than the corresponding nonhuman residue may be selected by phage display.

Antibodies herein may have a light chain variable domain comprising an amino acid sequence represented by the formula: FRL1-CDRL1-FRL2-CDRL2-FRL3-CDRL3-FRL4, where "FRL1- 4" represents the four framework regions and "CDRL1-3" represents the three hypervariable regions of an anti-CD117 antibody variable light domain. FRL1-4 may be derived from a consensus sequence (for example the most common amino acids of a class, subclass or subgroup of heavy or light chains of human immunoglobulins) or may be derived from an individual human antibody framework region or from a combination of different framework region sequences. In one embodiment, the variable light FR is provided by a consensus sequence of a human immunoglobulin subgroup as compiled by Kabat et al., supra.

The human variable light FR sequence may have substitution therein, e.g. where the human FR residue is replaced by a corresponding mouse residue, but replacement with the nonhuman residue is not necessary. For example, a replacement residue other than the corresponding nonhuman residue may be selected by phage display. Methods for generating humanized anti-CD117 antibodies of interest herein are elaborated in more detail below.

Anti-CD117 Agents, Antibodies, and Antigen-Binding Fragments Thereof

Provided herein are agents that bind cluster of differentiation 117 (CD117). Such agents may be referred to as anti-CD117 agents and may include anti-CD117 antibodies, anti-CD117 antibody fragments (e.g., antigen binding fragments), and anti-CD117 antibody derivatives. In some embodiments, the agent is isolated (e.g., separated from a component of its natural environment (e.g., an animal, a biological sample)). In some embodiments, the agent is non- naturally occurring (e.g., produced by human intervention). In some embodiments, the agent is a humanized antibody, or an antigen binding fragment thereof. In some embodiments, the agent is a derivative of a humanized antibody that binds CD117. In some embodiments, the agent binds CD117 under laboratory conditions (e.g., binds CD117 in vitro, binds CD117 in a flow cytometry assay, binds CD117 in an ELISA). In some embodiments, the agent binds CD117 under physiological conditions (e.g., binds CD117 in a cell in a subject).

Generally, the anti-CD117 agent provided herein comprises at least one immunoglobulin heavy chain variable domain and at least one immunoglobulin light chain variable domain. In some embodiments, an anti-CD117 agent herein comprises two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains. Typically, each immunoglobulin heavy chain variable domain of the anti-CD117 agent comprises first, second, and third heavy chain complementarity determining regions (CDRs; CDRH1 , CDRH2, CDRH3), and each immunoglobulin light chain variable domain of the anti-CD117 agent comprises first, second, and third light chain CDRs (CDRL1, CDRL2, CDRL3).

CDRH1

In some embodiments, the first heavy chain CDR (CDRH1) of an anti-CD117 agent provided herein comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅ (SEQ ID NO: 100), where X₁ is S, T, N, E, or D; X₂ is Y or H; X₃ is G, T, W, D, Y, or N; X₄ is M, I, or V; and X₅ is S, H, N, V, or A. In some embodiments, the CDRH1 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 100. In some embodiments, the CDRH1 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 100. In some embodiments, the CDRH1 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 100.

The amino acid X₁ of SEQ ID NO: 100 may be substituted with any amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 100 is substituted with a conservative amino acid (e.g., conservative to S, T, N, E, and/or D). In some embodiments, the amino acid X₁ of SEQ ID NO: 100 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 100 is substituted with an acid amino acid.

The amino acid X₂ of SEQ ID NO: 100 may be substituted with any amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 100 is substituted with a conservative amino acid (e.g., conservative to Y and/or H). In some embodiments, the amino acid X₂ of SEQ ID NO: 100 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 100 is substituted with a basic amino acid.

The amino acid X₃ of SEQ ID NO: 100 may be substituted with any amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 100 is substituted with a conservative amino acid (e.g., conservative to G, T, W, D, Y, and/or N). In some embodiments, the amino acid X₃ of SEQ ID NO: 100 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₃ of SEQ ID NO: 100 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 100 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 100 is substituted with an acidic amino acid. The amino acid X₄ of SEQ ID NO: 100 may be substituted with any amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 100 is substituted with a conservative amino acid (e.g., conservative to M, I, and/or V). In some embodiments, the amino acid X₄ of SEQ ID NO: 100 is substituted with a hydrophobic amino acid.

The amino acid X₅ of SEQ ID NO: 100 may be substituted with any amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 100 is substituted with a conservative amino acid (e.g., conservative to S, H, N, V, and/or A). In some embodiments, the amino acid X₅ of SEQ ID NO: 100 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 100 is substituted with a basic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 100 is substituted with a hydrophobic amino acid.

In some embodiments, the CDRH1 of anti-CD117 agent provided herein comprises an amino acid sequence chosen from SYGMS (SEQ ID NO: 31), TYTIH (SEQ ID NO: 32), NYGMS (SEQ ID NO: 33), SYWMN (SEQ ID NO: 34), NYDMS (SEQ ID NO: 35), EHYMV (SEQ ID NO: 36), NYWMN (SEQ ID NO: 37), SYYIS (SEQ ID NO: 38), SYGVS (SEQ ID NO: 39), DYWMS (SEQ ID NO: 40), and DYNMA (SEQ ID NO: 41).

CDRH2

In some embodiments, the second heavy chain CDR (CDRH2) of an anti-CD117 agent provided herein comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇X₁₈X₁₉ (SEQ ID NO: 101), where X₁ is T, Y, M, G, E, R, A, or D; X₂ is I or M; X₃ is S, R, N, H, K, or no amino acid; X₄ is L, T, W, Y, or no amino acid; X₅ is K, G, S, D, or no amino acid; X₆ is G, P, S, or T; X₇ is G, S, N, I, or R; X₈ is G, S, D, or N; X₉ is T, S, G, D, Y, or R; X₁₀ is Y, F, E, S, G, L, K, D, or N; X₁₁ is T, I, F, or Y; X₁₂ is Y, H, R, F, S, N, or V; X₁₃ is Y, L, E, S, P, or D; X₁₄ is P, N, A, G, or S; X₁₅ is D, Q, E, F, L, or V; X₁₆ is S, K, or Y; X₁₇ is L, V, F, M, G, S, or N; X₁₈ is R or K; and X₁9 is G, D, or R. In some embodiments, the CDRH2 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 101. In some embodiments, the CDRH2 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 101. In some embodiments, the CDRH2 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 101.

The amino acid X₁ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to T, Y, M, G, E, R, A, and/or D). In some embodiments, the amino acid X₁ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 101 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₁ of SEQ ID NO: 101 is substituted with an acidic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 101 is substituted with a basic amino acid.

The amino acid X₂ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to I and/or M). In some embodiments, the amino acid X₂ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid.

The amino acid X₃ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to S, R, N, H, K, or no amino acid). In some embodiments, the amino acid X₃ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 101 is substituted with basic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 101 is substituted with no amino acid.

The amino acid X₄ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to L, T, W, Y, and/or no amino acid). In some embodiments, the amino acid X₄ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 101 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 101 is substituted with no amino acid.

The amino acid X₅ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to K, G, S, D, and/or no amino acid). In some embodiments, the amino acid X₅ of SEQ ID NO: 101 is substituted with a basic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₅ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 101 is substituted with an acidic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 101 is substituted with no amino acid. The amino acid X₆ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to G, P, S, and/or T). In some embodiments, the amino acid X₆ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₆ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid.

The amino acid X₇ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to G, S, N, I, and/or R). In some embodiments, the amino acid X₇ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₇ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 101 is substituted with a basic amino acid.

The amino acid X₈ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to G, S, D, and/or N). In some embodiments, the amino acid X₈ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₈ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 101 is substituted with an acidic amino acid.

The amino acid X₉ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to T, S, G, D, Y, and/or R). In some embodiments, the amino acid X₉ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₉ of SEQ ID NO: 101 is substituted with an acidic amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 101 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 101 is substituted with a basic amino acid.

The amino acid X₁₀ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to Y, F, E, S, G, L, K, D, and/or N). In some embodiments, the amino acid X₁₀ of SEQ ID NO: 101 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 101 is substituted with an acidic amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 101 is substituted with a basic amino acid.

The amino acid X₁₁ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to T, I, F, and/or Y). In some embodiments, the amino acid X₁₁ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 101 is substituted with an aromatic amino acid.

The amino acid X₁₂ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to Y, H, R, F, S, N, and/or V). In some embodiments, the amino acid X₁₂ of SEQ ID NO: 101 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 101 is substituted with a basic amino acid. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid.

The amino acid X₁₃ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 101 is substituted with a conservative amino acid (e.g., conservative to Y, L, E, S, P, and/or D). In some embodiments, the amino acid X₁₃ of SEQ ID NO: 101 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 101 is substituted with an acidic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation.

The amino acid X₁₄ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁₄ of SEQ ID NO: 101 may be substituted with a conservative amino acid (e.g., conservative to P, N, A, G, and/or S). In some embodiments, the amino acid X₁₄ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₁₄ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₄ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid.

The amino acid X₁₅ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁₅ of SEQ ID NO: 101 may be substituted with a conservative amino acid (e.g., conservative to D, Q, E, F, L, and/or V). In some embodiments, the amino acid X₁5 of SEQ ID NO: 101 is substituted with an acidic amino acid. In some embodiments, the amino acid X₁₅ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₅ of SEQ ID NO: 101 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁₅ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid.

The amino acid X₁₆ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁₆ of SEQ ID NO: 101 may be substituted with a conservative amino acid (e.g., conservative to S, K, and/or Y). In some embodiments, the amino acid X₁₆ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₆ of SEQ ID NO: 101 is substituted with a basic amino acid. In some embodiments, the amino acid X₁₆ of SEQ ID NO: 101 is substituted with an aromatic amino acid.

The amino acid X₁₇ of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁₇ of SEQ ID NO: 101 may be substituted with a conservative amino acid (e.g., conservative to L, V, F, M, G, S, and/or N). In some embodiments, the amino acid X₁₇ of SEQ ID NO: 101 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₇ of SEQ ID NO: 101 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁₇ of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₁₇ of SEQ ID NO: 101 is substituted with a hydrophilic amino acid.

The amino acid X₁8 of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁8 of SEQ ID NO: 101 may be substituted with a conservative amino acid (e.g., conservative to R and/or K). In some embodiments, the amino acid X₁8 of SEQ ID NO: 101 is substituted with a basic amino acid.

The amino acid X₁9 of SEQ ID NO: 101 may be substituted with any amino acid. In some embodiments, the amino acid X₁9 of SEQ ID NO: 101 may be substituted with a conservative amino acid (e.g., conservative to G, D, and/or R). In some embodiments, the amino acid X₁9 of SEQ ID NO: 101 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₁9 of SEQ ID NO: 101 is substituted with an acidic amino acid. In some embodiments, the amino acid X₁₉ of SEQ ID NO: 101 is substituted with a basic amino acid.

In some embodiments, the CDRH2 of anti-CD117 agent provided herein comprises an amino acid sequence chosen from TISGGGTYTYYPDSLRG (SEQ ID NO: 42), TIRGGGSFTYYPDSVKG (SEQ ID NO: 43), YINPSSGYTHYNQKFKD (SEQ ID NO: 44), TISGGGDFTYYPDSMRR (SEQ ID NO: 45), MIHPSDSEIRLNQKFKD (SEQ ID NO: 46), YISSGGGSFFYPDTVKG (SEQ ID NO: 47), GINPNNGGTSYNQKFKG (SEQ ID NO: 48), EIRLKSNNYLTHYAESVKG (SEQ ID NO: 49), RIHPSDSEIRLNQKFKD (SEQ ID NO: 50), YINTGTISTKYNENFKG (SEQ ID NO: 51), AMWSGGSTDYNSGLKS (SEQ ID NO: 52), DIKYDGSDTNYVPSLKN (SEQ ID NO: 53), TISYDGRSIYYRDSVKG (SEQ ID NO: 54), and AIWSGGSTDYNSALKS (SEQ ID NO: 55).

CDRH3

In some embodiments, the third heavy chain CDR (CDRH3) of an anti-CD117 agent provided herein comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₃X₇X₈X₉X₁₀X₁₁X₁₂X₁₃Y (SEQ ID NO: 102), where X₁ is D, E, L, G, I, or H; X₂ is W, R, D, G, E, L, or no amino acid; X₃ is D, W, Y, A, R, F, or no amino acid; X₄ is D, R, A, Y, I, or no amino acid; X₅ is S, G, P, I, Y, or no amino acid; X₆ is Y, A, W, T, S, D, or no amino acid; X₇ is F, M, P, Y, G, or no amino acid; X₈ is D, A, F, E, R, or no amino acid; X₉ is Y, D, F, A, I, or S; X₁₀ is Y, H, N, or S; X₁₁ is T, W, Y, or P; X₁₂ is M or F; and X₁₃ is A, T, or D. In some embodiments, the third heavy chain CDR (CDRH3) of an anti-CD117 agent provided herein comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 102. In some embodiments, the CDRH3 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 102. In some embodiments, the CDRH3 comprises an amino acid sequence of SEQ ID NO: 102. In some embodiments, the CDRH3 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 102.

The amino acid X₁ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., conservative to D, E, L, G, I, and/or H). In some embodiments, the amino acid X₁ of SEQ ID NO: 102 is substituted with an acidic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 102 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₁ of SEQ ID NO: 102 is substituted with a basic amino acid. The amino acid X₂ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., conservative to W, R, D, G, E, L, and/or no amino acid). In some embodiments, the amino acid X₂ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 102 is substituted with a basic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 102 is substituted with an acidic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 102 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₂ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 102 is substituted with no amino acid.

The amino acid X₃ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., conservative to D, W, Y, A, R, F, and/or no amino acid). In some embodiments, the amino acid X₃ of SEQ ID NO: 102 is substituted with an acidic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 102 is substituted with a basic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 102 is substituted with no amino acid.

The amino acid X₄ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., D, R, A, Y, I, and/or no amino acid). In some embodiments, the amino acid X₄ of SEQ ID NO: 102 is substituted with an acidic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 102 is substituted with a basic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 102 is substituted with no amino acid.

The amino acid X₅ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., S, G, P, I, Y, and/or no amino acid). In some embodiments, the amino acid X₅ of SEQ ID NO: 102 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 102 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₅ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 102 is substituted with no amino acid.

The amino acid X₆ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., Y, A, W, T, S, D, and/or no amino acid). In some embodiments, the amino acid X₆ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 102 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 102 is substituted with an acidic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 102 is substituted with no amino acid.

The amino acid X₇ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., F, M, P, Y, G, and/or no amino acid). In some embodiments, the amino acid X₇ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 102 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₇ of SEQ ID NO: 102 is substituted with no amino acid.

The amino acid X₈ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., D, A, F, E, R, and/or no amino acid). In some embodiments, the amino acid X₈ of SEQ ID NO: 102 is substituted with an acidic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 102 is substituted with a basic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 102 is substituted with no amino acid.

The amino acid X₉ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., Y, D, F, A, I, and/or S). In some embodiments, the amino acid X₉ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 102 is substituted with an acidic amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 102 is substituted with a hydrophilic amino acid.

The amino acid X₁₀ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., Y, H, N, and/or S). In some embodiments, the amino acid X₁₀ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 102 is substituted with a basic amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 102 is substituted with a hydrophilic amino acid.

The amino acid X₁₁ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., T, W, Y, and/or P). In some embodiments, the amino acid X₁₁ of SEQ ID NO: 102 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 102 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 102 is substituted with an amino acid residue that influences chain orientation.

The amino acid X₁₂ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., M and/or F). In some embodiments, the amino acid X₁₂ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 102 is substituted with an aromatic amino acid.

The amino acid X₁₃ of SEQ ID NO: 102 may be substituted with any amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 102 is substituted with a conservative amino acid (e.g., A, T, and/or D). In some embodiments, the amino acid X₁₃ of SEQ ID NO: 102 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 102 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 102 is substituted with an acidic amino acid.

In some embodiments, the CDRH3 of anti-CD117 agents provided herein comprises an amino acid sequence chosen from DWDDSYFDY (SEQ ID NO: 56), DRWRD (SEQ ID NO: 57), EDYAGAMDF (SEQ ID NO: 58), LGDYPWFAY (SEQ ID NO: 59), GEAIITPFAY (SEQ ID NO: 60), IRRDYSMDY (SEQ ID NO: 61), EIHTMAY (SEQ ID NO: 62), GDYEYNWFTY (SEQ ID NO: 63), EDGRSYYFDY (SEQ ID NO: 64), HLFYYDGRSYPFAY (SEQ ID NO: 65), and GDYEYSWFTY (SEQ ID NO: 66). CDRL1

In some embodiments, the first light chain CDR (CDRL1) of an anti-CD117 agent provided herein comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁ X₂SX₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁ eX₁1 (SEQ ID NO: 103), where X₁ is S, K, or R; X₂ is A, S, or R; X₄ is Q, S, T, or E; X₅ is S, G, D, or no amino acid; X₆ is L, D, I, N, or no amino acid; X₇ is L, V, I, H, or no amino acid; X₈ is N, H, G, S, or no amino acid; X₉ is S, G, or no amino acid; X₁₀ is G, S, or no amino acid; X₁₁ is D, N, S, or no amino acid; X₁₂ is I, Q, L, G, or no amino acid; X₁₃ is S, K, I, R, N, or no amino acid; X₁₄ is N, T, or no amino acid; X₁₅ is Y, F, or no amino acid; X₁₆ is L, M, or V; and X₁₇ is N, T, H, S, A, orY. In some embodiments, the CDRL1 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 103. In some embodiments, the CDRL1 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 103. In some embodiments, the CDRL1 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 103.

The amino acid X₁ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., S, K, and/or R). In some embodiments, the amino acid X₁ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 103 is substituted with a basic amino acid.

The amino acid X₂ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., A, S, and/or R). In some embodiments, the amino acid X₂ of SEQ ID NO: 103 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 103 is substituted with a basic amino acid.

The amino acid X₄ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., Q, S, T, and/or E). In some embodiments, the amino acid X₄ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 103 is substituted with an acidic amino acid.

The amino acid X₅ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., S, G, D, and/or no amino acid). In some embodiments, the amino acid X₅ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 103 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₅ of SEQ ID NO: 103 is substituted with an acidic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₆ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino X₆ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., L, D, I, N, and/or no amino acid). In some embodiments, the amino acid X₆ of SEQ ID NO: 103 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 103 is substituted with an acidic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₇ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., L, V, I, H, and/or no amino acid). In some embodiments, the amino acid X₇ of SEQ ID NO: 103 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 103 is substituted with a basic amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₈ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., N, H, G, S, and/or no amino acid). In some embodiments, the amino acid X₈ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 103 is substituted with a basic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 103 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₈ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₉ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., S, G, and/or no amino acid). In some embodiments, the amino acid X₉ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 103 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₉ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₁₀ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., G, S, and/or no amino acid). In some embodiments, the amino acid X₁₀ of SEQ ID NO: 103 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₀ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₁₁ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., D, N, S, and/or no amino acid). In some embodiments, the amino acid X₁₁ of SEQ ID NO: 103 is substituted with an acidic amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₁ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₁₂ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., I, Q, L, G, and/or no amino acid). In some embodiments, the amino acid X₁₂ of SEQ ID NO: 103 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₂ is SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 103 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₁₂ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₁₃ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., S, K, I, R, N, and/or no amino acid). In some embodiments, the amino acid X₁₃ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 103 is substituted with a basic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 103 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₃ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₁₄ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁₄ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., N, T, and/or no amino acid). In some embodiments, the amino acid X₁₄ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₄ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₁₅ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁₅ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., Y, F, and/or no amino acid). In some embodiments, the amino acid X₁₅ of SEQ ID NO: 103 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁₅ of SEQ ID NO: 103 is substituted with no amino acid.

The amino acid X₁₆ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁₆ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., L, M, and/or V). In some embodiments, the amino acid X₁₆ of SEQ ID NO: 103 is substituted with a hydrophobic amino acid.

The amino acid X₁₇ of SEQ ID NO: 103 may be substituted with any amino acid. In some embodiments, the amino acid X₁₇ of SEQ ID NO: 103 is substituted with a conservative amino acid (e.g., N, T, H, S, A, and/or Y). In some embodiments, the amino acid X₁₇ of SEQ ID NO: 103 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁₇ of SEQ ID NO: 103 is substituted with a basic amino acid. In some embodiments, the amino acid X₁₇ of SEQ ID NO: 103 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₁₇ of SEQ ID NO: 103 is substituted with an aromatic amino acid.

In some embodiments, the CDRL1 of an anti-CD117 agent provided herein comprises an amino acid sequence chosen from SASQDISNYLN (SEQ ID NO: 67), KSSQSLLNSGNQKNYLT (SEQ ID NO: 68), SASSSLIYMH (SEQ ID NO: 69), RASQDIRNYLS (SEQ ID NO: 70), KSSQSLLNSSNQKNYLA (SEQ ID NO: 71), RSSQSLVHSDGNTYLH (SEQ ID NO: 72), RSSQSLVHSDGSTYLH (SEQ ID NO: 73), KRSTGDIGSNYVY (SEQ ID NO: 74), RASEDIHNGLA (SEQ ID NO: 75), KSSQSLLSSGNQKNFLA (SEQ ID NO: 76) and KRSTGNIGSNYVH (SEQ ID NO: 77).

CDRL2

In some embodiments, the second light chain CDR (CDRL2) of anti-CD117 agent provided herein comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₃X₇ (SEQ ID NO: 104), where X₁ is Y, W, S, F, K, R, or N; X₂ is T, A, V, or D; X₃ is S, D, or I; X₄ is S, T, N, R, K, or P; X₅ is L or R; X₆ is H, Q, E, A, F, or P; and X₇ is S or D. In some embodiments, the CDRL2 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 104. In some embodiments, the CDRL2 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 104. In some embodiments, the CDRL2 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 104. The amino acid X₁ of SEQ ID NO: 104 may be substituted with any amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 104 is substituted with a conservative amino acid (e.g., Y, W, S, F, K, R, and/or N). In some embodiments, the amino acid X₁ of SEQ ID NO: 104 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 104 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 104 is substituted with a basic amino acid.

The amino acid X₂ of SEQ ID NO: 104 may be substituted with any amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 104 is substituted with a conservative amino acid (e.g., T, A, V, and/or D). In some embodiments, the amino acid X₂ of SEQ ID NO: 104 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 104 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 104 is substituted with an acidic amino acid.

The amino acid X₃ of SEQ ID NO: 104 may be substituted with any amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 104 is substituted with a conservative amino acid (e.g., S, D, and/or I). In some embodiments, the amino acid X₃ of SEQ ID NO: 104 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 104 is substituted with an acidic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 104 is substituted with a hydrophobic amino acid.

The amino acid X₄ of SEQ ID NO: 104 may be substituted with any amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 104 is substituted with a conservative amino acid (e.g., S, T, N, R, K, and/or P). In some embodiments, the amino acid X₄ of SEQ ID NO: 104 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 104 is substituted with a basic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 104 is substituted with an amino acid residue that influences chain orientation.

The amino acid X₅ of SEQ ID NO: 104 may be substituted with any amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 104 is substituted with a conservative amino acid (e.g., L and/or R). In some embodiments, the amino acid X₅ of SEQ ID NO: 104 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 104 is substituted with a basic amino acid.

The amino acid X₆ of SEQ ID NO: 104 may be substituted with any amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 104 is substituted with a conservative amino acid (e.g., H, Q, E, A, F, and/or P). In some embodiments, the amino acid X₆ of SEQ ID NO: 104 is substituted with a basic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 104 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 104 is substituted with an acidic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 104 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 104 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 104 is substituted with an amino acid residue that influences chain orientation.

The amino acid X₇ of SEQ ID NO: 104 may be substituted with any amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 104 is substituted with a conservative amino acid (e.g., S and/or D). In some embodiments, the amino acid X₇ of SEQ ID NO: 104 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 104 is substituted with an acidic amino acid.

In some embodiments, the CDRL2 of an anti-CD117 agent provided herein comprises an amino acid sequence chosen from YTSSLHS (SEQ ID NO: 78), YTSSLQS (SEQ ID NO: 79), WASTRES (SEQ ID NO: 80), STSNLAS (SEQ ID NO: 81), YTSRLQS (SEQ ID NO: 82), FASTRES (SEQ ID NO: 83), KVSNRFS (SEQ ID NO: 84), RVSNRFS (SEQ ID NO: 85), RDDKRPD (SEQ ID NO: 86), NAISLHS (SEQ ID NO: 87), and WASPRQS (SEQ ID NO: 88).

CDRL3

In some embodiments, the third light chain CDR (CDRL3) of an anti-CD117 agent provided herein comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉ (SEQ ID NO: 105), where X₁ is Q, H, S, or L; X₂ is Q, N, H, or S; X₃ is Y, D, W, G, H, T, or S; X₄ is S, Y, or T; X₅ is K, G, T, S, H, D, or no amino acid; X₆ is V, Y, L, T, F, G, S, or no amino acid; X₇ is P, S, or I; X₈ is W, L, Y, P, T, or S; and X₉ is T, V, or A. In some embodiments, the CDRL3 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the CDRL3 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the CDRL3 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 105.

The amino acid X₁ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., Q, H, S, and/or L). In some embodiments, the amino acid X₁ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 105 is substituted with a basic amino acid. In some embodiments, the amino acid X₁ of SEQ ID NO: 105 is substituted with a hydrophobic amino acid. The amino acid X₂ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., Q, N, H, and/or S). In some embodiments, the amino acid X₂ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₂ of SEQ ID NO: 105 is substituted with a basic amino acid.

The amino acid X₃ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., Y, D, W, G, H, T, and/or S). In some embodiments, the amino acid X₃ of SEQ ID NO: 105 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 105 is substituted with an acidic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 105 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₃ of SEQ ID NO: 105 is substituted with a basic amino acid. In some embodiments, the amino acid X₃ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid.

The amino acid X₄ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., S, Y, and/or T). In some embodiments, the amino acid X₄ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₄ of SEQ ID NO: 105 is substituted with an aromatic amino acid.

The amino acid X₅ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., K, G, T, S, H, D, and/or no amino acid). In some embodiments, the amino acid X₅ of SEQ ID NO: 105 is substituted with a basic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 105 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₅ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 105 is substituted with an acidic amino acid. In some embodiments, the amino acid X₅ of SEQ ID NO: 105 is substituted with no amino acid.

The amino acid X₆ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., V, Y, L, T, F, G, S, and/or no amino acid). In some embodiments, the amino acid X₆ of SEQ ID NO: 105 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 105 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₆ of SEQ ID NO: 105 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₆ of SEQ ID NO: 105 is substituted with no amino acid.

The amino acid X₇ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., P, S, and/or I). In some embodiments, the amino acid X₇ of SEQ ID NO: 105 is substituted with an amino acid residue that influences chain orientation. In some embodiments, the amino acid X₇ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₇ of SEQ ID NO: 105 is substituted with a hydrophobic amino acid.

The amino acid X₈ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., W, L, Y, P, T, and/or S). In some embodiments, the amino acid X₈ of SEQ ID NO: 105 is substituted with an aromatic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 105 is substituted with a hydrophobic amino acid. In some embodiments, the amino acid X₈ of SEQ ID NO: 105 is substituted with an amino acid that influences chain orientation. In some embodiments, the amino acid X₈ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid.

The amino acid X₉ of SEQ ID NO: 105 may be substituted with any amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 105 is substituted with a conservative amino acid (e.g., T, V, and/or A). In some embodiments, the amino acid X₉ of SEQ ID NO: 105 is substituted with a hydrophilic amino acid. In some embodiments, the amino acid X₉ of SEQ ID NO: 105 is substituted with a hydrophobic amino acid.

In some embodiments, the CDRL3 of an anti-CD117 agent provided herein comprises an amino acid sequence chosen from QQYSKVPWT (SEQ ID NO: 89), QNDYGYPLT (SEQ ID NO: 90), HHWSSYT (SEQ ID NO: 91), QQGYTLPWT (SEQ ID NO: 92), QQHYSTPPT (SEQ ID NO: 93), SQTTHVPLT (SEQ ID NO: 94), LQSTHFPWT (SEQ ID NO: 95), QSYSSGITV (SEQ ID NO: 96), QQYYNYPWT (SEQ ID NO: 97), QQYYDSPLA (SEQ ID NO: 98), and QSYSSGISV (SEQ ID NO: 99).

CDR sets

In some embodiments, an anti-CD117 agent comprises an immunoglobulin heavy chain variable domain comprising a set of CDRs (i.e. , CDRH1, CDRH2, CDRH3); and an immunoglobulin light chain variable domain comprising a set of CDRs (i.e., CDRL1 , CDRL2, CDRL3). In some embodiments, an anti-CD117 agent herein comprises two immunoglobulin heavy chain variable domains each comprising a set of CDRs (i.e., CDRH1, CDRH2, CDRH3); and two immunoglobulin light chain variable domains each comprising a set of CDRs (i.e. , CDRL1 , CDRL2, CDRL3). Sets of CDRs may comprise any combination of CDR amino acid sequences (i.e., CDRH1, CDRH2, CDRH3; and CDRL1, CDRL2, CDRL3) provided herein. In some embodiments, an immunoglobulin heavy chain variable domain comprises a set of CDRH1, CDRH2, and CDRH3 amino acid sequences, and an immunoglobulin light chain variable domain comprises a set of CDRL1, CDRL2, and CDRL3 amino acid sequences chosen from sets 1-15 provided in the following Table.

Table 2. CDR sets

In some embodiments, all CDRs are from the same set. For example, for an anti-CD117 agent comprising two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains, each immunoglobulin heavy chain variable domain may comprise a set of CDRH1, CDRH2, and CDRH3 amino acid sequences from set 1, and each immunoglobulin light chain variable domain may comprise a set of CDRL1, CDRL2, and CDRL3 amino acid sequences from set 1.

In some embodiments, CDRs are from different sets. For example, for an anti-CD117 agent comprising two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains, each immunoglobulin heavy chain variable domain may comprise a set of CDRH1, CDRH2, and CDRH3 amino acid sequences from set 1, and each immunoglobulin light chain variable domain may comprise a set of CDRL1, CDRL2, and CDRL3 amino acid sequences from set 2. In another example, for an anti-CD117 agent comprising two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains, one immunoglobulin heavy chain variable domain may comprise a set of CDRH1, CDRH2, and CDRH3 amino acid sequences from set 1 and the other immunoglobulin heavy chain variable domain may comprise a set of CDRH1, CDRH2, and CDRH3 amino acid sequences from set 2; and one immunoglobulin light chain variable domain may comprise a set of CDRL1, CDRL2, and CDRL3 amino acid sequences from set 1 and other immunoglobulin light chain variable domain may comprise a set of CDRL1,

CDRL2, and CDRL3 amino acid sequences from set 2. In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof described herein comprises: a CDRH1 comprising the sequence of any one of SEQ ID NOs:35 and 40; a CDRH2 comprising the sequence of any one of SEQ ID NOs:47 and 53; and a CDRH3 comprising the sequence of any one of SEQ ID NOs:59 and 64.

In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof described herein comprises: a CDRL1 comprising the sequence of any one of SEQ ID NOs:70 and 75; a CDRL2 comprising the sequence of any one of SEQ ID NOs:82 and 87; and a CDRL3 comprising the sequence of any one of SEQ ID NOs:92 and 97.

In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof described herein comprises: a CDRH1 comprising the sequence of any one of SEQ ID NOs:35 and 40; a CDRH2 comprising the sequence of any one of SEQ ID NOs:47 and 53; a CDRH3 comprising the sequence of any one of SEQ ID NOs:59 and 64; a CDRL1 comprising the sequence of any one of SEQ ID NOs:70 and 75; a CDRL2 comprising the sequence of any one of SEQ ID NOs:82 and 87; and a CDRL3 comprising the sequence of any one of SEQ ID NOs:92 and 97.

In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof described herein comprises: a CDRH1 comprising the sequence of SEQ ID NO:35; a CDRH2 comprising the sequence of SEQ ID NO:47; a CDRH3 comprising the sequence of SEQ ID NO:59; a CDRL1 comprising the sequence of SEQ ID NO:70; a CDRL2 comprising the sequence of SEQ ID NO:82; and a CDRL3 comprising the sequence of SEQ ID NO:92.

In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof described herein comprises: a CDRH1 comprising the sequence of SEQ ID NO:40; a CDRH2 comprising the sequence of SEQ ID NO:53; a CDRH3 comprising the sequence of SEQ ID NO:64; a CDRL1 comprising the sequence of SEQ ID NO:75; a CDRL2 comprising the sequence of SEQ ID NO:87; and a CDRL3 comprising the sequence of SEQ ID NO:97.

VH

An anti-CD117 agent provided herein may comprise a heavy chain variable domain (VH). In some embodiments, a heavy chain variable domain (VH) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence

DVKLVESGGGLVKPGGSLKLSCAASGFTFSSYGMSWLRQTPEKRLEWVATISGGGTYT

YYPDSLRGRFTISRDNAKNNLYLQMRSLRSDDTALYYCAR-

DWDDSYFDYWGQGTTLTVSS (SEQ ID NO: 1), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 1. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 1. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 1. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 1.

EVKLVESGGGLVKPGGSLKLSCAASGFTFSSYGMSWVRQTPEKRLEWVATIRGGGSFT YYPDSVKGRFTISRDNAKN KLYLQMSSLRSEDTALYYCAR-

DWDDSYFDYWGQGTTLTVSS (SEQ ID NO: 2), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 2. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 2. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 2. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 2.

QVQLQQSGAELARPGASVKMSCKASDYTFTTYTIHWVKQRPGQGLEWLGYINPSSGYT HYNQKFKDKATLTADKSSSTAYVQLSSLTSEDSAVYYCSR-DRWRDWGQGTTLTVSS (SEQ ID NO: 3), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 3. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 3. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 3. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 3.

EVKLVESGGGLVKPGGSLKLSCATSGFTFNNYGMSWVRQTPEKRLEWVATISGGGDFT

YYPDSMRRRFTISRDNAKNNLYLQMSSLRSEDTALYYCAR-

DWDDSYFDYWGQGTTLTVSS (SEQ ID NO: 4), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 4. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 4. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 4. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 4.

DVKLVESGGGLVKPGGSLKLSCAASGFTFSSYGMSWLRQTPEKRLEWVATISGGGTYT YYPDSLRGRFTISRDNAKNNLYLQMRSLRSDDTALYYCAR-DWDDSYFDYWGQGTTLTVS (SEQ ID NO: 5), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 5. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 5. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 5. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 5. An anti-CD117 agent provided herein may comprise a heavy chain variable domain (VH). In some embodiments, a heavy chain variable domain (VH) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence

QVQLQQPGAELVRPAASVKLSCKASGYSFTSYWMNWVKQRPGQGLEWIGMIHPSDSEI

RLNQKFKDKATLTVDKSSSTVYMQLSSPTSEDSAVYYCAR-

EDYAGAMDFWGQGTSVTVSS (SEQ ID NO: 6), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 6. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 6. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 6. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 6.

EVQLVESGGDLVKPGGSLKLSCVASGFAFSNYDMSWVRQTPDKRLEWVAYISSGGGSF FYPDTVKGRFTISRDNAKNTLYLQMTSLKSEDTAMYYCAG-LGDYPWFAYWGQGTLVTVSA (SEQ ID NO: 7), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 7. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 7. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 7. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 7.

EVQLQQSGPELVKPGASVKMSCKASGYTFTEHYMVWVKQSHGKSLEWIGGINPNNGGT SYNQKFKGKATLTVDKSSSTAYMELRSLTSEDSAVYYCARGEAIITPFAYWAQGTLVTVSA (SEQ ID NO: 8), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 8.

EVKLEESGGGLVQPGGSMKLSCVASGFTFSNYWMNWVRQSPEKGLEWVAEIRLKSNNYL THYAESVKGRFSISRDDSKSSVYLQMNNFRPEDTGIYYCTRIRRDYSMDYWGQGTSVTVS S (SEQ ID NO: 9), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 9. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 9. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 9. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 9.

QVQLQQPGAELVRPGASVKLSCKASGYSFTSYWMNWVKQRPGQGLEWIGRIHPSDSEI

RLNQKFKDKATLTVDKSSSTVYMQLSSPTSEDSAVYYCTR-

EDYAGAMDFWGQGSSVTVSS (SEQ ID NO: 10), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 10. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 10. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 10. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 10.

QVQLQQSGAELAKPGSSVKISCKASGYTFTSYYISWIKQTTGQGLEFIGYINTGTISTKY NENFKGKATLTVDKSSSTAFMQLSSLTPDDSAVYYCAREIHTMAYWGQGVMVTVSS (SEQ ID NO: 11), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 11. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 11. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 11. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 11.

QVQLKESG PG LVQPSQTLSLTCTVSG FSLTSYGVSWVRQPPG KG LEWI GAM WSGGSTDY NSGLKSRLSISRDTSKSQVLLKMNSLQTEDTAMYFCARGDYEYNWFTYWGQGTLVTVSS (SEQ ID NO: 12), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 12. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 12. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 12. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 12.

EVQLVESGGGLVQPGASLKLSCVASGFTFSDYWMSWVRQTPGKTMEWIGDIKYDGSDTN Y VPSLKNRFTISRDNAKSTLYLQMSNVRSEDTATYYCTREDGRSYYFDYWGQGVMVTVSS (SEQ ID NO: 13), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 13. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 13. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 13. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 13.

EVQLVESGGGLVQPGRSLKLSCAASGFTFSDYNMAWVRQAPKKGLEWVATISYDGRSIYY RDSVKGRFTISRDNAKTTLYLQMDSLRSEDTATYYCARHLFYYDGRSYPFAYWGQGTLVT VSS (SEQ ID NO: 14), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 14. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 14. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 14. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 14. An anti-CD117 agent provided herein may comprise a heavy chain variable domain (VH). In some embodiments, a heavy chain variable domain (VH) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence

QVQLKESGPGLVQPSQTLSLTCTVSGFSLTSYGVSWVRQPPGKGLEWIGAIWSGGSTDY NSALKSRLSITRDPSRSQVLLKMNSLQTEDTAMYFCARGDYEYSWFTYWGQGTLVTVSS (SEQ ID NO: 15), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 15. In some embodiments, a VH comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 15. In some embodiments, a VH comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 15. In some embodiments, a VH comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 15.

In some embodiments, a VH of an anti-CD117 agent provided herein comprises a polypeptide chosen from SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11 , SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, and SEQ ID NO: 15.

An anti-CD117 antibody or antigen-binding fragment thereof provided herein may comprise a VH comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:7. In some embodiments, any of the anti-CD117 antibody or antigen-binding fragment thereof provided herein may comprise a VH comprising the sequence of SEQ ID NO:7. In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a CDRH1 comprising the sequence of SEQ ID NO:35; a CDRH2 comprising the sequence of SEQ ID NO:47; a CDRH3 comprising the sequence of SEQ ID NO:59; and a VH comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:7.

An anti-CD117 antibody or antigen-binding fragment thereof provided herein may comprise a VH comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:13. In some embodiments, any of the anti-CD117 antibody or antigen-binding fragment thereof provided herein may comprise a VH comprising the sequence of SEQ ID NO:13. In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a CDRH1 comprising the sequence of SEQ ID NO:40; a CDRH2 comprising the sequence of SEQ ID NO:53; a CDRH3 comprising the sequence of SEQ ID NO:64; and a VH comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO: 13.

VL

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DIQMTQTTSSLSASLGDRVTISCSASQDISNYLNWYQQKPDGTVKLLIYYTSSL HSGVPSRFSGSGSGTDYSLTISNLEPEDIATYYCQQYSKVPWTFGGGTKLEIK (SEQ ID NO:

16), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 16. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 16. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 16. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 16.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DIQMTQTTSSLSASLGDRVTISCSASQDISNYLNWYQQKPDGTVKLLIYYTSSL QSGVPSRFSGSGSGTDYSLTISDLEPEDIATYYCQQYSKVPWTFGGGTKLEIK (SEQ ID NO:

17), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 17. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 17. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 17. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 17. An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DIVMTQSPSSLTVTAGEKVTLSCKSSQSLLNSGNQKNYLTWYQQHPGQPPKLLIYWASTRE SGVPDRFTGSGSGTDFTLTISSVQAEDLAVYYCQNDYGYPLTFGAGAKLELK (SEQ ID NO:

18), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 18. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 18. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 18. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 18.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DIQMTQTTSSLSASLGDRVTITCSASQDISNYLNWYQQKPDGTVKLLIYYTSSL HSGVPSRFSGSGSGTDYSLTISNLEPEDIATYYCQQYSKVPWTFGGGTKLEIR (SEQ ID NO:

19), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 19. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 19. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 19. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 19.

20), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 20. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 20. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 20. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 20.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence QIVLTQSPAIMSASLGDEVTLTCSASSSLIYMHWYQQKSATSPKLLIYSTSNL ASGVPSRFSGSGSGTFFSLTISSVEAGDAADYYCHHWSSYTFGGGTRLEIK (SEQ ID NO: 21), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 21. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 21. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 21. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 21.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DIQMTQITSSLSASLGDRVTFSCRASQDIRNYLSWYQQKPDGTVKLLIYYTSRL QSGVPSRFSGSGSGTDYSLTIRNLDQEDIATYFCQQGYTLPWTFGGGTKLEIN (SEQ ID NO: 22), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 22. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 22. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 22. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 22. An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DIVMTQSPSSLAMSVGQKVTMSCKSSQSLLNSSNQKNYLAWYQQKPGQSPKLLVYFASTR ESGVPDRFIGSGSGTDFTLTISSVQSEDLADYFCQQHYSTPPTFGGGTKLEIK (SEQ ID NO:

23), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 23. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 23. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 23. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 23.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DVVMTQTPLSLPVSLGDQASISCRSSQSLVHSDGNTYLHWYLQKPGQSPKLLIYKVSNR FSGVPDRFSGSGSGTDFTLKISRVEAEDLGVYFCSQTTHVPLTFGAGTKLELK (SEQ ID NO:

24), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 24. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 24. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 24. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 24.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence QIVLTQSPAIMSASLGDEVTLTCSASSSLIYMHWYQQKSATSPKLLIYSTSNL ASGVPSRFSGSGSGTFYSLTISSVEAGDAADYYCHHWSSYTFGGGTRLEIK (SEQ ID NO:

25), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 25. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 25. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 25. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 25.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DVLMTQTPVSLPVSLGGQVSISCRSSQSLVHSDGSTYLHWYLRKPGQSPQLL IYRVSNRFSGVPDRFSGSGSGTDFTLKISRVEPEDLGVYYCLQSTHFPWTFGGGTKLELK (SEQ ID NO: 26), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 26. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 26. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 26. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 26.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence QFVLTQ-PNSVSTNLGSTVKLSCKRSTGDIGSNYVYWYQQHEGRSPTTMIYRDDKR PDGVPDRFSGSIDRSSNSALLTINNVQTEDEADYFCQSYSSGITVFGGGTKLTVL (SEQ ID NO: 27), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 27. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 27. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 27. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 27. An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DIQMTQSPASLSASLGETVTIECRASEDIHNGLAWYQQKPGKSPQLLIY NAISLHSGVPSRFSGSGSGTQYSLNINSLQSEDVASYFCQQYYNYPWTFGGGTKLELK (SEQ ID NO: 28), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 28. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 28. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 28. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 28.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence DIVMTQSPSSLAVSPGETVTIHCKSSQSLLSSGNQKNFLAWYQQKPGQSPKLLIYWASPRQ SGVPDRFIGSGSGTDFTLTISSVQAEDLAIYYCQQYYDSPLAFGSGTKLEIK (SEQ ID NO: 29), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 29. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 29. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 29. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 29.

An anti-CD117 agent provided herein may comprise a light chain variable domain (VL). In some embodiments, a light chain variable domain (VL) of an anti-CD117 agent provided herein comprises a polypeptide that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence QFVLTQ-PNSVSTNLGSSVKLSCKRSTGNIGSNYVHWYQQHEGRSPTTMIYRDDKR PDGVPDRFSGSIDRSSNSALLTISNVETEDEADYFCQSYSSGISVFGGGTKLTVP (SEQ ID NO: 30), e.g., 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, identical to the amino acid sequence of SEQ ID NO: 30. In some embodiments, a VL comprises a polypeptide that is at least 90% identical to the amino acid sequence of SEQ ID NO: 30. In some embodiments, a VL comprises a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 30. In some embodiments, a VL comprises a polypeptide that is 100% identical to the amino acid sequence of SEQ ID NO: 30.

In some embodiments, a VL of an anti-CD117 agent provided herein comprises a polypeptide chosen from SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, SEQ ID NO: 24, SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, and SEQ ID NO: 30.

An anti-CD117 antibody or antigen-binding fragment thereof provided herein may comprise a VL comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:22. In some embodiments, any of the anti-CD117 antibody or antigen-binding fragment thereof provided herein may comprise a VL comprising the sequence of SEQ ID NO:22. In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a CDRL1 comprising the sequence of SEQ ID NO:70; a CDRL2 comprising the sequence of SEQ ID NO:82; a CDRL3 comprising the sequence of SEQ ID NO:92; and a VL comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:22.

An anti-CD117 antibody or antigen-binding fragment thereof provided herein may comprise a VL comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:28. In some embodiments, any of the anti-CD117 antibody or antigen-binding fragment thereof provided herein may comprise a VL comprising the sequence of SEQ ID NO:28. In some embodiments, an anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a CDRL1 comprising the sequence of SEQ ID NO:75; a CDRL2 comprising the sequence of SEQ ID NO:87; a CDRL3 comprising the sequence of SEQ ID NO:97; and a VL comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:28. Examples of VH and VL

An anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a VH comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:7 and a VL comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:22. In some of any embodiments, any of the anti- CD117 antibody or antigen-binding fragment thereof provided herein comprises a VH comprising the sequence of SEQ ID NO:7 and a VL comprising a sequence the sequence of SEQ ID NO:22.

An anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a VH comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO: 13 and a VL comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:28. . In some of any embodiments, any of the anti- CD117 antibody or antigen-binding fragment thereof provided herein comprises a VH comprising the sequence of SEQ ID NO:13 and a VL comprising a sequence the sequence of SEQ ID NO:28.

An anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a CDRH1 comprising the sequence of SEQ ID NO:35; a CDRH2 comprising the sequence of SEQ ID NO:47; a CDRH3 comprising the sequence of SEQ ID NO:59; and a VH comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:7; and a CDRL1 comprising the sequence of SEQ ID NO:70; a CDRL2 comprising the sequence of SEQ ID NO:82; a CDRL3 comprising the sequence of SEQ ID NO:92; and a VL comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:22. An anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a CDRH1 comprising the sequence of SEQ ID NO:35; a CDRH2 comprising the sequence of SEQ ID NO:47; a CDRH3 comprising the sequence of SEQ ID NO:59; and a VH comprising the sequence of SEQ ID NO:7; and a CDRL1 comprising the sequence of SEQ ID NO:70; a CDRL2 comprising the sequence of SEQ ID NO:82; a CDRL3 comprising the sequence of SEQ ID NO:92; and a VL comprising the sequence of SEQ ID NO:22. An anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a CDRH1 comprising the sequence of SEQ ID NO:40; a CDRH2 comprising the sequence of SEQ ID NO:53; a CDRH3 comprising the sequence of SEQ ID NO:64; and a VH comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:13; and a CDRL1 comprising the sequence of SEQ ID NO:75; a CDRL2 comprising the sequence of SEQ ID NO:87; a CDRL3 comprising the sequence of SEQ ID NO:97; and a VL comprising a sequence having at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) sequence identity to the sequence of SEQ ID NO:28. An anti-CD117 antibody or antigen-binding fragment thereof provided herein comprises a CDRH1 comprising the sequence of SEQ ID NO:40; a CDRH2 comprising the sequence of SEQ ID NO:53; a CDRH3 comprising the sequence of SEQ ID NO:64; and a VH comprising the sequence of SEQ ID NO: 13; and a CDRL1 comprising the sequence of SEQ ID NO:75; a CDRL2 comprising the sequence of SEQ ID NO:87; a CDRL3 comprising the sequence of SEQ ID NO:97; and a VL comprising the sequence of SEQ ID NO:28.

Fc

An anti-CD117 agent provided herein may comprise a fragment crystallizable region (Fc region). An Fc region typically forms the tail of an antibody and can interact with certain cell surface receptors and certain components of the complement system. An Fc region may include, for example, two polypeptides, each derived from the second (CH2) and third (CH3) constant domains of an antibody heavy chain.

The amino acid sequence of a wild-type CH2-CH3 portion of an Fc region is provided below (positioning is as in EU index as in Kabat et al. (1992) SEQUENCES OF PROTEINS OF IMMUNOLOGICAL INTEREST, National Institutes of Health Publication No. 91-3242) (SEQ ID NO: 107).

In some embodiments, an Fc region includes one or more modifications (e.g., one or more amino acid substitutions, insertions, or deletions relative to a comparable wild-type Fc region). Agents comprising modified Fc regions (variant agents) typically have altered phenotypes relative to agents comprising wild-type Fc regions. A variant agent phenotype may be expressed as altered serum half-life, altered stability, altered susceptibility to cellular enzymes, or altered effector function (e.g., as assayed in an NK-dependent or macrophage-dependent assay). Fc region modifications that alter effector function may include modifications that increase binding to activating receptors (e.g., FcyRIIA (CD16A)) and reduce binding to inhibitory receptors (e.g., FcyRIIB (CD32B)) (see, e.g., Stavenhagen, J.B. et al. (2007) Cancer Res. 57(18):8882-8890). Examples of variants of human lgG1 Fc regions with reduced binding to CD32B and/or increased binding to CD16A contain F243L, R292P, Y300L, V305I and/or P396L substitutions. Amino acid positions correspond to the amino acid numbering of the CH2-CH3 domain provided above.

In some embodiments, an Fc region includes one or more modifications that reduce or abrogate binding of the Fc to Fc receptors. Such modifications may include amino acid substitutions at positions 234, 235, 265, and 297 (see e.g., U.S. Patent No 5,624,821, which is incorporated by reference herein). Example substitutions include one or more of L234A, L235A, D265A and N297Q. Amino acid positions correspond to the amino acid numbering of the CH2-CH3 domain provided above.

In some embodiments, an Fc region includes one or more modifications that alter (relative to a wild-type Fc region) the Ratio of Affinities of the modified Fc region to an activating FcyR (such as FcyRIIA or FcyRIIIA) relative to an inhibiting FcyR (such as FcyRIIB):

Where a modified Fc region has a Ratio of Affinities greater than 1, an anti-CD117 agent herein may have particular use in providing a therapeutic or prophylactic treatment of a disease, disorder, or infection, or the amelioration of a symptom thereof, where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcyR is desired, e.g., cancer or infectious disease. Where a modified Fc region has a Ratio of Affinities less than 1, an anti- CD117 agent herein may have particular use in providing a therapeutic or prophylactic treatment of a disease or disorder, or the amelioration of a symptom thereof, where a decreased efficacy of effector cell function mediated by FcyR is desired, e.g., autoimmune or inflammatory disorders. Table 3 lists example single, double, triple, quadruple and quintuple amino acid substitutions having a Ratio of Affinities greater than 1 or less than 1 (see e.g., PCT Publication Nos. WO 04/063351; WO 06/088494; WO 07/024249; WO 06/113665; WO 07/021841; WO 07/106707; WO 2008/140603, each of which is incorporated by reference herein). Amino acid positions correspond to the amino acid numbering of the CH2-CH3 domain provided above. Table 3: Example Single and Multiple Substitutions Listed by Ratio of Affinities

Agents That Competitively Bind with An Anti-CD117 Agent

Provided herein are anti-CD117 agents that competitively bind, or are capable of competitively binding, with one or more anti-CD117 agents described herein. In particular, provided herein are anti-CD117 agents that compete, or are capable of competing, with one or more anti- CD117 agents described herein for binding to CD117. Such agents that compete, or are capable of competing, with anti-CD117 agents described herein may be referred to as competitor agents. In certain instances, an agent (i.e., competitor agent) may be considered to compete for binding to CD117 when the competitor binds to the same general region of CD117 as an anti-CD117 agent described herein (i.e., extracellular region or leucine-rich binding domain). In certain instances, an agent (i.e., competitor agent) may be considered to compete for binding to CD117 when the competitor binds to the exact same region of CD117 as an anti-CD117 agent described herein (e.g., exact same peptide (linear epitope) or exact same surface amino acids (conformational epitope)). In certain instances, an agent (i.e., competitor agent) may be considered capable of competing for binding to CD117 when the competitor binds to the same general region of CD117 as an anti-CD117 agent described herein (i.e., extracellular region or leucine-rich binding domain) under suitable assay conditions. In certain instances, an agent (i.e., competitor agent) may be considered capable of competing for binding to CD117 when the competitor binds to the exact same region of CD117 as an anti-CD117 agent described herein (e.g., exact same peptide (linear epitope) or exact same surface amino acids (conformational epitope)) under suitable assay conditions.

In certain instances, an agent (i.e., competitor agent) may be considered to compete for binding to CD117 when the competitor blocks the binding of one or more anti-CD117 agents described herein to CD117. In certain instances, an agent (i.e., competitor agent) may be considered capable of competing for binding to CD117 when the competitor blocks the binding of one or more anti-CD117 agents described herein to CD117 under suitable assay conditions. Whether a competitor blocks the binding of one or more anti-CD117 agents described herein to CD117 may be determined using a suitable competition assay or blocking assay, such as, for example, a blocking assay as described herein. A competitor agent may block binding of one or more anti-CD117 agents described herein to CD117 in a competition or blocking assay by 50% or more, and conversely, one or more anti-CD117 agents described herein may block binding of the competitor agent to CD117 in a competition or blocking assay by about 50% or more. For example, an agent (i.e., competitor agent) may block binding of one or more anti- CD117 agents described herein to CD117 in a competition or blocking assay by about 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%, and conversely, one or more anti- CD117 agents described herein may block binding of the competitor agent to CD117 in a competition or blocking assay by about 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%.

In certain instances, an agent (i.e., competitor agent) may be considered to compete for binding to CD117 when the competitor binds to CD117 with a similar affinity as one or more anti-CD117 agents described herein. In certain instances, an agent (i.e., competitor agent) may be considered capable of competing for binding to CD117 when the competitor binds to CD117 with a similar affinity as one or more anti-CD117 agents described herein under suitable assay conditions. In some embodiments, an agent (i.e., competitor agent) is considered to compete for binding to CD117 when the competitor binds to CD117 with an affinity that is at least about 50% of the affinity of one or more anti-CD117 agents described herein. For example, an agent (i.e., competitor agent) may be considered to compete for binding to CD117 when the competitor binds to CD117 with an affinity that is at least about 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of the affinity of one or more anti- CD117 agents described herein. A competitor agent may comprise any feature described herein for anti-CD117 agents.

Also provided herein are anti-CD117 agents that bind to, or are capable of binding to, the same epitope as one or more anti-CD117 agents described herein. In particular, provided herein are anti-CD117 agents that compete with one or more anti-CD117 agents described herein for binding to the same epitope on CD117. Such agents that bind the same epitope may be referred to as epitope competitors. In certain instances, an epitope competitor may bind to the exact same region of CD117 as an anti-CD117 agent described herein (e.g., exact same peptide (linear epitope) or exact same surface amino acids (conformational epitope)). In certain instances, an epitope competitor blocks the binding of one or more anti-CD117 agents described herein to CD117. An epitope competitor may block binding of one or more anti-CD117 agents described herein to CD117 in a competition assay by about 50% or more, and conversely, one or more anti-CD117 agents described herein may block binding of the epitope competitor to CD117 in a competition assay by 50% or more. In certain instances, an epitope competitor binds to CD117 with a similar affinity as one or more anti-CD117 agents described herein. In some embodiments, an epitope competitor binds to CD117 with an affinity that is at least about 50% of the affinity of one or more anti-CD117 agents described herein. For example, an epitope competitor may bind to CD117 with an affinity that is at least about 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of the affinity of one or more anti-CD117 agents described herein. An epitope competitor may comprise any feature described herein for anti-CD117 agents.

Antibody Preparation

In some embodiments, an anti-CD117 agent is an antibody. Methods for generating anti- CD117 antibodies and variants of anti-CD117 antibodies are described in the Examples below. In some embodiments, an anti-CD117 agent is a humanized antibody, or an antigen binding fragment thereof. Humanized anti-CD117 antibodies may be prepared, e.g., in a genetically engineered (i.e., transgenic) mouse (e.g., from Medarex) that, when presented with an immunogen, can produce a human antibody that does not necessarily require CDR grafting. These antibodies are fully human (100% human protein sequences) from animals such as mice in which the non-human antibody genes are suppressed and replaced with human antibody gene expression. Antibodies may be generated against CD117 when presented to these genetically engineered mice or other animals that can produce human frameworks for the relevant CDRs.

Where a variant is generated, the parent antibody is prepared. Example techniques for generating such nonhuman antibody and parent antibodies are described in the following sections.

Antigen Preparation

The antigen for production of antibodies may be, e.g., intact CD117, particularly expressed in cells, or a portion of CD117 (e.g., N-terminal domain, C-terminal domain, a cytoplasmic domain, an intra-organelle domain, a transmembrane domain, an extracellular domain, an ectodomain, a TIR domain, a leucine-rich domain, or a CD117 fragment comprising a desired epitope). Other forms of antigens useful for generating antibodies will be apparent to those skilled in the art.

Polyclonal Antibodies

Polyclonal antibodies may be raised in animals (vertebrate or invertebrates, including mammals, birds and fish, including cartilaginous fish) by multiple subcutaneous (sc) or intraperitoneal (ip) injections of a relevant antigen and an adjuvant. It may be useful to conjugate the relevant antigen to a protein or other carrier that is immunogenic in the species to be immunized, e.g., keyhole limpet hemocyanin, serum albumin, bovine thyroglobulin, or soybean trypsin inhibitor using a bifunctional or derivatizing agent, for example, maleimidobenzoyl sulfosuccinimide ester (conjugation through cysteine residues), N- hydroxysuccinimide (through lysine residues), glutaraldehyde, succinic anhydride, SOCI₂, or R¹N=C=NR, where R and R¹ are different alkyl groups. Non-protein carriers (e.g., colloidal gold) also may be used for antibody production.

Animals are immunized against the antigen, immunogenic conjugates, or derivatives by combining, e.g., 100 μg or 5 μg of the protein or conjugate (for rabbits or mice, respectively) with three volumes of Freund's complete adjuvant and injecting the solution intradermally at multiple sites. One month later the animals are boosted with one-fifth to one-tenth of the original amount of peptide or conjugate in Freund's complete adjuvant by subcutaneous injection at multiple sites. Seven to 14 days later the animals are bled and the serum is assayed for antibody titer. Animals are boosted until the titer plateaus. Often, the animal is boosted with the conjugate of the same antigen, but conjugated to a different protein and/or through a different cross-linking reagent. Conjugates also can be made in recombinant cell culture as protein fusions. Also, aggregating agents such as alum are suitably used to enhance the immune response.

Monoclonal Antibodies

Monoclonal antibodies may be made using the hybridoma method first described by Kohler et al., Nature, 256:495 (1975), or may be made by other methods such as recombinant DNA methods (U.S. Pat. No. 4,816,567). In the hybridoma method, a mouse or other appropriate host animal, such as a hamster or macaque monkey, is immunized as hereinabove described to elicit lymphocytes that produce or are capable of producing antibodies that will specifically bind to the protein used for immunization. Alternatively, lymphocytes may be immunized in vitro. Lymphocytes then are fused with myeloma cells using a suitable fusing agent, such as polyethylene glycol, to form a hybridoma cell (Goding, Monoclonal Antibodies: Principles and Practice, pp.59-103 (Academic Press, 1986)).

The hybridoma cells thus prepared are seeded and grown in a suitable culture medium that may contain one or more substances that inhibit the growth or survival of the unfused, parental myeloma cells. For example, if the parental myeloma cells lack the enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT or HPRT), the culture medium for the hybridomas typically will include hypoxanthine, aminopterin, and thymidine (HAT medium), which substances prevent the growth of HGPRT -deficient cells. Preferred myeloma cells are those that fuse efficiently, support stable high-level production of antibody by the selected antibody-producing cells, and are sensitive to a medium such as HAT medium. Among these, preferred myeloma cell lines are murine myeloma lines, such as SP- 2 or X63-Ag8-653 cells available from the American Type Culture Collection, Rockville, Md. USA. Human myeloma and mouse-human heteromyeloma cell lines also have been described for the production of human monoclonal antibodies (Kozbor, J. Immunol., 133:3001 (1984); Brodeur et al., Monoclonal Antibody Production Techniques and Applications, pp. 51-63 (Marcel Dekker, Inc., New York, 1987)).

Culture medium in which hybridoma cells are growing is assayed for production of monoclonal antibodies directed against the antigen. The binding specificity of monoclonal antibodies produced by hybridoma cells may be determined by immunoprecipitation, by an in vitro binding assay, such as radioimmunoassay (RIA) or enzyme-linked immunoabsorbant assay (ELISA), or by flow cytometric analysis of cells expressing the membrane antigen. The binding affinity of the monoclonal antibody can, for example, be determined by the Scatchard analysis of Munson et al., Anal. Biochem., 107:220 (1980).

After hybridoma cells are identified that produce antibodies of the desired specificity, affinity, and/or activity, the clones may be subcloned by limiting dilution procedures and grown by standard methods (Goding, Monoclonal Antibodies: Principles and Practice, pp.59-103 (Academic Press, 1986)). Suitable culture media for this purpose include, for example, D-MEM or RPMI-1640 medium. In addition, the hybridoma cells may be grown in vivo as ascites tumors in an animal. The monoclonal antibodies secreted by the subclones are suitably separated from the culture medium, ascites fluid, or serum by conventional immunoglobulin purification procedures such as, for example, protein A-Sepharose, hydroxylapatite chromatography, gel electrophoresis, dialysis, or affinity chromatography.

DNA encoding the monoclonal antibodies is readily isolated and sequenced using conventional procedures (e.g., by using oligonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of the monoclonal antibodies). Alternatively, cDNA may be prepared from mRNA and the cDNA then subjected to DNA sequencing. The hybridoma cells serve as a preferred source of such genomic DNA or RNA for cDNA preparation. Once isolated, the DNA may be placed into expression vectors, which are well known in the art, and which are then transfected into host cells such as E coli cells, simian COS cells, Chinese hamster ovary (CHO) cells, or myeloma cells that do not otherwise produce immunoglobulin protein, to obtain the synthesis of monoclonal antibodies in the recombinant host cells. Recombinant production of antibodies will be described in more detail below. Humanization and Amino Acid Sequence Variants

General methods for humanization of antibodies are described, for example, in U.S. Patent Nos. 5861155, 6479284, 6407213, 6639055, 6500931 , 5530101 , 5585089, 5693761 , 5693762, 6180370, 5714350, 6350861 , 5777085, 5834597, 5882644, 5932448, 6013256, 6129914, 6210671 , 6329511, 5225539, 6548640, and 5624821 , each of which is incorporated by reference herein. In certain embodiments, it may be desirable to generate amino acid sequence variants of these humanized antibodies, particularly where these improve the binding affinity or other biological properties of the antibody.

Amino acid sequence variants of the anti-CD117 antibody are prepared by introducing appropriate nucleotide changes into the anti-CD117 antibody DNA, or by peptide synthesis. Such variants include, for example, deletions from, and/or insertions into and/or substitutions of, residues within the amino acid sequences of the anti-CD117 antibodies for the examples herein. Any combination of deletion, insertion, and substitution is made to arrive at the final construct, provided that the final construct possesses the desired characteristics. The amino acid changes also may alter post-translational processes of the humanized or variant anti- CD117 antibody, such as changing the number or position of glycosylation sites.

One method for identification of certain residues or regions of the anti-CD117 antibody that are preferred locations for mutagenesis is called "alanine scanning mutagenesis," as described by Cunningham and Wells Science, 244:1081-1085 (1989). Here, a residue or group of target residues are identified (e.g., charged residues such as arg, asp, his, lys, and glu) and replaced by a neutral or negatively charged amino acid (most preferably alanine or polyalanine) to affect the interaction of the amino acids with CD117 antigen. Those amino acid locations demonstrating functional sensitivity to the substitutions then are refined by introducing further or other variants at, or for, the sites of substitution. Thus, while the site for introducing an amino acid sequence variation is predetermined, the nature of the mutation per se need not be predetermined. For example, to analyze the performance of a mutation at a given site, alanine scanning or random mutagenesis is conducted at the target codon or region and the expressed anti-CD117 antibody variants are screened for the desired activity. Amino acid sequence insertions include amino- and/or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing a hundred or more residues, as well as intrasequence insertions of single or multiple amino acid residues. Examples of terminal insertions include an N-terminal methionyl residue or the antibody fused to an epitope tag. Other insertional variants include the fusion of an enzyme or a polypeptide that increases the serum half-life of the antibody to the N- or C-terminus of the antibody. Another type of variant is an amino acid substitution variant. These variants have at least one amino acid residue removed from the antibody molecule and a different residue inserted in its place. The sites of greatest interest for substitutional mutagenesis include the hypervariable regions, but FR alterations are also contemplated. Conservative substitutions are preferred, but more substantial changes may be introduced and the products may be screened. Examples of substitutions are listed below:

Example Amino Acid Residue Substitutions Ala (A) val; leu; ile; val Arg (R) lys; gin; asn; lys Asn (N) gin; his; asp, lys; gin; arg Asp (D) glu; asn Cys (C) ser; ala Gin (Q) asn; glu Glu (E) asp; gin Gly (G) ala

His (H) asn; gin; lys; arg

Ile (I) leu; val; met; ala; leu; phe; norleucine

Leu (L) norleucine; ile; val; ile; met; ala; phe

Lys (K) arg; gin; asn

Met (M) leu; phe; ile

Phe (F) leu; val; ile; ala; tyr

Pro (P) ala

Ser (S) thr

Thr (T) ser

T rp (W) tyr; phe

Tyr (Y) trp; phe; thr; ser

Val (V) ile; leu; met; phe; ala; norleucine

Substantial modifications in the biological properties of an antibody are accomplished by selecting substitutions that differ significantly in their effect on maintaining (a) the structure of the polypeptide backbone in the area of the substitution, for example, as a sheet or helical conformation, (b) the charge or hydrophobicity of the molecule at the target site, or (c) the bulk of the side chain. Naturally occurring residues are divided into groups based on common side- chain properties:

(1) hydrophobic: norleucine, met, ala, val, leu, ile;

(2) neutral hydrophilic: cys, ser, thr; (3) acidic: asp, glu;

(4) basic: asn, gin, his, lys, arg;

(5) residues that influence chain orientation: gly, pro; and

(6) aromatic: trp, tyr, phe

Non-conservative substitutions will entail exchanging a member of one of these classes for another class.

Any cysteine residue not involved in maintaining the proper conformation of the antibody also may be substituted, to improve the oxidative stability of the molecule and prevent aberrant crosslinking. Conversely, cysteine bond(s) may be added to the antibody to improve its stability (particularly where the antibody is an antibody fragment such as an Fv fragment).

One type of substitutional variant involves substituting one or more hypervariable region residues of a parent antibody (e.g., a humanized or human antibody). Generally, the resulting variant(s) selected for further development will have improved biological properties relative to the parent antibody from which they are generated. A convenient way for generating such substitutional variants is affinity maturation using phage display. Briefly, several hypervariable region sites (e.g., 6-7 sites) are mutated to generate all possible amino acid substitutions at each site.

The antibody variants thus generated are displayed in the monovalent fashion from filamentous phage particles as fusions to the gene III product of M13 packaged within each particle. The phage-displayed variants are then screened for their biological activity (e.g., binding affinity) as herein disclosed. In order to identify candidate hypervariable region sites for modification, alanine-scanning mutagenesis can be performed to identify hypervariable region residues contributing significantly to antigen binding. Alternatively, or in addition, it may be beneficial to analyze a crystal structure of the antigen-antibody complex to identify contact points between the antibody and antigen. Such contact residues and neighboring residues are candidates for substitution according to the techniques elaborated herein. Once such variants are generated, the panel of variants is subjected to screening as described herein and antibodies with superior properties in one or more relevant assays may be selected for further development.

Another type of amino acid variant of the antibody alters the original glycosylation pattern of the antibody. By altering is meant deleting one of more carbohydrate moieties found in the antibody, and/or adding one or more glycosylation sites that are not present in the antibody. Glycosylation of antibodies is typically either N-linked and/or O-linked. N-linked refers to the attachment of the carbohydrate moiety to the side chain of an asparagine residue. The tripeptide sequences asparagine-X-serine and asparagine-X-threonine, where X is any amino acid except proline, are the most common recognition sequences for enzymatic attachment of the carbohydrate moiety to the asparagine side chain. Thus, the presence of either of these tripeptide sequences in a polypeptide creates a potential glycosylation site. O-linked glycosylation refers to the attachment of one of the sugars N-acetylgalactosamine, galactose, or xylose to a hydroxyamino acid, most commonly serine or threonine, although 5- hydroxyproline or 5-hydroxylysine may also be used.

Addition of glycosylation sites to the antibody is conveniently accomplished by altering the amino acid sequence such that it contains one or more of the above-described tripeptide sequences (for N-linked glycosylation sites). The alteration may also be made by the addition of, or substitution by, one or more serine or threonine residues to the sequence of the original antibody (for O-linked glycosylation sites).

Nucleic acid molecules encoding amino acid sequence variants of anti-CD117 antibodies herein are prepared by a variety of methods known in the art. These methods include, but are not limited to, isolation from a natural source (in the case of naturally occurring amino acid sequence variants) or preparation by oligonucleotide-mediated (or site-directed) mutagenesis, PCR mutagenesis, and cassette mutagenesis of an earlier prepared variant or a non-variant version of an anti-CD117 antibody.

Human Antibodies

As an alternative to humanization, human antibodies can be generated. For example, transgenic animals (e.g., mice) may be generated that are capable, upon immunization, of producing a full repertoire of human antibodies in the absence of endogenous immunoglobulin production. For example, a homozygous deletion of the antibody heavy chain joining region (JH) gene in chimeric and germ-line mutant mice results in complete inhibition of endogenous antibody production. Transfer of the human germ-line immunoglobulin gene array into such germ-line mutant mice can result in the production of human antibodies upon antigen challenge (see, e.g., Jakobovits et al., Proc. Natl. Acad. Sci. USA, 90:2551 (1993); Jakobovits et al. , Nature, 362:255-258(1993); Bruggermann et al. , Year in Immuno., 7:33 (1993); and U.S. Pat. Nos. 5,591,669, 5,589,369 and 5,545,807). Human antibodies also can be derived from phage-display libraries (Hoogenboom et al., J. Mol. Biol., 227:381 (1991); Marks et al., J. Mol. Biol., 222:581-597 (1991); and U.S. Pat. Nos. 5,565,332 and 5,573,905). Human antibodies also may be generated by in vitro activated B cells (see U.S. Pat. Nos. 5,567,610 and 5,229,275). Antigen-Binding Antibody Fragments

In certain embodiments, an anti-CD117 agent is an antibody fragment that retains at least one desired activity, including antigen binding. Various techniques have been developed for the production of antibody fragments. In some instances, these fragments are derived via proteolytic digestion of intact antibodies (see, e.g., Morimoto et al. , Journal of Biochemical and Biophysical Methods 24:107-117(1992) and Brennan et al., Science 229:81 (1985)). In some instances, these fragments are produced directly by recombinant host cells. For example, Fab'-SH fragments can be directly recovered from E. coli and chemically coupled to form F(ab’)2 fragments (Carter et al., Bio/Technology 10:163-167 (1992)). In some instances, the F(ab’)2 is formed using the leucine zipper GCN4 to promote assembly of the F(ab’)2 molecule. According to another approach, Fv, Fab or F(ab’)2 fragments can be isolated directly from recombinant host cell culture. Other techniques for the production of antibody fragments will be apparent to the skilled practitioner.

Multispecific Antibodies and other Agents

In some embodiments, an anti-CD117 agent comprises a first binding moiety and a second binding moiety, where the first binding moiety is specifically reactive with a first molecule that is CD117 and the second binding moiety is specifically reactive with a second molecule that is a molecular species different from the first molecule. Such agents may comprise a plurality of first binding moieties, a plurality of second binding moieties, or a plurality of first binding moieties and a plurality of second binding moieties. Preferably, the ratio of first binding moieties to second binding moieties is about 1:1, although it may range from about 1000:1 to about 1 : 1000, where the ratio may be measured in terms of valency.

In those embodiments where the first moiety is an antibody, the second binding moiety may also be an antibody. In some embodiments, the first and second moieties are linked via a linker moiety, which may have two to many hundreds or even thousands of valencies for attachment of first and second binding moieties by one or different chemistries. Examples of bispecific antibodies include those that are reactive against two different epitopes; in some instances, one epitope is a CD117 epitope and the second epitope is on an unrelated soluble molecule. In some embodiments, the bispecific antibody is reactive against an epitope on CD117 and against an epitope on a different molecule found on the surface of a different cell.

Compositions herein may also comprise a first agent and a second agent, where the first agent comprises a first binding moiety specifically reactive with a first molecule (e.g., CD117) and the second agent comprises a second binding moiety specifically reactive with a second molecule that is a molecular species different than the first molecule. The first and/or second agent may be an antibody. The ratio of first agent to second agent may range from about 1,000: 1 to 1:1,000, although the preferred ratio is about 1 :1. In some embodiments, it may be desirable to generate multispecific (e.g., bispecific) anti-CD117 antibodies having binding specificities for at least two different epitopes. Certain bispecific antibodies may bind to two different epitopes of CD117. Bispecific antibodies can be prepared as full-length antibodies or antibody fragments (e.g., F(ab')₂ bispecific antibodies).

According to one method for making bispecific antibodies, the interface between a pair of antibody molecules can be engineered to maximize the percentage of heterodimers that are recovered from recombinant cell culture. The preferred interface comprises at least a part of the CH3 domain of an antibody constant domain. In this method, one or more small amino acid side chains from the interface of the first antibody molecule are replaced with larger side chains (e.g., tyrosine or tryptophan). Compensatory "cavities" of identical or similar size to the large side chain(s) are created on the interface of the second antibody molecule by replacing large amino acid side chains with smaller ones (e.g., alanine or threonine). This provides a mechanism for increasing the yield of the heterodimer over other unwanted end products such as homodimers (see e.g., WO96/27011 published Sep. 6, 1996).

Bispecific antibodies include cross-linked or "heteroconjugate" antibodies. For example, one of the antibodies in the heteroconjugate can be coupled to avidin, the other to biotin. Heteroconjugate antibodies may be made using any convenient cross-linking methods. Suitable cross-linking agents are well known in the art, and are disclosed in U.S. Pat. No. 4,678,980, along with a number of cross-linking techniques.

Any suitable technique may be used for generating bispecific antibodies from antibody fragments. For example, bispecific antibodies can be prepared using chemical linkage. In certain methods, intact antibodies are proteolytically cleaved to generate F(ab’)2 fragments (see e.g., Brennan et al., Science 229:81 (1985), which is incorporated by reference herein). These fragments are reduced in the presence of the dithiol complexing agent sodium arsenite to stabilize vicinal dithiols and prevent intermolecular disulfide formation. The Fab' fragments generated are then converted to thionitrobenzoate (TNB) derivatives. One of the Fab'-TNB derivatives is then reconverted to the Fab'-thiol by reduction with mercaptoethylamine and is mixed with an equimolar amount of the other Fab'-thiol derivative to form the bispecific antibody. In yet a further embodiment, Fab'-SH fragments directly recovered from E. coli can be chemically coupled in vitro to form bispecific antibodies (see e.g., Shalaby et al., J. Exp. Med. 175:217-225 (1992), which is incorporated by reference herein).

Any suitable technique for making and isolating bispecific antibody fragments directly from recombinant cell culture may be used. For example, bispecific antibodies have been produced using leucine zippers (see e.g., Kostelny et al., J. Immunol. 148(5): 1547-1553 (1992), which is incorporated by reference herein). The leucine zipper peptides from the Fos and Jun proteins were linked to the Fab' portions of two different antibodies by gene fusion. The antibody homodimers were reduced at the hinge region to form monomers and then reoxidized to form the antibody heterodimers. This method can also be utilized for the production of antibody homodimers. The "diabody" technology described by Hollinger et al. , Proc. Natl. Acad. Sci. USA 90:6444-6448 (1993) has provided an alternative mechanism for making bispecific antibody fragments. The fragments comprise a heavy chain variable domain (VH) connected to a light chain variable domain (VL) by a linker that is too short to allow pairing between the two domains on the same chain. Accordingly, the VH and VL domains of one fragment are forced to pair with VL and VH domains of another fragment, thereby forming two antigen-binding sites. Another strategy for making bispecific antibody fragments by the use of single chain Fv (scFv) dimers (see e.g., Gruber et al., J. Immunol. 152:5368 (1994), which is incorporated by reference herein). In certain instances, a bispecific antibody may be a "linear antibody" produced as described in Zapata et al. Protein Eng. 8(10): 1057-1062 (1995), which is incorporated by reference herein.

Antibodies with two valencies or more are contemplated herein. An antibody (or polymer or polypeptide) herein comprising one or more binding sites per arm or fragment thereof will be referred to herein as a "multivalent" antibody. For example, a "bivalent" antibody herein comprises two binding sites per Fab or fragment thereof whereas a "trivalent" polypeptide herein comprises three binding sites per Fab or fragment thereof. In a multivalent polymer herein, the two or more binding sites per Fab may be binding to the same or different antigens. For example, the two or more binding sites in a multivalent polypeptide herein may be directed against the same antigen, for example against the same parts or epitopes of said antigen or against two or more same or different parts or epitopes of said antigen; and/or may be directed against different antigens; or a combination thereof. Thus, a bivalent polypeptide herein, for example, may comprise two identical binding sites, may comprise a first binding sites directed against a first part or epitope of an antigen and a second binding site directed against the same part or epitope of said antigen or against another part or epitope of said antigen; or may comprise a first binding sites directed against a first part or epitope of an antigen and a second binding site directed against a different antigen. However, as will be clear from the description hereinabove, the technology herein is not limited thereto, in the sense that a multivalent polypeptide herein may comprise any number of binding sites directed against the same or different antigens. In one embodiment the multivalent polypeptide comprises at least two ligand binding elements, one of which contains one or more CDR peptide sequences shown herein. In another embodiment the multivalent polypeptide comprises three ligand binding sites, each independently selected from the CDR sequences disclosed herein. In certain embodiments, at least one of the ligand binding elements binds CD117. In one embodiment, at least one of the ligand binding elements binds another target. In one embodiment, there are up to 10,000 binding elements in a multivalent binding molecule, and the ligand binding elements may be linked to a scaffold.

An antibody (or polymer or polypeptide) herein that contains at least two binding sites per Fab or fragment thereof, in which at least one binding site is directed against a firs antigen and a second binding site directed against a second antigen different from the first antigen, may also be referred to as "multispecific." Thus, a "bispecific" polymer comprises at least one site directed against a first antigen and at least one second site directed against a second antigen, whereas a "trispecific" is a polymer that comprises at least one binding site directed against a first antigen, at least one further binding site directed against a second antigen, and at least one further binding site directed against a third antigen: and the like. Accordingly, in their simplest form, a bispecific polypeptide herein is a bivalent polypeptide (per Fab) of the technology provided herein. However, as will be clear from the description hereinabove, the technology herein is not limited thereto, in the sense that a multispecific polypeptide herein may comprise any number of binding sites directed against two or more different antigens.

Other Modifications

Other modifications of an anti-CD117 agent are contemplated. For example, technology herein also pertains to immunoconjugates comprising an antibody described herein (e.g., an anti-CD117 antibody) conjugated to a cytotoxic agent such as a toxin (e.g., an enzymatically active toxin of bacterial, fungal, plant or animal origin, or fragments thereof), or a radioactive isotope (for example, a radioconjugate), or a cytotoxic drug. Such conjugates are sometimes referred to as "agent-drug conjugates" or "ADC." Conjugates are made using a variety of bifunctional protein coupling agents such as N-succinimidyl-3-(2-pyridyldithiol) propionate (SPDP), iminothiolane (IT), bifunctional derivatives of imidoesters (such as dimethyl adipimidate HCL), active esters (such as disuccinimidyl suberate), aldehydes (such as glutaraldehyde), bis-azido compounds (such as bis-(p-azidobenzoyl)hexanediamine), bis- diazonium derivatives (such as bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such as tolyene 2,6-diisocyanate), and bis-active fluorine compounds (such as 1 ,5-difluoro- 2, 4-dinitrobenzene).

Anti-CD117 agents (e.g., anti-CD117 antibodies) disclosed herein may be formulated as immunoliposomes. Liposomes containing an antibody are prepared by methods know in the art, such as described in Epstein et al., Proc. Natl. Acad. Sci. USA 82:3688 (1985); Hwang et al., Proc. Natl. Acad. Sci. USA 77:4030 (1980); and U.S. Pat. Nos. 4,485,045 and 4,544,545. Liposomes with enhanced circulation time are disclosed in U.S. Pat. No. 5,013,556. For example, liposomes can be generated by the reverse phase evaporation method with a lipid composition comprising phosphatidylcholine, cholesterol and PEG-derivatized phosphatidylethanolamine (PEG-PE). Liposomes are extruded through filters of defined pore size to yield liposomes with the desired diameter. Fab' fragments of an antibody provided herein can be conjugated to the liposomes as described in Martin et al., J. Biol. Chem. 257:286-288 (1982) via a disulfide interchange reaction. Another active ingredient is optionally contained within the liposome.

Enzymes or other polypeptides can be covalently bound to an anti-CD117 agent (e.g., anti- CD117 antibody) by techniques well known in the art such as the use of the heterobifunctional cross-linking reagents discussed above. In some embodiments, fusion proteins comprising at least the antigen binding region of an antibody provided herein linked to at least a functionally active portion of an enzyme can be constructed using recombinant DNA techniques well known in the art (see, e.g., Neuberger et al., Nature 312:604-608 (1984)).

In certain embodiments, it may be desirable to use an antibody fragment, rather than an intact antibody, to increase penetration of target tissues and cells, for example. In such instances, it may be desirable to modify the antibody fragment in order to increase its serum half-life. This may be achieved, for example, by incorporation of a salvage receptor binding epitope into the antibody fragment (e.g., by mutation of the appropriate region in the antibody fragment or by incorporating the epitope into a peptide tag that is then fused to the antibody fragment at either end or in the middle, e.g., by DNA or peptide synthesis; see, e.g., W096/32478 published Oct. 17, 1996).

In some embodiments, any of the antibodies or antigen fragments thereof disclosed herein are conjugated or hybridized to an oligonucleotide label. In some embodiments, the oligonucleotide label includes a sample barcode sequence, a binding site for a primer and an anchor. In some embodiments, the oligonucleotide label can be conjugated or hybridized to any of the detectable markers or labels disclosed herein. In some embodiments, the oligonucleotide label is a polymeric sequence. In some embodiments, the terms "oligonucleotide" and "polynucleotide" are used interchangeably to refer to a single-stranded multimer of nucleotides from about 2 to about 500 nucleotides in length. In some embodiments, any of the oligonucleotide labels described herein can be synthetic, made enzymatically (e.g., via polymerization), or using a "split-pool" method. In some embodiments, any of the oligonucleotide labels described herein can include ribonucleotide monomers (i.e. , can be oligoribonucleotides) and/or deoxyribonucleotide monomers (i.e., oligodeoxyribonucleotides). In some embodiments, any of the oligonucleotide labels described herein can include a combination of both deoxyribonucleotide monomers and ribonucleotide monomers in the oligonucleotide (e.g., random or ordered combination of deoxyribonucleotide monomers and ribonucleotide monomers). In some embodiments, the oligonucleotide label can be 4 to 10, 10 to 20, 21 to 30, 31 to 40, 41 to 50, 51 to 60, 61 to 70, 71 to 80, 80 to 100, 100 to 150, 150 to 200, 200 to 250, 250 to 300, 300 to 350, 350 to 400, or 400-500 nucleotides in length. In some embodiments, any of the oligonucleotide labels described herein can include one or more functional moieties that are attached (e.g., covalently or non-covalently) to another structure. In some embodiments, any of the oligonucleotide labels described herein can include one or more detectable labels (e.g., a radioisotope or fluorophore). In some embodiments, the anchor is a defined polymer, e.g., a polynucleotide or oligonucleotide sequence, which is designed to hybridize to a complementary oligonucleotide sequence. In some embodimentsthe anchor is designed for the purpose of generating a double stranded construct oligonucleotide sequence. In some embodiments, the anchor is positioned at the 3' end of the construct oligonucleotide sequence. In other embodiments, the anchor is positioned at the 5' end of the construct oligonucleotide sequence. Each anchor is specific for its intended complementary sequence.

In some embodiments, the sample barcode sequence is a polymer, e.g., a polynucleotide, which when it is a functional element, is specific for a single ligand. In some embodiments, the sample barcode sequence can be used for identifying a particular cell or substrate, e.g., Drop- seq microbead. In some embodiments, the sample barcode sequence can be formed of a defined sequence of DNA, RNA, modified bases or combinations of these bases, as well as any other polymer defined above. In some embodiments, the sample barcode sequence is about 2 to 4 monomeric components, e.g., nucleotide bases, in length. In other embodiments, the barcode is at least about 1 to 100 monomeric components, e.g., nucleotides, in length. Thus in various embodiments, the barcode is formed of a sequence of at least 1 , 2, 3, 4, 5, 6,

7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,

33, 34, 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,

58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82,

83, 84, 85, 86, 87, 88, 89, 80, 91, 92, 93, 94, 95, 96, 97, 98, 99 or up to 100 monomeric components, e.g., nucleic acids. In some embodiments, the sample barcode sequence is a particular barcode that can be unique relative to other barcodes.

In some of any embodiments, the sample barcode sequences can have a variety of different formats. For example, sample barcode sequences can include polynucleotide barcodes, random nucleic acid and/or amino acid sequences, and synthetic nucleic acid and/or amino acid sequences. A sample barcode sequence can be attached to an analyte or to another moiety or structure in a reversible or irreversible manner. A sample barcode sequences can be added to, for example, a fragment of a deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) sample before or during sequencing of the sample. Sample barcode sequences can allow for identification and/or quantification of individual sequencing-reads (e.g., a barcode can be or can include a unique molecular identifier or "UMI").

Sample barcode sequences can spatially-resolve molecular components found in biological samples, for example, at single-cell resolution (e.g., a barcode can be or can include a "spatial barcode"). In some embodiments, a barcode includes both a UMI and a spatial barcode. In some embodiments, a barcode includes two or more sub-barcodes that together function as a single barcode. For example, a polynucleotide barcode can include two or more polynucleotide sequences (e.g., sub-barcodes) that are separated by one or more nonbarcode sequences.

In some embodiments, the binding site for a primer is a functional component of the oligonucleotide which itself is an oligonucleotide or polynucleotide sequence that provides an annealing site for amplification of the oligonucleotide. The binding site for a primer can be formed of polymers of DNA, RNA, PNA, modified bases or combinations of these bases, or polyamides, etc. In some embodiments, the binding site for a primer is about 10 of such monomeric components, e.g., nucleotide bases, in length. In other embodiments, the binding site for a primer is at least about 5 to 100 monomeric components, e.g., nucleotides, in length. Thus in various embodiments, the binding site for a primer is formed of a sequence of at least

5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, 55, 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65, 66, 67, 68, 69, 70, 71 , 72, 73, 74, 75, 76, 77, 78, 79, 80,

81 , 82, 83, 84, 85, 86, 87, 88, 89, 80, 91 , 92, 93, 94, 95, 96, 97, 98, 99 or up to 100 monomeric components, e.g., nucleic acids. In certain embodiments, the binding site for a primer can be a generic sequence suitable as a annealing site for a variety of amplification technologies. Amplification technologies include, but are not limited to, DNA-polymerase based amplification systems, such as polymerase chain reaction (PCR), real-time PCR, loop mediated isothermal amplification (LAMP, MALBAC), strand displacement amplification (SDA), multiple displacement amplification (MDA), recombinase polymerase amplification (RPA) and polymerization by any number of DNA polymerases (for example, T4 DNA polymerase, Sulfulobus DNA polymerase, Klenow DNA polymerase, Bst polymerase, Phi29 polymerase) and RNA-polymerase based amplification systems (such as T7-, T3-, and SP6-RNA- polymerase amplification), nucleic acid sequence based amplification (NASBA), self- sustained sequence replication (3SR), rolling circle amplification (RCA), ligase chain reaction (LCR), helicase dependent amplification (I), ramification amplification method and RNA-seq. Methods for conjugating or hybridizing an oligonucleotide label can be performed in a manner set forth in WO/2018/144813, WO/2016/018960, WO/2018/089438, WO/2014/182528, WO/2018/026873, WO/2021/188838.

In some embodiments, a modification can optionally be introduced into the antibodies ( e.g within the polypeptide chain or at either the N- or C-terminal), e.g., to extend in vivo half-life, such as PEGylation or incorporation of long-chain polyethylene glycol polymers (PEG). Introduction of PEG or long chain polymers of PEG increases the effective molecular weight of the polypeptides, for example, to prevent rapid filtration into the urine. In some embodiments, a lysine residue in the sequence is conjugated to PEG directly or through a linker. Such linker can be, for example, a Glu residue or an acyl residue containing a thiol functional group for linkage to the appropriately modified PEG chain. An alternative method for introducing a PEG chain is to first introduce a Cys residue at the C-terminus or at solvent exposed residues such as replacements for Arg or Lys residues. This Cys residue is then site-specifically attached to a PEG chain containing, for example, a maleimide function. Methods for incorporating PEG or long chain polymers of PEG are known in the art (described, for example, in Veronese, F. M., et al., Drug Disc. Today 10: 1451-8 (2005); Greenwald, R. B., et al., Adv. Drug Deliv. Rev. 55: 217-50 (2003); Roberts, M. J., et al., Adv. Drug Deliv. Rev., 54: 459-76 (2002)), the contents of which are incorporated herein by reference.

Covalent modifications of an anti-CD117 agent (e.g., anti-CD117 antibody) are also included within the scope of this technology. For example, modifications may be made by chemical synthesis or by enzymatic or chemical cleavage of an anti-CD117 antibody. Other types of covalent modifications of an antibody are introduced into the molecule by reacting targeted amino acid residues of the antibody with an organic derivatizing agent that is capable of reacting with selected side chains or the N- or C-terminal residues. Example covalent modifications of polypeptides are described in U.S. Pat. No. 5,534,615, specifically incorporated herein by reference. A preferred type of covalent modification of the antibody comprises linking the antibody to one of a variety of non-proteinaceous polymers, e.g., polyethylene glycol, polypropylene glycol, or polyoxyalkylenes, in the manner set forth in U.S. Pat. Nos. 4,640,835; 4,496,689; 4,301,144; 4,670,417; 4,791 ,192 or 4,179,337.

Nucleic Acids, Vectors, Host Cells, and Recombinant Methods

Technology described herein also provides isolated nucleic acids encoding an anti-CD117 agent (e.g., anti-CD117 antibody), vectors and host cells comprising the nucleic acid, and recombinant techniques for the production of the agent or antibody. A nucleic acid herein may include one or more subsequences, each referred to as a polynucleotide.

Provided herein are nucleic acids (e.g., isolated nucleic acids) comprising a nucleotide sequence that encodes an anti-CD117 agent or antibody, or fragment thereof. In some embodiments, a nucleic acid encodes an immunoglobulin heavy chain variable domain of an anti-CD117 agent provided herein. In some embodiments, a nucleic acid encodes an immunoglobulin light chain variable domain of an anti-CD117 agent provided herein. In some embodiments, a nucleic acid encodes an immunoglobulin heavy chain variable domain and an immunoglobulin light chain variable domain of an anti-CD117 agent provided herein. In some embodiments, a nucleic acid comprises a nucleotide sequence that encodes an amino acid sequence of any one of SEQ ID NOs: 1-99. For example, a nucleic acid may comprise a nucleotide sequence that encodes a CDR amino acid of any one of SEQ ID NOs: 31-99. A nucleic acid may comprise a nucleotide sequence that encodes an immunoglobulin heavy chain variable domain amino acid sequence of any one of SEQ ID NOs: 1-15. A nucleic acid may comprise a nucleotide sequence that encodes an immunoglobulin light chain variable domain amino acid sequence of any one of SEQ ID NOs: 16-30.

Provided herein is an isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin heavy chain variable domain of any of the anti-CD117 agent, antibodies or antigen-binding fragments thereof described herein. In some of any embodiments, the immunoglobulin heavy chain variable domain comprises the sequence of nucleotides set forth in any of SEQ ID NOs: 108-122.

Provided herein is an isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin light chain variable domain of any of the anti-CD117 agent, antibodies or antigen-binding fragments thereof described herein. In some of any embodiments, the immunoglobulin light chain variable domain comprises the sequence of nucleotides set forth in any of SEQ ID NOs: 123-137.

Provided herein is an isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin heavy chain variable domain and the immunoglobulin light chain variable domain of any of the anti-CD117 agent, antibodies or antigen-binding fragments thereof described herein.

In some of any embdiments, the nucleotide sequence that encodes the immunoglobulin heavy chain variable domain comprises the sequence set forth in any of SEQ ID NOs: 108-122; and the immunoglobulin light chain variable domain comprises the sequence of amino acids set forth in any of SEQ ID NOs: 123-137.

In some of any embodiments, any of the nucleic acids provided herein comprise a signal sequence. In some of any embodiments, any of the nucleic acids described ehrein do not comprise a signal sequence. For recombinant production of an anti-CD117 agent or antibody, a nucleic acid encoding the anti-CD117 agent or antibody may be isolated and inserted into a replicable vector for further cloning (amplification of the DNA) or for expression. In certain instances, an anti-CD117 agent or antibody may be produced by homologous recombination, e.g., as described in U.S. Pat. No.

5,204,244, specifically incorporated herein by reference. DNA encoding an anti-CD117 agent or antibody can be readily isolated and sequenced using conventional procedures (e.g., by using oligonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of the antibody). Many vectors are available. The vector components generally include, but are not limited to, one or more of the following: a signal sequence, and origin of replication, one or more marker genes, an enhancer element, a promoter, and a transcription termination sequence, e.g., as described in U.S. Pat. No. 5,534,615 issued Jul. 9, 1996 and specifically incorporated herein by reference.

Suitable host cells for cloning or expressing DNA in vectors herein are prokaryote, yeast, or higher eukaryote cells. Suitable prokaryotes for this purpose include eubacteria, such as Gram-negative or Gram-positive organisms, for example, Enterobacteriaceae such as Escherichia, e.g., E. coli, Enterobacter, Erwinia, Klebsiella, Proteus, Salmonella, e.g., Salmonella typhimurium, Serratia, e.g., Serratia marcescans, and Shigella, as well as Bacilli such as B. subtilis and B. licheniformis (e.g., B. licheniformis 41 P disclosed in DD 266,710 published 12 Apr. 1989), Pseudomonas such as P. aeruginosa, and Streptomyces. One preferred E. coli cloning host is E. coli 294 (ATCC 31 ,446), although other strains such as E. coli B, E. coli X₁ 776 (ATCC 31 ,537), and E. coli W3110 (ATCC 27,325) are suitable. These examples are illustrative rather than limiting.

In addition to prokaryotes, eukaryotic microbes such as filamentous fungi or yeast are suitable cloning or expression hosts for anti-CD117 agent or antibody-encoding vectors. Saccharomyces cerevisiae, or common baker's yeast, is the most commonly used among lower eukaryotic host microorganisms. A number of other genera, species, and strains are commonly available and useful herein, such as Schizosaccharomyces pombe; Kluyveromyces hosts such as, e.g., K. lactis, K. fragilis (ATCC 12,424), K. bulgaricus (ATCC 16,045), K. wickeramii (ATCC 24,178), K. waltii (ATCC 56,500), K. drosophilarum (ATCC 36,906), K. thermotolerans, and K. marxianus; yarrowia (EP 402,226); Pichia pastoris (EP 183,070); Candida; Trichoderma reesia (EP 244,234); Neurospora crassa; Schwanniomyces such as Schwanniomyces occidentalis; and filamentous fungi such as, e.g., Neurospora, Penicillium, Tolypocladium, and Aspergillus hosts such as A. nidulans and A. niger. Suitable host cells for the expression of anti-CD117 agents or antibodies (e.g., glycosylated anti-CD117 agents or antibodies) are derived from multicellular organisms. Examples of invertebrate cells include plant and insect cells. Numerous baculoviral strains and variants and corresponding permissive insect host cells from hosts such as Spodoptera frugiperda (caterpillar), Aedes aegypti (mosquito), Aedes albopictus (mosquito), Drosophila melanogaster (fruitfly), and Bombyx mori (silk moth) have been identified. A variety of viral strains for transfection are publicly available, e.g., the L-1 variant of Autographa californica NPV and the Bm-5 strain of Bombyx mori NPV, and such viruses may be used as the virus herein according to the present technology, particularly for transfection of Spodoptera frugiperda cells. Plant cell cultures of cotton, corn, potato, soybean, petunia, tomato, and tobacco can also be utilized as hosts.

Suitable host cells for the expression of anti-CD117 agents/antibodies also may include vertebrate cells (e.g., mammalian cells). Vertebrate cells may be propagated in culture (tissue culture). Examples of useful mammalian host cell lines include monkey kidney CV1 line transformed by SV40 (COS-7, ATCC CRL 1651); human embryonic kidney line (293 or 293 cells subcloned for growth in suspension culture, Graham et al., J. Gen Virol. 36:59 (1977)); baby hamster kidney cells (BHK, ATCC CCL 10); Chinese hamster ovary cells/-DHFR (CHO, Urlaub et al., Proc. Natl. Acad. Sci. USA 77:4216 (1980)); mouse Sertoli cells (TM4, Mather, Biol. Reprod. 23:243-251 (1980)); monkey kidney cells (CV1 ATCC CCL 70); African green monkey kidney cells (VERO-76, ATCC CRL-1587); human cervical carcinoma cells (HELA, ATCC CCL 2); canine kidney cells (MDCK, ATCC CCL 34); buffalo rat liver cells (BRL 3A, ATCC CRL 1442); human lung cells (W138, ATCC CCL 75); human liver cells (Hep G2, HB 8065); mouse mammary tumor (MMT 060562, ATCC CCL51); TRI cells (Mather et al., Annals N.Y. Acad. Sci. 383:44-68 (1982)); MRC 5 cells; FS4 cells; and a human hepatoma line (Hep G2).

Host cells may be transformed with the above-described expression or cloning vectors for antibody production and cultured in conventional nutrient media modified as appropriate for inducing promoters, selecting transformants, or amplifying the genes encoding the desired sequences.

Host cells used to produce an agent/antibody herein may be cultured in a variety of media. Commercially available media such as Ham's F10 (Sigma), Minimal Essential Medium ((MEM), (Sigma), RPMI-1640 (Sigma), and Dulbecco's Modified Eagle's Medium ((DMEM), Sigma) are suitable for culturing the host cells. In addition, any of the media described in Ham et al., Meth. Enz. 58:44 (1979), Barnes et al., Anal. Biochem.102:255 (1980), U.S. Pat. Nos. 4,767,704; 4,657,866; 4,927,762; 4,560,655; or 5,122,469; WO 90/03430; WO 87/00195; or U.S. Pat. Re. 30,985 may be used as culture media for the host cells. Any of these media may be supplemented as necessary with hormones and/or other growth factors (such as insulin, transferrin, or epidermal growth factor), salts (such as sodium chloride, calcium, magnesium, and phosphate), buffers (such as HEPES), nucleotides (such as adenosine and thymidine), antibiotics (such as GENTAMYCIN™), trace elements (defined as inorganic compounds usually present at final concentrations in the micromolar range), and glucose or an equivalent energy source. Any other necessary supplements may also be included at appropriate concentrations that would be known to those skilled in the art. The culture conditions, such as temperature, pH, and the like, are those previously used with the host cell selected for expression, and will be apparent to the ordinarily skilled artisan.

When using recombinant techniques, an agent/antibody can be produced intracellularly, in the periplasmic space, or directly secreted into the medium. If the antibody is produced intracellularly, as a first step, the particulate debris, either host cells or lysed fragments, is removed, for example, by centrifugation or ultrafiltration. Carter et al. , Bio/Technology 10:163- 167 (1992) describe a procedure for isolating antibodies that are secreted to the periplasmic space of E. coli. Briefly, cell paste is thawed in the presence of sodium acetate (pH 3.5), EDTA, and phenylmethylsulfonylfluoride (PMSF) over about 30 min. Cell debris can be removed by centrifugation. Where the antibody is secreted into the medium, supernatants from such expression systems are generally first concentrated using a commercially available protein concentration filter, for example, an Amicon or Millipore Pellicon ultrafiltration unit. A protease inhibitor such as PMSF may be included in any of the foregoing steps to inhibit proteolysis and antibiotics may be included to prevent the growth of adventitious contaminants.

The agent/antibody composition prepared from the cells can be purified using, for example, hydroxyl apatite chromatography, gel electrophoresis, dialysis, and affinity chromatography, with affinity chromatography being the preferred purification technique. The suitability of protein A as an affinity ligand depends on the species and isotype of any immunoglobulin Fc domain that is present in the antibody. Protein A can be used to purify antibodies that are based on human heavy chains (Lindmark et al., J. Immunol. Meth. 62:1-13 (1983)). Protein G is recommended for all mouse isotypes and for human g3 (Guss et al., EMBO J. 5:15671575 (1986)). The matrix to which the affinity ligand is attached is most often agarose, but other matrices are available. Mechanically stable matrices such as controlled pore glass or poly(styrenedivinyl)benzene allow for faster flow rates and shorter processing times than can be achieved with agarose. Where the antibody comprises a Cm domain, Bakerbond ABX.TM. resin (J. T. Baker, Phillipsburg, N.J.) is useful for purification. Other techniques for protein purification, such as fractionation on an ion-exchange column, ethanol precipitation, Reverse Phase HPLC, chromatography on silica, chromatography on heparin SEPHAROSE™, chromatography on an anion or cation exchange resin (such as a polyaspartic acid column), chromatofocusing, SDS-PAGE, and ammonium sulfate precipitation are also available depending on the antibody to be recovered.

Following any preliminary purification step(s), the mixture comprising the agent or antibody of interest and contaminants may be subjected to low pH hydrophobic interaction chromatography using an elution buffer at a pH between about 2.5-4.5, and may be performed at low salt concentrations (e.g., from about 0-0.25M salt).

Pharmaceutical Formulations, Dosing, and Routes of Administration

The present technology provides anti-CD117 agents and antibodies and related compositions, which may be useful for elimination of CD117 expressing cells from the body, for example, and for identification and quantification of the number of CD117 expressing cells in tissue samples, for example.

Therapeutic methods and compositions of the present technology may be referred to as "CD117-based" in order to indicate that these therapies can change the relative or absolute numbers of undesirable or toxic CD117 expressing cells such as lymphomas or autoimmune B lymphocytes.

One way to control the amount of undesirable CD117 expressing cells in a patient is by providing a composition that comprises one or more anti-CD117 antibodies to cause cytotoxic activity towards the CD 117-expressing cells, for example.

Anti-CD117 agents or antibodies may be formulated in a pharmaceutical composition that is useful for a variety of purposes, including the treatment of diseases, disorders, or physical trauma. Pharmaceutical compositions comprising one or more anti-CD117 agents or antibodies herein may be used to administer pharmaceutical compositions herein to a patient in need thereof, and according to one embodiment of the technology, kit are provided that include such devices. Such devices and kits may be designed for routine administration, including self-administration, of the pharmaceutical compositions herein.

Therapeutic formulations of an agent or antibody may be prepared for storage by mixing the agent or antibody having the desired degree of purity with optional physiologically acceptable carriers, excipients or stabilizers (Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980)), in the form of lyophilized formulations or aqueous solutions. Acceptable carriers, excipients, or stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid and methionine; preservatives (such as octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride, benzethonium chloride; phenol, butyl or benzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; salt-forming counter-ions such as sodium; metal complexes (e.g., Zn-protein complexes); and/or non-ionic surfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG).

Formulations herein may also contain more than one active compound as necessary for the particular indication being treated, preferably those with complementary activities that do not adversely affect each other. Such molecules are suitably present in combination in amounts that are effective for the purpose intended.

Active ingredients may also be entrapped in microcapsule prepared, for example, by coacervation techniques or by interfacial polymerization, for example, hydroxymethylcellulose or gelatin-microcapsule and poly-(methylmethacylate) microcapsule, respectively, in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nanoparticles and nanocapsules) or in macroemulsions. Such techniques are disclosed in Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980).

Formulations for in vivo administration generally are sterile. This may be accomplished for instance by filtration through sterile filtration membranes, for example.

Sustained-release preparations may be prepared. Suitable examples of sustained-release preparations include semipermeable matrices of solid hydrophobic polymers containing the agent/antibody, which matrices are in the form of shaped articles, e.g., films, or microcapsule. Examples of sustained-release matrices include polyesters, hydrogels (for example, poly(2- hydroxyethyl-methacrylate), or poly(vinyl alcohol)), polylactides (U.S. Pat. No. 3,773,919), copolymers of L-glutamic acid and .gamma. ethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the Lupron Depot.TM. (injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate), and poly-D-(-)-3-hydroxybutyric acid. While polymers such as ethylene-vinyl acetate and lactic acid-glycolic acid enable release of molecules for over 100 days, certain hydrogels release proteins for shorter time periods. When encapsulated agents/antibodies remain in the body for a long time, they may denature or aggregate as a result of exposure to moisture at 37° C, resulting in a loss of biological activity and possible changes in immunogenicity. Rational strategies can be devised for stabilization depending on the mechanism involved. For example, if the aggregation mechanism is discovered to be intermolecular S to S bond formation through thio-disulfide interchange, stabilization may be achieved by modifying sulfhydryl residues, lyophilizing from acidic solutions, controlling moisture content, using appropriate additives, and developing specific polymer matrix compositions.

For therapeutic applications, anti-CD117 agents, e.g., antibodies, provided herein are administered to a mammal, e.g., a human, in a pharmaceutically acceptable dosage form such as those discussed above, including those that may be administered to a human intravenously as a bolus or by continuous infusion over a period of time, or by intramuscular, intraperitoneal, intra-cerebrospinal, subcutaneous, intra-articular, intrasynovial, intrathecal, oral, topical, or inhalation routes.

For the prevention or treatment of disease, the appropriate dosage of agent or antibody will depend on the type of disease to be treated, as defined above, the severity and course of the disease, whether the antibody is administered for preventative or therapeutic purposes, previous therapy, the patient's clinical history and response to the antibody, and the discretion of the attending physician. The antibody is suitably administered to the patient at one time or over a series of treatments.

Depending on the type and severity of the disease, about 1 μg/kg to about 50 mg/kg (e.g., 0.1- 20 mg/kg) of antibody may be an initial candidate dosage for administration to the patient, whether, for example, by one or more separate administrations, or by continuous infusion. A typical daily or weekly dosage might range from about 1 μg/kg to about 20 mg/kg or more, depending on the factors mentioned above. For repeated administrations over several days or longer, depending on the condition, the treatment is repeated until a desired suppression of disease symptoms occurs. However, other dosage regimens may be useful. The progress of this therapy is easily monitored by conventional techniques and assays, including, for example, radiographic imaging. Detection methods using the antibody to determine CD117 levels in bodily fluids or tissues may be used in order to optimize patient exposure to the therapeutic antibody.

In some embodiments, a composition comprising an anti-CD117 agent herein (e.g., a mAb that interferes with CD117 activity) is administered as a monotherapy, and in some embodiments, the composition comprising the anti-CD117 agent is administered as part of a combination therapy. In some cases, the effectiveness of the agent or antibody in preventing or treating disease may be improved by administering the agent or antibody serially or in combination with another agent that is effective for those purposes, such as a chemotherapeutic drug for treatment of cancer or a microbial infection. In other cases, the anti-CD117 agent may serve to enhance or sensitize cells to chemotherapeutic treatment, thus permitting efficacy at lower doses and with lower toxicity. Certain combination therapies include, in addition to administration of the composition comprising an agent that reduces the number of CD117 expressing cells, delivering a second therapeutic regimen selected from the group consisting of administration of a chemotherapeutic agent, radiation therapy, surgery, and a combination of any of the foregoing.

Such other agents may be present in the composition being administered or may be administered separately. Also, the anti-CD117 agent may be suitably administered serially or in combination with the other agent or modality, e.g., chemotherapeutic drug or radiation for treatment of cancer, infection, and the like, or an immunosuppressive drug.

Research and Diagnostic, Including Clinical Diagnostic, Uses for Anti-CD117

Agents Herein

Provided herein are diagnostic reagents comprising an anti-CD117 agent described herein. For example, anti-CD117 agents, e.g., antibodies, provided herein may be used to detect and/or purify CD117, e.g., from bodily fluid(s) or expressed on cells in bodily fluids or tissues. Also provided herein are methods for detecting CD117. For example, a method may comprise contacting a sample (e.g., a biological sample known or suspected to contain CD117) with an anti-CD117 agent provided herein, and, if the sample contains CD117, detecting CD117:anti- CD117 complexes. Also provided herein are reagents comprising and anti-CD117 agent described herein and methods for detecting CD117 for research purposes.

Anti-CD117 antibodies, for example, may be useful in diagnostic assays for CD117, e.g., detecting its presence in specific cells, tissues, or bodily fluids. Such diagnostic methods may be useful in diagnosis, e.g., of a hyperproliferative disease or disorder. Thus clinical diagnostic uses as well as research uses are comprehended herein.

In some embodiments, an anti-CD117 agent or antibody comprises a detectable marker or label. In some embodiments, an anti-CD117 agent or antibody is conjugated to a detectable marker or label. For example, for research and diagnostic applications, an anti-CD117 agent or antibody may be labeled with a detectable moiety. Numerous labels are available which are generally grouped into the following categories:

(a) Radioisotopes, such as ³⁵S, ¹⁴C, ¹²⁵l, ³H, and ¹³¹l. The antibody can be labeled with the radioisotope using the techniques described in Current Protocols in Immunology, Volumes 1 and 2, Coligen et al., Ed. Wiley- Interscience, New York, N.Y., Pubs. (1991), for example, and radioactivity can be measured using scintillation counting.

(b) Fluorescent labels such as rare earth chelates (europium chelates) or fluorescein and its derivatives, rhodamine and its derivatives, dansyl, Lissamine, phycoerythrin, Texas Red and Brilliant Violet™ are available. The fluorescent labels can be conjugated to the antibody using the techniques disclosed in Current Protocols in Immunology, supra, for example. Fluorescence can be quantified using a flow cytometer, imaging microscope or fluorimeter.

(c) Various enzyme-substrate labels are available and U.S. Pat. No. 4,275,149 provides a review of some of these. The enzyme generally catalyzes a chemical alteration of the chromogenic substrate that can be measured using various techniques. For example, the enzyme may catalyze a color change in a substrate, which can be measured spectrophotometrically. Alternatively, the enzyme may alter the fluorescence or chemiluminescence of the substrate. Techniques for quantifying a change in fluorescence are described above. The chemiluminescent substrate becomes electronically excited by a chemical reaction and may then emit light that can be measured (using a chemilluminometer, for example) or donates energy to a fluorescent acceptor. Examples of enzymatic labels include luciferases (e.g., firefly luciferase and bacterial luciferase; U.S. Pat. No. 4,737,456), luciferin, 2,3-dihydrophthalazinediones, malate dehydrogenase, urease, peroxidase such as horseradish peroxidase (HRPO), alkaline phosphatase, beta-galactosidase, glucoamylase, lysozyme, saccharide oxidases (e.g., glucose oxidase, galactose oxidase, and glucose-e- phosphate dehydrogenase), heterocyclicoxidases (such as uricase and xanthine oxidase), lactoperoxidase, microperoxidase, and the like. Techniques for conjugating enzymes to antibodies are described in O'Sullivan et al. , Methods for the Preparation of Enzyme-Antibody Conjugates for use in Enzyme Immunoassay, in Methods in Enzym. (ed J. Langone & H. Van Vunakis), Academic press, New York, 73:147-166 (1981).

Examples of enzyme-substrate combinations include, for example:

(i) Horseradish peroxidase (HRP) with hydrogen peroxidase as a substrate, where the hydrogen peroxidase oxidizes a dye precursor (e.g., orthophenylene diamine (OPD) or 3,3',5,5'-tetramethyl benzidine hydrochloride (TMB));

(ii) alkaline phosphatase (AP) with para-Nitrophenyl phosphate as chromogenic substrate; and (iii) .beta.-D-galactosidase (.beta.-D-Gal) with a chromogenic substrate (e.g., p-nitrophenyl-β-D-galactosidase) or fluorogenic substrate 4-methylumbelliferyl-. beta.-D- galactosidase.

Numerous other enzyme-substrate combinations may be used (e.g., U.S. Pat. Nos. 4,275,149 and 4,318,980, each of which is incorporated by reference herein).

In certain instances, the label is indirectly conjugated with the agent or antibody. The skilled artisan will be aware of various techniques for achieving this. For example, an antibody can be conjugated with biotin and any of the three broad categories of labels mentioned above can be conjugated with avidin, or vice versa. Biotin binds selectively to avidin and thus, the label can be conjugated with the antibody in this indirect manner. Alternatively, to achieve indirect conjugation of the label with the antibody, the antibody is conjugated with a small hapten (e.g., digoxin) and one of the different types of labels mentioned above is conjugated with an anti-hapten antibody (e.g., anti-digoxin antibody). Thus, indirect conjugation of the label with the antibody can be achieved.

In some embodiments, and anti-CD117 agent or antibody need not be labeled, and the presence thereof can be detected, e.g., using a labeled antibody which binds to an anti-CD117 antibody.

In some embodiments, an anti-CD117 agent or antibody herein is immobilized on a solid support or substrate. In some embodiments, an anti-CD117 agent or antibody herein is non- diffusively immobilized on a solid support (e.g., the anti-CD117 agent or antibody does not detach from the solid support). A solid support or substrate can be any physically separable solid to which an anti-CD117 agent or antibody can be directly or indirectly attached including, but not limited to, surfaces provided by microarrays and wells, and particles such as beads (e.g., paramagnetic beads, magnetic beads, microbeads, nanobeads), microparticles, and nanoparticles. Solid supports also can include, for example, chips, columns, optical fibers, wipes, filters (e.g., flat surface filters), one or more capillaries, glass and modified or functionalized glass (e.g., control led- pore glass (CPG)), quartz, mica, diazotized membranes (paper or nylon), polyformaldehyde, cellulose, cellulose acetate, paper, ceramics, metals, metalloids, semiconductive materials, quantum dots, coated beads or particles, other chromatographic materials, magnetic particles; plastics (including acrylics, polystyrene, copolymers of styrene or other materials, polybutylene, polyurethanes, TEFLON™, polyethylene, polypropylene, polyamide, polyester, polyvinylidenedifluoride (PVDF), and the like), polysaccharides, nylon or nitrocellulose, resins, silica or silica-based materials including silicon, silica gel, and modified silicon, Sephadex®, Sepharose®, carbon, metals (e.g., steel, gold, silver, aluminum, silicon and copper), inorganic glasses, conducting polymers (including polymers such as polypyrole and polyindole); micro or nanostructured surfaces such as nucleic acid tiling arrays, nanotube, nanowire, or nanoparticulate decorated surfaces; or porous surfaces or gels such as methacrylates, acrylamides, sugar polymers, cellulose, silicates, or other fibrous or stranded polymers. In some embodiments, the solid support or substrate may be coated using passive or chemically-derivatized coatings with any number of materials, including polymers, such as dextrans, acrylamides, gelatins or agarose. Beads and/or particles may be free or in connection with one another (e.g., sintered). In some embodiments, a solid support or substrate can be a collection of particles. In some embodiments, the particles can comprise silica, and the silica may comprise silica dioxide. In some embodiments the silica can be porous, and in certain embodiments the silica can be non-porous. In some embodiments, the particles further comprise an agent that confers a paramagnetic property to the particles. In certain embodiments, the agent comprises a metal, and in certain embodiments the agent is a metal oxide, (e.g., iron or iron oxides, where the iron oxide contains a mixture of Fe2+ and Fe3+). An anti-CD117 agent or antibody may be linked to a solid support by covalent bonds or by non-covalent interactions and may be linked to a solid support directly or indirectly (e.g., via an intermediary agent such as a spacer molecule or biotin).

Agents and antibodies provided herein may be employed in any known assay method, such as flow cytometry, immunohistochemistry, immunofluorescence, mass cytometry (e.g., Cytof instrument), competitive binding assays, direct and indirect sandwich assays, and immunoprecipitation assays. Zola, Monoclonal Antibodies: A Manual of Techniques, pp. 147- 158 (CRC Press, Inc. 1987).

Flow cytometry and mass cytometry assays generally involve the use of a single primary antibody to specifically identify the presence of the target molecule expressed on the surface of a dispersed suspension of individual cells. The dispersed cells are typically obtained from a biological fluid sample, e.g., blood, but may also be obtained from a dispersion of single cells prepared from a solid tissue sample such as spleen or tumor biopsy. The primary antibody may be directly conjugated with a detectable moiety, e.g., a fluorophore such as phycoerythrin for flow cytometry or a heavy metal chelate for mass cytometry. Alternatively, the primary antibody may be unlabeled or labeled with an undetectable tag such as biotin, and the primary antibody is then detected by a detectably labeled secondary antibody that specifically recognizes the primary antibody itself or the tag on the primary antibody. The labeled cells are then analyzed in an instrument capable of single cell detection, e.g., flow cytometer, mass cytometer, fluorescence microscope or brightfield light microscope, to identify those individual cells in the dispersed population or tissue sample that express the target recognized by the primary antibody. Detailed description of the technological basis and practical application of flow cytometry principles may be found in, e.g., Shapiro, Practical Flow Cytometry, 4^th Edition, Wiley, 2003.

Sandwich assays involve the use of two antibodies, each capable of binding to a different immunogenic portion, or epitope, of the protein that is detected. In a sandwich assay, the test sample analyte is bound by a first antibody that is immobilized on a solid support, and thereafter a second antibody binds to the analyte, thus forming an insoluble three-part complex. See, e.g., U.S. Pat. No. 4,376,110. The second antibody may itself be labeled with a detectable moiety (direct sandwich assays) or may be measured using an anti- immunoglobulin antibody that is labeled with a detectable moiety (indirect sandwich assay). For example, one type of sandwich assay is an ELISA assay, in which case the detectable moiety is an enzyme. In a cell ELISA, the target cell population may be attached to the solid support using antibodies first attached to the support and that recognize different cell surface proteins. These first antibodies capture the cells to the support. CD117 on the surface of the cells can then be detected by adding anti-CD117 antibody to the captured cells and detecting the amount of CD117 antibody attached to the cells. In certain instances, fixed and permeabilized cells may be used, an in such instances, surface CD117 and intracellular CD117 may be detected.

For immunohistochemistry, the blood or tissue sample may be fresh or frozen or may be embedded in paraffin and fixed with a preservative such as formalin, for example.

The agents or antibodies herein also may be used for in vivo diagnostic assays. Generally, the antibody is labeled with a radionuclide (such as ¹¹¹ In, "Tc, ¹⁴C, ¹³¹l, ¹²⁵l, ³H, ³²P, or ³⁵S) so that the bound target molecule can be localized using immunoscintillography.

Detection of CD117

Provided herein are agents and methods for detecting CD117 in cells. In some embodiments, the CD117 is detected on the surface of the cell. In some embodiments, the CD117 is detected intracellularly. In some embodiments, the detection of CD117 is in vitro. In some embodiments, the detection of CD117 is in vivo.

In particular embodiments, the dection of CD117 can be on immune cells. Detection of CD117 in immune cells may refer to detection on the surface of immune cells (e.g., by surface staining) and/or inside immune cells (e.g., by intracellular staining). In some embodiments, agents and methods are provided for detecting CD117 in a heterogeneous population of immune cells. A heterogeneous population of immune cells may comprise two or more types of immune cells. For example, a heterogeneous population of immune cells may comprise two or more of B cells, plasmacytoid dendritic cells (pDCs), lymphocytes, leukocytes, T cells, monocytes, macrophages, neutrophils, myeloid dendritic cells (mDCs), innate lymphoid cells, mast cells, eosinophils, basophils, natural killer cells, and the like. In some embodiments, a heterogeneous population of immune cells comprises peripheral blood mononuclear cells (PBMCs) which may include, for example, T cells, B cells, natural killer cells, and monocytes.

Generally, cells are contacted with an anti-CD117 agent described herein (e.g., in a flow cytometry assay as described herein; or any suitable protein or cell detection assay). In some embodiments, CD117 is detected at a significant level in certain immune cells by an anti- CD117 agent described herein. CD117 may be detected at a significant level by an anti- CD117 agent described herein in certain immune cells and not significantly detected in other immune cells. The level of CD117 detection in certain immune cells may vary according to certain factors such as, for example, type of detection assay, type of detection reagent (e.g., type of dye), antibody concentration, donor cell variability, and the like.

Detection of CD117 at a significant level may refer to a particular signal to noise (S:N) ratio (e.g., threshold or range) measured in a flow cytometry assay.

In some embodiments, CD117 is detected at a significant level in hematopoietic stem cells (HSC), multipotent progenitors (MPP), common myeloid progenitors (CMP, and mast cells. In certain instances, hematopoietic stem cells may be identified by the expression of Sca-1, CD27, CD34, CD38, CD43, CD48, CD117, and CD150. Sca-1, or stem cells antigen-1 , is an 18 kDa mouse glycosyl phosphatidylinositol (GPI)-anchored cell surface protein of the LY6 gene protein. CD27 is a member of the tumor necrosis factor receptor superfamily. CD34 is a transmembrane phsophoglycoprotein that is a member of single-pass transmembrane sialomucin proteins. CD43, or leukosialin or sialophorin, is a transmembrane cell surface protein. CD150, or signaling lymphocytic activation molecule 1 (SLAMF1), is a protein in the signaling lymphocytic activation molecule (SLAM) family. CD117, KIT proto-oncogene receptor tyrosine kinase or mast/stem cell growth factor receptor (SCFR), is a member of the receptor tyrosine kinase III family.

CD117 is a cytokine receptor expressed on the surface of HSCs as well as other cell types. CD117 consists of an extracellular domain, a transmembrane domain, a juxtamembrane domain, and an intracellular tyrosine kinase domain. The extracellular domain is composed of five immunoglobulin-like domains, and the protein kinase domain is interrupted by a hydrophilic insert sequence of about 80 amino acids. The ligand stem cell factor binds via the second and third immunoglobulin domains. The two isoforms of CD117 in both mice and humans, caused by alternative splicing, differs by only four amino acids: glycine, asparagine, asparagine, and lysine (GNNK). These amino acid are either present or absent upstream of CD117's transmembrane domain.

In addition to hematopoietic stem cells, CD117 is detected on gastrointestinal stromal tumors (GISTs), a subset of mesenchymal tumors of the Gl tract, non-small cell lung cancer, acute myeloid leukemia (AML), as well as melanoma.

In some embodiments, CD117 is not significantly detected in certain mature human peripheral blood lymphocytes. For example, CD117 may not be significantly detected in mature peripheral blood lymphocytes (e.g., B lymphocytes, T lymphocytes, and/or natural killer (NK) cells). No significant detection of CD117 in certain lymphocytes may refer to a particular signal to noise (S:N) ratio (e.g., threshold or range) measured in a flow cytometry assay. In some embodiments, no significant detection of noise (N) in certain lymphocytes refers to a signal to noise (S:N) ratio of about 1.5 or less. In some embodiments, no significant detection of CD117 in certain lymphocytes refers to a signal to noise (S:N) ratio of about 1 or less.

In some embodiments, the detection of CD117 can be in a biological sample from a subject. In some embodiments, the biological sample can be a solid tissue isolated from the subject. The solid tissue may comprise solid tissue from one or more of adipose tissue, bladder, bone, brain breast cervix, endothelium, gallbladder, kidney, liver, lung, lymph, ovary, prostate, salivary gland, stomach, testis, thyroid, urethra, uterus, vagina, and vulva. In some embodiments, the biological sample can be a fluid sample isolated from the subject. In some embodiments, the fluid comprises one or more of amniotic fluid, bile, blood, breast milk, breast fluid, cerebrospinal fluid, lavage fluid, lymphatic fluid, mucous, plasma, saliva, semen, serum, spinal fluid, sputum, tears, umbilical cord blood, urine, and vaginal fluid.

In some embodiments, the sample comprises immune cells. In some embodiments, the sample comprises a heterogeneous population of immune cells. In some embodiments, the immune cell is selected from B cells, plasmacytoid dendritic cells (pDCs), lymphocytes, leukocytes, T cells, monocytes, macrophages, neutrophils, myeloid dendritic cells (mDCs), innate lymphoid cells, mast cells, eosinophils, basophils, natural killer cells, and peripheral blood mononuclear cells (PBMCs).

In some of any embodiments, any of the antibodies or antigen binding fragments thereof provided herein can be used in the characterization of single cells by measurement of gene- expression levels and cellular proteins. Among such known single cell sequencing platforms suitable for integration with the antibodies or antigen binding fragments thereof described herein is the Drop-seq method, including, but not limited to, microfluidic, plate-based, or microwell, Seq-Well™ method and adaptations of the basic protocol, and InDrop™ method.

In another embodiment, a single cell sequencing platform suitable for integration with the antibodies or antigen binding fragments thereof described herein is lOx genomics single cell 3' solution or single cell V(D)J solution, either run on Chromium controller, or dedicated Chromium single cell controller. Other suitable sequencing methods include Wafergen iCell8™ method, Microwell-seq method, Fluidigm Cl™ method and equivalent single cell products. Still other known sequencing protocols useful with the antibodies or antigen binding fragments thereof described herein include BD Resolve™ single cell analysis platform and ddSeq (from lllumina® Bio-Rad® SureCell™ WTA 3' Library Prep Kit for the ddSEQ™ System, 2017, Pub. No. 1070-2016-014-B, lllumina Inc., Bio-Rad Laboratories, Inc.). In still other embodiment, the antibodies or antigen binding fragments thereof described herein are useful with combinatorial indexing based approaches (sci-RNA-seq™ method or SPLiT-seq™ method) and Spatial Transcriptomics, or comparable spatially resolved sequencing approaches. The methods and compositions described herein can also be used as an added layer of information on standard index sorting (FACS) and mRNA-sequencing-based approaches.

In some of any embodiments, any of the antibodies or antigen binding fragments thereof described herein can be used to detect the presence, absence or amount of the various nucleic acids, proteins, targets, oligonucleotides, amplification products and barcodes described herein.

In some embodiments, the biological sample is from a healthy subject. In some embodiments, the sample is from a subject with a disease or condition. In some embodiments, the detection of CD117 indicates the presence or absence of a disease or disorder. In some embodiments, the disease or disorder is a cancer, an autoimmune disorder, an inflammatory disorder, a neurologic disorder, or an infection. In some embodiments, the cancer is the cancer is acute myeloid leukemia, acute lymphoblastic leukemia, colorectal, ovarian, gynecologic, liver, glioblastoma, Hodgkin lymphoma, chronic lymphocytic leukemia, esophagus, gastric, pancreas, colon, kidney, head and neck, lung and melanoma.

In some embodiments, the disease or disorder is associated with CD117 expression. In some embodiments, the disease or disorder is associated with aberrant CD117 expression. In some embodiments, the disease or disorder is associated with Natural Killer (NK), alpha beta T cells, gamma delta T cells, CD8+ T cells, monocytes, or dendritic cells. In some embodiments, the disease or disorder is associated with Natural Killer (NK) cells. In some embodiments, the disease or disorder is associated with alpha beta T cells. In some embodiments, the disease or disorder is associated with gamma delta T cells. In some embodiments, the disease or disorder is associated with CD8+ T cells. In some embodiments, the disease or disorder is associated with monocytes. In some embodiments, the disease or disorder is associated with dendritic cells. In some of any embodiments, the disease or disorder is chosen from non-viral cancers, virus-associated cancers, cancers associated with HBV infection, cancers associated with Epstein-Barr virus (EBV) infection, cancers associated with polyomavirus infection, erythema nodosum leprosum (ENL), autoimmune diseases, autoimmune inflammation, autoimmune thyroid diseases, B-cell lymphoma, T-cell lymphoma, acute myeloid leukemia, Hodgkin's Disease, acute myelogenous leukemia, acute myelomonocytic leukemia, acute lymphoblastic leukemia, chronic myelogenous leukemia, chronic lymphocytic leukemia, B cell large cell lymphoma, malignant lymphoma, acute leukemia, lymphosarcoma cell leukemia, B-cell leukemias, myelodysplastic syndromes, solid phase cancer, herpes viral infections, and/or rejection of transplanted tissues or organs.

In some embodiments, the disease or disorder is a cancer, an infectious disease, or an autoimmune disorder.

In some embodiments, the disease or disorder is a cancer. In some embodiments, the cancer is metastatic melanoma, a solid tumor, bladder cancer, head and neck squamous cell carcinoma, hepatocellular carcinoma, hepatic metastasis of colonic origin, papillary thyroid carcinoma, acute myeloid leukemia, or asymptomatic myeloma.

In some embodiments, the disease or disorder is an infectious disease. In some embodiments, the infectious disease is human immunodeficiency virus (HIV), chronic hepatitis C, cytomegalovirus, or hantavirus.

In some embodiments, the disease or disorder is an autoimmune disorder. In some embodiments, the autoimmune disorder is Chrohn's disease, multiple sclerosis, systemic sclerosis, ocular myasthenia gravis, psoriasis or rheumatoid arthritis. In some embodiments, the autoimmune disorder is Chrohn's disease, multiple sclerosis, systemic sclerosis, ocular myasthenia gravis, psoriasis or rheumatoid arthritis.

In some embodiments, any of the antibodies or antigen binding fragments thereof can be used in generating a nucleic acid molecule comprising all or a portion of the sequence of the oligonucleotide or a complement thereof. In some of any embodiments, the antibody or antigen binding fragment thereof can be used in a method of associating presence or abundance of CD117 with a location of interest of a tissue sample.

In some embodiments, any of the antibodies or antigen binding fragments thereof can be used in the construction of a protein library. In some of any embodiments, the construction of a protein library comprises sequencing. In some of any embodiments, the construction of a protein library comprises the use of flow cytometry.

In some of any embodiments, provided herein is a method of detecting CD117, comprising a) contacting a sample with the antibody or antigen binding fragment thereof of any of the antibodies or antigen binding fragments thereof under conditions to bind said antibody or antigen binding fragment thereof to a CD117 receptor on said sample, wherein the binding generates the production of a receptor/antibody or antigen binding fragment thereof of complex; b) detecting the presence of the receptor/antibody or antigen binding fragment thereof of complexes; c) wherein the detecting comprises the presence or absence of the CD117 receptor on said sample. In some of any embodiments, provided herein is a method of treating or preventing a disease or disorder associated with CD117 in a subject, comprising: a) contacting a sample known or suspected to contain CD117 with the antibody or antigen binding fragment thereof any of the antibodies or antigen binding fragments thereof, b) detecting the presence of complexes comprising CD117 and the antibody or antigen binding fragment thereof; wherein the presence of the complexes indicates the presence of a disease or disorder; and c) administering to the subject the antibody or antigen binding fragment thereof of any of the antibodies or antigen binding fragments thereof.

In some of any embodiments, provided herein is a method of diagnosing a disease or disorder, comprising: a) isolating a sample from a subject, b) incubating the sample with the antibody or antigen binding fragment thereof of any of any of the antibodies or antigen binding fragments thereof, for a period of time sufficient to generate CD117:anti-CD117 complexes; c) detecting the presence or absence of the CD117:anti-CD117 complexes from the isolated tissue, and d) associating presence or abundance of CD117 with a location of interest of a tissue sample.

In some of any embodiments, the increase of CD117 over a control level in the location of interest of the tissue sample is indicative of a disease or disorder in a subject.

In some of any embodiments, the detection comprises hybridization of a detectable moiety to the antibody or antigen binding fragment thereof. In some of any embodiments, the sample is contacted with a second antibody. In some of any embodiments, the second antibody is an antibody comprising a detectable moiety. In some of any embodiments, the detectable moiety comprises an oligonucleotide. In some of any embodiments, the detectable moiety comprises a fluorescent label. In some of any embodiments, the measurement comprises sequencing. In some of any embodiments, the detectable moiety comprises immunofluorescence. In some of any embodiments, the sample is a formalin-fixed paraffin-embedded sample. In some of any embodiments, the sample comprises a cell. In some of any embodiments, the sample comprises a tissue sample

Kits Incorporating Anti-CD117 Agents Herein

An anti-CD117 agent (e.g., an anti-CD117 antibody) herein may be provided in a kit, for example, a packaged combination of reagents in predetermined amounts with instructions for use (e.g., instructions for performing a diagnostic assay; instructions for performing a laboratory assay). In some embodiments, the kit is a diagnostic kit configured to detect CD117 in a sample (e.g., a biological sample). Where the anti-CD117 agent is labeled with a fluorophore, the kit may include an identical isotype negative control irrelevant antibody to control for non-specific binding of the anti-CD117 agent. Where the anti-CD117 agent is labeled with an enzyme, the kit may include substrates and cofactors required by the enzyme (e.g., substrate precursor which provides the detectable chromophore or fluorophore). Additional additives may be included such as stabilizers, buffers (e.g., a block buffer or lysis buffer), and the like. The relative amounts of the various reagents may be varied widely to provide for concentrations in solution of the reagents that substantially optimize the sensitivity of the assay. In certain instances, reagents may be provided as dry powders (e.g., lyophilized powder), including excipients that on dissolution will provide a reagent solution having the appropriate concentration.

Articles of Manufacture

In another aspect of the present technology, an article of manufacture containing materials useful for the treatment, or diagnosis, of the disorders described herein is provided. An article of manufacture may comprise a container and a label. Suitable containers include, for example, bottles, vials, syringes, and test tubes. Containers may be formed from a variety of materials such as glass or plastic. A container may hold a composition that is effective for treating a condition and may have a sterile access port (for example the container may be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle). An active anti-CD117 agent in the composition may be an anti-CD117 antibody. A label on, or associated with, the container indicates that the composition is used for treating, or diagnosing a condition of choice. The article of manufacture may further comprise a second container comprising a pharmaceutically acceptable buffer, such as phosphate-buffered saline, Ringer's solution and dextrose solution; and may further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, syringes, and package inserts with instructions for use.

Certain Terms Used Herein

An "agent" as described herein generally refers to an antibody, antibody fragment or antigenbinding fragment thereof, or any derivative or variant of such antibody, antibody fragment or antigen-binding fragments thereof, iincluding but not limited to immunoconjugates, labeled antibodies and antigen-binding antibody fragments.

An "acceptor human framework" generally refers to a framework comprising the amino acid sequence of a heavy chain variable domain (VH) framework or a light chain variable domain (VL) framework derived from a human immunoglobulin framework or a human consensus framework, as defined herein. An acceptor human framework "derived from" a human immunoglobulin framework or a human consensus framework may comprise the same amino acid sequence thereof, or it may contain amino acid sequence changes. In some embodiments, the number of framework amino acid changes are 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less. In some embodiments, the VH and/or VL acceptor human framework(s) is(are) identical in sequence to the VH and/or VL human immunoglobulin framework amino acid sequence or human consensus framework amino acid sequence. "Framework" or "FR" generally refers to variable domain residues other than hypervariable region (HVR) residues. The FR of a variable domain generally consists of four FR domains: FR1 ; FR2; FR3; and FR4. Accordingly, the HVR and FR sequences generally appear in the following sequence in VH (or VL): FR1-H1(L1)-FR2-H2(L2)-FR3-H3(L3)-FR4.

A "human consensus framework" generally refers to a framework that represents the most commonly occurring amino acid residues in a selection of human immunoglobulin VL or VH framework sequences. Generally, the selection of human immunoglobulin VL or VH sequences is from a subgroup of variable domain sequences. Generally, the subgroup of sequences is a subgroup as in Kabat et al., Sequences of Proteins of Immunological Interest, Fifth Edition, NIH Publication 91-3242, Bethesda Md. (1991), vols. 1-3. In some embodiments, for the VL, the subgroup is subgroup kappa I as in Kabat et al., supra. In some embodiments, for the VH, the subgroup is subgroup III as in Kabat et al., supra.

The term "hypervariable region" or "HVR" generally refers to each of the regions of an antibody variable domain that are hypervariable in sequence and/or form structurally defined loops ("hypervariable loops"). Generally, native four-chain antibodies comprise six HVRs; three in the VH (H1, H2, H3), and three in the VL (L1 , L2, L3). HVRs generally comprise amino acid residues from the hypervariable loops and/or from the "complementarity determining regions" (CDRs), the latter being of highest sequence variability and/or involved in antigen recognition.

The precise amino acid sequence boundaries of a given CDR or FR can be readily determined using any number of well-known schemes, including those described in Kabat et al. (1991), "Sequences of Proteins of Immunological Interest," 5^th Ed. Public Health Service, National Institutes of Health, Bethesda, MD ("Kabat" numbering scheme), Al-Lazikani et al. , (1997) JMB 273,927-948 ("Chothia" numbering scheme), MacCallum et al., J. Mol. Biol. 262:732-745 (1996), "Antibody-antigen interactions: Contact analysis and binding site topography," J. Mol. Biol. 262, 732-745," ("Contact" numbering scheme), Martin et al., Proc. Natl. Acad. Sci., 86:9268-9272 (1989) ("AbM" numbering scheme), Lefranc MP et al., "IMGT unique numbering for immunoglobulin and T cell receptor variable domains and Ig superfamily V-like domains," Dev Comp Immunol, 2003 Jan;27(1):55-77 ("IMGT" numbering scheme), and Honegger A and Pluckthun A, "Yet another numbering scheme for immunoglobulin variable domains: an automatic modeling and analysis tool," J Mol Biol, 2001 Jun 8;309(3):657-70, ("Aho" numbering scheme). The boundaries of a given CDR or FR may vary depending on the scheme used for identification. For example, the Kabat scheme is based on structural alignments, while the Chothia scheme is based on structural information. Numbering for both the Kabat and Chothia schemes is based upon the most common antibody region sequence lengths, with insertions accommodated by insertion letters, for example, "30a" and deletions appearing in some antibodies. The two schemes place certain insertions and deletions ("indels") at different positions, resulting in differential numbering. The Contact scheme is based on analysis of complex crystal structures and is similar in many respects to the Chothia numbering scheme.

Table 4, below, lists exemplary position boundaries of CDRH1 , CDRH2, CDRH3, and CDRL1 , CDRL2, and CDRL3 as identified by Kabat, Chothia, and Contact schemes, respectively. For CDRH1, residue numbering is listed using both the Kabat and Chothia numbering schemes. FRs are located between CDRs, for example, with FRH1 located between CDRH1 and CDRH2, and so forth. It is noted that because the shown Kabat numbering scheme places insertions at H35A and H35B, the end of the Chothia CDRH1 loop when numbered using the shown Kabat numbering convention varies between H32 and H34, depending on the length of the loop.

Table 4

1 - Kabat et al. (1991), "Sequences of Proteins of Immunological Interest," 5^th Ed. Public Health Service, National Institutes of Health, Bethesda, MD

2 - Al-Lazikani et al., (1997) JMB 273,927-948

CDRs also comprise "specificity determining residues," or "SDRs," which are residues that contact a particular antigen. Unless otherwise indicated, HVR residues and other residues in the variable domain (e.g., FR residues) are numbered herein according to Kabat et al., supra.

The term "variable region" or "variable domain" generally refers to the domain of an antibody heavy or light chain that is involved in binding the antibody to antigen. The variable domains of the heavy chain and light chain (VH and VL, respectively) of a native antibody generally have similar structures, with each domain comprising four conserved framework regions (FRs) and three hypervariable regions (HVRs). See, e.g., Kindt et al. Kuby Immunology, 6th ed., W.H. Freeman and Co., page 91 (2007). A single VH or VL domain may be sufficient to confer antigen-binding specificity. Furthermore, antibodies that bind a particular antigen may be isolated using a VH or VL domain from an antibody that binds the antigen to screen a library of complementary VL or VH domains, respectively. See, e.g., Portolano et al. , J. Immunol. 150:880-887 (1993); Clarkson et al., Nature 352:624-628 (1991). "Affinity" generally refers to the strength of the sum total of non-covalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Unless indicated otherwise, "binding affinity" refers to intrinsic binding affinity, which reflects a 1:1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its partner Y can generally be represented by a dissociation constant (K_d). Affinity can be measured by common methods known in the art, including those described herein. Specific illustrative and example embodiments for measuring binding affinity are described elsewhere herein. In some instances, antibodies herein bind to a target (e.g., CD117) with a high affinity, e.g., a K_d value of no more than about 1 x 10^-7 M; preferably no more than about 1 x 10^-8 M; and preferably no more than about 5 x 10^-9 M.

An "affinity matured" antibody generally refers to an antibody with one or more alterations in one or more hypervariable regions (HVRs), compared to a parent antibody that does not possess such alterations. Preferably, such alterations result in improved affinity of the antibody for its target antigen.

The term "anti-CD117 agent" generally refers to a molecule that is, or comprise, one or more anti-CD117 antibodies, CD117-binding antibody fragments, or CD117-binding antibody derivatives.

The terms "anti-CD117 antibody" and "an antibody that binds to CD117" generally refer to an antibody that is capable of binding CD117 with sufficient affinity and/or specificity such that the antibody is useful as a research tool, diagnostic agent and/or therapeutic agent in targeting CD117. In some embodiments, the extent of binding of an anti-CD117 antibody (or antigen- binding fragment thereof) to an unrelated, non-CD117 protein is less than about 10% of the binding of the antibody to CD117 as measured, e.g., by a radioimmunoassay (RIA) or by Scatchard analysis or by surface plasmon resonance, such as, for example, Biacore. In certain embodiments, an antibody that binds to CD117 has a dissociation constant (kD) of 0.1 mM, 100 nM, 10 nM, 1 nM, 0.1 nM, 0.01 nM, or 0.001 nM (e.g., 10^-7 M or less, e.g., from 10^-7 M to 10^-13 M). In certain embodiments, an anti-CD117 antibody binds to an epitope of CD117 that is conserved among CD117 from different species. The term "antibody" herein is used in the broadest sense and includes polyclonal and monoclonal antibodies, including intact antibodies and functional (antigen-binding) antibody fragments, including fragment antigen binding (Fab) fragments, F(ab')₂ fragments, Fab' fragments, Fv fragments, recombinant IgG (rlgG) fragments, variable heavy chain (VH) regions capable of specifically binding the antigen, single chain antibody fragments, including single chain variable fragments (scFv), and single domain antibodies (e.g., sdAb, sdFv, nanobody) fragments. The term encompasses genetically engineered and/or otherwise modified forms of immunoglobulins, such as intrabodies, peptibodies, chimeric antibodies, fully human antibodies, humanized antibodies, and heteroconjugate antibodies, multispecific, e.g., bispecific, antibodies, diabodies, triabodies, and tetrabodies, tandem di-scFv, tandem tri-scFv. Unless otherwise stated, the term "antibody" should be understood to encompass functional antibody fragments thereof. The term also encompasses intact or full-length antibodies, including antibodies of any class or sub-class, including IgG and sub-classes thereof, IgM, IgE, IgA, and IgD.

An "antibody derivative" generally refers to a molecule other than an intact antibody that comprises a portion derived from an intact antibody (or antigen-binding fragment thereof) and that binds the antigen to which the intact antibody (or antigen-binding fragment thereof) binds. Examples of antibody derivatives include but are not limited to single chain variable fragments (scFv), diabodies, triabodies, and the like, aptamers comprising multiple antigen-binding antibody fragments, single chain variable fragments, diabodies, triabodies, and the like.

An "antibody fragment" or "antigen-binding antibody fragment" generally refers to a molecule other than an intact antibody that comprises a portion of an intact antibody that binds the antigen to which the intact antibody binds. Examples of antibody fragments include but are not limited to Fv, Fab, Fab', Fab'-SH, F(ab')2 and multispecific antibodies formed from antibody fragments.

The terms "full length antibody," "intact antibody," and "whole antibody" are used herein interchangeably to refer to an antibody having a structure substantially similar to a native antibody structure or having heavy chains that contain an Fc region as defined herein.

The term "Fc region" generally refers to a C-terminal region of an immunoglobulin heavy chain that contains at least a portion of the constant region. The term includes native sequence Fc regions and variant Fc regions. In one embodiment, a human IgG heavy chain Fc region extends from Cys226, or from Pro230, to the carboxyl-terminus of the heavy chain. However, the C-terminal lysine (Lys447) of the Fc region may or may not be present. Unless otherwise specified herein, numbering of amino acid residues in the Fc region or constant region is according to the EU numbering system, also called the EU index, as described in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md., 1991.

An "antibody that binds to the same epitope" as a reference antibody (e.g., an antibody that binds CD117) generally refers to an antibody that blocks binding of the reference antibody to its antigen in a competition assay by 50% or more, and conversely, the reference antibody blocks binding of the antibody to its antigen in a competition assay by 50% or more.

The term "chimeric" antibody generally refers to an antibody in which a portion of the heavy and/or light chain is derived from a particular source or species, while the remainder of the heavy and/or light chain is derived from a different source or species.

A "human antibody" generally refers to an antibody that possesses and amino acid sequence corresponding to that of an antibody produced by a human or a human cell or derived from a non-human source that utilizes human antibody repertoires or other human antibody-encoding sequences. This definition of a human antibody specifically excludes a "humanized" antibody comprising non-human antigen-binding residues.

A "humanized" antibody generally refers to a chimeric antibody comprising amino acid residues from non-human HVRs and amino acid residues from human FRs. In certain embodiments, a humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the HVRs (e.g., CDRs) correspond to those of a non-human antibody, and all or substantially all of the FRs correspond to those of a human antibody. A humanized antibody optionally may comprise at least a portion of an antibody constant region derived from a human antibody. In some embodiments, a humanized antibody (or antigen-binding fragment or derivative thereof), when aligned with the antibody from which the acceptor framework regions were derived, includes one or more amino acid substitutions (or deletions or insertions) at desired locations. In some such embodiments, the amino acid residue(s) substituted (or inserted or deleted) at a particular position in the human (or other) or other FR corresponds to the amino acid residue(s) at the corresponding location(s) in the parent antibody (i.e., the non-human antibody from which the CDRs or HVRs were derived). A "humanized form" of an antibody, e.g., a non-human antibody, refers to an antibody that has undergone humanization.

The term "antibody drug conjugate" (ADC) or "immunoconjugate" generally refers to a particular class of agent-drug conjugates. Here, "agent-drug conjugate" is an anti-CD117 agent (e.g., an anti-CD117 antibody or CD117-binding fragment or derivative thereof) conjugated to one or more heterologous molecule(s), including, but not limited to, a cytotoxic agent. The term "cytotoxic agent" generally refers to a substance that inhibits or prevents a cellular function and/or causes cell death or destruction. Cytotoxic agents include, but are not limited to, radioactive isotopes (e.g., At²¹¹, I¹³¹, I¹²⁵, Y⁹⁰, Re¹⁸⁶, Re¹⁸⁸, Sm¹⁵³, Bi²¹², P³², Pb²¹², and radioactive isotopes of Lu); chemotherapeutic agents or drugs (e.g., methotrexate, adriamycin, vinca alkaloids (vincristine, vinblastine, etoposide), doxorubicin, melphalan, mitomycin C, chlorambucil, daunorubicin or other intercalating agents); growth inhibitory agents; enzymes and fragments thereof such as nucleolytic enzymes; antibiotics; toxins such as small molecule toxins or enzymatically active toxins of bacterial, fungal, plant or animal origin, including fragments and/or variants thereof; and the various antitumor or anticancer agents disclosed below.

A "diagnostic reagent" generally refers to a compound, e.g., a target-specific antibody (or antigen-binding thereof) used to perform a diagnostic assay. "Effector functions" generally refer to those biological activities attributable to the Fc region of an antibody, which vary with the antibody isotype. Examples of antibody effector functions include: C1q binding and complement dependent cytotoxicity (CDC); Fc receptor binding; antibody-dependent cell-mediated cytotoxicity (ADCC); phagocytosis; down regulation of cell surface receptors (e.g. B cell receptor); and B cell activation.

An "effective amount" of an agent, e.g., a pharmaceutical formulation, generally refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic or prophylactic result.

The term "epitope" generally refers to the particular site on an antigen molecule to which an antibody binds.

The terms "host cell", "host cell line", and "host cell culture" are used interchangeably and generally refer to cells into which exogenous nucleic acid has been introduced, including the progeny of such cells. Host cells include "transformants" and "transformed cells," which include the primary transformed cell and progeny derived therefrom without regard to the number of passages. Progeny may not be completely identical in nucleic acid content to a parent cell, but may contain mutations. Mutant progeny that have the same function or biological activity as screened or selected for in the originally transformed cell are included herein.

A "rabbit antibody" generally refers to an antibody that possesses an amino acid sequence that corresponds to that of an antibody produced by a rabbit or a rabbit cell or derived from a non-rabbit source that utilizes rabbit antibody repertoires or other rabbit antibody-encoding sequences. An "immunoconjugate" generally refers to an antibody (or antigen-binding fragment or derivative thereof) conjugated to one or more heterologous molecule(s), including, but not limited to, a cytotoxic agent. An immunoconjugate is equivalent to the term "antibody drug conjugate" (ADC).

An "individual" or "patient" or "subject" generally is a mammal. Mammals include, but are not limited to, domesticated animals (e.g., cows, sheep, cats, dogs, and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In certain embodiments, the individual or subject is a human.

An "isolated" molecule (e.g., nucleic acid, antibody) generally refers to a molecule that has been separated from a component of its original environment (e.g., the natural environment if it is naturally occurring, or a host cell if expressed exogenously), and thus is altered by human intervention (e.g., "by the hand of man") from its original environment. In some embodiments, for example, an antibody is purified to greater than 95% or 99% purity as determined by, for example, electrophoretic (e.g., SDS-PAGE, isoelectric focusing (I EF), capillary electrophoresis) or chromatographic (e.g., ion exchange or reverse phase HPLC). An isolated nucleic acid may refer to a nucleic acid molecule contained in cells that ordinarily contain the nucleic acid molecule, but the nucleic acid molecule is present extrachromosomally or at a chromosomal location that is different from its natural chromosomal location. In some embodiments, an isolated nucleic acid can be provided with fewer non-nucleic acid components (e.g., protein, lipid) than the amount of components that are present in a source sample. A composition comprising isolated nucleic acid can be about 50% to greater than 99% free of non-nucleic acid components. A composition comprising isolated nucleic acid can be about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or greater than 99% free of non-nucleic acid components. "Isolated nucleic acid encoding an anti-CD117 antibody" or "isolated polynucleotide encoding an anti-CD117 antibody" generally refers to one or more nucleic acid molecules encoding antibody heavy and light chains (or fragments thereof), including such nucleic acid molecule(s) in a single vector or separate vectors, and such nucleic acid molecule(s) present at one or more locations in a recombinant host cell.

The term "CD117" generally refers to any native, mature CD117 that results from processing of a CD117 precursor protein in a cell. The term includes CD117 from any vertebrate source, including mammals such as primates (e.g., humans and cynomolgus or rhesus monkeys) and rodents (e.g., mice and rats), unless otherwise indicated. The term also includes naturally occurring variants of CD117, e.g., splice variants or allelic variants. The amino acid sequence of an example human CD117 protein is shown in FIG. 1 (SEQ ID NO: 106). The term "CD117-positive cell" generally refers to any cell that expresses CD117 on its surface or on an intracellular membrane or organelle (e.g., endosome, ER, Golgi apparatus, lysosome, and the like). Some cells, including those infected by a microbe or associated with some cancer types and tumors, exhibit up-regulation of CD117 expression.

The term "monoclonal antibody" generally refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e. , the individual antibodies comprising the population are identical (as assessed at the level of Ig heavy and/or light chain amino acid sequence) and/or bind the same epitope, except for possible variant antibodies, e.g., containing naturally occurring mutations or arising during production of a monoclonal antibody preparation, such variants generally being present in minor amounts. In contrast to polyclonal antibody preparations, which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody of a monoclonal antibody preparation is directed against a single determinant on an antigen. Thus, the modifier "monoclonal" indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies, and is not to be construed as requiring production of the antibody by any particular method. For example, the monoclonal antibodies to be used in accordance with the present technology may be made by a variety of techniques, including, but not limited to, the hybridoma method, recombinant DNA methods, phage-display methods, and methods utilizing transgenic animals containing all or part of the human immunoglobulin loci, such methods and other example methods for making monoclonal antibodies being described herein.

The term "package insert" generally refers to instructions customarily included in commercial packages of therapeutic products, that contain information about the indications, usage, dosage, administration, combination therapy, contraindications and/or warnings concerning the use of such therapeutic products. "Percent (%) amino acid sequence identity" with respect to a reference polypeptide sequence generally refers to the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the reference polypeptide sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared.

The term "pharmaceutical composition" generally refers to a preparation that is in such form as to permit the biological activity of an active ingredient contained therein to be effective, and which contains no additional components which are unacceptably toxic to a subject to which the formulation would be administered.

A "pharmaceutically acceptable carrier" generally refers to an ingredient in a pharmaceutical formulation, other than an active ingredient, which is nontoxic to a subject. A pharmaceutically acceptable carrier includes, but is not limited to, a buffer, excipient, stabilizer, or preservative.

As used herein, "treatment" (and grammatical variations thereof such as "treat" or "treating") generally refers to clinical intervention in an attempt to alter the natural course of the individual being treated, and can be performed either for prophylaxis or during the course of clinical pathology. Desirable effects of treatment include, but are not limited to, preventing occurrence or recurrence of disease, alleviation of symptoms, diminishment of any direct or indirect pathological consequences of the disease, preventing metastasis, decreasing the rate of disease progression, amelioration or palliation of the disease state, and remission or improved prognosis. In some embodiments, antibodies herein are used to delay development of a disease or to slow the progression of a disease.

The term "vector" generally refers to a nucleic acid molecule capable of propagating another nucleic acid to which it is linked. The term includes the vector as a self-replicating nucleic acid structure as well as the vector incorporated into the genome of a host cell into which it has been introduced. Certain vectors are capable of directing the expression of nucleic acids to which they are operatively linked. Such vectors are referred to herein as "expression vectors."

Examples

The examples set forth below illustrate certain embodiments and do not limit the technology.

Example 1 : Creation and Characterization of anti-CD117 Hybridomas

Hybridomas that secrete monoclonal antibody that reacts with CD117 as expressed in vivo can be prepared as described in this Example. The resulting anti-CD117 antibodies can be used for a variety of purposes, including in diagnostic assays, examples of which are provided in the examples below.

Common strains of laboratory mice, e.g., BALB/c or C57/BL6, or rats, e.g., Sprague Dawley, are suitable hosts for immunization with a CD117 immunogen. Following successful immunization of mice, hybridomas are formed using standard protocols to fuse myeloma cells with spleen and draining lymph node cells harvested from the animals. Following selection fusions, in HAT medium and cloning to approximately one cell/well in microtiter plates, the culture supernatants against CD117-expressing cell transfectants, e.g., HEK 293 or RBL, by flow cytometry. Wells with successful staining profiles are then subcultured into larger vessels until sufficient cells are present to allow subcloning. Further characterization of the hybridoma subclone candidates can again be performed by flow cytometry using CD117-transfected cells. Clones selected as the best candidates are then further screened, for example, by flow cytometry against human blood cells divided into distinct subsets (e.g., lymphocytes, and the like) as well as against one or more cell lines generated from diseased and/or infected human cells. As compared to an isotype control, the percentage of positive cells in each blood cell subset can be quantified.

One example of an ideal candidate clone will have strong reactivity against pluripotent hematopoietic progenitor cells, immune cells that express CD117 but no appreciable reactivity against other cell populations. In certain instances, an ideal candidate clone can detect CD117 on the surface of pluripotent hematopoietic progenitor cells and acute myeloid leukemia (AML) cells.

Example 2: Sequencing of the Anti-CD117 Antibody Variable Regions

Cells from well-performing anti-CD117 hybridoma cell lines (described in Example 1, above) were grown in standard mammalian tissue culture media. Total RNA was isolated from hybridoma cells from various clones expressing anti-CD117 monoclonal antibodies using a procedure based on the RNeasy Mini Kit (Qiagen). The RNA was used to generate first strand cDNA. Both light chain and heavy chain variable domain cDNAs were amplified by a 5'-RACE technique. Positive clones were prepared by PCR and then subject to DNA sequencing of multiple clones.

Amino acid sequences of the individual variable domains (CDRs and Framework regions), including CDR1 , CDR2, and CDR3 regions, for both the heavy and light chains for fifteen different antibodies (clones), designated AB 1-15 (also referred to herein as antibodies 1-15, and clones 1-15), are shown in FIGS. 2A and 2B. The various heavy and light chain CDR sequences are shown in Table 5, below. Table 5: CDR Sequences and Sequence ID Numbers of VH and VL domains for representative anti-CD117 monoclonal antibodies

Example 3: Detection of Cells Expressing CD117

This example describes flow cytometry-based detection of human peripheral blood mononuclear cells (PBMCs) and cancer cell line using certain anti-CD117 monoclonal antibodies provided herein.

Materials and Methods

PBMC Isolation Whole blood from healthy volunteers was collected in heparinized cell preparation tubes. The blood was diluted with phosphate buffered saline (PBS) 2-4 times of volume. The diluted blood suspension (35 mL ) was layered carefully over 15 mL of Lymphopure™ in a 50 mL conical tube, and centrifuged at 400 x g for 30 to 40 minutes in a swinging-bucket rotor without brake. The mononuclear cell layer was transferred to a fresh 50 mL conical tube. The mononuclear cell layer was mixed with PBS and centrifuged at 300 x g for 5 minutes. The supernatant was removed and the pellet was washed twice with PBS, and centrifuged. The resulting pellet was resuspended in fluorescence activated cell sorting (FACS) was buffer.

Surface Staining

PBMCs and cancer cells were counted and adjusted in Cell Staining Buffer (BioLegend, cat. #420201) to a cell density of 0.7-1x10⁷ cells/mL. A 100 μL cell suspension (0.7-1x10^® total cells) was stained with various cell surface markers (CD14, CD34, and/or CD117) for 30 minutes in the dark.

All reagents used are from BioLegend unless otherwise indicated.

Flow Cytometry/Gating Hierarchy

Single cells were identified by SSC-A and FSC-A (FIGS. 4A-4F), of which lymphocytes, monocytes, and granulocytes were identified based on their forward (FSC-A) and side scatter (SSC-A) profiles. Monocytes expressing CD14 were excluded from the population of cells, and CD34⁺ hematopoietic stem cells were identified within the CD14- cell population.

Results

Anti-CD117 antibodies recognized CD117 on both Kasumi-3 cells and human PBMCs.

Example 4: Functional Assay

This example describes a functional assay based on the M07E cell line that expresses CD117 on the cell surface.

Experimental

M07E cells were cultured at 0.5 x 10⁶ cells/ml for two days, and culture medium was replaced by serum-free medium prior to assay. M07E cells were diluted into 5 x 10⁶ cells/ml and aliquoted into 200 mI cells/tube. To test antibodies for agonistic activity, M07E cells were incubated with 5μg of antibody on ice for 15 minutes, and then incubated for 5 minutes at 37°C. As a negative control, isotype control antibody was used, and 100 ng/ml stem cell factor (SCF) was used as a positive control. After incubation, cells were fixed with 4% paraformaldehyde (PFA), permeabilized, and stained with anti-phosphorylated ribosomal protein S6 (RPS6). Cells and samples were collected for flow cytometry.

To test antibodies for antagonistic activity, M07E cells were incubated with 5μg of antibody as outlined above. After which, SCF (100 ng/ml) was added to each sample and incubated for 15 minutes on ice. Cells were washed twice with FACS wash buffer, and then stained with biotin-conjugated anti-human SCF antibody for 15 minutes on ice. Cells were then washed twice with FACS wash buffer, and then incubated with PE-streptavidin. Cells and samples were analyzed and relative MFI signaling was compared to isotype control.

Results

Downstream signaling through CD117 was activated by SCF at 5 minutes. Phosphorylation of RPS6 through PI3K and MAPK pathways was used as the readout (FIG. 8).

Example 5: Blocking Assay

This example describes a blocking assay performed using anti-CD117 antibodies described herein.

Blocking Assay

For blocking studies, M07E cells were incubated with 5μg purified AB1 , AB4, AB7, AB8, AB10, AB11, AB12, AB13, AB14, AB15, or Commercial ABI for 15 minutes in the dark. In some instances, no blocking agents were used. After incubation with or without blocking agent, cells were incubated with PE-conjugated antibody or isotype control or 15 minutes. Cells were washed, acquired on a BD Cantoll, and analyzed using FlowJo software.

Calculations for % Blocking

Percentage original MFI was calculated by dividing the MFI of samples blocked with AB1, AB4, AB7, AB8, AB10, AB11 , AB12, AB13, AB14, AB15, and Commercial ABI antibody by the MFI of samples blocked with isotype control. This value was subtracted from 100 to get a blocking percentage. The formula is shown below:

Results

Table 6: MFI and % Blocking

Example 6: Examples of sequences

Provided below are examples of amino acid sequences related to the technology described herein.

Table 7. CDR Sequences and Sequence ID Numbers for Anti-CD117 Antibodies

CDRH1

X₁X₂X₃X₄X₅ (SEQ ID NO: 100) X₁= S, T, N, E, or D X₂= Y or H X₈= G, T, W, D, Y, or N X₄= M, I, or V X₈= S, H, N, V, or A

CDRH2 X₁ X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇X₁₈X₁₉ (S EQ ID NO: 101) X₁=T, Y, M, G, E, R, A, or D X₂= I or M X₃= S, R, N, H, K, or no amino acid X₄= L, T, W, Y, or no amino acid X₅= K, G, S, D, or no amino acid X₆= G, P, S, or T

X₇= G, S, N, I, or R X₈= G, S, D, or N

X₉= T, S, G, D, Y, or R X₁₀=Y, F, E, S, G, L, K, D, or N X₁₁= T, I, F, or Y X₁₂= Y, H, R, F, S, N, or V X₁₃= Y, L, E, S, P, or D X₁₄= P, N, A, G, or S X₁₅= D, Q, E, F, L, or V X₁₆= S, K, or Y X₁₇= L, V, F, M, G, S, or N X₁₈= R or K X₁₉= G, D, or R

CDRH3

X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃Y (SEQ ID NO: 102) X₁= D, E, L, G, I, or H

X₂= W, R, D, G, E, L, or no amino acid

X₃= D, W, Y, A, R, F, or no amino acid X₄= D, R, A, Y, I, or no amino acid X₅= S, G, P, I, Y, or no amino acid X₆= Y, A, W, T, S, D, or no amino acid

X₇= F, M, P, Y, G, or no amino acid X₈= D, A, F, E, R, or no amino acid

X₉= Y, D, F, A, I, or S X₁₀= Y, H, N, or S X₁₁= T, W, Y, or P X₁₂= M or F X₁₃= A, T, or D

CDRL1 X₁X₂SX₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇ (SEQ ID NO: 103) X₁= S, K, or R

X₂= A, S, or R X₄= Q, S, T, or E X₈= S, G, D, or no amino acid X₆= L, D, I, N, or no amino acid X₇= L, V, I, H, or no amino acid X₈= N, H, G, S, or no amino acid X₉= S, G, or no amino acid X₁₀= G, S, or no amino acid X₁₁= D, N, S, or no amino acid X₁₂= I, Q, L, G, or no amino acid X₁₃= S, K, I, R, N, or no amino acid X₁₄= N, T, or no amino acid X₁5= Y, F, or no amino acid X₁₆= L, M, or V X₁₇= N, T, H, S, A, or Y

CDRL2 X₁X₂X₃X₄X₅X₆X₇ (SEQ ID NO: 104) X₁= Y, W, S, F, K, R, or N

X₂= T, A, V, or D X₈= S, D, or I X₄= S, T, N, R, K, or P X₈= L or R X₆= H, Q, E, A, F, or P X₇= S or D CDRL3 X₁X₂X₃X₄X₅X₆X₇X₈X₉ (SEQ ID NO: 105) X₁=Q, H, S, orL X₂=Q, N, H, orS X₈= Y, D, W, G, H, T, orS X₄=S, Y, orT X₅= K, G, T, S, H, H, D, or no amino acid X₆= V, Y, L, T, F, G, S, or no amino acid X₇= P, S, or I X₈= W, L, Y, P, T, or S X₉= T, V, or A

Precursor human CD117 protein sequence (UniProtKB - P10721 (KIT HumanVNCBI

Reference Sequence: NP 00213.1) (SEQ ID NO: 106)

Provided below are examples of nucleotide (NT) sequences related to the technology described herein.

Example 7: Examples of embodiments

The examples set forth below illustrate certain embodiments and do not limit the technology. A1. An anti-CD117 agent that binds CD117 under laboratory or physiologicaLconditions, wherein the agent comprises at least one immunoglobulin heavy chain variable domain and/or at least one immunoglobulin light chain variable domain, wherein: a) each immunoglobulin heavy chain variable domain of the anti-CD117 agent comprises first, second, and third heavy chain complementarity determining regions (CDRs), wherein the first heavy chain CDR (CDRH1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅ (SEQ ID NO: 100), wherein X₁ is S, T, N, E, or D, X₂ is Y or H, X₈ is G, T, W, D, Y, or N,

X₄ is M, I, or V, and X₈ is S, H, N, V, or A; the second heavy chain CDR (CDRH2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence

X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇X₁₈X₁₉ (SEQ ID NO: 101), wherein X₁ is T, Y, M, G, E, R, A, or D, X₂ is I or M, X₃ is S, R, N, H, K, or no amino acid, X₄ is L, T, W, Y, or no amino acid, X₅ is K, G, S, D, or no amino acid, X₆ is G, P, S, or T,

X7 is G, S, N, I, or R, X₈ is G, S, D, or N,

X₉ is T, S, G, D, Y, or R, X₁₀ is Y, F, E, S, G, L, K, D, or N, X₁₁ is T, I, F, or Y, X₁₂ is Y, H, R, F, S, N, or V, X₁₃ is Y, L, E, S, P, or D, X₁₄ is P, N, A, G, or S, X₁₅ is D, Q, E, F, L, or V, X₁₆ is S, K, or Y, X₁₇ is L, V, F, M, G, S, or N X₁₈ is R or K, and X₁₉ is G, D, or R; and the third heavy chain CDR (CDRH3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃Y (SEQ ID NO: 102), wherein X₁ is D, E, L, G, I, or H, X₂ is W, R, D, G, E, L, or no amino acid, X₃ is D, W, Y, A, R, F, or no amino acid, X₄ is D, R, A, Y, I, or no amino acid, X₅ is S, G, P, I, Y, or no amino acid, X₆ is Y, A, W, T, S, D, or no amino acid, X₇ is F, M, P, Y, G, or no amino acid, X₈ is D, A, F, E, R, or no amino acid,

X₉ is Y, D, F, A, I, or S, X₁₀ is Y, H, N, or S, X₁₁ is T, W, Y, or P, X₁₂ is M or F, X₁₃ is A, T, or D; and/or b) each immunoglobulin light chain variable domain of the anti-CD117 agent comprises first, second, and third light chain CDRs, wherein the first light chain CDR (CDRL1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂SX₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇ (SEQ ID NO: 103), wherein X₁= S, K, or R,

X₂= A, S, or R,

X₄= Q, S, T, or E,

X₅= S, G, D, or no amino acid, X₆= L, D, I, N, or no amino acid,

X₇= L, V, I, H, or no amino acid, X₈= N, H, G, S, or no amino acid, X₉= S, G, or no amino acid, X₁₀= G, S, or no amino acid, X₁₁= D, N, S, or no amino acid, X₁₂= I, Q, L, G, or no amino acid, X₁₃= S, K, I, R, N, or no amino acid, X₁₄= N, T, or no amino acid, X₁₅= Y, F, or no amino acid, X₁₆= L, M, or V, X₁₇= N, T, H, S, A, or Y; the second light chain (CDRL2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇ (SEQ ID NO: 104), wherein X₁= Y, W, S, F, K, R, or N,

X₂= T, A, V, or D, X₈= S, D, or I,

X₄= S, T, N, R, K, or P, X₈= L or R, X₆= H, Q, E, A, F, or P, and X₇= S or D; and the third light chain CDR (CDRL3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉ (SEQ ID NO: 105), wherein X₁= Q, H, S, or L,

X₂= Q, N, H, or S, X₈= Y, D, W, G, H, T, or S, X₄= S, Y, or T, X₈= K, G, T, S, H, H, D, or no amino acid, X₆= V, Y, L, T, F, G, S, or no amino acid,

X₇= P, S, or I, X₈= W, L, Y, P, T, or S, and X₉= T, V, or A.

A2. The anti-CD117 agent of embodiment A1 , wherein the CDRH1 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 100.

A3. The anti-CD117 agent of embodiment A1 , wherein the CDRH1 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 100.

A4. The anti-CD117 agent of embodiment A1 , wherein the CDRH1 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 100.

A5. The anti-CD117 agent of embodiment A1 , wherein the CDRH1 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 100.

A6. The anti-CD117 agent of any one of embodiments A1 to A5, wherein the CDRH2 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 101.

A7. The anti-CD117 agent of any one of embodiments A1 to A5, wherein the CDRH2 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 101.

A8. The anti-CD117 agent of any one of embodiments A1 to A5, wherein the CDRH2 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 101.

A9. The anti-CD117 agent of any one of embodiments A1 to A5, wherein the CDRH2 comprises an amino acid sequence that is at least 100% identical to the amino acid sequence of SEQ ID NO: 101. A10. The anti-CD117 agent of any one of embodiments A1 to A9, wherein the CDRH3 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 102.

A11. The anti-CD117 agent of any one of embodiments A1 to A9, wherein the CDRH3 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 102.

A12. The anti-CD117 agent of any one of embodiments A1 to A9, wherein the CDRH3 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 102.

A13. The anti-CD117 agent of any one of embodiments A1 to A9, wherein the CDRH3 comprises an amino acid sequence that is at least 100% identical to the amino acid sequence of SEQ ID NO: 102.

A14. The anti-CD117 agent of any one of embodiments A1 to A13, wherein the CDRL1 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 103.

A15. The anti-CD117 agent of any one of embodiments A1 to A13, wherein the CDRL1 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 103.

A16. The anti-CD117 agent of any one of embodiments A1 to A13, wherein the CDRL1 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 103.

A17. The anti-CD117 agent of any one of embodiments A1 to A13, wherein the CDRL1 comprises an amino acid sequence that is at least 100% identical to the amino acid sequence of SEQ ID NO: 103.

A18. The anti-CD117 agent of any one of embodiments A1 to A17, wherein the CDRL2 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 104. A19. The anti-CD117 agent of any one of embodiments A1 to A17, wherein the CDRL2 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 104.

A20. The anti-CD117 agent of any one of embodiments A1 to A17, wherein the CDRL2 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 104.

A21. The anti-CD117 agent of any one of embodiments A1 to A17, wherein the CDRL2 comprises an amino acid sequence that is at least 100% identical to the amino acid sequence of SEQ ID NO: 104.

A22. The anti-CD117 agent of any one of embodiments A1 to A21, wherein the CDRL3 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 105.

A23. The anti-CD117 agent of any one of embodiments A1 to A21, wherein the CDRL3 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 105.

A24. The anti-CD117 agent of any one of embodiments A1 to A21, wherein the CDRL3 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 105.

A25. The anti-CD117 agent of any one of embodiments A1 to A21, wherein the CDRL3 comprises an amino acid sequence that is at least 100% identical to the amino acid sequence of SEQ ID NO: 105.

A26. The anti-CD117 agent of any one embodiments A1 to A25, wherein the CDRH1 comprises an amino acid sequence chosen from SYGMS (SEQ ID NO: 31), TYTIH (SEQ ID NO: 32), NYGMS (SEQ ID NO: 33), SYWMN (SEQ ID NO: 34), NYDMS (SEQ ID NO: 35), EHYMV (SEQ ID NO: 36), NYWMN (SEQ ID NO: 37), SYYIS (SEQ ID NO: 38), SYGVS (SEQ ID NO: 39), DYWMS (SEQ ID NO: 40), and DYNMA (SEQ ID NO: 41).

A27. The anti-CD117 agent of any one of embodiments A1 to A26, wherein the CDRH2 comprises an amino acid sequence chosen from TISGGGTYTYYPDSLRG (SEQ ID NO: 42), TIRGGGSFTYYPDSVKG (SEQ ID NO: 43), YINPSSGYTHYNQKFKD (SEQ ID NO: 44), TISGGGDFTYYPDSMRR (SEQ ID NO: 45), MIHPSDSEIRLNQKFKD (SEQ ID NO: 46), YISSGGGSFFYPDTVKG (SEQ ID NO: 47), GINPNNGGTSYNQKFKG (SEQ ID NO: 48), EIRLKSNNYLTHYAESVKG (SEQ ID NO: 49), RIHPSDSEIRLNQKFKD (SEQ ID NO: 50), YINTGTISTKYNENFKG (SEQ ID NO: 51), AMWSGGSTDYNSGLKS (SEQ ID NO: 52), DIKYDGSDTNYVPSLKN (SEQ ID NO: 53), TISYDGRSIYYRDSVKG (SEQ ID NO: 54), and AIWSGGSTDYNSALKS (SEQ ID NO: 55).

A28. The anti-CD117 agent of any one of embodiments A1 to A27, wherein the CDRH3 comprises an amino acid sequence chosen from DWDDSYFDY (SEQ ID NO: 56), DRWRD (SEQ ID NO: 57), EDYAGAMDF (SEQ ID NO: 58), LGDYPWFAY (SEQ ID NO: 59), GEAIITPFAY (SEQ ID NO: 60), IRRDYSMDY (SEQ ID NO: 61), EIHTMAY (SEQ ID NO: 62), GDYEYNWFTY (SEQ ID NO: 63), EDGRSYYFDY (SEQ ID NO: 64), HLFYYDGRSYPFAY (SEQ ID NO: 65), and GDYEYSWFTY (SEQ ID NO: 66).

A29. The anti-CD117 agent of any one of embodiments A1 to A28, wherein the CDRL1 comprises an amino acid sequence chosen from SASQDISNYLN (SEQ ID NO: 67), KSSQSLLNSGNQKNYLT (SEQ ID NO: 68), SASSSLIYMH (SEQ ID NO: 69), RASQDIRNYLS (SEQ ID NO: 70), KSSQSLLNSSNQKNYLA (SEQ ID NO: 71), RSSQSLVHSDGNTYLH (SEQ ID NO: 72), RSSQSLVHSDGSTYLH (SEQ ID NO: 73), KRSTGDIGSNYVY (SEQ ID NO: 74), RASEDIHNGLA (SEQ ID NO: 75), KSSQSLLSSGNQKNFLA (SEQ ID NO: 76), and KRSTGNIGSNYVH (SEQ ID NO: 77).

A30. The anti-CD117 agent of any one of embodiments A1 to A29, wherein CDRL2 comprises an amino acid sequence chosen from YTSSLHS (SEQ ID NO: 78), YTSSLQS (SEQ ID NO: 79), WASTRES (SEQ ID NO: 80), STSNLAS (SEQ ID NO: 81), YTSRLQS (SEQ ID NO: 82), FASTRES (SEQ ID NO: 83), KVSNRFS (SEQ ID NO: 84), RVSNRFS (SEQ ID NO: 85), RDDKRPD (SEQ ID NO: 86), NAISLHS (SEQ ID NO: 87), and WASPRQS (SEQ ID NO: 88).

A31. The anti-CD117 agent of any one of embodiments A1 to A30, wherein CDRL3 comprises an amino acid sequence chosen from QQYSKVPWT (SEQ ID NO: 89), QNDYGYPLT (SEQ ID NO: 90), HHWSSYT (SEQ ID NO: 91), QQGYTLPWT (SEQ ID NO: 92), QQHYSTPPT (SEQ ID NO: 93), SQTTHVPLT (SEQ ID NO: 94), LQSTHFPWT (SEQ ID NO: 95), QSYSSGITV (SEQ ID NO: 96), QQYYNYPWT (SEQ ID NO: 97), QQYYDSPLA (SEQ ID NO: 98), and QSYSSGISV (SEQ ID NO: 99). A32. The anti-CD117 agent of any one of embodiments A1 to A31, which comprises two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains. A33. The anti-CD117 agent of embodiment A32, wherein the two immunoglobulin heavy chain variable domains each comprise a set of CDRH1, CDRH2, and CDRH3 amino acid sequences.

A34. The anti-CD117 agent of embodiment A32 and A33, wherein the two immunoglobulin light chain variable domains each comprise a set of CDRL1 , CDRL2, and CDRL3 amino acid sequences.

A35. The anti-CD117 agent of any one of embodiments A1 to A34, wherein each immunoglobulin heavy chain variable domain comprises a set of CDRH1, CDRH2, CDRH3 amino acid sequences and each immunoglobulin light chain variable domain comprises a set of CDRL1, CDRL2, and CDRL3 amino acid sequences chosen from sets 1-15:

A36. The anti-CD117 agent of embodiment A35, wherein all CDR sequences are from the same set. A37. The anti-CD117 agent of any one of embodiments A1 to A36, wherein the agent is isolated.

A38. The anti-CD117 agent of any one of embodiments A1 to A37, wherein the agent is non- naturally occurring.

A39. The anti-CD117 agent of any one of embodiments A1 to A38, wherein the agent is an antibody, or antigen-binding fragment thereof. A40. The anti-CD117 agent of any one of embodiments A1 to A38, wherein the agent is an antibody, or derivative thereof.

A41. The anti-CD117 agent of any one of embodiments A1 to A40, wherein the agent is a humanized antibody, or an antigen binding fragment thereof.

A42. The anti-CD117 agent of any one of embodiments A1 to A40, wherein the agent is a derivative of a humanized antibody that binds CD117.

A43. The anti-CD117 agent of any one of embodiments A1 to A42, wherein the agent comprises a detectable marker or label.

A44. The anti-CD117 agent of any one of embodiments A1 to A43, wherein the agent is conjugated to a detectable marker or label.

A45. The anti-CD117 agent of any one of embodiments A1 to A44, wherein the agent is non- diffusively immobilized on a solid support.

A46. A diagnostic reagent comprising the anti-CD117 agent of any one of embodiments A1 to A45.

A47. A kit comprising the anti-CD117 agent of any one of embodiments A1 to A45 or the diagnostic reagent of embodiment A46.

A48. A diagnostic kit configured to detect CD117 in a biological sample, wherein the kit comprises the anti-CD117 agent of any one of embodiments A1 to A45 or the diagnostic reagent of embodiment A46.

A49. An isolated nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin heavy chain variable domain of the anti-CD117 agent of any one of embodiments A1 to A45.

A50. An isolated nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin light chain variable domain of the anti-CD117 agent of any one of embodiments A1 to A45. A51. A recombinant expression vector comprising a first expression cassette and a second expression cassette, wherein the first expression cassette comprises a promoter and a nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin heavy chain variable domain of the anti-CD117 agent of any one of embodiments A1 to A45, and the second expression cassette comprises a promoter and a nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin light chain variable domain of the anti- CD117 agent of any one of embodiments A1 to A45.

A52. A recombinant host cell transfected with the recombinant expression vector of embodiment A51.

A53. A method of detecting CD117, comprising contacting a sample known or suspected to contain CD117 with the anti-CD117 agent of any one of embodiments A1 to A45, and, if the sample contains CD117, detecting CD117:anti-CD117 complexes.

B1. A first anti-CD117 agent that binds CD117 under laboratory or physiological conditions, wherein the first agent competitively binds, or is capable of competitively binding, with a second anti-CD117 agent, which second agent is the anti-CD117 agent of any one of embodiments A1 to A36.

B2. A first anti-CD117 agent that binds CD117 under laboratory or physiological conditions, wherein the first agent binds to, or is capable of binding to, the same epitope as a second anti- CD117 agent, which second agent is the anti-CD117 agent of any one of embodiments A1 to A 36.

B3. The first anti-CD117 agent of embodiment B1 or B2, wherein the first agent and/or second agent is isolated.

B4. The first anti-CD117 agent of any one of embodiments B1 to B3, wherein the first agent and/or second agent is non-naturally occurring.

B5. The first anti-CD117 agent of any one of embodiments B1 to B4, wherein the first agent and/or second agent is an antibody, or derivative.

B6. The first anti-CD117 agent of any one of embodiments B1 to B4, wherein the first agent and/or second agent is an antibody, or derivative thereof. B7. The first anti-CD117 agent of any one of embodiments B1 to B6, wherein the first agent and/or second agent is a humanized antibody, or an antigen binding fragment thereof.

B8. The first anti-CD117 agent of any one of embodiments B1 to B6, wherein the first agent and/or second agent is a derivative of a humanized antibody that binds CD117.

B9. The first anti-CD117 agent of any one of embodiments B1 to B8, comprising a detectable marker or label.

B10. The first anti-CD117 agent of any one of embodiments B1 to B9, wherein the first agent is conjugated to a detectable marker or label.

B11. The first anti-CD117 agent of any one of embodiments B1 to B10, wherein the first agent is non-diffusively immobilized on a solid support.

B12. A diagnostic reagent comprising the first anti-CD117 agent of any one of embodiments B1 to B11.

B13. A kit comprising the first anti-CD117 agent of any one of embodiments B1 to B11 or the diagnostic reagent of embodiment B12.

B14. A diagnostic kit configured to detect CD117 in a biological sample, wherein the kit comprises the first anti-CD117 agent of any one of embodiments B1 to B11 or the diagnostic reagent of embodiment B12.

B15. An isolated nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin heavy chain variable domain of the first anti-CD117 agent of any one of embodiments B1 to B11.

B16. An isolated nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin light chain variable domain of the first anti-CD117 agent of any one of embodiments B1 to B11.

B17. A recombinant expression vector comprising a first expression cassette and a second expression cassette, wherein the first expression cassette comprises a promoter and a nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin heavy chain variable domain of the first anti-CD117 agent of any one of embodiments B1 to B 11 , and the second expression cassette comprises a promoter and a nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin light chain variable domain of the first anti-CD117 agent of any one of embodiments B1 to B11.

B18. A recombinant host cell transfected with the recombinant expression vector of embodiment B17.

B19. A method of detecting CD117, comprising contacting a sample known or suspected to contain CD117 with the first anti-CD117 agent of any one of embodiments B1 to B11 , and, if the sample contains CD117, detecting CD117:anti-CD117 complexes.

C1. An anti-CD117 agent for detecting CD117 in a heterogeneous population of cells, wherein CD117 is detected at a significant level in hematopoietic stem cells in the population, and CD117 is not significantly detected in other cells in the population.

C2. The anti-CD117 agent of embodiment C1 , wherein the anti-CD117 agent comprises at least on immunoglobulin heavy chain variable domain and at least one immunoglobulin light chain variable domain, wherein: i) each immunoglobulin heavy chain variable domain of the anti-CD117 agent comprises first, second, and third heavy chain complementarity determining regions (CDRs); and ii) each immunoglobulin light chain variable domain of the anti-CD117 agent comprises first, second, and third light chain CDRs.

C3. The anti-CD117 agent of embodiment C2, wherein the first heavy chain CDR (CDRH1) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅ (SEQ ID NO: 100), wherein X₁ is S, T, N, E, or D,

X₂ is Y or H, X₈ is G, T, W, D, Y, or N,

X₄ is M, I, or V, and X₈ is S, H, N, V, or A.

C4. The anti-CD117 agent of embodiment C2 or C3, wherein the second heavy chain CDR (CDRH2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁0X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇X₁₃X₁₉ (SEQ ID NO: 101), wherein X₁ is T, Y, M, G, E, R, A, or D, X₂ is I or M, X₃ is S, R, N, H, K, or no amino acid, X₄ is L, T, W, Y, or no amino acid, X₅ is K, G, S, D, or no amino acid, X₆ is G, P, S, or T,

X₇ is G, S, N, I, or R, X₈ is G, S, D, or N,

X₉ is T, S, G, D, Y, or R, X₁₀ is Y, F, E, S, G, L, K, D, or N, X₁₁ is T, I, F, or Y, X₁₂ is Y, H, R, F, S, N, or V, X₁₃ is Y, L, E, S, P, or D, X₁₄ is P, N, A, G, or S, X₁₅ is D, Q, E, F, L, or V,

X₁₆ is S, K, or Y, X₁₇ is L, V, F, M, G, S, or N X₁8 is R or K, and X₁₉ is G, D, or R.

C5. The anti-CD117 agent of embodiment C2, C3, or C4, wherein the third heavy chain CDR (CDRH3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃Y (SEQ ID NO: 102), wherein X₁ is D, E, L, G, I, or H, X₂ is W, R, D, G, E, L, or no amino acid, X₃ is D, W, Y, A, R, F, or no amino acid, X₄ is D, R, A, Y, I, or no amino acid, X₅ is S, G, P, I, Y, or no amino acid, X₆ is Y, A, W, T, S, D, or no amino acid, X₇ is F, M, P, Y, G, or no amino acid, X₈ is D, A, F, E, R, or no amino acid,

X₉ is Y, D, F, A, I, or S, X₁₀ is Y, H, N, or S, X₁₁ is T, W, Y, or P, X₁₂ is M or F, and X₁₃ is A, T, or D.

C6. The anti-CD117 agent of any one of embodiments C2 to C5, wherein the first light chain CDR (CDRL1) comprising an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂SX₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇ (SEQ ID NO: 103), wherein X₁ is S, K, or R, X₂ is A, S, or R, X₄ is Q, S, T, or E, X₅ is S, G, D, or no amino acid, X₆ is L, D, I, N, or no amino acid, X₇ is L, V, I, H, or no amino acid, X₈ is N, H, G, S, or no amino acid, X₉ is S, G, or no amino acid, X₁₀ is G, S, or no amino acid, X₁₁ is D, N, S, or no amino acid, X₁₂ is I, Q, L, G, or no amino acid, X₁₃ is S, K, I, R, N, or no amino acid, X₁₄ is N, T, or no amino acid, X₁5 is Y, F, or no amino acid, X₁₆ is L, M, or V, and X₁₇ is N, T, H, S, A, or Y.

C7. The anti-CD117 agent of any one of embodiments C2 to C6, wherein the second light chain CDR (CDRL2) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₃X₇ (SEQ ID NO: 104), wherein X₁ is Y, W, S, F, K, R, or N,

X₂ is T, A, V, or D, X₈ is S, D, or I, X₄ is S, T, N, R, K, or P, X₈ is L or R, X₆ is H, Q, E, A, F, or P, and X₇ is S or D.

C8. The anti-CD117 agent of any one of embodiments C2 to C7, wherein the third light chain CDR (CDRL3) comprises an amino acid sequence that is at least 80% (e.g., 80%, 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%) identical to the amino acid sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉ (SEQ ID NO: 105), wherein X₁ is Q, H, S, or L,

X₂ is Q, N, H, or S, X₈ is Y, D, W, G, H, T, or S, X₄ is S, Y, or T, X₈ is K, G, T, S, H, H, D, or no amino acid, X₆ is V, Y, L, T, F, G, S, or no amino acid,

X7 is P, S, or I, X₈ is W, L, Y, P, T, or S, and X₉ is T, V, or A.

C9. The anti-CD117 agent of any one of embodiments C2 to C8, wherein the CDRH1 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 100.

C10. The anti-CD117 agent of any one of embodiments C2 to C8, wherein the CDRH1 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 100.

C11. The anti-CD117 agent of any one of embodiments C2 to C8, wherein the CDRH1 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 100.

C12. The anti-CD117 agent of any one of embodiments C2 to C8, wherein the CDRH1 comprises an amino acid sequence that is at least 100% identical to the amino acid sequence of SEQ ID NO: 100.

C13. The anti-CD117 agent of any one of embodiments C2 to C12, wherein the CDRH2 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 101. C14. The anti-CD117 agent of any one of embodiments C2 to C12, wherein the CDRH2 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 101.

C15. The anti-CD117 agent of any one of embodiments C2 to C12, wherein the CDRH2 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 101.

C16. The anti-CD117 agent of any one of embodiments C2 to C12, wherein the CDRH2 comprises an amino acid sequence that is at least 100% identical to the amino acid sequence of SEQ ID NO: 101.

C17. The anti-CD117 agent of any one of embodiments C2 to C16, wherein the CDRH3 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence SEQ ID NO: 102.

C18. The anti-CD117 agent of any one of embodiments C2 to C16, wherein the CDRH3 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence SEQ ID NO: 102.

C19. The anti-CD117 agent of any one of embodiments C2 to C16, wherein the CDRH3 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence SEQ ID NO: 102.

C20. The anti-CD117 agent of any one of embodiments C2 to C16, wherein the CDRH3 comprises an amino acid sequence that is at least 100% identical to the amino acid sequence SEQ ID NO: 102.

C21. The anti-CD117 agent of any one of embodiments C2 to C20, wherein the CDRL1 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 103.

C22. The anti-CD117 agent of any one of embodiments C2 to C20, wherein the CDRL1 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 103. C23. The anti-CD117 agent of any one of embodiments C2 to C20, wherein the CDRL1 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 103.

C24. The anti-CD117 agent of any one of embodiments C2 to C20, wherein the CDRL1 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 103.

C25. The anti-CD117 agent of any one of embodiments C2 to C24, wherein the CDRL2 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 104.

C26. The anti-CD117 agent of any one of embodiments C2 to C24, wherein the CDRL2 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 104.

C27. The anti-CD117 agent of any one of embodiments C2 to C24, wherein the CDRL2 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 104.

C28. The anti-CD117 agent of any one of embodiments C2 to C24, wherein the CDRL2 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 104.

C29. The anti-CD117 agent of any one of embodiments C2 to C28, wherein the CDRL3 comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 105.

C30. The anti-CD117 agent of any one of embodiments C2 to C28, wherein the CDRL3 comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 105.

C31. The anti-CD117 agent of any one of embodiments C2 to C28, wherein the CDRL3 comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 105. C32. The anti-CD117 agent of any one of embodiments C2 to C28, wherein the CDRL3 comprises an amino acid sequence that is 100% identical to the amino acid sequence of SEQ ID NO: 105.

C33. The anti-CD117 agent of any one embodiments C2 to C32, wherein the CDRH1 comprises an amino acid sequence chosen from SYGMS (SEQ ID NO: 31), TYTIH (SEQ ID NO: 32), NYGMS (SEQ ID NO: 33), SYWMN (SEQ ID NO: 34), NYDMS (SEQ ID NO: 35), EHYMV (SEQ ID NO: 36), NYWMN (SEQ ID NO: 37), SYYIS (SEQ ID NO: 38), SYGVS (SEQ ID NO: 39), DYWMS (SEQ ID NO: 40), and DYNMA (SEQ ID NO: 41).

C34. The anti-CD117 agent of any one of embodiments C2 to C33, wherein the CDRH2 comprises an amino acid sequence chosen from TISGGGTYTYYPDSLRG (SEQ ID NO: 42), TIRGGGSFTYYPDSVKG (SEQ ID NO: 43), YINPSSGYTHYNQKFKD (SEQ ID NO: 44), TISGGGDFTYYPDSMRR (SEQ ID NO: 45), MIHPSDSEIRLNQKFKD (SEQ ID NO: 46), YISSGGGSFFYPDTVKG (SEQ ID NO: 47), GINPNNGGTSYNQKFKG (SEQ ID NO: 48), EIRLKSNNYLTHYAESVKG (SEQ ID NO: 49), RIHPSDSEIRLNQKFKD (SEQ ID NO: 50), YINTGTISTKYNENFKG (SEQ ID NO: 51), AMWSGGSTDYNSGLKS (SEQ ID NO: 52), DIKYDGSDTNYVPSLKN (SEQ ID NO: 53), TISYDGRSIYYRDSVKG (SEQ ID NO: 54), and AIWSGGSTDYNSALKS (SEQ ID NO: 55).

C35. The anti-CD117 agent of any one of embodiments C2 to C34, wherein the CDRH3 comprises an amino acid sequence chosen from DWDDSYFDY (SEQ ID NO: 56), DRWRD (SEQ ID NO: 57), EDYAGAMDF (SEQ ID NO: 58), LGDYPWFAY (SEQ ID NO: 59), GEAIITPFAY (SEQ ID NO: 60), IRRDYSMDY (SEQ ID NO: 61), EIHTMAY (SEQ ID NO: 62), GDYEYNWFTY (SEQ ID NO: 63), EDGRSYYFDY (SEQ ID NO: 64), HLFYYDGRSYPFAY (SEQ ID NO: 65), and GDYEYSWFTY (SEQ ID NO: 66).

C36. The anti-CD117 agent of any one of embodiments C2 to C35, wherein the CDRL1 comprises an amino acid sequence chosen from SASQDISNYLN (SEQ ID NO: 67), KSSQSLLNSGNQKNYLT (SEQ ID NO: 68), SASSSLIYMH (SEQ ID NO: 69), RASQDIRNYLS (SEQ ID NO: 70), KSSQSLLNSSNQKNYLA (SEQ ID NO: 71), RSSQSLVHSDGNTYLH (SEQ ID NO: 72), RSSQSLVHSDGSTYLH (SEQ ID NO: 73), KRSTGDIGSNYVY (SEQ ID NO: 74), RASEDIHNGLA (SEQ ID NO: 75), KSSQSLLSSGNQKNFLA (SEQ ID NO: 76), and KRSTGNIGSNYVH (SEQ ID NO: 77).

C37. The anti-CD117 agent of any one of embodiments C2 to C36, wherein CDRL2 comprises an amino acid sequence chosen from YTSSLHS (SEQ ID NO: 78), YTSSLQS (SEQ ID NO: 79), WASTRES (SEQ ID NO: 80), STSNLAS (SEQ ID NO: 81), YTSRLQS (SEQ ID NO: 82), FASTRES (SEQ ID NO: 83), KVSNRFS (SEQ ID NO: 84), RVSNRFS (SEQ ID NO: 85), RDDKRPD (SEQ ID NO: 86), NAISLHS (SEQ ID NO: 87), and WASPRQS (SEQ ID NO: 88).

C38. The anti-CD117 agent of any one of embodiments C2 to C37, wherein CDRL3 comprises an amino acid sequence chosen from QQYSKVPWT (SEQ ID NO: 89), QNDYGYPLT (SEQ ID NO: 90), HHWSSYT (SEQ ID NO: 91), QQGYTLPWT (SEQ ID NO: 92), QQHYSTPPT (SEQ ID NO: 93), SQTTHVPLT (SEQ ID NO: 94), LQSTHFPWT (SEQ ID NO: 95), QSYSSGITV (SEQ ID NO: 96), QQYYNYPWT (SEQ ID NO: 97), QQYYDSPLA (SEQ ID NO: 98), and QSYSSGISV (SEQ ID NO: 99).

C39. The anti-CD117 agent of any one of embodiments C1 to C38, which comprises two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains.

C40. The anti-CD117 agent of embodiment C39, wherein the two immunoglobulin heavy chain variable domains each comprise a set of CDRH1, CDRH2, and CDRH3 amino acid sequences.

C41. The anti-CD117 agent of embodiment C39 and C40, wherein the two immunoglobulin light chain variable domains each comprise a set of CDRL1 , CDRL2, and CDRL3 amino acid sequences.

C42. The anti-CD117 agent of any one of embodiments C2 to C41, wherein each immunoglobulin heavy chain variable domain comprises a set of CDRH1, CDRH2, CDRH3 amino acid sequences and each immunoglobulin light chain variable domain comprises a set of CDRL1, CDRL2, and CDRL3 amino acid sequences chosen from sets 1-15:

C43. The anti-CD117 agent of embodiment C42, wherein all CDR sequences are from the same set.

C44. The anti-CD117 agent of any one of embodiments C1 to C43, wherein the agent is isolated.

C45. The anti-CD117 agent of embodiment C44, wherein CD117 is detected in hematopoietic stem cells using a flow cytometry assay.

C46. The anti-CD117 agent of any one of embodiments C1 to C45, wherein CD117 is not significantly detected in other cells in the population, wherein the other immune cells comprise one or more of B cells, T cells, and monocytes.

C47. The anti-CD117 agent of any one of embodiments C1 to C46, wherein the agent is non- naturally occurring.

C48. The anti-CD117 agent of any one of embodiments C1 to C47, wherein the agent is an antibody, or antigen-binding fragment thereof.

C49. The anti-CD117 agent of any one of embodiments C1 to C48, wherein the agent is an antibody, or derivative thereof.

C50. The anti-CD117 agent of any one of embodiments C1 to C49, wherein the agent is a humanized antibody, or an antigen binding fragment thereof.

C51. The anti-CD117 agent of any one of embodiments C1 to C50, wherein the agent is a derivative of a humanized antibody that binds CD117.

C52. The anti-CD117 agent of any one of embodiments C1 to C51, wherein the agent comprises a detectable marker or label.

C53. The anti-CD117 agent of any one of embodiments C1 to C52, wherein the agent is conjugated to a detectable marker or label.

C54. The anti-CD117 agent of any one of embodiments C1 to C53, wherein the agent is non- diffusively immobilized on a solid support. C55. A diagnostic reagent comprising the anti-CD117 agent of any one of embodiments C1 to C54.

C56. A kit comprising the anti-CD117 agent of any one of embodiments C1 to C54 or the diagnostic reagent of embodiment C55.

C57. A diagnostic kit configured to detect CD117 in a biological sample, wherein the kit comprises the anti-CD117 agent of any one of embodiments C1 to C54 or the diagnostic reagent of embodiment C55.

C58. An isolated nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin heavy chain variable domain of the anti-CD117 agent of any one of embodiments C1 to C57.

C59. An isolated nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin light chain variable domain of the anti-CD117 agent of any one of embodiments C1 to C57.

C60. A recombinant expression vector comprising a first expression cassette and a second expression cassette, wherein the first expression cassette comprises a promoter and a nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin heavy chain variable domain of the anti-CD117 agent of any one of embodiments C1 to C59, and the second expression cassette comprises a promoter and a nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin light chain variable domain of the anti- CD117 agent of any one of embodiments C1 to C59.

C61. A recombinant host cell transfected with the recombinant expression vector of embodiment C60.

C62. A method of detecting CD117, comprising contacting a sample known or suspected to contain CD117 with the anti-CD117 agent of any one of embodiments C1 to C61 , and, if the sample contains CD117, detecting CD117:anti-CD117 complexes.

The entirety of each patent, patent application, publication and document referenced herein hereby is incorporated by reference. Citation of the above patents, patent applications, publications and documents is not an admission that any of the foregoing is pertinent prior art, nor does it constitute any admission as to the contents or date of these publications or documents. Their citation is not an indication of a search for relevant disclosures. All statements regarding the date(s) or contents of the documents is based on available information and is not an admission as to their accuracy or correctness.

Modifications may be made to the foregoing without departing from the basic aspects of the technology. Although the technology has been described in substantial detail with reference to one or more specific embodiments, those of ordinary skill in the art will recognize that changes may be made to embodiments specifically disclosed in this application, yet these modifications and improvements are within the scope and spirit of the technology.

The technology illustratively described herein suitably may be practiced in the absence of any element(s) not specifically disclosed herein. Thus, for example, in each instance herein any of the terms "comprising," "consisting essentially of," and "consisting of' may be replaced with either of the other two terms. The terms and expressions which have been employed are used as terms of description and not of limitation, and use of such terms and expressions do not exclude nay equivalents of the features shown and described or portions thereof, and various modifications are possible within the scope of the technology claimed. The term "a" or "an" can refer to one of or a plurality of the elements it modifies (e.g., "a reagent" can mean one or more reagents) unless it is contextually clear either one of the elements or more than one of the elements is described. The term "about" as used herein refers to a value within 10% of the underlying parameter (i.e. , plus or minus 10%), and use of the term "about" at the beginning of a string of values modifies each of the values (i.e., "about 1, 2, and 3" refers to about 1, about 2, and about 3). For example, a weight of "about 100 grams" can include weights between 90 grams and 110 grams. Further, when a listing of values is described herein (e.g., about 50%, 60%, 70%, 80%, 85%, or 86%) the listing included all intermediate and fractional values thereof (e.g., 54%, 85.4%). Thus, it should be understood that although the present technology has been specifically disclosed by representative embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and such modifications and variations are considered within the scope of this technology.

Certain embodiments of the technology are set forth in the claim(s) that follow(s).

Claims

What is claimed is:

1. An anti-CD117 antibody or antigen-binding fragment thereof comprising one or more of: a) an immunoglobulin heavy chain variable domain comprising:

(ii) a heavy chain complementary determining region 2 (CDRH2) comprising the sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂ X₁3X₁₄X₁₅X₁₆X₁₇ X₁₈X₁₉ (SEQ ID NO: 101), wherein X₁ is T, Y, M, G, E, R, A, or D; X₂ is I or M; X₃ is S, R, N, H, K, or no amino acid; X₄ is L, T, W, Y, or no amino acid; X₅ is K, G, S, D, or no amino acid; X₆ is G, P, S, or T; X₇ is G, S, N, I, or R; X₈ is G, S, D, or N; X₉ is T, S, G, D, Y, or R; X₁₀ is Y, F, E, S, G, L, K, D, or N; X₁₁ is T, I, F, or Y; X₁₂ is Y, H, R, F, S, N, or V; X₁₃ is Y, L, E, S, P, or D; X₁₄ is P, N, A, G, or S; X₁₅ is D, Q, E, F, L, or V; X₁₆ is S, K, or Y; X₁₇ is L, V, F, M, G, S, or N; X₁₈ is R or K; and X₁₉ is G, D, or R;

(iii) a heavy chain complementary determining region 3 (CDRH3) comprising the sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃Y (SEQ ID NO: 102), wherein X₁ is D, E, L, G, I, or H; X₂ is W, R, D, G, E, L, or no amino acid; X₃ is D, W, Y, A, R, F, or no amino acid; X₄ is D, R, A, Y, I, or no amino acid; X₅ is S, G, P, I, Y, or no amino acid; X₆ is Y, A, W, T, S, D, or no amino acid; X₇ is F, M, P, Y, G, or no amino acid; X₈ is D, A, F, E, R, or no amino acid; X₉ is Y, D, F, A, I, or S ; X₁₀ is Y, H, N, or S; X₁₁ is T, W, Y, or P; X₁₂ is M or F; and X₁₃ is A, T, or D; b) an immunoglobulin light chain variable domain comprising:

(i) a light chain complementary determining region 1 (CDRL1) comprising the sequence X₁X₂SX₄X₅X₃X₇X₈X₉X₁₀X₁₁X₁₂X₁₃X₁₄X₁₅X₁₆X₁₇ (SEQ ID NO: 103), wherein X₁ is S, K, or R; X₂ is A, S, or R; X₄ is Q, S, T, or E; X₅ is S, G, D, or no amino acid; X₆ is L, D, I, N, or no amino acid; X₇ is L, V, I, H, or no amino acid; X₈ is N, H, G, S, or no amino acid; X₉ is S, G, or no amino acid; X₁₀ is G, S, or no amino acid; X₁₁ is D, N, S, or no amino acid; X₁₂ is I, Q, L, G, or no amino acid; X₁₃ is S, K, I, R, N, or no amino acid; X₁₄ is N, T, or no amino acid; X₁₅ is Y, F, or no amino acid; X₁₆ is L, M, or V; and X₁₇ is N, T, H, S, A, or Y;

(ii) a light chain complementary determining region 2 (CDRL2) comprising the sequence X₁X₂X₃X₄X₅X₃X₇ (SEQ ID NO: 104), wherein X₁ is Y, W, S, F, K, R, or N; X₂ is T, A, V, or D; X₈ is S, D, or I; X₄ is S, T, N, R, K, or P; X₅ is L or R; X₆ is H, Q, E, A, F, or P; and X₇ is S or D; and (iii) a light chain complementary determining region 3 (CDRL3) comprising the sequence X₁X₂X₃X₄X₅X₆X₇X₈X₉ (SEQ ID NO: 105), wherein X₁ is Q, H, S, or L; X₂ is Q, N, H, or S; X₃ is Y, D, W, G, H, T, or S; X₄ is S, Y, or T; X₅ is K, G, T, S, H, H, D, or no amino acid; X₆ is V, Y, L, T, F, G, S, or no amino acid; X₇ is P, S, or I; X₈ is W, L, Y, P, T, or S; and X₉ is T, V, or A.

2. The antibody or antigen-binding fragment thereof of claim 1 , wherein the immunoglobulin heavy chain variable domain comprises a CDRH1 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, and 41 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, and 41 ; a CDRH2 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 42, 43, 44,

45, 46, 47, 48, 49, 50, 51, 52, 53, 54 and 55 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 42, 43, 44, 45,

46, 47, 48, 49, 50, 51, 52, 53, 54 and 55; and a CDRH3 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65 and 66 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65 and 66.

3. The antibody or antigen-binding fragment thereof of claim 1 or claim 2, wherein the immunoglobulin light chain variable domain comprises a CDRL1 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 67, 68, 69, 70, 71 , 72, 73, 74, 75, 76, and 77, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, and 77; a CDRL2 comprising the sequence of amino acids set forth in any of SEQ ID NO: 78, 79, 80, 81 , 82, 83, 84, 85, 86, 87 and 88 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 78, 79, 80, 81 , 82, 83, 84, 85, 86, 87 and 88; and a CDRL3 comprising the sequence of amino acids set forth in any of SEQ ID NOs: 89, 90, 91 , 92, 93, 94, 95, 96, 97, 98 and 99, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 and 99.

4. The antibody or antigen-binding fragment thereof of any of claims 1-3, wherein the CDRH1 comprises the sequence of amino acids set forth in any of SEQ ID NOs: 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, and 41, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, and 41 ; the CDRH2 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 and 55, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54 and 55; the CDRH3 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65 and 66, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 56, 57, 58, 59, 60, 61, 62, 63, 64, 65 and 66; the CDRL1 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 67, 68, 69, 70, 71 , 72, 73, 74, 75, 76, and 77, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 67, 68, 69, 70, 71 , 72, 73, 74, 75, 76, and 77; the CDRL2 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 78, 79, 80, 81, 82, 83, 84, 85, 86, 87 and 88 or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 78, 79, 80, 81, 82, 83, 84, 85, 86, 87 and 88; and the CDRL3 comprises a sequence of amino acids set forth in any of SEQ ID NOs: 89, 90, 91 , 92, 93, 94, 95, 96, 97, 98 and 99, or a sequence of amino acids that exhibits at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to any of SEQ ID NOs: 89, 90, 91 , 92, 93, 94, 95, 96, 97, 98 and 99.

5. The antibody or antigen-binding fragment thereof of any of claims 1-4, wherein the immunoglobulin heavy chain variable domain comprises the amino acid sequence set forth in any of SEQ ID NOs: 1 , 2, 3, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, and 15 or a sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to any of SEQ ID NOs: 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15.

6. The antibody or antigen-binding fragment thereof of any of claims 1-5, wherein the immunoglobulin light chain variable domain comprises the amino acid sequence set forth in any of SEQ ID NOs: 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29 and 30 or a sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to any of SEQ ID NOs: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30.

7. The antibody or antigen-binding fragment thereof of any of claims 1-6, wherein the immunoglobulin heavy chain variable domain comprises the amino acid sequence set forth in any of SEQ ID NOs: 1 , 2, 3, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, and 15 or a sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to any of SEQ ID NOs: 1 , 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 and the immunoglobulin light chain variable domain comprises the amino acid sequence set forth in any of SEQ ID NOs: 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29 and 30, or a sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to any of SEQ ID NOs: 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29 and 30.

8. The antibody or antigen-binding fragment thereof of any of claims 1-7, comprising one immunoglobulin heavy chain variable domain and one immunoglobulin light chain variable domain.

9. The antibody or antigen-binding fragment thereof of any of claims 1-8, comprising two immunoglobulin heavy chain variable domains and two immunoglobulin light chain variable domains.

10. The antibody or antigen-binding fragment thereof of any of claims 1-9, wherein the antibody or antigen-binding fragment thereof is isolated.

11. The antibody or antigen-binding fragment thereof of any of claims 1-10, wherein the antibody or antigen-binding fragment thereof is humanized.

12. The antibody or antigen-binding fragment thereof of any of claims 1-11, wherein the antibody or antigen-binding fragment thereof is conjugated to a detectable marker or label.

13. The antibody or antigen-binding fragment thereof of claim 12, wherein the detectable marker or label comprises a detectable moiety or oligonucleotide label.

14. The antibody or antigen-binding fragment thereof of any of claims 1-13, wherein the antibody or antigen-binding fragment thereof is non-diffusively immobilized on a solid support.

15. The antibody or antigen-binding fragment thereof of any of claims 1-14, the antibody or antigen-binding fragment thereof is a single chain fragment.

16. The antibody or antigen-binding fragment thereof of claim 15, wherein the single chain fragment is a single chain variable fragment (scFv).

17. The antibody or antigen-binding fragment thereof of any of claims 1-16, wherein the antibody or antigen-binding fragment thereof specifically binds to CD117.

18. The antibody or antigen-binding fragment thereof of any of claims 1-17, wherein antibody or antigen-binding fragment thereof induces or inhibits phosphorylation of CD117.

19. The antibody or antigen-binding fragment thereof of any of claims 1-18, for use in the detection of CD117 in a sample.

20. The antibody or antigen-binding fragment thereof of claim 19, wherein the sample comprises a cell.

21. The antibody or antigen-binding fragment thereof of claim 20, wherein the cell comprises a cancer cell or a non-cancer cell.

22. The antibody or antigen-binding fragment thereof of any of claims 19- 21, wherein the detection is performed in vitro.

23. The antibody or antigen-binding fragment thereof of any of claims 19- 21, wherein the detection is performed in vivo.

24. A diagnostic reagent comprising the antibody or antigen-binding fragment thereof of any of claims 1-23.

25. A kit comprising the antibody or antigen-binding fragment thereof of any of claims 1-23, or the diagnostic reagent of claim 24.

26. A composition comprising the antibody or antigen-binding fragment thereof of any of claims 1-23, and a pharmaceutically acceptable excipient.

27. An isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin heavy chain variable domain of the antibody or antigen-binding fragment thereof of any of claims 1-23.

28. The isolated nucleic acid of claim 27, wherein the immunoglobulin heavy chain variable domain comprises the sequence of nucleotides set forth in any of SEQ ID NOs: 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 , and 122.

29. An isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin light chain variable domain of the antibody or antigen-binding fragment thereof of any of claims 1-23.

30. The isolated nucleic acid molecule of claim 29, wherein the immunoglobulin light chain variable domain comprises the sequence of nucleotides set forth in any of SEQ ID NOs: 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, and 137.

31. An isolated nucleic acid comprising a nucleotide sequence that encodes the immunoglobulin heavy chain variable domain and the immunoglobulin light chain variable domain of the antibody or antigen-binding fragment thereof of any of claims 1-23.

32. The isolated nucleic acid of claim 31, wherein the nucleotide sequence that encodes the immunoglobulin heavy chain variable domain comprises the sequence set forth in any of SEQ ID NOs: 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 , and 122; and the immunoglobulin light chain variable domain comprises the sequence of amino acids set forth in any of SEQ ID NOs: 123, 124, 125, 126, 127, 128, 129, 130, 131 , 132, 133, 134, 135, 136, and 137.

33. A recombinant expression vector comprising a first expression cassette and a second expression cassette, wherein the first expression cassette comprises a nucleic acid molecule comprising a nucleotide sequence that encodes the immunoglobulin heavy chain variable domain of the antibody or antigen-binding fragment thereof of any one of claims 1-23, and the second expression cassette comprises a nucleic acid molecule comprising a nucleotide sequence that encodes an immunoglobulin light chain variable domain of the antibody or antigen-binding fragment thereof of any one of claims 1-23.

34. The recombinant expression vector of claim 33, wherein the first and second expression cassettes comprise a promoter.

35. A host cell transfected with the recombinant expression vector of any of claim 33 or claim 34.

36. A method of detecting CD117 in a sample, comprising, a) contacting a sample with the antibody or antigen-binding fragment thereof of any of claims 1-23, under conditions to bind said antibody or antigen binding fragment thereof to a CD117 receptor on said sample, wherein the binding generates the production of one or more receptor/antibody or antigen binding fragment thereof complexes; and b) detecting the presence of the complexes, wherein the detecting comprises the presence or absence of the CD117 receptor on said sample.

37. A method of treating or preventing a disease or disorder associated with CD117 in a subject, comprising: a) contacting a sample known or suspected to contain a CD117 receptor with the antibody or antigen-binding fragment thereof of any of claims 1-23; b) detecting the presence of complexes comprising CD117 and the antibody or antigen-binding fragment thereof, wherein the presence of the complexes indicates the presence of a disease or disorder; and c) administering to the subject the antibody or antigen-binding fragment thereof of any of claims 1-23.

38. A method of diagnosing a disease or disorder, comprising: a) isolating a sample from a subject; b) incubating the sample with the antibody or antigen binding fragment thereof of any of claims 1-23, for a period of time sufficient to generate complexes comprising CD117 and the antibody or antigen-binding fragment thereof; and c) detecting the presence or absence of the complexes.

39. The method of claim 38, further comprising: d) associating presence or abundance of CD117 with the prognosis of a disease or disorder.

40. The method of claim 38, further comprising: d) associating presence or abundance of CD117 with a location of interest of a tissue sample.

41. The antibody or antigen binding fragment thereof of any of claims 1-23, for use in a method of detecting CD117 in a tissue sample.

42. The antibody or antigen binding fragment thereof of any of claims 1-23, for use in the construction of a protein library.

43. The antibody or antigen binding fragment thereof of claim 42, wherein the construction of a protein library comprises sequencing or flow cytometry.