WO2018187158A1 - Combination therapy of cancer with anti-endoglin antibodies and anti-programmed death receptor agents - Google Patents

Abstract

The present application relates to an anti-endoglin antibody in combination with an anti-PD-1 antibody. The present application relates to an anti-endoglin antibody in combination with an anti-PD-L1 antibody. The present application relates to an anti-endoglin antibody in combination with an anti-PD-1 antibody and an anti-PD-L1 antibody. The present application also relates to an anti-endoglin antibody in combination with Nivolumab, Pidilizumab and PDR001, Pembrolizumab, BMS-936559, Avelumab or Atezolizumab. Another aspect relates to the use of the combinations of the antibodies for use in treating cancers and metastases thereof.

Description

COMBINATION THERAPY OF CANCER WITH ANTI-ENDOGLIN ANTIBODIES AND ANTI-PROGRAMMED DEATH RECEPTOR AGENTS

CROSS-REFERENCE

[0001] This application claims the benefit of priority to U.S. Provisional Application No.

62/483,054, filed April 7, 2017, which application is incorporated herein by reference in its entirety.

SEQUENCE LISTING

[0002] The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on March 23, 2018, is named 35882-737_601_SL.txt and is 31,902 bytes in size.

BACKGROUND OF THE INVENTION

[0003] Cancer is the second leading cause of human death next to coronary disease. Worldwide, millions of people die from cancer every year. In the United States alone, cancer causes the death of well over a half-million people each year, with some 1.4 million new cases diagnosed per year. While deaths from heart disease have been declining significantly, those resulting from cancer generally are on the rise. In the early part of the next century, cancer is predicted to become the leading cause of death. Moreover, even for those cancer patients that initially survive their primary cancers, common experience has shown that their lives are dramatically altered. Many cancer patients experience strong anxieties driven by the awareness of the potential for recurrence or treatment failure. Many cancer patients experience significant physical debilitations following treatment.

SUMMARY OF THE INVENTION

[0004] Tumor immunity may control or eradicate cancer. Effector T cells that express CD8 may directly binds to tumor cells and mediate cell lysis of the tumor cells. However, effector T cells may contain the Programmed Death- 1 (PD-1) receptor that, when bound to the PD-L1 or PD-L2 ligand, maintains the effector T cell in a state of exhaustion, such that it will not mediate tumor cell lysis. Antibodies to PD-1 and to PD-L1 inhibit T cell exhaustion to allow anti-tumor effects mediated by T cells. Myeloid cells are also found within the tumor that can suppress cancer immunity. Myeloid derived suppressor cells (MDSC) may impair effector T cell function and also impair the activity of macrophages directed against tumor cells.

[0005] Provided herein is the use of one or more pharmaceutical compositions or one or more medicaments described herein for immunotherapy. In one instance, the immunotherapy is for increasing the activity of T cells. In another instance, the immunotherapy is for treating a cancer or a metastasis thereof. In yet another instance, provided herein is a method of increasing T cell activation, the method comprising administering to a subject an effective amount of one or more pharmaceutical compositions or one or more medicaments disclosed herein. In some instances, an immune response inhibits myeloid derived suppressor cell (MDSC) function. In other instances, an immune response releases inhibition of T cell function by PD-1 or PD-L1.

[0006] The present inventors have identified that endoglin is expressed on activated myeloid derived suppressor cells (MDSCs), a cell type that inhibits cancer immunity by a mechanism of action that is distinct from the inhibition of T cell function mediated by the PD-1 receptor binding to the PD-L1 ligand.

[0007] Provided herein are antibodies that specifically bind to endoglin. Such antibodies have in vitro and in vivo purification, detection, and therapeutic uses. Also provided herein are antibodies that bind to one or more species or variants of endoglin and treat a cancer or a metastasis thereof. Further provided herein are methods of treating a cancer in a subject by administering an anti- endoglin antibody in combination with an anti -PD-1 antibody or an anti-PD-Ll antibody.

[0008] The heavy and light chains of the anti-endoglin antibodies or antigen-binding fragments thereof confer the anti-angiogenesis activity of the proteins. Reference to an anti-endoglin antibody herein also refers to an antigen-binding fragment that contains the CDRs of the sequences provided herein.

[0009] An anti-endoglin antibody to be used in the described methods can be, for example, a monoclonal antibody, a mouse-human chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a human antibody, a humanized antibody, a deimmunized antibody, or a humanized-deimmunized antibody.

[0010] An anti -PD-1 antibody or an antigen-binding fragment thereof to be used in the described methods can be, for example, a monoclonal antibody, a chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a humanized antibody, a deimmunized antibody, a human antibody, or a combination thereof.

[0011] An anti-PD-Ll antibody or an antigen-binding fragment thereof to be used in the described methods can be, for example, a monoclonal antibody, a chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a humanized antibody, a deimmunized antibody, a human antibody, or a combination thereof.

[0012] Anti-endoglin antibodies, or antigen-binding fragments thereof, can be used in a

pharmaceutical composition in combination with a pharmaceutical composition comprising an anti- PD-1 antibody or an anti-PD-Ll antibody to treat or prevent various forms of cancer, solid tumors, and metastases and the like. It will be understood that throughout the disclosure, one will recognize that reference to an antibody may also be used to refer to an antigen-binding fragment.

[0013] It will be understood that reference herein to an anti-endoglin antibody or an antigen binding fragment thereof refers to a polypeptide that specifically binds to endoglin and inhibits or neutralizes the activity of endoglin.

[0014] It will be understood that reference herein to an anti-PD-1 antibody or an antigen binding fragment thereof refers to a polypeptide that specifically binds to PD-1 and inhibits or neutralizes the activity of PD-1.

[0015] It will be understood that reference herein to an anti-PD-Ll antibody or an antigen binding fragment thereof refers to a polypeptide that specifically binds to PD-L1 and inhibits or neutralizes the activity of PD-L1.

[0016] Provided herein is an anti-endoglin antibody or an antigen-binding fragment thereof, that comprises a VL CDRl set forth as SEQ ID NO: 12, a VL CDR2 set forth as SEQ ID NO: 13, a VL CDR3 set forth as SEQ ID NO: 14, a VH CDRl set forth as SEQ ID NO: 15, a VH CDR2 set forth as SEQ ID NO: 16, and a VH CDR3 set forth as SEQ ID NO: 17.

[0017] An anti-endoglin antibody to be administered in the recited methods can be, in some instances, a mouse-human chimeric antibody. Provided herein is a chimeric anti-endoglin antibody or an antigen-binding fragment thereof, that comprises a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 3 and a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 1. In some instances, the chimeric anti-endoglin antibody comprises a heavy chain constant region having an amino acid sequence set forth as SEQ ID NO: 4 and a light chain constant region comprises an amino acid sequence set forth as SEQ ID NO: 2.

[0018] An anti-endoglin antibody to be administered in the recited methods can be, in some instances, a humanized antibody, a deimmunized antibody, or a humanized and deimmunized antibody. Such antibodies include, but are not limited to, an antibody that comprises a light chain variable region set forth as SEQ ID NO: 23, 24, 25, 26, 27, 28, 29, or 30 and a heavy chain variable region set forth as SEQ ID NO: 18, 19, 20, 21, or 22. In one instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 26 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20. In another instance, an exemplary anti-endoglin antibody or antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

[0019] In one instance, an antibody described herein comprises a bispecific antibody. A bispecific antibody can bind, for example, to endoglin and PD-1. A bispecific antibody can bind,

alternatively, to endoglin and PD-Ll . A bispecific antibody can bind, alternatively to PD-1 and PD- Ll .

[0020] In one instance, an antibody described herein comprises a heteroconjugate antibody or a multispecific antibody; that is, a heteroconjugate antibody or a multispecific antibody, in one non- limiting example, can be synthetically generated to bind to endoglin, PD-1 and PD-Ll .

[0021] A pharmaceutical composition described herein can include an isolated or purified anti- endoglin antibody. A pharmaceutical composition described herein can include an isolated or purified anti-PD-1 antibody. A pharmaceutical composition described herein can include an isolated or purified anti-PD-Ll antibody. A combination described herein, in some instances, can include an isolated or purified anti-endoglin antibody and an isolated or purified anti-PD-1 antibody. A combination described herein, in some instances, can include an isolated or purified anti-endoglin antibody and an isolated or purified anti-PD-Ll antibody. A combination described herein, in some instances, can include an isolated or purified anti-endoglin antibody, an isolated or purified anti-PD-1 antibody and an isolated or purified anti-PD-Ll antibody.

[0022] In one aspect, an antibody described herein can be modified to alter a pharmacokinetic property of the compound such as, for example, in vivo stability, solubility, bioavailability or half- life. Such modifications include, but are not limited to, PEGylation and/or glycosylation.

[0023] The antibodies described herein can be formulated for rapid or extended delivery using conventional means. In one non-limiting embodiment, rapid delivery is, for example, by intravenous injection (infusion). In another non-limiting embodiment, extended delivery is, for example, by subcutaneous deposition or intravitreal administration.

[0024] Provided herein are pharmaceutical compositions of antibodies and antigen-binding fragments described herein and a pharmaceutically acceptable carrier or excipient. The

pharmaceutical compositions comprise therapeutically effective amounts of the antibodies and antigen-binding fragments described herein and an acceptable carrier or excipient. Therapeutically effective amounts of each antibody are described below and in the Examples.

[0025] Antibodies and antigen-binding fragments thereof as described herein can be used to treat cancers such as solid tumors, semi-solid and metastases thereof. Additionally, these antibodies and antigen-binding fragments thereof described herein can be used in the formulation of a medicament for the treatment of cancers such as solid tumors and metastases thereof.

[0026] Provided herein is a method for treating a cancer or a metastasis thereof in a subject, by administering to the subject an anti-endoglin antibody or an antigen-binding fragment thereof and an anti-PD-1 antibody or antigen-binding fragment thereof, whereby the cancer or the metastasis thereof. In one instance, the antibodies are administered in a single combination. The antibodies can be administered sequentially, separately, or simultaneously.

[0027] Provided herein is a method for treating a cancer or a metastasis thereof in a subject, by administering to the subject an anti-endoglin antibody or an antigen-binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof, whereby the cancer or the metastasis thereof. In one instance, the antibodies are combined in a single combination. In another instance, the antibodies can be administered sequentially, separately, or simultaneously. In some instances, inducing an immune response comprises treating a cancer or a metastasis thereof in the subject.

[0028] Provided herein is a method for treating a cancer or a metastasis thereof, by administering to the subject an anti-endoglin antibody or an antigen-binding fragment thereof, an anti-PD-Ll antibody or antigen -binding fragment thereof, and an anti-PD-1 antibody or antigen -binding fragment thereof, whereby the cancer or the metastasis thereof. In one instance, the antibodies are administered in a single combination. In another instance, the antibodies can be administered sequentially, separately, or simultaneously.

[0029] Representative examples of anti-PD-1 antibodies include, but are not limited to Nivolumab (OPDIVO®), Pidilizumab (formerly CT-01 1) and PDR001.

[0030] Representative examples of anti-PD-Ll antibodies include, but are not limited to

Pembrolizumab (KEYTRUDA®), BMS-936559, Avelumab (BAVENCIO®) and Atezolizumab (TECENTRIQ®).

[0031] Inhibiting tumor growth through stimulating cancer immunity in a subj ect by administering one or more compositions provided herein to a subject. In one instance, stimulating tumor immunity alleviates symptoms associated with a cancer or a metastasis thereof. Stimulating cancer immunity can cause decreased tumor size, prevention of tumor progression, decreased cell proliferation, increased apoptosis, and/or increase the survival (progression free survival "PFS") of a subject being treated.

[0032] Provided herein is a method of treating a cancer or a metastasis thereof in a subject by administering the combination of antibodies described herein. Administration of the antibodies can prolong life of the subject being treated.

[0033] A cancer/tumor to be treated using the methods described herein includes, but is not limited to, a solid tumor or a semi-solid tumor; a tumor can be a primary tumor or a metastatic tumor. Exemplary cancers to be treated using a method described herein include, but are not limited to, a kidney cancer (e.g., a renal cell carcinoma), a lung cancer (e.g., a primary non-small cell lung cancer, or a metastatic non-small cell lung cancer), melanoma (e.g., a primary melanoma, an unresectable melanoma or a metastatic melanoma), a head and neck cancer (e.g., a head and neck squamous cell carcinoma), a Merkel cell carcinoma, a urothelial cancer (e.g., a locally advanced urothelial cancer or a metastatic urothelial cancer), a breast cancer, a pancreatic cancer, an ovarian cancer, a uterine cancer, a colorectal cancer, a prostate cancer, a bladder cancer, a liver cancer, a sarcoma, a myeloma, and a lymphoma, or a metastasis of any of such tumors. In one instance, the cancer is a sarcoma or a metastasis thereof including, but not limited to, a uterine sarcoma, an angiosarcoma, a stromal sarcoma, an osteosarcoma, a chondrosarcoma and a leiomyosarcoma. In another instance, the cancer is a carcinoma or a metastasis thereof including, but not limited to, a carcinoma of a cervix, a lung, a prostate, a breast, head and neck, a colon, a liver or an ovary, an adenocarcinoma, an adenosquamous carcinoma, a papillary serous adenocarcinoma, and a clear cell adenocarcinoma. In another instance, the cancer is a brain cancer or a metastasis thereof including, but not limited to, a glioblastoma multiforme (GBM), a glioma, an astrocytoma, a meningioma, a pituitary tumor, a Craniopharyngioma, a germ cell tumor, a pineal region tumor, a

Medulloblastoma, and a Primary CNS lymphoma. In another instance, the cancer is a breast cancer or a metastasis thereof including, but not limited to, a Luminal A cancer, Luminal B, Triple negative/basal-like, or HER2 type. Non -limiting examples of Luminal A breast cancers include, for example, ER+ and/or PR+, HER2-, and low Ki67 breast cancers. Non-limiting examples of Luminal B breast cancers include, for example, ER+ and/or PR+, HER2+, or HER2- with high Ki67 breast cancers. Non-limiting examples of Triple negative/basal-like breast cancers include, for example, ER-, PR-, HER2- breast cancers. Non-limiting examples of HER2 type breast cancers include, for example, ER-, PR-, HER2+ breast cancers. In another instance, the cancer is a colorectal cancer or a metastasis thereof including, but not limited to, a cancer of a colon, a rectum (anus) or an appendix. In another instance, the cancer is a lung cancer or a metastasis thereof including, but not limited to, a non-small cell lung cancer or a small cell lung cancer. In another instance, the cancer is a kidney cancer or a metastasis thereof including, but not limited to, a renal cell carcinoma (e.g., a clear cell renal cell carcinoma, a papillary renal cell carcinoma, or a chromophobe renal cell carcinoma), a transitional cell carcinoma, a Wilms tumor

(nephroblastoma), or a renal cell sarcoma.

[0034] The method can further include surgical removal of a tumor and/or administration of one or more anti-cancer agents. One or more additional anti-cancer agents can be administered prior to, concomitant with, or subsequent to, administration of antibodies described herein. One or more additional anti -cancer agents can be administered within a week before the antibodies, within a week after the antibodies, or the one or more additional anti-cancer agents can be administered on the same day as the antibodies. If one or more additional anti-cancer agents are administered on the same day as the antibodies, administration can be sequential or simultaneous.

[0035] Provided herein is a method of stimulating cancer immunity by contacting a cell or tissue with a therapeutically effective amount of a combination of antibodies as described herein sufficient to treat a cancer or a metastasis thereof. Provided herein is a method of inhibiting growth of tumor cells by contacting tumor cells with, or administering to a subject, a therapeutically effective amount of a combination of antibodies as described herein sufficient to inhibit growth of tumor cells.

[0036] Provided herein is a method, comprising contacting a cancerous tissue with one or more antibodies as described herein, wherein contacting inhibits cancer cell growth, proliferation, cell division, incudes apoptosis, induces ADCC, etc. The cancerous tissue to be treated can be, for example, a cultured tissue biopsy sample or can be present in a subject. [0037] Provided herein is a method of preventing or treating a cell proliferative disorder by administering to a subject having or at risk of having a cell proliferative disorder a therapeutically effective amount of one or more antibodies provided herein effective to treat the cell proliferative disorder. The cell proliferative disorder can be, for example a benign tumor or a malignant tumor, a solid tumor, a semi-solid tumor or a non-solid tumor; and the tumor can be a primary tumor, a metastatic tumor or a non-metastatic tumor. The treatment can result in improving the subject's condition and can be assessed by determining if one or more of the following factors has occurred: decreased cell proliferation, increased survival of the subject, decreased numbers of cells, increased apoptosis, and/or decreased survival of at least a portion of the cells comprising the cell proliferative disorder. One or more of these occurrences may, in some cases, result in partial or total elimination of a tumor or metastases and prolongation of survival of the subject.

[0038] In the methods provided herein, a subject to be treated can be a human or a non-human subject. Antibodies and the anti -cancer agent or treatments provided herein can be administered once or multiple times depending on the health of the subject, the progression of the disease or condition, and the efficacy of the treatment. Adjustments to therapy and treatments can be made throughout the course of treatment (e.g., the dosage of an antibody in a pharmaceutical

composition) as empirically determined by a medical practitioner.

[0039] Antibodies can be administered locally, regionally or systemically, such as, for example, administration by subcutaneous, subcutaneous, intravitreal, intradermal, intravenous, intra-arterial, intraperitoneal or intramuscular injection, or any other suitable route of administration.

[0040] Additionally, anti-endoglin antibodies and an anti-PD-1 antibody or an anti-PD-Ll antibody (or antigen-binding fragment thereof) described herein can also be used in combination with other known therapies and/or compounds for the treatment of a cancer. Examples of such compounds include, but are not limited to ipilimumab (YERVOY®), Bevacizumab (A VASTEST®),

ranibizumab (LUCENTIS®), Aflibercept (EYLEA®), sunitinib (SUTENT®), sorafenib

( EXAVAR®), axitinib (INLYTA®), pazopanib (VOTRIENT®). Examples of other therapies include, but are not limited to, irradiation, surgery or administration of one or more

chemotherapeutic agents. In certain instances, the one or more chemotherapeutic agents include, but are not limited to docetaxel (TAXOTERE®) as well as platinum based chemotherapeutic agents such as, for example, cisplatin, carboplatin, and oxaliplatin. In some instances, the pharmaceutical compositions of the present invention may be administered after administration of surgery and/or one or more chemotherapeutic agents. In other instances, the pharmaceutical compositions of the present invention may be administered after administration of surgery and/or one or more chemotherapeutic agents has failed to treat a cancer described herein. [0041] Provided herein is a method of monitoring the efficacy of one or more of any of the methods provided herein. Increased levels of soluble endoglin have been correlated with decreased survival in cancer subjects. Thus, in one aspect, levels of soluble endoglin can be monitored prior to, and during, therapy. A decrease in the levels of soluble endoglin can, therefore, be one indication that a therapeutic regimen is effective in treating the subject.

[0042] One embodiment of the present application contemplates the use of any of the compositions described herein to formulate a medicament for treating a cancer described herein. Medicaments can be formulated based on the physical characteristics of the subject needing treatment, and can be formulated in single or multiple unit formulations based on the stage of, for example, cancerous tissue. Medicaments can be packaged in a suitable package with appropriate labels for the distribution to hospitals and clinics wherein the label is for the indication of treating a cancer as described herein in a subject. Medicaments can be packaged as a single or multiple units.

Instructions for the dosage and administration of the compositions described herein can be included with the packages.

[0043] Provided herein is an anti-endoglin antibody or an antigen-binding fragment thereof for use in the treatment of cancer or a metastasis thereof by separate, simultaneous or sequential administration with an anti-PD-1 antibody or an antigen-binding fragment thereof and/or an anti- PD-L1 antibody or an antigen-binding fragment thereof.

[0044] Provided herein is an anti-PD-1 antibody or an antigen-binding fragment thereof, and/or an anti-PD-Ll antibody or an antigen -binding fragment thereof, for use in the treatment of cancer or a metastasis thereof by separate, simultaneous or sequential administration with an anti-endoglin antibody or an antigen-binding fragment thereof.

INCORPORATION BY REFERENCE

[0045] All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference in its entirety unless otherwise specifically noted.

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the disclosure are utilized, and the accompanying drawings of which: [0047] FIG. 1 illustrates tumor volume after treatment in an orthotopic model and provides plot of tumor growth in mice bearing MC38 colorectal cancer tumors implanted in the cecum, which is a portion of the large intestine. Following the orthotopic tumor implantation, mice are treated with control rat IgGlantibody, rat IgGl antibody to mouse PD-1, rat IgGl antibody M1043 to mouse endoglin, human chimeric IgGl antibody TRC105 to human and mouse endoglin, or a combination of Ml 043 and TRC105. The bar height in the figure denotes the mean size of the tumors in each group following treatment and the individual data points indicate the size of the tumors in each animal in each group.

[0048] FIGS. 2A-2B are graphs showing the results of treatment of tumors in mouse models. FIG. 2A depicts the number of tumor lesions (AOM-DSS model) and illustrates the effect of control and test reagents. FIG. 2B depicts the number of tumor lesions in an AOM-DSS model in test groups compared to controls.

[0049] Figure 3 illustrates survival after tumor induction and treatment with control and test reagents in a subcutaneous MC38 model.

DETAILED DESCRIPTION OF THE INVENTION

[0050] It is to be understood that this application is not limited to particular formulations or process parameters, as these may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. Further, it is understood that a number of methods and materials similar or equivalent to those described herein can be used in the practice of the present inventions.

[0051] In accordance with the present application, there may be employed conventional molecular biology, microbiology, and recombinant DNA techniques as explained fully in the art.

[0052] Anti-endoglin antibodies can be used in combination with anti-PD-1 or anti-PD-Ll antibodies to treat or prevent various forms of cancer, such as, for example, solid tumors, semisolid tumors, and metastases. Described herein are methods of treating or various forms of primary tumors, and metastases thereof, and the like via the administration of the pharmaceutical compositions described herein. The pharmaceutical compositions described herein can stimulate tumor immunity to inhibit cancer growth.

[0053] As used herein, the terms "about" and "approximately," when used to modify a numeric value or numeric range, indicate that deviations of up to about 0.2%, about 0.5%, about 1%, about 2%), about 5%), about 7.5%, or about 10% (or any integer between about 1% and 10%) above or below the value or range remain within the intended meaning of the recited value or range.

[0054] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise. Thus for example, references to "a method" include one or more methods, and/or steps of the type described herein and/or which will become apparent to those persons skilled in the art upon reading this disclosure.

ANTIBODY TERMINOLOGY

[0055] As used herein, the term "antibody" refers to an immunoglobulin (Ig) whether natural or partly or wholly synthetically produced. The term also covers any polypeptide or protein having a binding domain which is, or is homologous to, an antigen-binding domain. The term further includes "antigen-binding fragments" and other interchangeable terms for similar binding fragments such as described below. Monoclonal antibodies, chimeric antibodies, human antibodies, bispecific antibodies, heteroconjugate antibodies, multispecific antibodies, humanized antibodies, deimmunized antibodies, and humanized and deimmunized antibodies are also contemplated by this term.

[0056] Native antibodies and native immunoglobulins are usually heterotetrameric glycoproteins of about 150,000 Daltons, composed of two identical light (L) chains and two identical heavy (H) chains. Each light chain is typically linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies among the heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain has at one end a variable domain ("V_H") followed by a number of constant domains ("C_H"). Each light chain has a variable domain at one end ("V_L") and a constant domain ("C_L") at its other end; the constant domain of the light chain is aligned with the first constant domain of the heavy chain, and the light-chain variable domain is aligned with the variable domain of the heavy chain. Particular amino acid residues are believed to form an interface between the light- and heavy-chain variable domains.

[0057] The terms "synthetic polynucleotide," "synthetic gene" or "synthetic polypeptide," as used herein, mean that the corresponding polynucleotide sequence or portion thereof, or amino acid sequence or portion thereof, is derived, from a sequence that has been designed, or synthesized de novo, or modified, compared to an equivalent naturally-occurring sequence. Synthetic

polynucleotides (antibodies or antigen binding fragments) or synthetic genes can be prepared by methods known in the art, including but not limited to, the chemical synthesis of nucleic acid or amino acid sequences. Synthetic genes are typically different from naturally-occurring genes, either at the amino acid, or polynucleotide level, (or both) and are typically located within the context of synthetic expression control sequences. Synthetic gene polynucleotide sequences, may not necessarily encode proteins with different amino acids, compared to the natural gene; for example, they can also encompass synthetic polynucleotide sequences that incorporate different codons but which encode the same amino acid (i.e., the nucleotide changes represent silent mutations at the amino acid level).

[0058] With respect to antibodies, the term "variable domain" refers to the variable domains of antibodies that are used in the binding and specificity of each particular antibody for its particular antigen. However, the variability is not evenly distributed throughout the variable domains of antibodies. Rather, it is concentrated in three segments called hypervariable regions (also known as CDRs) in both the light chain and the heavy chain variable domains. More highly conserved portions of variable domains are called the "framework regions" or "FRs." The variable domains of unmodified heavy and light chains each contain four FRs (FR1, FR2, FR3 and FR4), largely adopting a β-sheet configuration interspersed with three CDRs which form loops connecting and, in some cases, part of the β-sheet structure. The CDRs in each chain are held together in close proximity by the FRs and, with the CDRs from the other chain, contribute to the formation of the antigen-binding site of antibodies (see Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991), pages 647-669).

[0059] The terms "hypervariable region" and "CDR" when used herein, refer to the amino acid residues of an antibody which are responsible for antigen-binding. The CDRs comprise amino acid residues from three sequence regions which bind in a complementary manner to an antigen and are known as CDR1, CDR2, and CDR3 for each of the V_H and V_L chains. In the light chain variable domain, the CDRs typically correspond to approximately residues 24-34 (CDRLl), 50-56

(CDRL2) and 89-97 (CDRL3), and in the heavy chain variable domain the CDRs typically correspond to approximately residues 31-35 (CDRHl), 50-65 (CDRH2) and 95-102 (CDRH3) according to Kabat et al., Id. It is understood that the CDRs of different antibodies may contain insertions, thus the amino acid numbering may differ. The Kabat numbering system accounts for such insertions with a numbering scheme that utilizes letters attached to specific residues (e.g., 27A, 27B, 27C, 27D, 27E, and 27F of CDRLl in the light chain) to reflect any insertions in the numberings between different antibodies. Alternatively, in the light chain variable domain, the CDRs typically correspond to approximately residues 26-32 (CDRLl), 50-52 (CDRL2) and 91-96 (CDRL3), and in the heavy chain variable domain, the CDRs typically correspond to approximately residues 26-32 (CDRHl), 53-55 (CDRH2) and 96-101 (CDRH3) according to Chothia and Lesk, J. Mol. Biol, 196: 901-917 (1987)).

[0060] As used herein, "framework region" or "FR" refers to framework amino acid residues that form a part of the antigen binding pocket or groove. In some embodiments, the framework residues form a loop that is a part of the antigen binding pocket or groove and the amino acids residues in the loop may or may not contact the antigen. Framework regions generally comprise the regions between the CDRs. In the light chain variable domain, the FRs typically correspond to

approximately residues 0-23 (FRLl), 35-49 (FRL2), 57-88 (FRL3), and 98-109 and in the heavy chain variable domain the FRs typically correspond to approximately residues 0-30 (FRH1), 36-49 (FRH2), 66-94 (FRH3), and 103-133 according to Kabat et al., Id. As discussed above with the Kabat numbering for the light chain, the heavy chain too accounts for insertions in a similar manner {e.g., 35A, 35B of CDRH1 in the heavy chain). Alternatively, in the light chain variable domain, the FRs typically correspond to approximately residues 0-25 (FRLl), 33-49 (FRL2) 53-90 (FRL3), and 97-109 (FRL4), and in the heavy chain variable domain, the FRs typically correspond to approximately residues 0-25 (FRH1), 33-52 (FRH2), 56-95 (FRH3), and 102-113 (FRH4) according to Chothia and Lesk, Id.

[0061] Constant domains (Fc) of antibodies are not involved directly in binding an antibody to an antigen but, rather, exhibit various effector functions, such as participation of the antibody in antibody-dependent cellular toxicity via interactions with, for example, Fc receptors (FcR). Fc domains can also increase bioavailability of an antibody in circulation following administration to a subject. Substitution of a murine Fc domain for a human Fc domain can also reduce side HAMA reactions.

[0062] Depending on the amino acid sequence of the constant domain of their heavy chains, immunoglobulins can be assigned to different classes. There are five major classes of

immunoglobulins: IgA, IgD, IgE, IgG, and IgM, and several of these can be further divided into subclasses (isotypes), e.g., IgGl, IgG2, IgG3, IgG4, IgAl, and IgA2. The heavy-chain constant domains (Fc) that correspond to the different classes of immunoglobulins are called α, δ, ε, γ, and μ, respectively. The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known. In some instances, a heavy chain constant region is an IgGl, an IgG2 {e.g., an IgG2a, an IgG2b, etc.), or an IgGl .

[0063] The "light chains" of antibodies from any vertebrate species can be assigned to one of two clearly distinct types, called kappa or ("κ") and lambda or ("λ"), based on the amino acid sequences of their constant domains.

[0064] The terms "antigen-binding portion of an antibody," "antigen-binding fragment," "antigen- binding domain," "antibody fragment" or a "functional fragment of an antibody" are used interchangeably herein to refer to one or more fragments of an antibody that retain the ability to specifically bind to an antigen and inhibit or neutralize its activity. Non-limiting examples of antibody fragments included within such terms include, but are not limited to, a Fab fragment, a monovalent fragment consisting of the V_L, V¾ C_L and C_HI domains; a F(ab')₂ fragment, a bivalent fragment containing two Fab fragments linked by a disulfide bridge at the hinge region; or a single chain Fv. The structures of such antibody fragments are known in the art.

[0065] "Chimeric" forms of non-human (e.g., murine) antibodies include chimeric antibodies which contain minimal sequence derived from a non-human Ig. For the most part, chimeric antibodies are murine antibodies in which at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin is inserted in place of the murine Fc. As used herein, reference to a chimeric antibody also refers to an antigen-binding fragment thereof that specifically binds to endoglin and inhibits its activity partially or completely.

[0066] The term "monoclonal antibody" as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts. Monoclonal antibodies are highly specific, being directed against a single antigenic site. Furthermore, in contrast to conventional (polyclonal) antibody preparations, which can include different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on the antigen. 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. Methods of making monoclonal antibodies are known in the art.

[0067] As used herein, "humanized" antibodies refer to forms of non-human (e.g., murine) antibodies that are specific chimeric immunoglobulins, immunoglobulin chains, or fragments thereof (such as Fv, Fab, Fab', F(ab')₂, scFv, or other antigen-binding subsequences of antibodies) that contain reduced, or minimal sequence derived from a non-human immunoglobulin. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a complementarity determining region (CDR) of the recipient are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat, or rabbit having the desired specificity, affinity, and biological activity. In some instances, Fv framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, the humanized antibody may comprise residues that are found neither in the recipient antibody nor in the imported CDR or framework sequences, but are included to further refine and optimize antibody performance. In general, a humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin consensus sequence. The humanized antibody optimally also will comprise at least a portion of an immunoglobulin constant region or domain (Fc), typically that of a human immunoglobulin. Antibodies may have Fc regions modified as described in, for example, WO 99/58572. Other forms of humanized antibodies have one or more CDRs (one, two, three, four, five or six) which are altered with respect to the original antibody, which are also termed one or more CDRs "derived from" one or more CDRs from the original antibody.

[0068] In other instances, a humanized antibody refers to a murine sequence in which one or more amino acid residues of one or more of the CDRs are replaced with an amino acid residue that reduces a human anti-mouse antibody (HAMA) response when the antibody is administered to a human subject compared to the murine sequence (i.e., a substitution which renders the variable heavy or light chain sequence as more "human". In other instances, a humanized antibody refers to a murine sequence in which one or more amino acid residues of one or more of the Framework regions (FR) are replaced with an amino acid residue that reduces a HAMA response when the antibody is administered to a human subject compared to the murine sequence. In other instances, a humanized antibody refers to a murine sequence in which one or more amino acid residues of one or more of the framework regions and one or more residues of one or more CDRs are replaced with an amino acid residue that reduces a HAMA response when the antibody is administered to a human subject compared to the murine sequence.

[0069] A humanized antibody also includes antibodies in which part, or all of the CDRs of the heavy and light chain are derived from a non-human monoclonal antibody, substantially all the remaining portions of the variable regions are derived from human variable region (both heavy and light chain), and the constant regions are derived from a human constant region. In one

embodiment, the CDR1, CDR2 and CDR3 regions of the heavy and light chains are derived from a non-human antibody. In yet another embodiment, at least one CDR (e.g., a CDR3) of the heavy and light chains is derived from a non-human antibody. Various combinations of CDR1, CDR2, and CDR3 can be derived from a non-human antibody and are contemplated herein. In one non-limiting example, one or more of the CDR1, CDR2 and CDR3 regions of each of the heavy and light chains are derived from a murine chimeric monoclonal antibody clone TRC105. As used herein, reference to a humanized antibody also refers to an antigen-binding fragment thereof that specifically binds to endoglin and inhibits its activity, partially or completely.

[0070] As used herein, a "deimmunized" antibody refers to an antibody in which one or more amino acid modifications in one or more T-cell epitopes are made to reduce the immunogenicity of the antibody when administered to a subject. In one non-limiting example, when the subject is a human, the antibody may be deimmunized such that the antibody has one or more human T cell epitopes modified. As used herein, reference to a deimmunized antibody also refers to an antigen- binding fragment thereof that specifically binds to endoglin and inhibits its activity, partially or completely. A deimmunized antibody, or antigen-binding fragment thereof, with one or more amino acid modifications in one or more T-cell epitopes are contemplated herein. In one non- limiting example, provided herein are antibodies, or antigen-binding fragments thereof, having at least one modification in at least one T-cell epitope. In another non-limiting example, provided herein are antibodies, or antigen-binding fragments thereof, having at least one amino acid modification in 1, 2, 3, 4, 5, 6, or 7 of the T-cell epitopes described herein. Additional non-limiting examples include antibodies, or antigen-binding fragments thereof, having more than one amino acid modification in more than one T-cell epitope. Any combination of the amino acid

modifications in any number of the antibodies, or antigen-binding fragments thereof, T-cell epitopes described above are contemplated herein. Methods of deimmunizing antibodies are known in the art and are contemplated herein. Individual epitopes found within antigens can be

preferentially presented by specific MHC class II allotypes, and similarly other specific epitopes within the same antigen may not be presented on MHC class II molecules at all. Such associations of particular epitopes with specific MCH class II molecules have been shown to depend upon the MHC class II allotype of the individual. The association of a specific epitope with a specific allotype can also be considered when modifying antibodies, or antigen-binding fragments thereof, for the removal of T-cell epitopes. Such considerations can allow for the highly specific

modification of an antibody, or antigen-binding fragment thereof, for specific allotypes (e.g., for specific populations of subjects having certain MHC class II allotypes). The MHC class II allotype of a subject or subjects can be easily determined by genotyping methods known in the art, and the association of T-cell epitopes with the given allotype thus easily identified, for consideration in modification of antibodies, or antigen-binding fragments thereof, tailored to that allotype.

Identification of associations between T-cell epitopes and MHC class II allotypes are described in more detail in the examples below. Contemplated herein are modified antibodies, or antigen- binding fragments thereof, that have T-cell epitope modifications tailored to the MHC class II associations identified for the given epitopes. Non-limiting, exemplary methods of deimmunization of an anti -endoglin antibody are described in, for example, U. S. Patent 8,221,753, which methods are incorporated herein by reference.

[0071] As used herein, a "humanized and deimmunized antibody" or a "humanized-deimmunized antibody" refers to a sequence which has been made more human to reduce a HAMA response and also contains fewer T cell epitopes than a non-humanized and non-deimmunized sequence. As used herein, reference to a humanized and deimmunized antibody also refers to an antigen-binding fragment thereof that specifically binds to endoglin and inhibits its activity, partially or completely. [0072] As used herein, a "human antibody" means an antibody having an amino acid sequence corresponding to that of an antibody produced by a human and/or has been made using any of the techniques for making human antibodies known in the art or disclosed herein. This definition of a human antibody includes antibodies comprising at least one human heavy chain polypeptide or at least one human light chain polypeptide. One such example is an antibody comprising murine light chain and human heavy chain polypeptides. Human antibodies can be produced using various techniques known in the art. In one embodiment, the human antibody is selected from a phage library, where that phage library expresses human antibodies. Human antibodies can also be made by introducing human immunoglobulin loci into transgenic animals, e.g., mice in which the endogenous immunoglobulin genes have been partially or completely inactivated. Alternatively, the human antibody may be prepared by immortalizing human B lymphocytes that produce an antibody directed against a target antigen (such B lymphocytes may be recovered from an individual or may have been immunized in vitro).

[0073] Other forms of single chain antibodies, such as diabodies are also encompassed. Diabodies are bivalent, bispecific antibodies in which VH and VL domains are expressed on a single polypeptide chain, but using a linker that is too short to allow for pairing between the two domains on the same chain, thereby forcing the domains to pair with complementary domains of another chain and creating two antigen binding sites (see, e.g., Holliger, P., et al., Proc. Natl. Acad. Sci. USA, 90:6444-6448 (1993); and Poljak, R. J., et al, Structure, 2: 1121-1123 (1994)).

[0074] For example, bispecific antibodies, monoclonal antibodies that have binding specificities for at least two different antigens, can be prepared using the antibodies disclosed herein. Methods for making bispecific antibodies are known in the art (see, e.g., Suresh et al., 1986, Methods in

Enzymology 121 :210). Traditionally, the recombinant production of bispecific antibodies was based on the coexpression of two immunoglobulin heavy chain-light chain pairs, with the two heavy chains having different specificities (Millstein and Cuello, 1983, Nature, 305, 537-539). Bispecific antibodies can be composed of a hybrid immunoglobulin heavy chain with a first binding specificity in one arm, and a hybrid immunoglobulin heavy chain-light chain pair (providing a second binding specificity) in the other arm. This asymmetric structure, with an immunoglobulin light chain in only one half of the bispecific molecule, facilitates the separation of the desired bispecific compound from unwanted immunoglobulin chain combinations. This approach is described in PCT Publication No. WO 94/04690.

[0075] According to one approach to making bispecific antibodies, antibody variable domains with the desired binding specificities (antibody-antigen combining sites) are fused to immunoglobulin constant domain sequences. The fusion preferably is with an immunoglobulin heavy chain constant domain, comprising at least part of the hinge, CH2 and CH3 regions. It is preferred to have the first heavy chain constant region (CHI), containing the site necessary for light chain binding, present in at least one of the fusions. DNAs encoding the immunoglobulin heavy chain fusions and, if desired, the immunoglobulin light chain, are inserted into separate expression vectors, and are cotransfected into a suitable host organism. This provides for great flexibility in adjusting the mutual proportions of the three polypeptide fragments in embodiments when unequal ratios of the three polypeptide chains used in the construction provide the optimum yields. It is, however, possible to insert the coding sequences for two or all three polypeptide chains in one expression vector when the expression of at least two polypeptide chains in equal ratios results in high yields or when the ratios are of no particular significance.

[0076] Heteroconjugate antibodies, comprising two covalently joined antibodies, are also within the scope of the invention. Such antibodies have been used to target immune system cells to unwanted cells (U.S. Pat. No. 4,676,980). Heteroconjugate antibodies may be made using any convenient cross-linking methods. Suitable cross-linking agents and techniques are well known in the art, and are described in U.S. Pat. No. 4,676,980.

[0077] Antibodies can be isolated and purified from the culture supernatant or ascites mentioned above by saturated ammonium sulfate precipitation, euglobulin precipitation method, caproic acid method, caprylic acid method, ion exchange chromatography (DEAE or DE52), or affinity chromatography using anti-Ig column or a protein A, G or L column such as described in more detail below. Throughout the present disclosure, reference to an antibody or an antigen-binding fragment thereof also refers to an "isolated antibody or an antigen-binding fragment thereof.

[0078] When constructing an immunoglobulin molecule, variable regions or portions thereof may be fused to, connected to, or otherwise joined to one or more constant regions or portions thereof to produce any of the antibodies described herein. This may be accomplished in a variety of ways known in the art, including but not limited to, molecular cloning techniques or direct synthesis of the nucleic acids encoding the molecules

[0079] As used herein, "immunoreactive" refers to binding agents, antibodies or fragments thereof that are specific to a sequence of amino acid residues ("binding site" or "epitope"), yet if are cross- reactive to other peptides/proteins, are not toxic at the levels at which they are formulated for administration to humans. The term "binding" refers to a direct association between two molecules, due to, for example, covalent, electrostatic, hydrophobic, and ionic and/or hydrogen-bond interactions under physiological conditions, and including interactions such as salt bridges and water bridges and any other conventional binding means. The term "preferentially binds" means that the binding agent binds to the binding site with greater affinity than it binds unrelated amino acid sequences. The terms "immunoreactive" and "preferentially binds" are used interchangeably herein.

[0080] Affinity can be at least 1-fold greater, at least 2-fold greater, at least 3-fold greater, at least 4-fold greater, at least 5-fold greater, at least 6-fold greater, at least 7-fold greater, at least 8-fold greater, at least 9-fold greater, 10-fold greater, at least 20-fold greater, at least 30-fold greater, at least 40-fold greater, at least 50-fold greater, at least 60-fold greater, at least 70-fold greater, at least 80-fold greater, at least 90-fold greater, at least 100-fold greater, or at least 1000-fold greater than the affinity of the binding agent for unrelated amino acid sequences.

[0081] As used herein, the term "affinity" refers to the equilibrium constant for the reversible binding of two agents and is expressed as Kd. Affinity of a binding protein to a ligand such as affinity of an antibody for an epitope can be, for example, from about 100 nanomolar (nM) to about 0.1 nM, from about 100 nM to about 1 picomolar (pM), or from about 100 nM to about 1 femtomolar (fM). As used herein, the term "avidity" refers to the resistance of a complex of two or more agents to dissociation after dilution. Apparent affinities can be determined by methods such as an enzyme linked immunosorbent assay (ELISA) or any other technique familiar to one of skill in the art. Avidities can be determined by methods such as a Scatchard analysis or any other technique familiar to one of skill in the art. In one embodiment, a molecule that specifically binds to an antigen binds to the antigen with an association constant (KA) that is at least 2 logs, 2.5 logs, 3 logs, 4 logs or greater than the K_A when the molecule binds non-specifically to another antigen. In one embodiment, a molecule that specifically binds to an antigen binds to the antigen with a K_d of 1 10^"6 M or less, 1 ^χ 10^"7 M or less, 1 ^χ 10^"8 M or less, 1 10^"9 M or less, 1 ^χ 10^"10 M or less, 1 ^χ 10^"11 M or less, or 1 ^χ 10^"12 M or less.

[0082] "Epitope" refers to that portion of an antigen or other macromolecule capable of forming a binding interaction with the variable region binding pocket of an antibody. Such binding interactions can be manifested as an intermolecular contact with one or more amino acid residues of one or more CDRs. Antigen binding can involve, for example, a CDR3 or a CDR3 pair or, in some cases, interactions of up to all six CDRs of the V_H and V_L chains. An epitope can be a linear peptide sequence (i.e., "continuous") or can be composed of noncontiguous amino acid sequences (i.e., "conformational" or "discontinuous"). An antibody can recognize one or more amino acid sequences; therefore an epitope can define more than one distinct amino acid sequence. Epitopes recognized by antibodies can be determined by peptide mapping and sequence analysis techniques well known to one of skill in the art. Binding interactions are manifested as intermolecular contacts with one or more amino acid residues of a CDR. [0083] "TRC105", as used herein, refers to an anti-endoglin antibody that specifically binds to human and mouse endoglin. TRC105 comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 1 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 3 . In some instances, the chimeric anti-endoglin antibody also comprises a light chain constant region having an amino acid sequence set forth as SEQ ID NO: 2 and a gamma 1 (γΐ) constant region having an amino acid sequence set forth as SEQ ID NO: 4.

[0084] "M1043" as used herein refers to an anti-endoglin antibody described by Olivier Nolan- Stevaux et al., "Endoglin Requirement for BMP9 Signaling in Endothelial Cells Reveals New Mechanism of Action for Selective Anti-Endoglin Antibodies", PLOS ONE, vol 7, Issue 12, December 2012, pp 1-12.

[0085] The term "specific" refers to a situation in which an antibody will not show any significant binding to molecules other than the antigen containing the epitope recognized by the antibody. The term is also applicable where for example, an antigen binding domain is specific for a particular epitope which is carried by a number of antigens, in which case the antibody will be able to bind to the various antigens carrying the epitope. The terms "preferentially binds" or "specifically binds" mean that the antibodies bind to an epitope with greater affinity than it binds unrelated amino acid sequences, and, if cross-reactive to other polypeptides containing the epitope, are not toxic at the levels at which they are formulated for administration to human use. In one aspect, such affinity is at least 1-fold greater, at least 2-fold greater, at least 3 -fold greater, at least 4-fold greater, at least 5- fold greater, at least 6-fold greater, at least 7-fold greater, at least 8-fold greater, at least 9-fold greater, 10-fold greater, at least 20-fold greater, at least 30-fold greater, at least 40-fold greater, at least 50-fold greater, at least 60-fold greater, at least 70-fold greater, at least 80-fold greater, at least 90-fold greater, at least 100-fold greater, or at least 1000-fold greater than the affinity of the antibody for unrelated amino acid sequences. The terms "immunoreactive," "binds," "preferentially binds" and "specifically binds" are used interchangeably herein. The term "binding" refers to a direct association between two molecules, due to, for example, covalent, electrostatic, hydrophobic, and ionic and/or hydrogen-bond interactions under physiological conditions, and includes interactions such as salt bridges and water bridges, as well as any other conventional means of binding.

[0086] "Isolated" (used interchangeably with "substantially pure" or "purified") when applied to polypeptides means a polypeptide or a portion thereof which, by virtue of its origin or

manipulation: (i) is present in a host cell as the expression product of a portion of an expression vector; or (ii) is linked to a protein or other chemical moiety other than that to which it is linked in nature; or (iii) does not occur in nature, for example, a protein that is chemically manipulated by appending, or adding at least one hydrophobic moiety to the protein so that the protein is in a form not found in nature. By "isolated" it is further meant a protein that is: (i) synthesized chemically; or (ii) expressed in a host cell and purified away from associated and contaminating proteins. The term generally means a polypeptide that has been separated from other proteins and nucleic acids with which it naturally occurs. Typically, the polypeptide is also separated from substances such as antibodies or gel matrices (polyacrylamide) which are used to purify it.

CANCER TERMINOLOGY

[0087] As used herein, "inducing a host immune response" means that a subject experiences alleviation or reduction of signs or symptoms of illness, and specifically includes, without limitation, prolongation of survival.

[0088] As used herein, the terms "proliferative disorder" and "proliferative condition" mean any pathological or non-pathological physiological condition characterized by aberrant or undesirable proliferation. The terms "cell proliferative disorder" and "cell proliferative condition" mean any pathological or non-pathological physiological condition characterized by aberrant or undesirable cell proliferation, as well as including conditions characterized by undesirable or unwanted cell proliferation or cell survival (e.g., due to deficient apoptosis), conditions characterized by deficient or aberrant or deficient apoptosis, as well as conditions characterized by aberrant or undesirable or unwanted cell survival. The term "differentiative disorder" means any pathological or non- pathological physiological condition characterized by aberrant or deficient differentiation.

[0089] Proliferative or differentiative disorders amenable to treatment include diseases conditions, benign and neoplastic, characterized by abnormal or undesirable cell numbers, cell growth or cell survival. Such disorders or conditions may therefore constitute a disease state and include all types of cancerous growths or oncogenic processes, metastatic tissues or malignantly transformed cells, tissues, or organs.

[0090] Cells comprising the proliferative or differentiative disorder may be aggregated in a cell mass or be dispersed. A "non-solid tumor" refers to neoplasias of the hematopoietic system, such as lymphomas, myelomas and leukemias, or neoplasias that are diffuse in nature, as they do not typically form a solid mass. Particular examples of leukemias include for example, acute and chronic lymphoblastic, myeloblastic and multiple myeloma.

[0091] The term "solid tumor" refers to neoplasias or metastases that typically aggregate together and form a mass. Such disorders include neoplasms or cancers, which can affect virtually any organ, cell or tissue type, e.g., carcinoma, sarcoma, melanoma, metastatic disorders or

hematopoietic neoplastic disorders. A metastatic tumor can arise from a multitude of primary tumor types, including but not limited to breast, lung, thyroid, head and neck, brain, lymph, gastrointestines (mouth, esophagus, stomach, small intestine, colon, rectum, etc.), genito-urinary tract (uterus, ovary, cervix, bladder, testicle, prostate, etc.), kidney, pancreas, liver, bone, muscle, skin, etc.

[0092] Carcinomas refer to malignancies of epithelial or endocrine tissue, and include respiratory system carcinomas, gastrointestinal system carcinomas, genitourinary system carcinomas, testicular carcinomas, breast carcinomas, prostatic carcinomas, endocrine system carcinomas, and

melanomas. Exemplary carcinomas include those forming from the cervix, lung, prostate, breast, head and neck, colon, liver and ovary. The term also includes carcinosarcomas, e.g., which include malignant tumors composed of carcinomatous and sarcomatous tissues. Adenocarcinoma includes a carcinoma of a glandular tissue, or in which the tumor forms a gland like structure.

[0093] A cancerous tissue to be treated is, for example, an endothelial tissue expressing an abnormal level of endoglin. As used herein, the term "transformed cells" refers to cells that have spontaneously converted to a state of unrestrained growth, i.e., they have acquired the ability to grow through an indefinite number of divisions in culture. Transformed cells may be characterized by such terms as neoplastic, anaplastic and/or hyperplastic, with respect to their loss of growth control. For purposes of this invention, the terms "transformed phenotype of malignant mammalian cells" and "transformed phenotype" are intended to encompass, but not be limited to, any of the following phenotypic traits associated with cellular transformation of mammalian cells:

immortalization, morphological or growth transformation, and tumorigenicity, as detected by prolonged growth in cell culture, growth in semi-solid media, or tumorigenic growth in immuno- incompetent or syngeneic animals.

[0094] The term "tumor cell antigen" is defined herein as an antigen that is present in higher quantities on a tumor cell or in body fluids than unrelated tumor cells, normal cells, or in normal body fluid. The antigen presence may be tested by any number of assays known to those skilled in the art and include without limitation negative and/or positive selection with antibodies, such as an ELISA assay, a radioimmunoassay and/or by Western Blot.

[0095] The terms "apoptosis" or "programmed cell death," refers to the physiological process by which unwanted or useless cells are eliminated during development and other normal biological processes. Apoptosis is a mode of cell death that occurs under normal physiological conditions and the cell is an active participant in its own demise ("cellular suicide"). It is most often found during normal cell turnover and tissue homeostasis, embryogenesis, induction and maintenance of immune tolerance, development of the nervous system and endocrine-dependent tissue atrophy. Cells undergoing apoptosis show characteristic morphological and biochemical features. These features include chromatin aggregation, nuclear and cytoplasmic condensation, partition of cytoplasm and nucleus into membrane bound vesicles (apoptotic bodies), which contain ribosomes,

morphologically intact mitochondria and nuclear material. In vivo, these apoptotic bodies are rapidly recognized and phagocytized by macrophages, dendritic cells or adjacent epithelial cells. Due to this efficient mechanism for the removal of apoptotic cells in vivo no inflammatory response is elicited. In vitro, the apoptotic bodies as well as the remaining cell fragments ultimately swell and finally lyse. This terminal phase of in vitro cell death has been termed "secondary necrosis." Apoptosis can be measured by methods known to those skilled in the art like DNA fragmentation, exposure of Annexin V, activation of caspases, release of cytochrome c, etc. A cell that has been induced to die is termed herein as an "apoptotic cell."

[0096] "Apoptosis inducing agent" is defined herein to induce apoptosis/programmed cell death, and include, for example, anti-endoglin antibodies, anti-PD-1 antibodies and anti-PD-Ll antibodies, irradiation, chemotherapeutic agents or receptor ligation agents, wherein cells, for example, tumor cells or endothelial cells are induced to undergo programmed cell death. Exemplary apoptosis inducing agents are described in more detail below.

[0097] Apoptosis can be tested using a standard Annexin V Apoptosis Assay NIH:OVCAR-3 cells are grown in 6-well plates (NUNC) and irradiated or treated with an antagonist (or in combination with another anti -cancer drug) for 4-48 hours, washed and stained with Annexin V-FITC (BD- Pharmingen) for 1 hour. Cells are analyzed by flow cytometry (Becton-Dickinson, CellQuest), counterstained with Propidium Iodide and analyzed again in the flow cytometer.

METHODS OF MAKING AND EXPRESSING ANTIBODIES

[0098] Chimeric, humanized, deimmunized, humanized and deimmunized, or human

immunoglobulins (or a combination thereof) may be constructed by means of genetic engineering using conventional methods known in the art. Chimeric, human, humanized and/or deimmunized antibodies generally have several potential advantages over mouse antibodies for use in human therapy. Because the effector portion of an antibody is human, or closer to human than a murine sequence, it is believed to interact better with the other parts of the human immune system {e.g., destroy the target cells more efficiently by complement-dependent cytotoxicity (CDC) or antibody- dependent cellular cytotoxicity (ADCC)). Additionally, the human immune system should not recognize the constant region of the modified/engineered antibody as foreign, and therefore the antibody response against such an injected antibody should, typically, be less than against a totally foreign mouse antibody. Finally, mouse antibodies are known to have a half-life in the human circulation that is much shorter than the half-life of more human antibodies. Chimeric, human, humanized and/or deimmunized antibodies can, presumably, have a half-life more similar to naturally-occurring human antibodies, allowing smaller and less frequent doses to be given. [0099] When increased affinity of an antibody is desired, residues within the CDRs of an antibody may be additionally substituted with other amino acids. Typically, no more than four amino acid residues in a CDR are changed, and most typically no more than two residues in the CDR will be changed, except for heavy chain CDR2, where as many as 10 residues may be changed. Changes in affinity can be measured by conventional methods such as those described herein (e.g., Biacore).

[00100] Chimeric, human, humanized and/or deimmunized antibodies can be constructed and produced using conventional techniques known in the art and those methods are contemplated for use herein. In addition, recombinantly-prepared antibodies can often be produced in large quantities, particularly when utilizing high level expression vectors.

[00101] Art-recognized techniques such as those provided and incorporated herein, can be used to modify nucleotides encoding amino acid sequences using recombinant techniques in restriction endonuclease sites.

[00102] For high level production, a widely used mammalian expression system is one which utilizes Lonza's powerful proprietary GS Gene Expression System™. This system uses a robust viral promoter and selection via glutamine metabolism to provide rapid development of high-yielding and stable mammalian cell lines according the manufacturer's instructions.

[00103] For alternative high level production, a widely used mammalian expression system is one which utilizes the gene amplification procedure offered by dehydrofolate reductase deficient ("dhfr- ") Chinese hamster ovary cells. The system is based upon the dehydrofolate reductase "dhfr" gene, which encodes the DFIFR enzyme, which catalyzes conversion of dehydrofolate to tetrahydrofolate. In order to achieve high production, dhfr- CHO cells are transfected with an expression vector containing a functional DHFR gene, together with a gene that encodes a desired protein. In this case, the desired protein is recombinant antibody heavy chain and/or light chain.

[00104] By increasing the amount of the competitive DHFR inhibitor methotrexate (MTX), the recombinant cells develop resistance by amplifying the dhfr gene. In standard cases, the amplification unit employed is much larger than the size of the dhfr gene, and as a result the antibody heavy chain is co-amplified.

[00105] When large scale production of the protein, such as the antibody chain, is desired, both the expression level and the stability of the cells being employed are taken into account.

[00106] The present application provides an isolated polynucleotide (nucleic acid) encoding an antibody or portion thereof as described herein, vectors containing such polynucleotides, and host cells and expression systems for transcribing and translating such polynucleotides into polypeptides. [00107] The present application also provides constructs in the form of plasmids, vectors, transcription or expression cassettes which comprise at least one polynucleotide as above.

[00108] The present application also provides a recombinant host cell which comprises one or more constructs as above. A nucleic acid encoding any antibody described herein forms an aspect of the present application, as does a method of production of the antibody, which method comprises expression from encoding nucleic acid therefrom. Expression can be achieved by culturing under appropriate conditions recombinant host cells containing the nucleic acid.

Following production by expression, an antibody or a portion thereof can be isolated and/or purified using any suitable technique, then used as appropriate.

[00109] Specific antibodies (or portions thereof) encoding nucleic acid molecules and vectors containing same described herein can be provided isolated and/or purified, e.g., from their natural environment, in substantially pure or homogeneous form, methods of purifying proteins and nucleic acids are known in the art and are contemplated for use herein.

[00110] Systems for cloning and expression of a polypeptide in a variety of different host cells are well known in the art and are contemplated for use herein.

[00111] Thus, a further aspect provides a host cell containing nucleic acid as disclosed herein using conventional methods known in the art. A still further aspect provides a method comprising introducing such nucleic acid into a host cell; the introduction can employ any available technique known in the art.

[00112] The introduction can be followed by causing or allowing expression from the nucleic acid, e.g., by culturing host cells under conditions for expression of the gene.

[00113] The present application also provides a method which comprises using a construct as stated above in an expression system in order to express the antibodies (or portions thereof) as above.

[00114] In a further embodiment, the full DNA sequence of the recombinant DNA molecule or cloned gene of an antibody or portion thereof described herein can be operatively linked to an expression control sequence which can be introduced into an appropriate host using methods conventionally known in the art.

[00115] As is well known in the art, DNA sequences can be expressed by operatively linking them to an expression control sequence in an appropriate expression vector and employing that expression vector to transform an appropriate host cell using methods conventionally known in the art.

[00116] A wide variety of host/expression vector combinations can be employed in expressing the DNA sequences of this invention and are known in the art. [00117] An antibody can then be isolated and/or purified using any suitable technique and used as appropriate.

[00118] Any of a wide variety of expression control sequences - sequences that control the expression of a DNA sequence operatively linked to it - can be used in these vectors to express the DNA sequences and are known in the art.

[00119] It will be understood that not all vectors, expression control sequences and hosts will function equally well to express the DNA sequences. Neither will all hosts function equally well with the same expression system. However, one skilled in the art will be able to select the proper vectors, expression control sequences, and hosts without undue experimentation to accomplish the desired expression without departing from the scope of this application. For example, in selecting a vector, the host must be considered because the vector must function in it. The vector's copy number, the ability to control that copy number, and the expression of any other proteins encoded by the vector, such as antibiotic markers, will also be considered. One of ordinary skill in the art can select the proper vectors, expression control sequences, and hosts to accomplish the desired expression without departing from the scope of this application. For example, in selecting a vector, the host is considered because the vector functions in it. The vector's copy number, the ability to control that copy number, and the expression of any other proteins encoded by the vector, such as antibiotic markers, can also be considered.

[00120] Considering these and other factors, a person skilled in the art will be able to construct a variety of vector/expression control sequence/host combinations that will express the DNA sequences on fermentation or in large scale animal culture.

[00121] A polynucleotide encoding an antibody or a portion thereof can be prepared recombinantly/synthetically in addition to, or rather than, cloned using methods known in the art.

[00122] Simultaneous incorporation of the antibody (or portion thereof)-encoding nucleic acids and the selected amino acid position changes can be accomplished by a variety of methods known to those skilled in the art, including for example, recombinant and chemical synthesis.

ENDOGLIN AND ANTI-ENDOGLIN ANTIBODIES

[00123] Endoglin (CD 105) is expressed on the cell surface as a 180 kDa homodimeric transmembrane protein. The external domain binds TGF-βΙ and -3 isoforms with high affinity (50 nM), and the transmembrane and the intracellular domains of CD 105 share a 71% sequence similarity with beta glycan. The human CD 105 gene is located on chromosome 9q34, identified using fluorescence in situ hybridization, and the coding region contains 14 exons, and two different isoforms (L and S) of CD 105 with capacity to bind TGF- β have been characterized. The L-CD105 consists of 633 amino acid residues with 47 amino acid residues in the cytoplasmic tail as opposed to the S-CD105, which consists of 600 amino acid residues with a 14 amino acid cytoplasmic tail. However, L-CD105 is the predominant form. CD 105 is constitutively phosphorylated in endothelial cells, mainly on serine and threonine residues, and this phosphorylation is due to the constitutively active TGF- β RII within the cell. TGF- β binding to CD 105 results in down- regulation of phosphorylation, similar to effects seen with protein kinase C inhibitors.

[00124] The murine CD 105 amino acid sequence contains the tripeptide arginine-glycine- aspartic acid (RGD) located in an exposed region of the extracellular domain. The RGD peptide is a key recognition structure found on ECM proteins such as fibronectin, vitronectin, von Willebrand factor (vWF), type I collagen, and fibrinogen and is recognized by cell surface integrins.

[00125] Several functions of CD 105 are associated with TGF-β signaling. TGF-β signals through heterodimeric receptors consisting of serine kinases, receptor I (RI), and receptor II (RII). Binding of TGF-β to the external domains of the receptor unmasks the cytoplasmic RII kinase activity that phosphorylates the TGF-β RI, which can then interact with downstream signalers such as the Smad proteins. CD 105 forms part of the TGF-β receptor complex but it can exist

independently on the cell surface. In many cells in vitro, CD 105 suppresses TGF-β signaling.

CD 105 also binds other growth factors such as activin A and bone morphogenic proteins (BMP) -7 and -2. Binding of TGF-β or other growth factor ligands to CD 105 requires the presence of at least the receptor RII, and it cannot bind ligands by itself. CD 105 association with receptors does not alter their affinity for the ligand itself. Upon association, the cytoplasmic domain of CD 105 is phosphorylated by TGF-β RI and TGF-β RII; then TGF-β RI, but not TGF-β RII, kinase dissociates from the receptor complex. Furthermore, CD 105 expression inhibits phosphorylation levels of TGF-β RII but increases that of TGF -β RI, resulting in increased phosphorylation of Smad 2 but not Smad 3. Since Smad 2 can interact with a variety of transcription factors, co-activators, and suppressors, phosphorylated Smad 2 may act as an integrator of multiple signals to modulate gene transcription. Thus, CD 105 modulates TGF-β functions via interaction with TGF-β RI and TGF-β RII and modifies the phosphorylation of downstream Smad proteins.

[00126] CD 105 is a member of the TGF-β receptor family that is expressed by proliferating endothelial cells. Normal levels of CD 105 are needed for endothelial cell proliferation. CD 105 expression is increased by cellular hypoxia through the production of hypoxia-inducible factor-1-α (HIF-1-α) and protects hypoxic cells from apoptosis.

[00127] CD 105 acts to modulate signaling of multiple kinase receptor complexes of the TGF-β superfamily, including TGF-β receptors (TGF^R), activin receptor-like kinases (ALK) and activin receptors. In the absence of CD 105, activation of TGF-β receptors results in

phosphorylation of SMAD proteins (SMAD 2 and 3) that inhibit endothelial cell growth. However, activation of CD 105 by TGF-β modulates SMAD protein phosphorylation (including the phosphorylation of SMAD 1, 5 and 8). The end result is release of the growth inhibitory effects of TGF-β receptor activation on endothelial cells. Prevention of CD 105 activation by anti-CD 105 antibody acts synergistically with TGF-β to suppress endothelial cell growth.

[00128] The CD 105 promoter is 2.6 kb in length but does not contain TATA or CAAT transcription initiation boxes. However, it has two GC-rich regions, consensus motifs for Spl, ets, GAT A, AP-2, NGF-β, and Mad, as well as TGF-β response elements. Nonetheless, CD 105 has a relatively restricted cellular distribution. The basal level of transcription appears to require an ets site at position -68 and the Spl sites, but the relative restriction of expression, for example, to endothelial cells, appears to involve multiple regulatory regions, in particular, one at -1294 to -932 and another very close to the transcription initiation site. CD 105 is up-regulated by TGF-β, and this has been shown to require a Spl site at -37 to -29, also involving one or more juxtaposed upstream SBE sites binding Smad 3 and/or 4 (which are activated by TGF-β signaling). Hypoxia is a common feature of ischemic tissues and tumors, and is a potent stimulator for CD 105 gene expression in vascular endothelial cells (ECs). Such an effect is potentiated in combination with TGF-β 1. The up-regulated CD105 can exert a self-protective role in ECs under hypoxic stress.

[00129] Vascular EC are the major source of CD 105. Other cell types including vascular smooth muscle cells, fibroblasts, macrophages, leukemic cells of pre-B and myelomonocytic origin, and erythroid precursors express CD 105 to a lesser extent.

[00130] Endoglin, also known as, inter alia, CD105 or edg-1, is a type I homodimeric membrane glycoprotein which is expressed at high levels in proliferating vascular endothelial cells. Endoglin has been targeted in antibody-based methods of reducing tumor vasculature, as EDG is a proliferation-associated antigen on endothelial and leukemia cells. Its expression is up-regulated in tumor-associated vascular endothelium.

[00131] Provided herein are antibodies that specifically bind to endoglin. These antibodies can bind endoglin and inhibit or neutralize its activity. In addition to their use for purification of endoglin, these antibodies are useful for detection of endoglin in a sample obtained from a subject, for diagnostic purposes, and therapeutic purposes. The antibodies provided herein can be used in the formulation of a medicament for the treatment of cancer or a metastasis thereof as described herein.

[00132] Murine monoclonal antibodies (mAbs) have been raised against human and murine endoglin which inhibit endoglin activity and which, in some instances, inhibit VEGF activity.

These murine antibodies are described in U.S. patents 5,928,641, 6,200,566, 6, 190,660, and 7,097,836, each of which is hereby incorporated in their entirety. Additionally, the ex vivo and in vivo efficiency of a number of these antibodies has been demonstrated; monoclonal antibodies that bind endoglin are of interest as endoglin modulating compounds. Therapeutic use of murine antibodies is not feasible, however, as administration of murine antibodies has a number of limitations, including immunogenicity in, for example, the form of human anti -mouse antibody (HAMA) responses.

[00133] To address problems associated with murine antibodies, chimeric antibodies that bind endoglin and inhibit its activity are described herein that exhibit reduced immunogenicity while maintaining and/or improving their specificity. These chimeric, humanized, deimmunized, and humanized-deimmunized anti-endoglin antibodies are useful for the diagnosis and treatment of various conditions and diseases as well as for purification and detection of endoglin. Antibodies against endoglin represent an important area for the development of therapies for the treatment of a cancer.

[00134] Provided herein are antibodies thereof that specifically bind to endoglin and inhibit (partially or fully) or manage/treat (partially or fully) tumor cell proliferation or tumor growth. Similarly, inhibition of endoglin function {e.g., signaling, binding, activation, and the like) is also included within the meaning of inhibiting or binding endoglin.

[00135] One can recognize that the antibodies that specifically bind endoglin generated using the methods described herein can be tested using the assays provided herein or known in the art for the ability to bind to endoglin using conventional methods including, but not limited to, ELISA. Affinity of antibodies described herein can also be determined using conventional methods including, but not limited to, Biacore or surface plasmon resonance.

[00136] Provided herein are isolated/purified antibodies that specifically bind to endoglin. Also provided herein are isolated/purified antibodies that specifically bind to endoglin and inhibit its activity. Also provided herein are recombinant antibodies that specifically bind to endoglin and inhibit its activity.

[00137] Provided herein is a chimeric anti-endoglin antibody that comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 1 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 3 . In some instances, the chimeric anti-endoglin antibody also comprises a light chain constant region having an amino acid sequence set forth as SEQ ID NO: 2 and a gamma 1 (γΐ) constant region having an amino acid sequence set forth as SEQ ID NO: 4.

[00138] Also provided herein are humanized and deimmunized anti-endoglin antibodies which contain heavy and light chain sequences as described above in the Summary of the

Invention. [00139] In another aspect, the present application provides an antibody capable of competing with an anti-endoglin antibody described herein under conditions in which at least 5% of an antibody having the V_H and V_L sequences of the antibody is blocked from binding to endoglin by competition with such an antibody in an ELISA assay. Such chimeric antibodies may be useful as chimeric anti-endoglin antibodies in accordance with the methods and combination

pharmaceuticals of the present application.

[00140] Provided herein are neutralizing antibodies that specifically bind to endoglin and modulate the activity of endoglin. The neutralizing antibody can for example, bind to endoglin and inhibit its activity and/or induce apoptosis of tumor cells. The assignee of the subject application has demonstrated that the antigen-binding variable regions of the anti-endoglin antibodies described here provide the effector functions of the antibodies (data not shown).

[00141] Inhibition of cancer/tumor cell proliferation and/or tumor growth by at least about 2- fold, at least about 3-fold, at least about 4-fold, at least about 5-fold, at least about 6-fold, at least about 7-fold, at least about 8-fold, at least about 9-fold, at least about 10-fold, at least about 20- fold, at least about 30-fold, at least about 40-fold, at least about 50-fold, at least about 60-fold, or greater than negative controls is indicative of inhibition of cancer/tumor cell proliferation and/or tumor growth. Inhibition of cancer/tumor cell proliferation and/or tumor growth by less than 2-fold greater than negative controls is indicative of an antibody that does not inhibit cancer/tumor cell proliferation and/or tumor growth.

[00142] Binding of an antibody described herein to endoglin can partially (e.g., about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%), about 95%, about 98%, about 99% or any number therebetween) or completely (100%) inhibit the activity of endoglin, thereby inhibiting tumor cell proliferation and/or inhibiting tumor growth. In some instances, binding of an antibody described herein to endoglin partially or completely inhibits VEGF activity. The neutralizing or inhibiting activity of a chimeric antibody can be determined using an in vitro assay and/or in vivo using art-recognized assays such as those described herein or otherwise known in the art.

[00143] Antibodies described herein are also useful in purification, detection or diagnostic applications.

ANTI-PD-1 OR ANTI-PD-LI AGENTS

[00144] Programmed cell death protein 1 (also known as PD-1 and CD279), is a cell surface receptor that plays an role in down-regulating the immune system and promoting self-tolerance by suppressing T cell inflammatory activity. PD-1 is an immune cell inhibitory molecule that is expressed on activated B cells, T cells, and myeloid cells. PD-1 nucleotide and amino acid sequences are well known in the art. A non-limiting, exemplary, human PD-1 amino acid sequence is set forth in GenBank deposit GI: 167857792.

[00145] PD-Ll is a ligand of PD-1. A non-limiting, exemplary, human PD-Ll amino acid sequence is set forth in GenBank UniProtKB/Swiss-Prot: Q9NZQ7.1.

[00146] PD-1 represents an immune checkpoint and guards against autoimmunity via a dual mechanism of promoting apoptosis (programmed cell death) in antigen-specific T-cells in lymph nodes while reducing apoptosis in regulatory T cells.

[00147] PD-1 is a member of the CD28/CTLA-4/ICOS costimulatory receptor family that delivers negative signals that affect T and B cell immunity. PD-1 is monomelic both in solution as well as on cell surface, in contrast to CTLA-4 and other family members that are all disulfide- linked homodimers.

[00148] Signaling through the PD-1 inhibitory receptor upon binding its ligand, PD-Ll, suppresses immune responses against autoantigens and tumors and plays a role in the maintenance of peripheral immune tolerance.

[00149] The interaction between PD-1 and PD-Ll results in a decrease in tumor infiltrating lymphocytes, a decrease in T cell receptor mediated proliferation, and immune evasion by the cancerous cells.

[00150] An "anti-PD-1 antibody" or an "anti-PD-Ll antibody" is an antibody that specifically binds to PD-1 or PD-Ll, respectively with sufficient affinity and specificity that it does not bind another protein. It will be understood that an anti-PD-1 antibody specifically binds to PD-1 and inhibits the activity of the PD-1 or prevents binding of PD-Ll to PD-1. It will be understood that an anti-PD-Ll antibody specifically binds to PD-Ll and inhibits binding of the protein to PD- 1. An anti-PD-1 antibody or an anti-PD-Ll antibody can be, for example, a monoclonal antibody, a mouse-human chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a human antibody, a humanized antibody, a deimmunized antibody, or a humanized- deimmunized antibody.

[00151] An anti-PD-1 antibody or an anti-PD-Ll antibody of the invention is intended to be used as a therapeutic agent in combination with an anti-endoglin antibody described herein to treat cancer.

[00152] Provided herein is a method for treating a cancer or a metastasis thereof in a subject in need thereof, by administering to the subject an anti-endoglin antibody and an anti-PD-1 antibody, whereby the cancer or the metastasis thereof is treated. [00153] Provided herein is a method for treating a cancer or a metastasis thereof in a subject in need thereof, by administering to the subject an anti-endoglin antibody and an anti-PD-Ll antibody, whereby the cancer or the metastasis thereof is treated.

[00154] Provided herein is a method for a cancer or a metastasis thereof is treated in a subject in need thereof, by administering to the subject an anti-endoglin antibody, an anti-PD-Ll antibody, and an anti-PD-Ll antibody, whereby the cancer or the metastasis thereof is treated.

[00155] Reference to an antibody in any of the described embodiments is also intended to include, in some instances, anti gen -binding fragments that specifically bind to endoglin, PD-1 or PD-L1 and inhibit the activity of the protein.

[00156] Provided herein is a method of affecting cell signaling pathways associated with tumor immunity. Tumor immunity involves T lymphocytes expressing CD8 that are known as effector T cells and T cells expressing CD4 known as T regulatory cells. T cells may express PD-1 receptors that cause T cell exhaustion and prevent effector T cell function when the PD-1 receptor binds the PD-L1 and/or PD-L2 ligand.

[00157] Tumor cells can be contacted (in vitro, in vivo or ex vivo) with one or more antibodies described herein. In one embodiment, an antibody is an anti-endoglin antibody. An anti- PD-1 antibody and/or an anti-PD-Ll antibody (or antigen-binding fragment thereof) can also be administered in connection with a pharmaceutical composition containing an anti-endoglin antibody. The antibodies can be administered sequentially or simultaneously.

[00158] Representative examples of anti-PD-1 antibodies include, but are not limited to: Nivolumab (OPDIVO®), Pidilizumab (formerly CT-011) and PDR001.

[00159] Representative examples of anti-PD-Ll antibodies include, but are not limited to: Pembrolizumab (KEYTRUDA®), BMS-936559, Avelumab (BAVENCIO®) and Atezolizumab (TECENTRIQ®).

[00160] Provided herein are isolated/purified antibodies that specifically bind to PD-1 and inhibit its activity, thereby treating a cancer or a metastasis thereof. Also provided herein are isolated/purified antibodies that specifically bind to PD-L1 and inhibit its activity, thereby treating the cancer or the metastasis thereof. Treating a cancer or a metastasis thereof encompasses inhibition of tumor cell proliferation, inhibition of tumor growth, reduction of tumor size or elimination of a tumor, and/or prolongation of the subject's life.

[00161] Inhibition of cancer/tumor cell proliferation and/or tumor growth by at least about 2- fold, at least about 3-fold, at least about 4-fold, at least about 5-fold, at least about 6-fold, at least about 7-fold, at least about 8-fold, at least about 9-fold, at least about 10-fold, at least about 20- fold, at least about 30-fold, at least about 40-fold, at least about 50-fold, at least about 60-fold, or greater than negative controls is indicative of inhibition of cancer/tumor cell proliferation and/or tumor growth. Inhibition of cancer/tumor cell proliferation and/or tumor growth by less than 2-fold greater than negative controls is not indicative of treatment of a cancer or metastasis thereof.

[00162] Provided herein are antibodies that specifically bind to PD-1 or PD-L1 and inhibit

(partially or fully) or manage/treat (partially or fully) tumor cell proliferation or tumor growth. Similarly, inhibition of PD-1 or PD-L1 function (e.g., signaling, binding, activation, and the like) is also included within the meaning of inhibiting or binding PD-1 or PD-L1.

[00163] Binding of an antibody to PD-1 or PD-L1 can partially (e.g., about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%), about 98%>, about 99% or any number therein) or completely inhibit, tumor cell proliferation and/or tumor growth. The activity of the antibody can be determined using an in vitro assay and/or in vivo using art-recognized assays such as those described herein or otherwise known in the art.

[00164] Exemplary, non-limiting dosages for anti-PD-1 antibodies and anti-PD-Ll antibodies are discussed in more detail below and in the Examples.

MODIFIED ANTIBODIES OR PORTIONS THEREOF

[00165] In some instances, an antibody or an antigen-binding fragment thereof described herein can further conjugated to a therapeutic label for use in therapeutic applications (i.e., an immunoconjugate or fusion protein).

[00166] As used herein, for purposes of the specification and claims, immunoconjugates refer to conjugates comprised of the anti-endoglin antibodies or fragments thereof according to the present invention and at least one therapeutic label.

[00167] Therapeutic labels include antitumor agents. Such antitumor agents are known in the art and include, but not limited to, toxins, chemotherapeutic drugs, enzymes, cytokines, radionuclides and photodynamic agents. Toxins include, but are not limited to, ricin A chain, mutant Pseudomonas exotoxins, diphtheria toxoid, streptonigrin, boamycin, saporin, gelonin, and pokeweed antiviral protein. Chemotherapeutic drugs include daunorubicin, methotrexate, and calicheamicins. Radionuclides include radiometals. Cytokines include, but are not limited to, transforming growth factor (TGF)-P, interleukins, interferons, and tumor necrosis factors.

Photodynamic agents include, but are not limited to, porphyrins and their derivatives. Additional therapeutic labels will be known in the art and are also contemplated herein. The methods for complexing the antibody or a fragment thereof with at least one antitumor agent are well known to those skilled in the art (i.e., antibody conjugates as reviewed by Ghetie et al., 1994, Pharmacol. Ther. 63 :209-34). Such methods may utilize one of several available heterobifunctional reagents used for coupling or linking molecules. Additional radionuclides are further described herein along with additional methods for linking molecules, such as therapeutic and diagnostic labels.

[00168] Antibodies can be modified using techniques known in the art for various purposes such as, for example, by addition of polyethylene glycol (PEG). PEG modification (PEGylation) can lead to one or more of improved circulation time, improved solubility, improved resistance to proteolysis, reduced antigenicity and immunogenicity, improved bioavailability, reduced toxicity, improved stability, and easier formulation (for a review see, Francis et al., International Journal of Hematology, 68: 1-18, 1998).

[00169] Fc portions of antibodies can be modified to increase half-life of the in circulation in blood when administered to a subject. Modifications can be determined using conventional means in the art such as, for example, described in U.S. Patent No. 7,217,798, which is hereby

incorporated by reference in its entirety.

[00170] Other methods of improving the half-life of antibody-based fusion proteins in circulation are also known such as, for example, described in U.S. Patent Nos. 7,091,321 and 6,737,056, each of which is hereby incorporated by reference. Additionally, antibodies may be produced or expressed so that they do not contain fucose on their complex N-glycoside-linked sugar chains. The removal of the fucose from the complex N-glycoside-linked sugar chains is known to increase effector functions of the antibodies and antigen-binding fragments, including but not limited to, antibody dependent cell-mediated cytotoxicity (ADCC) and complement dependent cytotoxicity (CDC). Similarly, antibodies that can bind endoglin can be attached at their C-terminal end to all or part of an immunoglobulin heavy chain derived from any antibody isotype, e.g., IgG, IgA, IgE, IgD and IgM and any of the isotype sub-classes, particularly IgGl, IgG2b, IgG2a, IgG3 and IgG4.

[00171] Additionally, the antibodies described herein can also be modified so that they are able to cross the blood-brain barrier. Such modification of the antibodies described herein allows for the treatment of brain diseases such as glioblastoma multiforme (GBM). Exemplary

modifications to allow proteins such as antibodies to cross the blood-brain barrier are described in US Patent Publication 20070082380 Al which is hereby incorporated by reference in its entirety.

[00172] Glycosylation of immunoglobulins has been shown to have significant effects on their effector functions, structural stability, and rate of secretion from antibody-producing cells (Leatherb arrow et al., Mol. Immunol. 22:407 (1985)). The carbohydrate groups responsible for these properties are generally attached to the constant (C) regions of the antibodies. For example, glycosylation of IgG at asparagine 297 in the CH 2 domain is required for full capacity of IgG to activate the classical pathway of complement-dependent cytolysis (Tao and Morrison, J. Immunol. 143 :2595 (1989)). Glycosylation of IgM at asparagine 402 in the C_H 3 domain is necessary for proper assembly and cytolytic activity of the antibody (Muraoka and Shulman, J. Immunol.

142:695 (1989)). Removal of glycosylation sites as positions 162 and 419 in the C_H 1 and C_H3 domains of an IgA antibody led to intracellular degradation and at least 90% inhibition of secretion (Taylor and Wall, Mol. Cell. Biol. 8:4197 (1988)). Additionally, antibodies may be produced or expressed so that they do not contain fucose on their complex N-glycoside-linked sugar chains. The removal of the fucose from the complex N-glycoside-linked sugar chains is known to increase effector functions of the antibodies and antigen-binding fragments, including but not limited to, antibody dependent cell-mediated cytotoxicity (ADCC) and complement dependent cytotoxicity (CDC). These "defucosylated" antibodies may be produced through a variety of systems utilizing molecular cloning techniques known in the art, including but not limited to, transgenic animals, transgenic plants, or cell-lines that have been genetically engineered so that they no longer contain the enzymes and biochemical pathways necessary for the inclusion of a fucose in the complex N- glycoside-linked sugar chains (also known as fucosyltransferase knock-out animals, plants, or cells). Non-limiting examples of cells that can be engineered to be fucosyltransferase knock-out cells include CHO cells, SP2/0 cells, NSO cells, and YB2/0 cells.

[00173] Glycosylation of immunoglobulins in the variable (V) region has also been observed. Sox and Hood reported that about 20% of human antibodies are glycosylated in the V region (Proc. Natl. Acad. Sci. USA 66:975 (1970)). Glycosylation of the V domain is believed to arise from fortuitous occurrences of the N-linked glycosylation signal Asn-Xaa-Ser/Thr in the V region sequence and has not been recognized in the art as playing a role in immunoglobulin function.

[00174] Glycosylation at a variable domain framework residue can alter the binding interaction of the antibody with antigen. The present invention includes criteria by which a limited number of amino acids in the framework or CDRs of an immunoglobulin chain are chosen to be mutated {e.g., by substitution, deletion, or addition of residues) in order to increase the affinity of an antibody.

[00175] Affinity for binding an antigen can, generally, be modulated by introducing one or more mutations into the V region framework, typically in areas adjacent to one or more CDRs and/or in one or more framework regions. Typically, such mutations involve the introduction of conservative amino acid substitutions that either destroy or create the glycosylation site sequences but do not substantially affect the hydropathic structural properties of the polypeptide. Typically, mutations that introduce a proline residue are avoided. Glycosylation of antibodies is further described in U.S. Patent No. 6,350,861, which is incorporated by reference herein with respect to glycosylation.

[00176] Antibodies can be formulated for short-term delivery or extended (long term) delivery.

[00177] Antibodies that bind to endoglin can also be used for purification of endoglin and/or to detect endoglin levels in a sample or subject to detect or diagnose a disease or disorder associated with endoglin as described in more detail below.

[00178] Antibodies which bind endoglin generated using such methods can be tested for one or more of their binding affinity, avidity, and neutralizing capabilities. Useful antibodies can be administered to a subject to inhibit, manage or treat a cancer or a metastasis thereof. In some instances, treatment prolongs progression-free survival of the subject.

[00179] Antibodies can be evaluated for one or more of binding affinity, association rates, disassociation rates and avidity. In one aspect, antibodies can be evaluated for their ability to neutralize the activity of endoglin, PD-1 or PD-Ll . Measurement binding affinity, association rates, disassociation rates and avidity can be accomplished using art-recognized assays including, but not limited to, an enzyme-linked-immunosorbent assay (ELISA), Scatchard Analysis, BIACORE analysis (Surface Plasmon Resonance), etc., as well as other assays commonly used and known to those of ordinary skill in the art.

[00180] Measurement of binding of antibodies to endoglin and/or the ability of the antibodies, for example, to inhibit the activity of endoglin, can be determined using, for example, an enzyme-linked-immunosorbent assay (ELISA), a competitive binding assay, an ELISPOT assay, or any other useful assay known in the art. These assays are commonly used and well-known to those of ordinary skill in the art.

[00181] In one non-limiting embodiment, an ELISA assay can be used to measure the binding capability of specific antibodies that bind to endoglin, PD-1 or PD-Ll .

[00182] Assays, such as an ELISA, also can be used to identify antibodies thereof which exhibit increased specificity for endoglin in comparison to other antibodies thereof. Assays, such as an ELISA, also can be used to identify antibodies thereof with bind to epitopes across one or more polypeptides and across one or more species of endoglin, PD-1 or PD-Ll . The specificity assay can be conducted by running parallel ELISAs in which a test antibody is screened concurrently in separate assay chambers for the ability to bind one or more epitopes on different species of the polypeptide containing the endoglin epitopes to identify antibodies thereof that bind to endoglin. Another technique for measuring apparent binding affinity familiar to those of skill in the art is a surface plasmon resonance technique (analyzed on a BIACORE 2000 system) (Liljeblad, et al, Glyco. J. 2000, 17:323-329). Standard measurements and traditional binding assays are described by Heeley, R. P., Endocr. Res. 2002, 28:217-229.

[00183] Antibodies that specifically bind to endoglin, antibodies that specifically bind to PD-

I, and antibodies that specifically bind to PD-L1 can also be assayed for their ability to treat various forms of cancer {e.g., primary tumors, recurring tumors, and metastases). Any suitable assay known to one of skill in the art can be used to monitor such effects. Several such techniques are described herein. In one example, the antibodies described herein are assayed for their ability to bind endoglin. In another example, affinity constants for the antibodies described herein are determined by surface plasmon resonance (SPR). In yet another example, the antibodies described herein are assayed for their effect on the inhibition or treatment of a cancer or a metastasis thereof.

II. Pharmaceutical Compositions

[00184] Each of the compounds described herein can be used as a pharmaceutical composition when combined with a pharmaceutically acceptable carrier or excipient. Such pharmaceutical compositions are useful for in vitro or in vivo analysis or for administration to a subject in vivo or ex vivo for treating a subject with the disclosed compounds.

[00185] Provided herein are pharmaceutical compositions (medicaments) containing an anti- endoglin antibody described herein capable of inhibiting one or more of the biological activities of endoglin.

[00186] For example, provided herein are pharmaceutical compositions (medicaments) containing an anti-endoglin antibody described herein capable of inhibiting or treating a cancer or a metastasis thereof.

[00187] Provided herein are pharmaceutical compositions (medicaments) containing an anti-

PD-1 antibody and/or an anti-PD-Ll antibody capable of inhibiting one or more of the biological activities of PD-1 and/or PD-L1.

[00188] Also provided herein are pharmaceutical compositions (medicaments) containing a combination of an anti-endoglin antibody, an anti-PD-1 antibody and/or an anti-PD-Ll antibody.

[00189] Pharmaceutical compositions containing an anti-endoglin antibody (or antigen- binding fragment thereof) can be administered sequentially or simultaneously with a

pharmaceutical composition containing an anti-PD-1 antibody and/or an anti-PD-Ll antibody. Such administrations include, but are not limited to, administration within about four weeks of each other, within about three weeks of each other, within about two weeks of each other, within about a week of each other, within a day of each other, within about 12 hours of each other, within about 6 hours of each other, within about 3 hours of each other, within about 1 hour of each other, within about 30 minutes of each other, on the same day, at the same time, or a combination thereof. When multiple doses of the composition of the present invention and/or the combined therapeutic moiety are contemplated, it is understood that doses of each can be empirically determined using known doses and concentrations based on the age, height, weight, health and other physical characteristics of a subject using standards of commercially available products.

[00190] When compositions are administered sequentially, a pharmaceutical composition comprising an anti-endoglin antibody described herein can be, for example, administered prior to or after a pharmaceutical composition comprising an anti-PD-1 antibody and/or an anti-PD-Ll antibody. Alternatively, a pharmaceutical composition comprising an anti-endoglin antibody described herein is administered after a pharmaceutical composition comprising an anti-PD-1 antibody and/or an anti-PD-Ll antibody. In some instances, a pharmaceutical composition contains both an anti-PD-1 antibody and an anti-PD-Ll antibody. In other instances, different

pharmaceutical compositions are prepared such that one contains an anti-PD-1 antibody and a second contains an anti-PD-Ll antibody.

[00191] When pharmaceutical compositions are administered simultaneously, a composition containing an anti-endoglin antibody can be administered at the same site, or at a different site than a pharmaceutical composition containing an anti-PD-1 antibody and/or an anti-PD-Ll antibody.

[00192] Also provided herein are pharmaceutical compositions (medicaments) containing an anti-endoglin antibody and an anti-PD-1 antibody and/or an anti-PD-Ll antibody, capable of inhibiting one or more of the biological activities of endoglin and PD-1 and/or PD-Ll, respectively, such as mitogenic activity, tumor cell proliferation, or tumor growth.

[00193] One would understand that treatment regimens may include one or more

administrations of each of the pharmaceutical compositions described herein. A pharmaceutical composition can be administered in a single dose or multiple doses. Administration of separate pharmaceutical compositions may be by the same route or by different routes.

[00194] In one embodiment, a pharmaceutical composition is administered every one to three weeks for six to 12 cycles or until tumor progression. The method can further include the step of administering a pharmaceutical composition for one to twelve weeks for up to two years. In another non-limiting example, the concurrent administration of an anti-endoglin antibody and an anti-PD-1 antibody or an anti-PD-Ll antibody occurs at week 1, followed by additional

administration of the compositions at week one, two, three or 4, wherein the concurrent

administration is repeated for six to twelve cycles or until tumor progression and followed by administration of the compositions for one to twelve weeks for up to two years.

[00195] In one non-limiting example of a method for treating cancer in a subject, the method includes surgical removal of the cancer and administration of an anti-endoglin antibody and an anti- PD-1 antibody or an anti-PD-Ll antibody at one to three weeks for 12 months or until tumor progression followed by concurrent administration of an anti-endoglin antibody and an anti-PD-1 antibody or an anti-PD-Ll antibody in a dose at week 12. Additionally, the concurrent

administration of an anti-endoglin antibody and an anti-PD-1 antibody or an anti-PD-Ll antibody can be repeated every one to three weeks for up to 6 cycles. Optionally, the method further includes administering an anti-endoglin antibody and an anti-PD-1 antibody or an anti-PD-Ll antibody every twelve weeks for up to two years. It will be understood that treatment regimens can be combined with monitoring methods provided herein to determine if and when additional doses of an anti-endoglin antibody and an anti-PD-1 antibody or an anti-PD-Ll antibody need be

administered.

[00196] Combination therapy may provide a synergistic and/or increased beneficial effect or may allow lower doses of a combination to provide a greater margin of safety and/or tolerance. The invention encompasses treatment protocols that enhance the prophylactic or therapeutic effect of an anti-endoglin antibody and an anti-PD-1 antibody and/or an anti-PD-Ll for preventing, managing, treating or ablation of cancer or other diseases.

[00197] An additional therapeutic treatment such as, for example, a chemotherapeutic agent as described herein can be administered to a subject as empirically determined by a practitioner. Compositions containing such additional therapeutic treatments can be administered in combination (either sequentially or simultaneously) with the other pharmaceutical compositions described herein. An additional therapy that may be administered to a subject in combination with the described methods is radiation and/or surgery.

[00198] In one non-limiting method for treating cancer provided herein, an additional therapeutic treatment includes surgical removal of the cancer, irradiation, one or more

chemotherapeutic agents, or a combination thereof, and simultaneous administration of one or more pharmaceutical compositions described herein. In one non-limiting aspect, administration of a pharmaceutical composition can be, for example, about a 20 minute intravenous infusion, about a 30-minute intravenous infusion, about a 40-minute intravenous infusion, about a 50-minute intravenous infusion, about a 60-minute intravenous infusion, about a 70-minute intravenous infusion, about a 80-minute intravenous infusion, about a 90-minute intravenous infusion, about a 100-minute intravenous infusion, or any integer therebetween.

[00199] Pharmaceutical compositions can include, in some instances, in addition to active ingredient, a pharmaceutically acceptable excipient, carrier, buffer, stabilizer or other materials well known to those in the art. Such materials should be non-toxic and should not interfere with the efficacy of the active ingredient(s). The precise nature of the carrier or other material will depend on the route of administration.

[00200] Formulations comprising an antibody or antigen-binding fragment, identified by the methods described herein can be prepared for storage by mixing the protein 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 those that are non-toxic 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, di saccharides, 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).

[00201] Acceptable carriers are physiologically acceptable to the administered subject and retain the therapeutic properties of the compounds with/in which it is administered. Acceptable carriers and their formulations are and generally described in, for example, Remington'

pharmaceutical Sciences (18th Edition, Ed., A. Gennaro, Mack Publishing Co., Easton, PA 1990). One exemplary carrier is physiological saline. The phrase "pharmaceutically acceptable carrier" as used herein means a pharmaceutically acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, solvent or encapsulating material, involved in carrying or transporting the subject compounds from the administration site of one organ, or portion of the body, to another organ, or portion of the body, or in an in vitro assay system. Each carrier is acceptable in the sense of being compatible with the other ingredients of the formulation and not injurious to a subject to whom it is administered. Nor should an acceptable carrier alter the specific activity of the subject compounds.

[00202] In one aspect, provided herein are pharmaceutically acceptable or physiologically acceptable compositions including solvents (aqueous or non-aqueous), solutions, emulsions, dispersion media, coatings, isotonic and absorption promoting or delaying agents, compatible with administration. Pharmaceutical compositions or formulations, therefore, refer to a composition suitable for therapeutic and/or diagnostic use in a subject. Pharmaceutical compositions and formulations include an amount of a compound described herein and a pharmaceutically or physiologically acceptable carrier.

[00203] Pharmaceutical compositions can be formulated to be compatible with a particular route of administration (i.e., systemic or local). Thus, pharmaceutical compositions include carriers, diluents, or excipients suitable for administration by various routes.

[00204] In another embodiment, the pharmaceutical compositions can further comprise, if needed, an acceptable additive in order to improve the stability of the compounds in composition and/or to control the release rate of the composition. Acceptable additives do not alter the specific activity of the subject compounds. Exemplary acceptable additives include, but are not limited to, a sugar such as mannitol, sorbitol, glucose, xylitol, trehalose, sorbose, sucrose, galactose, dextran, dextrose, fructose, lactose and mixtures thereof. Acceptable additives can be combined with acceptable carriers and/or excipients such as dextrose. Alternatively, exemplary acceptable additives include, but are not limited to, a surfactant such as polysorbate 20 or polysorbate 80 to increase stability of the peptide and decrease gelling of the solution. The surfactant can be added to the composition in an amount of 0.01% to 5% of the solution. Addition of such acceptable additives increases the stability and half-life of the pharmaceutical composition in storage.

[00205] Pharmaceutical compositions can be administered, for example, by injection, including, but not limited to, subcutaneous, intravitreal, intradermal, intravenous, intra-arterial, intraperitoneal, or intramuscular injection. Excipients and carriers for use in formulation of compositions for each type of injection are contemplated herein. The following descriptions are by example only and are not meant to limit the scope of the compositions. Pharmaceutical

compositions for injection include, for example, aqueous solutions (where water soluble) or dispersions, and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersion. For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, CREMOPHOR EL™ (BASF, Parsippany, N.J.) or phosphate buffered saline (PBS). The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyetheylene glycol, and the like), and suitable mixtures thereof. Fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Antibacterial and antifungal agents include, for example, parabens, chlorobutanol, phenol, ascorbic acid and thimerosal. Isotonic agents, for example, sugars, polyalcohols such as mannitol, sorbitol, and sodium chloride may be included in the composition. The resulting solutions can be packaged for use as is, or lyophilized; the lyophilized preparation can later be combined with a sterile solution prior to administration. For intravenous, injection, or injection at the site of affliction, the active ingredient can be in the form of a parenterally acceptable aqueous solution which is pyrogen-free and has suitable pH, isotonicity and stability. Those of relevant skill in the art are well able to prepare suitable solutions using, for example, isotonic vehicles such as Sodium Chloride Injection, Ringer's Injection, Lactated Ringer's Injection. Preservatives, stabilizers, buffers, antioxidants and/or other additives may be included, as needed. Sterile injectable solutions can be prepared by incorporating an active ingredient in the required amount in an appropriate solvent with one or a combination of ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the active ingredient into a sterile vehicle which contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the methods of preparation are vacuum drying and freeze drying which yields a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.

[00206] Pharmaceutical compositions can be conventionally administered intravenously, such as by injection of a unit dose, for example. For injection, an active ingredient can be in the form of a parenterally acceptable aqueous solution which is substantially pyrogen-free and has suitable pH, isotonicity and stability. One can prepare suitable solutions using, for example, isotonic vehicles such as Sodium Chloride Injection, Ringer's Injection, Lactated Ringer's Injection. Preservatives, stabilizers, buffers, antioxidants and/or other additives may be included, as required. Additionally, pharmaceutical compositions can be administered via aerosolization. (Lahn et al., Aerosolized Anti-T-cell-Receptor Antibodies Are Effective against Airway Inflammation and Hyperreactivity, Int. Arch. Allergy Immuno., 134: 49-55 (2004)).

[00207] In one embodiment, the pharmaceutical composition is lyophilized, for example, to increase shelf-life in storage. When the pharmaceutical compositions are considered for use in medicaments or any of the methods provided herein, it is contemplated that the composition can be substantially free of pyrogens such that the pharmaceutical composition will not cause an inflammatory pharmaceutical reaction or an unsafe allergic reaction when administered to a human subject. Testing pharmaceutical compositions for pyrogens and preparing pharmaceutical compositions substantially free of pyrogens are well understood to one or ordinary skill of the art and can be accomplished using commercially available kits.

[00208] Acceptable carriers can contain a compound that stabilizes a pharmaceutical composition, increases or delays absorption, or increases or delays clearance. Such compounds include, for example, carbohydrates, such as glucose, sucrose, or dextrans; low molecular weight proteins; compositions that reduce the clearance or hydrolysis of peptides; or excipients or other stabilizers and/or buffers. Agents that delay absorption include, for example, aluminum

monostearate and gelatin. Detergents can also be used to stabilize or to increase or decrease the absorption of compositions, including liposomal carriers. To protect from digestion the compound can be complexed with a composition to render it resistant to acidic and enzymatic hydrolysis, or the compound can be complexed in an appropriately resistant carrier such as a liposome. Means of protecting compounds from digestion are known in the art (see, e.g., Fix (1996) Pharm Res.

13 : 1760 1764; Samanen (1996) 7. Pharm. Pharmacol. 48: 119 135; and U.S. Pat. No. 5,391,377, describing lipid compositions for oral delivery of therapeutic agents).

[00209] The phrase "pharmaceutically acceptable" refers to molecular entities and compositions that are physiologically tolerable and do not typically produce an allergic or similar untoward reaction, such as gastric upset, dizziness and the like, when administered to a subject.

[00210] The term "unit dose" when used in reference to a therapeutic composition refers to physically distinct units suitable as unitary dosage for subjects, each unit containing a

predetermined quantity of active material calculated to produce the desired therapeutic effect in association with the required diluent; i.e., carrier, or vehicle.

[00211] The compositions can be administered in a manner compatible with the dosage formulation, and in a therapeutically effective amount. The quantity to be administered depends on the subject to be treated, capacity of the subject's immune system to utilize the active ingredient, and degree of binding capacity desired. Precise amounts of active ingredient required to be administered depend on the judgment of the practitioner and are peculiar to each individual.

Suitable regimes for initial administration and booster shots are also variable, but are typified by an initial administration followed by repeated doses at one or more hour intervals by a subsequent injection or other administration. Alternatively, continuous intravenous infusions sufficient to maintain concentrations in the blood are contemplated.

[00212] One embodiment contemplates the use of the pharmaceutical compositions described herein to make a medicament for treating a condition, disease or disorder described herein. Medicaments can be formulated based on the physical characteristics of the subject needing treatment, and can be formulated in single or multiple formulations based on the stage of the condition, disease or disorder. Medicaments can be packaged in a suitable package with appropriate labels for the distribution to hospitals and clinics wherein the label is for the indication of treating a subject having a disease described herein. Medicaments can be packaged as a single or multiple units. Instructions for the dosage and administration of the pharmaceutical compositions can be included with the packages as described below. The present application is directed to medicaments of an anti-endoglin antibody described herein above and a pharmaceutically acceptable carrier. In another embodiment, the present application is directed to medicaments of an anti-PD-1 or anti-PD- Ll antibody (or antigen-binding fragment thereof) described herein above and a pharmaceutically acceptable carrier. In yet another embodiment, the present application is directed to medicaments of an anti-endoglin antibody and an anti-PD-1 or anti-PD-Ll antibody described herein above and a pharmaceutically acceptable carrier.

[00213] In one embodiment of the present invention, the pharmaceutical compositions are formulated to be free of pyrogens such that they are acceptable for administration to human subjects. Testing compositions for pyrogens and preparing pharmaceutical compositions free of pyrogens are well understood to one of ordinary skill in the art.

[00214] One embodiment of the present invention contemplates the use of any of the pharmaceutical compositions of the present invention to make a medicament for treating a cancer or a metastasis thereof as described herein. Medicaments can be formulated based on the physical characteristics of the subject needing treatment, and can be formulated in single or multiple formulations based on the disorder. Medicaments can be packaged in a suitable package with appropriate labels for the distribution to hospitals and clinics wherein the label is for the indication of treating a disorder as described herein in a subject. Medicaments can be packaged as a single or multiple units. Instructions for the dosage and administration of the pharmaceutical compositions can be included with the packages.

III. Methods of Use

[00215] Provided herein is a method of treating a subject (human or non-human) by administering to the subject a pharmaceutical composition of an antibody that preferentially binds to endoglin. The methods described herein further include treating a subject (human or non-human) by administering to the subject a pharmaceutical composition of an anti-PD-1 or anti-PD-Ll antibody. In certain instances, the methods include administering a single pharmaceutical composition containing both an anti-endoglin antibody and an anti-PD-1 antibody to a subject. In certain instances, the methods include administering a single pharmaceutical composition containing both an anti-endoglin antibody and an anti-PD-Ll antibody to a subject. In certain instances, the methods include administering a single pharmaceutical composition containing an anti-endoglin antibody, an anti-PD-1 antibody and an anti-PD-Ll antibody to a subject.

[00216] In one instance, provided herein is a method of treating a cancer with a

pharmaceutical composition that comprises an anti-endoglin antibody and a pharmaceutical composition that comprises Nivolumab (OPDIVO®). [00217] In another instance, provided herein is a method of treating a cancer with a pharmaceutical composition that comprises an anti-endoglin antibody and a pharmaceutical composition that comprises Pidilizumab (formerly CT-011).

[00218] In another instance, provided herein is a method of treating a cancer with a pharmaceutical composition that comprises an anti-endoglin antibody and a pharmaceutical composition that comprises PDR001.

[00219] In another instance, provided herein is a method of treating a cancer with a pharmaceutical composition that comprises an anti-endoglin antibody and a pharmaceutical composition that comprises Pembrolizumab (KEYTRUDA®).

[00220] In another instance, provided herein is a method of treating a cancer with a pharmaceutical composition that comprises an anti-endoglin antibody and a pharmaceutical composition that comprises BMS-936559.

[00221] In another instance, provided herein is a method of treating a cancer with a pharmaceutical composition that comprises an anti-endoglin antibody and a pharmaceutical composition that comprises Avelumab (BAVENCIO®).

[00222] In another that instance, provided herein is a method of treating a cancer with a pharmaceutical composition comprising an anti-endoglin antibody and a pharmaceutical composition that comprises Atezolizumab (TECENTRIQ®).

[00223] An effective response of the present invention is achieved when the subject experiences partial or total alleviation or reduction of signs or symptoms of illness, and specifically includes, without limitation, prolongation of survival. The expected progression -free survival (PFS) times may be measured in months to years, depending on prognostic factors including the number of relapses, stage of disease, and other factors. Prolonging survival includes without limitation times of at least 1 month (mo), about at least 2 mos., about at least 3 mos., about at least 4 mos., about at least 6 mos., about at least 1 year, about at least 2 years, about at least 3 years, about at least 4 years, about at least 5 years, etc. Overall or progression-free survival (PFS) can be also measured in months to years. Alternatively, an effective response may be that a subject's symptoms or cancer burden remain static and do not worsen. Further indications of treatment of indications are described in more detail below.

[00224] Pharmaceutical compositions of antibodies described herein can be used as non- therapeutic agents {e.g., as affinity purification agents). Generally, in one such embodiment, a protein of interest is immobilized on a solid phase such a Sephadex resin or filter paper, using conventional methods known in the art. The immobilized protein is contacted with a sample containing the target of interest (or fragment thereof) to be purified, and thereafter the support is washed with a suitable solvent that will remove substantially all the material in the sample except the target protein, which is bound to the immobilized antibody. Finally, the support is washed with another suitable solvent, such as glycine buffer, pH 5.0, which will release the target protein. In addition to purification, compositions can be used for detection, diagnosis and therapy of a cancer or a metastasis thereof associated with endoglin, PD-1 and/or PD-L1.

[00225] A pharmaceutical composition provided herein may have a pH of from about 4.0 to about 7.5. In one embodiment, a formulation provided herein may have a pH of about 4.5, about 4.6, about 4.7, about 4.8, about 4.69, about 5.0, about 5.1, about 5.2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, about 6.0, about 6.1, about 6.2, about 6.3, about 65.4, about 6.5, about 6.6, about 6.7, about 6.8, about 6.9, or about 7.0.

[00226] The term "contacting" as used herein refers to adding together a solution or composition of a compound with a liquid medium bathing the polypeptides, cells, tissue or organ from an organism. Alternately, "contacting" refers to mixing together a solution or composition of a compound, with a liquid such as blood, serum, or plasma derived from an organism. For in vitro or ex vivo applications, a composition can also comprise another component, such as dimethyl sulfoxide (DMSO). DMSO facilitates the uptake of the compounds or solubility of the compounds. The solution comprising the test compound may be added to the medium bathing the cells, tissues, or organs, or mixed with another liquid such as blood, by utilizing a delivery apparatus, such as a pipette-based device or syringe-based device. For in vivo applications, contacting can occur, for example, via administration of a pharmaceutical composition to a subject by any suitable means.

[00227] A "subject" {e.g., a mammal such as a human or a non-human animal such as a primate, rodent, cow, horse, pig, sheep, camel, llama, etc.) can be a mammal who exhibits one or more clinical manifestations and/or symptoms of a cancer or a metastasis thereof described herein. In certain situations, a subject may be asymptomatic and yet still have clinical manifestations of the disease or disorder. An antibody can be conjugated to a therapeutic moiety or be a fusion protein containing a therapeutic label. An antibody can be conjugated to a detectable label or be a fusion protein containing a detectable label. In one embodiment, the antibody can be conjugated to both a therapeutic label and a detectable moiety. An antibody can be conjugated to, or recombinantly engineered with, an affinity tag {e.g., a purification tag). Affinity tags such as, for example, a His6 tag (SEQ ID NO: 9), avidin, etc. are conventional in the art.

[00228] Antibodies or thereof provided herein are such that they can be conjugated or linked to a therapeutic label and/or an imaging or a detectable label and/or an affinity tag. Methods for conjugating or linking polypeptides are well known in the art. Associations (binding) between compounds and labels include any means known in the art including, but not limited to, covalent and non-covalent interactions, chemical conjugation as well as recombinant techniques.

[00229] Exemplary diseases or conditions contemplated for treatment with the combination of pharmaceutical compositions described herein include various forms of cancer and metastases thereof.

[00230] The terms "recurrence", "relapse" or "relapsed" refer to the return of a cancer or disease after clinical assessment of the disappearance of disease. A diagnosis of distant metastasis or local recurrence can be considered a relapse.

[00231] The term "maintenance therapy" refers to scheduled retreatment that is given to help maintain a previous treatment's effects. Maintenance therapy is often given to help keep cancer in remission or prolong a response to a specific therapy regardless of disease progression.

[00232] The term "progression-free survival" in oncology refers to the length of time during and after treatment that a cancer does not grow. Progression-free survival includes the amount of time subjects have experienced a complete response or a partial response, as well as the amount of time subjects have experienced stable disease.

[00233] In one aspect, provided herein is a method of preventing or treating a cancer or a metastasis in a subject by administering any of the pharmaceutical compositions provided herein to a subject suffering from cancer or metastasis. Such a subject can be symptomatic or asymptomatic.

[00234] In some cases, administration of the pharmaceutical composition prolongs life of the subject being treated, reduces tumor volume, eliminates a tumor, decreases cell proliferation, increases apoptosis of tumor cells, or a combination thereof.

[00235] If needed, the methods can further include surgical removal of the cancer and/or administration of an additional anti-cancer agent or treatment. Anti-cancer agents have been provided elsewhere herein.

[00236] In one aspect, symptoms of the subject suffering from cancer are ameliorated.

Amelioration can be manifested as, for example, reduction in pain, reduced tumor size, elimination of tumors, prevention of increases in tumor size or progression or of disease, prevention of formation of metastasis, or inhibition of metastatic growth, or a combination thereof.

[00237] In one aspect, administration of the pharmaceutical compositions reduces or eliminates the need for the subject to undergo surgery or treatment with one or more additional anti-cancer agents or treatments.

Treatment with Anti-Endoglin Antibodies and Anti-PD-1 or Anti-PD-Ll Agents

[00238] Provided herein are methods of preventing or treating a cancer or a metastasis thereof, comprising administering to a subject in need thereof a pharmaceutical composition that comprises an anti-endoglin antibody and a pharmaceutical composition that comprises an anti-PD-1 antibody, at the same time or at different times, thereby preventing, treating, ameliorating, or lessening the cancer, a metastasis, or its severity.

[00239] Provided herein are methods of preventing or treating a cancer or a metastasis thereof, comprising administering to a subject in need thereof a pharmaceutical composition that comprises an anti-endoglin antibody and a pharmaceutical composition that comprises an anti-PD- Ll antibody, at the same time or at different times, thereby preventing, treating, ameliorating, or lessening the cancer, a metastasis, or its severity.

[00240] Provided herein are methods of preventing or treating a cancer or a metastasis thereof, comprising administering to a subject in need thereof a pharmaceutical composition that comprises an anti-endoglin antibody, a pharmaceutical composition that comprises an anti-PD-1 antibody and a pharmaceutical composition that comprises an anti-PD-Ll antibody, at the same time or at different times, thereby preventing, treating, ameliorating, or lessening the cancer, a metastasis, or its severity.

[00241] As used herein, "treatment" refers to prevention of onset of symptoms, or prevention of progression of a cancer or a metastasis thereof. As used herein, "inhibition," "treatment" and "treating" are used interchangeably and refer to, for example, stasis of symptoms, prolongation of survival, partial or full amelioration of symptoms, and partial or full eradication of a tumor or metastases. The terms "cancer" and "tumor" are used interchangeably herein.

[00242] Pharmaceutical compositions can be administered to a subject in a therapeutically effective amount that is effective for producing some desired therapeutic effect by inhibiting a disease or disorder at a reasonable benefit/risk ratio applicable to any medical treatment. For the administration of the present compositions to human subjects, the compositions can be formulated by methodology known by one in the art. A therapeutically effective amount is an amount achieves at least partially a desired therapeutic or prophylactic effect in an organ or tissue. The amount of an anti-endoglin antibody or an anti-PD-1 antibody or an anti-PD-Ll antibody necessary to bring about prevention and/or therapeutic treatment of a disease or disorder is not fixed per se. The amount of antibody administered may vary with the type of disease, extensiveness of the disease, and size of the mammal suffering from the disease or disorder. In one embodiment, two antibodies described herein are administered to a subject in combination as described above. Administration in combination can refer to administration in a single pharmaceutical composition or in separate pharmaceutical compositions. Thus, the invention provides pharmaceutical compositions comprising antibodies described herein for combination therapy by simultaneous, separate or sequential administration of the pharmaceutical compositions. [00243] "Administering" is referred to herein as providing one or more compositions to a subject in a manner that results in the composition being inside the subject's body. Such an administration can be by any route including, without limitation, locally, regionally or systemically by subcutaneous, intravitreal, intradermal, intravenous, intra-arterial, intraperitoneal, or

intramuscular administration (e.g., injection).

[00244] Actual dosage levels of the active ingredients in the compositions can be varied so as to obtain an amount of the active ingredient that is effective to achieve the desired therapeutic response for a particular subject, composition, and mode of administration, without being toxic to the subject. The selected dosage level will depend upon a variety of factors including the activity of the particular compound employed, the route of administration, the time of administration, the rate of excretion of the particular compound being employed, the duration of the treatment, other drugs, compounds and/or materials used in combination with the particular composition employed, the age, sex, weight, condition, general health and prior medical history of the subject being treated, and like factors well known in the medical arts.

[00245] The anti-endoglin antibodies described herein can be administered to a subject in various dosing amounts and over various time frames. Non-limiting doses include about 0.01 mg/kg, about 0.05 mg/kg, about 0.1 mg/kg, about 0.5 mg/kg, about 1 mg/kg, about 5 mg/kg, about 10 mg/kg, about 20 mg/kg, about 30 mg/kg, about 40 mg/kg, about 50 mg/kg, about 60 mg/kg, about 70 mg/kg, about 80 mg/kg, about 90 mg/kg, about 100 mg/kg, about 125 mg/kg, about 150 mg/kg, about 175 mg/kg, about 200 mg/kg, or any integer in between.

[00246] Additionally, the dose(s) of an antibody can be administered daily, every other day, twice a week, weekly, every two weeks, every three weeks, every 4 weeks, every 6 weeks, every 8 weeks, every 12 weeks, or any combination thereof.

[00247] Dosing cycles are also contemplated such as, for example, administering antibodies one or twice a week for about 2, about 3, about 4, about 5 or about 6 weeks, followed by about 1, about 2, about 3, about 4, about 5, or about 6 weeks without therapy. Alternatively, depending upon the response of a subject to therapy, cycling time between treatments can be about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 1 1 or about 12 months. Additional dosing cycles including, for example, different combinations of the doses and weekly cycles described herein are also contemplated within the invention and as described in the

Examples.

[00248] "Contacting" is defined herein as a means of bringing a composition as provided herein in physical proximity with a cell, organ, tissue or fluid as described herein. Contacting encompasses systemic or local administration of any of the compositions provided herein and includes, without limitation, in vitro, in vivo and/or ex vivo procedures and methods. "Combining" and "contacting" are used interchangeably herein and are meant to be defined in the same way.

[00249] A physician or veterinarian can readily determine and prescribe the effective amount

(ED50) of the composition required. For example, the physician or veterinarian could start doses of the compounds employed in the composition at levels lower than that required in order to achieve the desired therapeutic effect and gradually increase the dosage until the desired effect is achieved. Alternatively, a dose can remain constant.

[00250] Pharmaceutical compositions can be administered to a subject by any convenient route such as described above. Regardless of the route of administration selected, the compounds of the present invention, which can be used in a suitable hydrated form, and/or the pharmaceutical compositions, are formulated into acceptable dosage forms such as described below or by other conventional methods known to those in the art.

[00251] Toxicity and therapeutic efficacy of compounds can be determined by standard procedures in cell cultures or experimental animals, e.g., for determining the LD₅₀ (the dose lethal to 50% of the population) and the ED₅₀ (the dose therapeutically effective in 50% of the

population). The dose ratio between toxic and therapeutic effects is the therapeutic index and it can be expressed as the ratio LD₅₀/ED₅₀. While compounds that exhibit toxic side effects may be used, care should be taken to design a delivery system that targets such compounds to the site of affected tissue in order to minimize potential damage to healthy cells and, thereby, reduce side effects.

[00252] Data obtained from cell culture assays and/or animal studies can be used in formulating a range of dosage for use in humans. The dosage of such compounds lies preferably within a range of circulating concentrations that include the ED₅₀ with little or no toxicity. The dosage may vary within this range depending upon the dosage form employed and the route of administration utilized. For any compound, a therapeutically effective dose can be estimated initially from cell culture assays. A dose can be formulated in animal models to achieve a circulating plasma concentration arrange that includes the IC₅₀ the concentration of the test compound which achieves a half-maximal inhibition) as determined in cell culture. Levels in plasma can be measured, for example, by high performance liquid chromatography. Such information can be used to more accurately determine useful doses in humans. Pharmaceutical compositions containing combinations of compounds can also be assessed using any of these methods.

[00253] In one embodiment, the invention contemplates inhibition of a cancer. The extent of the cancer and, therefore, the extent of inhibition achieved can be evaluated by a variety of methods, such as are described herein. [00254] The unique specificity of the antibodies which recognize (e.g., preferentially bind or specifically bind) endoglin, PD-1 or PD-Ll and inhibits growth of the cancer, induces a T cell response that kills cancer cells, induces apoptosis of cancer cells, and/or inhibits tumor cell proliferation. Antibodies can be administered to a subject suffering from various forms of cancer (primary tumors and metastases). In some instances where a cancer has metastasized, a subject can be treated for more than one type of cancer tissue.

[00255] Non-limiting dosages of Anti-PD-1 Antibodies or Anti -PD-Ll Antibodies for administration to human subjects are as follows:

1 mg/kg IV infused over 1 hr on the same day every three weeks (q3wk) for 4 doses; subsequent doses of nivolumab as a single agent are 240 mg IV q2wk infused over 1 hour (hr)

Urothelial Cancer Ni ol umab (QPDIVQ®) 240 mg IV q2wk infused over 1 hr.

Non-Small Cell Lung Pembrolizumab 200 mg IV infusion over 30 minutes Cancer (KEYTRUDA®) q3wk.

Metastatic Non- Small Pembrolizumab 200 mg IV infusion over 30 minutes Cell Lung Cancer (KEYTRUDA®) q3wk.

Unresectable Melanoma Pembrolizumab 2 mg/kg IV infusion over 30

(KEYTRUDA®) minutes q3wk.

Metastatic Melanoma Pembrolizumab 2 mg/kg IV infusion over 30

(KEYTRUDA®) minutes q3wk.

Head & Neck Squamous Pembrolizumab 2 mg/kg IV infusion over 30 Cell Carcinoma (KEYTRUDA®) minutes q3wk.

Urothelial Cancer Avelumab (BAVENCIO®) adults and pediatric patients aged

>12 yr at about 10 mg/kg IV once every 2 weeks (q2wk)

Merkel Cell Carcinoma Avelumab (BAVENCIO®) adults and pediatric patients aged

>12 yr at about 10 mg/kg IV once every 2 weeks (q2wk)

Non-Small Cell Lung Atezolizumab 1200 mg IV q3wk infused over 60 Cancer (TECENTRIQ®) min q3wk. If the first infusion is tolerated, all subsequent infusions may be administered IV over 30 minutes q3wk.

Locally Advanced Atezolizumab 1200 mg IV q3wk infused over 60 Urothelial Cancer (TECENTRIQ®) min q3wk. If the first infusion is tolerated, all subsequent infusions may be administered IV over 30 minutes q3wk.

Metastatic Urothelial Atezolizumab 1200 mg IV q3wk infused over 60 Cancer (TECENTRIQ®) min q3wk. If the first infusion is tolerated, all subsequent infusions may be administered IV over 30 minutes q3wk.

[00256] One would understand that, in addition to administration of the pharmaceutical compositions described herein, it is contemplated herein that a subject can also be treated with one or more additional anti -cancer agents (e.g., adjunct therapy). The terms "cancer inhibitor" and "anti-cancer agent" are used herein, for purposes of the specification and claims, to mean a compound or molecule including, but not limited to, chemotherapeutic agents that function to stimulate the immune response of the subject being treated. Anti-cancer agents are known in the art and all types are contemplated herein. In certain instances, the one or more chemotherapeutic agents include, but are not limited to docetaxel (TAXOTERE®) as well as platinum based chemotherapeutic agents such as, for example, cisplatin, carboplatin, and oxaliplatin. Other non- limiting examples of compounds and molecules include natural and synthetic biomolecules such as paclitaxel, O-(chloroacetyl-carbomyl) fumagillol ("TNP-470" or "AGM 1470"), thrombospondin- 1, thrombospondin-2, angiostatin, platelet factor-4, gro-beta, human interferon-inducible protein 10 ("IP10"), interleukin 12, Ro 318220, tricyclodecan-9-yl xanthate ("D609"), irsogladine, 8,9- dihydroxy-7-methyl-benzo[b] quinolizinium bromide ("GPA 1734"), medroxyprogesterone, a combination of heparin and cortisone, glucosidase inhibitors, genistein, thalidomide, diamino- antraquinone, herbimycin, ursolic acid, and oleanolic acid.

[00257] Multiple combinations of these anti-PD-1 and anti-PD-Ll antibodies can be administered with the anti-endoglin antibodies described herein. In one embodiment, combinations may result in the use of lower doses for the described antibodies or antigen binding. Such alterations in dosing may result from synergistic effects of the combinations of the antibodies.

Cancer

[00258] The combination of pharmaceutical compositions described herein can be used to treat cancerous tumors and metastases. The compositions can also be used in the formulations of medicaments for the treatment cancerous tumors and metastases.

[00259] The terms "tumor" and "cancer" are used herein to refer to a cancerous tissue (as compared to expression by normal tissue of the same type). Tumors can include solid tumors and semi -solid tumors. Tumor and cancer as used herein also include a metastasis of any of the tumors or cancers described herein.

[00260] A cancerous tissue to be treated is, for example, an endothelial tissue expressing an abnormal level of endoglin, PD-1 and/or PD-Ll . [00261] A cancer to be treated using a method described herein includes, but is not limited to, a kidney cancer (e.g., a renal cell carcinoma), a lung cancer (e.g., a primary non-small cell lung cancer, or a metastatic non-small cell lung cancer), melanoma (e.g., a primary melanoma, an unresectable melanoma or a metastatic melanoma), a head and neck cancer (e.g., a head and neck squamous cell carcinoma), a Merkel cell carcinoma, a urothelial cancer (e.g., a locally advanced urothelial cancer or a metastatic urothelial cancer), a breast cancer, a pancreatic cancer, an ovarian cancer, a uterine cancer, a colorectal cancer, a prostate cancer, a bladder cancer, a liver cancer, a sarcoma, a myeloma, a brain cancer (e.g., a glioblastoma multiforme, a glioma, etc.) and a lymphoma.

[00262] In one instance, a cancer to be treated using the pharmaceutical compositions and methods described herein is a lung cancer, a renal cancer, a melanoma, a urothelial cancer, a colorectal cancer, or a metastasis of any thereof.

[00263] It will be appreciated that a "subject suffering from a cancer or a metastasis thereof of the invention may express a mutant protein (tumor associated antigen) or a mutant gene and not yet be symptomatic for the disease. In one non-limiting example of colon cancer (which is associated with the mutant K-ras protein), a subject with a mutant K-ras protein in some cells of the colon is a subject to be treated even though that subject may not yet be symptomatic for colon cancer. "Signs or symptoms of illness" represent clinically recognized manifestations or indications of disease.

[00264] By "treating" a subject suffering from tumor or metastasis, it is meant that the subject's symptoms are partially alleviated, totally alleviated, or remain static following treatment. A subject that has been treated can exhibit a partial or total alleviation of tumor load. This is intended to encompass prophylaxis, therapy and cure. In one non-limiting example, a subject suffering from a highly metastatic cancer (e.g., breast cancer) is treated where additional metastasis either do not occur, or are reduced in number as compared to a subject who does not receive treatment. In another non-limiting example, a subject is treated where the subject's solid cancer either becomes reduced in size or does not increase in size as compared to a subject who does not receive treatment. In yet another non-limiting example, the number of cancer cells in a treated subject either does not increase or is reduced as compared to the number of cancer cells in a subject who does not receive treatment. Improvement can also be defined, for example, as decreased cell proliferation, decreased numbers of cells, increased apoptosis, and/or increased survival of the subject being treated.

[00265] Treatment of a cancer or a metastasis thereof includes stasis, partial or total elimination of a cancerous growth or tumor compared to treatment with a placebo. Treatment or partial elimination includes, for example, a fold reduction in growth or tumor size and/or volume such as about 2-fold, about 3-fold, about 4-fold, about 5-fold, about 10-fold, about 20-fold, about 50-fold, or any fold reduction in between. Similarly, treatment or partial elimination can include a percent reduction in growth or tumor size and/or volume of about 1%, about 2%, about 3%, about 4%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%), about 90%, about 95% or any percentage reduction in between.

[00266] Treatment of a cancer or a metastasis thereof includes, in some instances, increasing progression-free survival (PFS) of a subject compared to treatment with a placebo. Progression-free survival may be increased by about 1 week or more, about 2 weeks or more, about 3 weeks or more, about 4 weeks or more, about 5 weeks or more, about 6 weeks or more, about 7 weeks or more, about 8 weeks or more, about 9 weeks or more, about 10 weeks or more, about 11 weeks or more, about 12 weeks or more, about 13 weeks or more, about 14 weeks or more, about 15 weeks or more, about 16 weeks or more, about 5 months or more, about 6 months or more, about 7 months or more, about 8 months or more, about 9 months or more, about 10 months or more, about 11 months or more, about 12 months or more.

[00267] It will be understood that reference to administration of an antibody also refers in some instances to administration of a pharmaceutical composition that comprises the antibody with one or more pharmaceutically acceptable excipients or carriers. In some instances, the one or more pharmaceutically acceptable excipients or carriers comprises a buffering agent, a polyol, a surfactant, a glidant, a stabilizing agent, or a combination thereof. The pH of the pharmaceutical composition can be empirically determined based upon the components of the composition;

exemplary pH values of a pharmaceutical composition include, but are not limited to a pH of from about 4.0 to about 6.5, where about refers to a value ±0.3. For example, a pH can be about 4.0, about 4.5, about 5.0, about 5.5, about 6.0 or about 6.5.

[00268] It will be understood that the following cancers are representative examples of a cancer to be treated by the methods described herein and other cancers are also contemplated.

Brain cancer

[00269] In one aspect, provided herein is a method to treat a brain cancer or a metastasis thereof. A brain cancer or a metastasis thereof to be treated includes, but is not limited to, a glioblastoma multiforme (GBM), a glioma, an astrocytoma, a meningioma, a pituitary tumor, a Craniopharyngioma, a germ cell tumor, a pineal region tumor, a Medulloblastoma, or a Primary CNS lymphoma.

[00270] In a method described herein, a subject in need thereof having a brain cancer or a metastasis thereof is administered a therapeutically effective amount of a pharmaceutical composition that comprises an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a brain cancer or a metastasis thereof is administered a therapeutically effective amount of a pharmaceutical composition that comprises an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a brain cancer or a metastasis thereof is administered a

therapeutically effective amount of a pharmaceutical composition that comprises an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof and an anti-PD-1 antibody or antigen-binding fragment thereof.

Lung cancer

[00271] In one aspect, provided herein is a method to treat a lung cancer or a metastasis thereof. The most common type of lung cancer is a non-small cell lung cancer (NSCLC), which accounts for approximately 80-85% of lung cancers and is divided into squamous cell carcinomas, adenocarcinomas, and large cell undifferentiated carcinomas. Small cell lung cancer accounts for 15-20% of lung cancers.

[00272] In a method described herein, a subject in need thereof having a small cell lung cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a small cell lung cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a small cell lung cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen- binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen- binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof.

[00273] In a method described herein, a subject in need thereof having a non-small cell lung cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a non-small cell lung cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a non-small cell lung cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof and an anti-PD-1 antibody or antigen-binding fragment thereof.

Uterine and Gynecological Cancers

[00274] Uterine cancers may refer to any of several different types of cancer which occur in the uterus, namely: uterine sarcomas {e.g., sarcomas of the myometrium, or muscular layer of the uterus, are most commonly leiomyosarcomas); endometrial cancer; and cervical cancer.

[00275] In a method described herein, a subject in need thereof having a uterine cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or anti gen -binding fragment thereof. In a method described herein, a subject in need thereof having a uterine cancer or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or anti gen -binding fragment thereof. In a method described herein, a subject in need thereof having a uterine cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-Ll antibody or antigen-binding fragment thereof.

[00276] In a method described herein, a subject in need thereof having a cervical cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or anti gen -binding fragment thereof. In a method described herein, a subject in need thereof having a cervical cancer or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or anti gen -binding fragment thereof. In a method described herein, a subject in need thereof having a cervical cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-Ll antibody or antigen-binding fragment thereof.

[00277] In a method described herein, a subject in need thereof having an endometrial cancer or a metastasis thereof is administered a therapeutically effective amount of s an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having an endometrial cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having an endometrial cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen- binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen- binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof.

[00278] In another aspect, provided herein is a method to treat endometrium cancer.

Endometrial cancer is a cancer that starts in the endometrium, the inner lining of the uterus. Some of the examples of the cancer of uterus and endometrium include, but are not limited to, adenocarcinomas, adenoacanthomas, adenosquamous carcinomas, papillary serous

adenocarcinomas, clear cell adenocarcinomas, uterine sarcomas, angiosarcomas, stromal sarcomas, malignant mixed mesodermal tumors, and leiomyosarcomas.

[00279] In another aspect, the method treats cervical cancer, preferably an adenocarcinoma in the cervix epithelial. Two main types of this cancer exist: squamous cell carcinoma and adenocarcinomas. The former constitutes about 80-90% of all cervical cancers and develops where the ectocervix (portion closest to the vagina) and the endocervix (portion closest to the uterus) join. The latter develop in the mucous-producing gland cells of the endocervix. Some cervical cancers have characteristics of both of these and are called adenosquamous carcinomas or mixed carcinomas.

Ovarian cancer

[00280] Ovarian cancer is classified according to the histology of the tumor, obtained in a pathology report. Surface epithelial-stromal tumor, also known as ovarian epithelial carcinoma, is the most typical type of ovarian cancer. It includes serous tumor, endometrioid tumor and mucinous cystadenocarcinoma. Sex cord-stromal tumor, including estrogen-producing granulosa cell tumor and virilizing Sertoli-Leydig cell tumor or arrhenoblastoma, accounts for 8% of ovarian cancers. Germ cell tumor accounts for approximately 30% of ovarian tumors but only 5% of ovarian cancers because most germ cell tumors are teratomas and most teratomas are benign. Germ cell tumor tends to occur in young women and girls. The prognosis depends on the specific histology of germ cell tumor, but overall is favorable. Mixed tumors contain elements of more than one of the above classes of tumor histology. [00281] Ovarian cancer can also be a secondary cancer, the result of metastasis from a primary cancer elsewhere in the body.

[00282] In some embodiments, the methods described herein treat an ovarian cancer selected from the following: an adenocarcinoma in the ovary and an adenocarcinoma that has migrated from the ovary into the abdominal cavity.

[00283] In another aspect, provided herein is a method of treating an ovarian cancer or a metastasis thereof, including epithelial ovarian tumors. In a method described herein, a subject in need thereof having an ovarian cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having an ovarian cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having an ovarian cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof.

Melanoma

[00284] A melanoma is a malignant tumor of melanocytes which are found predominantly in skin but also in the bowel and the eye (uveal melanoma). It is one of the rarer types of skin cancer but causes the majority of skin cancer related deaths. Malignant melanoma is a serious type of skin cancer caused by uncontrolled growth of pigment cells, called melanocytes. Melanomas also include, but are not limited to, a choroidal melanoma, malignant melanomas, cutaneous melanomas and intraocular melanomas.

[00285] Melanoma may be divided into the following types: Lentigo maligna, Lentigo maligna melanoma, superficially spreading melanoma, acral lentiginous melanoma, mucosal melanoma, nodular melanoma, polypoid melanoma, desmoplastic melanoma, amelanotic melanoma, soft-tissue melanoma, and uveal melanoma.

[00286] In a method described herein, a subject in need thereof having a melanoma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a melanoma or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a melanoma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-Ll antibody or antigen-binding fragment thereof.

Colon Cancer and Colorectal Cancer

[00287] Colorectal cancer (also called colon cancer or large bowel cancer) includes, for example, cancerous growths in the colon, rectum (anus) and appendix. With 655,000 deaths worldwide per year, it is the third most common form of cancer and the second leading cause of cancer-related death in the Western world. Many colorectal cancers are thought to arise from adenomatous polyps in the colon. These mushroom-like growths are usually benign, but some may develop into cancer over time.

[00288] In a method described herein, a subject in need thereof having a colorectal cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a colorectal cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a colorectal cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof.

Breast cancer

[00289] As used herein, "breast cancer" also encompasses a phenotype that displays a predisposition towards developing breast cancer in an individual.

[00290] A breast cancer to be treated using the methods described herein includes any type of breast cancer that can develop in a female subject. For example, the breast cancer may be characterized as Luminal A (ER+ and/or PR+, HER2-, low Ki67), Luminal B (ER+ and/or PR+, HER2+ (or HER2- with high Ki67), Triple negative/basal-like (ER-, PR-, HER2-) or HER2 type (ER-, PR-, HER2+). In another example, the breast cancer may be resistant to therapy or therapies such as alkylating agents, platinum agents, taxanes, vinca agents, anti-estrogen drugs, aromatase inhibitors, ovarian suppression agents, endocrine/hormonal agents, bisphophonate therapy agents or targeted biological therapy agents.

[00291] A lobular carcinoma in situ and a ductal carcinoma in situ are breast cancers that have developed in the lobules and ducts, respectively, but have not spread to the fatty tissue surrounding the breast or to other areas of the body. Infiltrating (or invasive) lobular and ductal carcinoma are cancers that have developed in the lobules and ducts, respectively, and have spread to either the breast's fatty tissue and/or other parts of the body. In one aspect, provided herein is a method of treating breast cancer, such as a ductal carcinoma in duct tissue in a mammary gland, a breast cancer that is Her2- and/or ER- and/or PR-. Other cancers of the breast that would benefit from treatment by the methods are medullary carcinomas, colloid carcinomas, tubular carcinomas, and inflammatory breast cancer.

[00292] In a method described herein, a subject in need thereof having a breast cancer is administered a therapeutically effective amount of a pharmaceutical composition that comprises In a method described herein, a subject in need thereof having a breast cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a colorectal cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a colorectal cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof.

Pancreatic cancer

[00293] In another aspect, provided herein is a method of treating pancreatic cancer selected from the following: an epithelioid carcinoma in the pancreatic duct tissue and an adenocarcinoma in a pancreatic duct. The most common type of pancreatic cancer is an adenocarcinoma, which occurs in the lining of the pancreatic duct.

[00294] In a method described herein, a subject in need thereof having a pancreatic cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a pancreatic cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a pancreatic cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof.

Prostate Cancer

[00295] In one other aspect, provided herein is a method to treat prostate cancer selected from the following: an adenocarcinoma or an adenocarcinoma that has migrated to the bone.

Prostate cancer develops in the prostate organ in men, which surrounds the first part of the urethra. The prostate has several cell types but 99% of tumors are adenocarcinomas that develop in the glandular cells responsible for generating seminal fluid.

[00296] In a method described herein, a subject in need thereof having a prostate cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a prostate cancer or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a prostate cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-Ll antibody or antigen-binding fragment thereof.

Head and Neck Cancers

[00297] Head and neck cancers {e.g., oral, laryngeal, nasopharyngeal, esophageal, etc.), refer to a group of biologically similar cancers originating from the upper aerodigestive tract, including the lip, oral cavity (mouth), nasal cavity, paranasal sinuses, pharynx, and larynx. Most head and neck cancers are squamous cell carcinomas, originating from the mucosal lining (epithelium) of these regions. Head and neck cancers often spread to the lymph nodes of the neck, and this is often the first (and sometimes only) manifestation of the disease at the time of diagnosis. Head and neck cancer is strongly associated with certain environmental and lifestyle risk factors, including tobacco smoking, alcohol consumption, and certain strains of the sexually transmitted human

papillomavirus. Management of subjects with head and neck cancers remains a formidable task. Cancers such as, hypopharyngeal cancer, laryngeal cancer, nasopharyngeal cancer, oropharyngeal cancer, may be treated using the compounds described herein.

[00298] In a method described herein, a subject in need thereof having an oral cancer, a laryngeal, a nasopharyngeal, or an esophageal cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having an oral cancer, a laryngeal, a nasopharyngeal, or an esophageal cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having an oral cancer, a laryngeal, a

nasopharyngeal, or an esophageal cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-Ll antibody or antigen-binding fragment thereof.

Kidney cancer

[00299] Kidney cancer (also called renal cell cancer, renal adenocarcinoma, and

hypernephroma) is a disease in which malignant cells are found in the lining of tubules in the kidney. Renal cell carcinoma is the most common form of kidney cancer arising from the proximal renal tubule. It is the most common type of kidney cancer in adults, responsible for approximately 80% of cases. A kidney cancer or a metastasis thereof includes, but is not limited to, a renal cell carcinoma {e.g., a clear cell renal cell carcinoma, a papillary renal cell carcinoma, or a

chromophobe renal cell carcinoma), a transitional cell carcinoma, a Wilms tumor

(nephroblastoma), or a renal cell sarcoma.

[00300] In a method described herein, a subject in need thereof having a kidney cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a kidney cancer or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a kidney cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-L1 antibody or antigen-binding fragment thereof.

Liver Cancer

[00301] In another aspect, provided herein is a method to treat primary liver cancer (cancer that begins in the liver). Primary liver cancer can occur in both adults and children. Liver cancer is characterized by the presence of malignant hepatic tumors - tumors or growths on or in the liver. They may be discovered on medical imaging (even for a different reason than the cancer itself), or may be present in subjects as an abdominal mass, abdominal pain, jaundice, or some other liver dysfunction. There are several types of liver cancer which may be treated using the described methods including, but not limited to, Hemangiomas, Hepatic adenomas, and Focal nodular hyperplasia.

[00302] In a method described herein, a subject in need thereof having a liver cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a liver cancer or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen-binding fragment thereof. In a method described herein, a subject in need thereof having a liver cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-Ll antibody or antigen-binding fragment thereof.

Lymphoma

[00303] Lymphoma is a type of cancer that originates in lymphocytes of the immune system.

They often originate in lymph nodes, presenting as an enlargement of the node (a tumor).

Lymphomas are closely related to lymphoid leukemias, which also originate in lymphocytes but typically involve only circulating blood and the bone marrow (where blood cells are generated in a process termed hematopoiesis) and do not usually form tumors. There are many types of lymphomas, and in turn, lymphomas are a part of the broad group of diseases called hematological neoplasms. Some forms of lymphoma are indolent {e.g., small lymphocytic lymphoma), compatible with a long life even without treatment, whereas other forms are aggressive {e.g., Burkitt's lymphoma), causing rapid deterioration and death.

[00304] The WHO Classification, published in 2001 and updated in 2008;

http://en.wikipedia.org/wiki/Lymphoma - cite_note-isbn92-832-241 l-6-2#cite_note-isbn92-832- 2411-6-2 is the latest classification of lymphoma and is based upon the foundations laid within the "Revised European-American Lymphoma classification" (REAL). This system groups lymphomas by cell type (i.e., the normal cell type that most resembles the tumor) and defining phenotypic, molecular or cytogenetic characteristics. There are three large groups: the B cell, T cell, and natural killer cell tumors. Other less common groups are also recognized. Hodgkin's lymphoma, although considered separately within the WHO (and preceding) classifications, is now recognized as being a tumor of, albeit markedly abnormal, lymphocytes of mature B cell lineage.

[00305] In a method described herein, a subject in need thereof having a lymphoma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a lymphoma or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a lymphoma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-Ll antibody or antigen-binding fragment thereof.

Sarcoma

[00306] A sarcoma is a cancer of the connective tissue (bone, cartilage, fat) resulting in mesoderm proliferation.

[00307] This is in contrast to carcinomas, which are of epithelial origin (breast, colon, pancreas, and others). However, due to an evolving understanding of tissue origin, the term

"sarcoma" is sometimes applied to tumors now known to arise from epithelial tissue. The term soft tissue sarcoma is used to describe tumors of soft tissue, which includes elements that are in connective tissue, but not derived from it (such as muscles and blood vessels).

[00308] Sarcomas are given a number of different names, based on the type of tissue from which they arise. For example, osteosarcoma arises from bone, chondrosarcoma arises from cartilage, and leiomyosarcoma arises from smooth muscle.

[00309] In a method described herein, a subject in need thereof having a sarcoma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a sarcoma or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a sarcoma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof.

Carcinoma

[00310] A carcinoma is any malignant cancer that arises from epithelial cells. Carcinomas invade surrounding tissues and organs and may metastasize, or spread, to lymph nodes and other sites.

[00311] Carcinoma, like all neoplasia, is classified by its histopathological appearance. Adenocarcinoma and squamous cell carcinoma, two common descriptive terms for tumors, reflect the fact that these cells may have glandular or squamous cell appearances respectively. Severely anaplastic tumors might be so undifferentiated that they do not have a distinct histological appearance (undifferentiated carcinoma).

[00312] Sometimes a tumor is referred to by the presumptive organ of the primary {e.g., carcinoma of the prostate) or the putative cell of origin (hepatocellular carcinoma, renal cell carcinoma).

[00313] Non-limiting examples of carcinomas include, but are not limited to, an

adenocarcinoma, a squamous cell carcinoma, a small cell carcinoma, a large cell undifferentiated carcinoma, and a Sinonasal undifferentiated carcinoma.

[00314] In a method described herein, a subject in need thereof having a carcinoma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a carcinoma or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or antigen -binding fragment thereof. In a method described herein, a subject in need thereof having a carcinoma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-Ll antibody or antigen-binding fragment thereof. Myeloma

[00315] Multiple myeloma (also known as MM, myeloma, plasma cell myeloma, or as

Kahler's disease after Otto Kahler) is a cancer of plasma cells. These immune cells are formed in bone marrow, are numerous in lymphatics and produce antibodies. Myeloma is regarded as incurable, but remissions may be induced with steroids, chemotherapy, thalidomide and stem cell transplants. Myeloma is part of the broad group of diseases called hematological malignancies.

[00316] In a method described herein, a subject in need thereof having a myeloma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or anti gen -binding fragment thereof. In a method described herein, a subject in need thereof having a myeloma or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or anti gen -binding fragment thereof. In a method described herein, a subject in need thereof having a myeloma or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti-PD-Ll antibody or antigen-binding fragment thereof.

Bladder cancer

[00317] Bladder cancer refers to any of several types of malignant growths of the urinary bladder. It is a disease in which abnormal cells multiply without control in the bladder. The bladder is a hollow, muscular organ that stores urine; it is located in the pelvis. The most common type of bladder cancer begins in cells lining the inside of the bladder and is called transitional cell carcinoma (sometimes urothelial cell carcinoma). 90% of bladder cancers are transitional cell carcinoma. The other 10% are squamous cell carcinoma, adenocarcinoma, sarcoma, small cell carcinoma and secondary deposits from cancers elsewhere in the body.

[00318] In a method described herein, a subject in need thereof having a bladder cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or anti gen -binding fragment thereof. In a method described herein, a subject in need thereof having a bladder cancer or a metastasis thereof is administered a therapeutically effective amount of an anti- endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-Ll antibody or anti gen -binding fragment thereof. In a method described herein, a subject in need thereof having a bladder cancer or a metastasis thereof is administered a therapeutically effective amount of an anti-endoglin antibody, or antigen-binding fragment thereof described herein in combination with an anti-PD-1 antibody or antigen-binding fragment thereof and an anti- PD-L1 antibody or antigen-binding fragment thereof.

Adjunct therapy

[00319] In accordance with the embodiments described herein, an adjunct therapy may be administered to a subject with one or more additional active or inactive agents. Where adjunct therapy is considered, simultaneous, separate or sequential administration of the anti-endoglin antibodies and the anti-PD-1 and/or anti-PD-Ll antibodies (or antigen-binding fragments thereof) can be used in addition to any of the agents described below.

[00320] Adjunct therapy agents can be, as needed, administered in combination with one or more additional therapeutic treatments including, but not limited to, ipilumumab, adriamycin, bevacizumab, axitinib, cabozantinib, cyclophosphamide, paclitaxel, pemetrexed, temozolomide, oxaliplatin, cetuximab, panitumumab, sorafenib, sunitinib, gefitinib, erlotinib, 5-fluorouracil (5-FU) irinotecan, topotecan, leucovorin, VELCADE®, lenalidomide, thalidomide, capecitabine, docetaxel and many other conventional cancer therapies described herein. As used herein, "radiation" refers to, for example, microwaves, ultraviolet (UV), infrared (IR), or alpha-, beta- or gamma-radiation. Radiation can be "focused" or locally delivered using conventional techniques to target radiation to the site of one or more tumors without radiating the entire body. One would understand that the listing of therapeutic regimens listed below represents conventional therapies, but the present invention encompasses other known therapeutic regimens which are not specifically disclosed herein.

[00321] In one embodiment, the cancer is ovarian cancer and the one or more additional therapeutic treatments is surgery, chemotherapy (e.g., doxorubicin, doxil, gemcitabine, Rubitecan, and platinum-based chemotherapeutics such as cisplatin, carboplatin and oxaliplatin), melphalan, paclitaxel, topoisomerase I inhibitors such as topotecan and irinotecan, taxane-based therapy, hormones, radiation therapy, whole body hypothermia, isoflavone derivatives such as Phenoxodial, cytotoxic macrolides such as Epothilones, angiogenesis inhibitors such as bevacizumab, signal transduction inhibitors such as trastuzumab, gene therapy, RNAi therapy, immunotherapy, monoclonal antibodies such as ipilumumab, phosphatidylinositol-like kinase inhibitors such as rapamycin, or any combination thereof. The combination therapy of the antibodies described herein with the ovarian cancer therapies may also provide for lower doses of either therapy, or both, due to a synergistic effect from the co-administration of the therapies.

[00322] In one embodiment, the cancer is renal/kidney cancer and the one or more additional therapeutic treatments is surgery, chemotherapy, pazopanib, interferon-alpha or IL-2. In yet another embodiment, the additional agent is a VEGF receptor inhibitor. Non-limiting examples of VEGF receptor inhibitors include , aflibercept (VEGF-Trap), sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib, and pazopanib. The combination therapy of the antibodies described herein with the kidney cancer therapies may also provide for lower doses of either therapy, or both, due to a synergistic effect from the co-administration of the therapies.

[00323] In one embodiment, the cancer is myeloma and the one or more additional therapeutic treatments is surgery, radiotherapy, VELCADE®, lenalidomide, or thalidomide. In one embodiment the additional agent is VELCADE®. The dosages for any of these therapies are known in the art and can be adjusted with combination therapy accordingly.

[00324] In one embodiment, the cancer is prostate cancer and the one or more additional therapeutic treatments is surgery, radiotherapy (e.g., external beam or brachytherapy), hormonal deprivation (androgen suppression, including with abiraterone), heat shock protein 90 (HSP90) inhibitors, chemotherapy (e.g., docetaxel, platinum-based chemotherapy such as cisplatin, carboplatin, satraplatin and oxaliplatin, taxanes, etc.), prednisone or prednisolone, cholesterol- lowering drugs such as statins, leutinizing hormone-releasing hormone (LURH) agonists, RNAi therapy, dendritic cell-based therapies, whole tumor cells genetically modified to secrete granulocyte macrophage - colony stimulating factor (GM-CSF) (also known as GVAX), or any combination thereof. In yet another embodiment, the additional agent is a VEGF receptor inhibitor. Non-limiting examples of VEGF receptor inhibitors include ranibizumab, aflibercept (VEGF-Trap), sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib, and pazopanib.

[00325] In one embodiment, the cancer is lung cancer and the one or more additional therapeutic treatments is surgery, radiotherapy (e.g., thoracic radiotherapy, radiation therapy with charged particles, Uracil-tegafur and Platinum-based chemotherapy (e.g., cisplatin, carboplatin, oxaliplatin, etc.) and vinorebline, Erlotinib (TARCEVA®), Gefitinib (IRESSA®), anti-epidermal growth factor receptor antibodies (e.g., Cetuximab), small molecule inhibitors of tyrosine kinases, direct inhibitors of proteins involved in lung cancer cell proliferation, Aurora kinase inhibitors, laser-induced thermotherapy, RNAi therapy, whole tumor cells genetically modified to secrete granulocyte macrophage - colony stimulating factor (GM-CSF) (also known as GVAX), or any combination thereof. Additional therapeutic treatments include Taxol or pemetrexed. In yet another embodiment, the additional agent is a VEGF receptor inhibitor. Non-limiting examples of VEGF receptor inhibitors include aflibercept, sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib, pegaptanib and pazopanib. The dosages for any of these therapies are known in the art and can be adjusted with combination therapy accordingly.

[00326] In one embodiment, the cancer is breast cancer and the one or more additional therapeutic treatments is surgery, monoclonal antibodies (e.g., Her-2 antibodies, herceptin), adjuvant chemotherapy such as single agent chemotherapy or combination chemotherapy (e.g., anthracycline- and taxane-based polychemotherapies, TAXOL®, or target-specific trastuzumab with or without endocrine manipulation with or without PMRT, vinorelbine), adriamycin, cyclophosphamide, capecitabine, taxotere, selective estrogen receptor modulators such as

Tamoxifen and Raloxifene, allosteric estrogen receptor modulators such as Trilostane, radiation (e.g., interstitial brachytherapy, Mammosite device, 3 -dimensional conformal external radiation and intraoperative radiotherapy), Aromatase inhibitors that suppress total body synthesis (e.g., anastrozole, exemestane and letrozole), RNAi therapy, intravenous analogs of rapamycin that are immunosuppressive and anti-proliferative such as Temsirolimus (CCI779), or any combination thereof. A review of methods for conducting three-dimensional in vitro tissue culture models of breast cancer are described by Kim et al., Breast Cancer Research Treatment 85(3): 281-91 (2004). Other in vivo and in vitro models for testing cancers are known and can be used to test antibodies described herein. In yet another embodiment, the additional agent is a VEGF receptor inhibitor. Non-limiting examples of VEGF receptor inhibitors include aflibercept, Sunitinib (SUTENT®), Sorafenib (NEXAVAR®), Axitinib, and Pazopanib. The dosages for any of these therapies are known in the art and can be adjusted with combination therapy accordingly.

[00327] In one embodiment, the cancer is colon cancer and the one or more additional therapeutic treatments is surgery, radiation therapy, and chemotherapy (e.g., 5-fluorouracil (5-FU), levamisole, leucovorin or semustine (methyl CCNU)), N-[2-(dimethylamino)ethyl]acridine-4- carboxamide and other related carboxamide anticancer drugs; non-topoisomerase II inhibitors, irinotecan, liposomal topotecan, taxane class of anticancer agents (e.g., paclitaxel or docetaxel), a compound of the xanthenone acetic acid class (e.g., 5,6-dimethylanthenone-4-acetic acid PMAA), laminarin, site- selective cyclic AMP Analogs (e.g., 8-chloroadenosine 3',5'-cyclic phosphate), pyranoindole inhibitors of Cox -2, carbazole inhibitors of Cox-2, tetrahydrocarbazole inhibitors of Cox-2, indene inhibitors of Cox-2, localized inhibitors of NTHES (e.g., anthranilic acids, aspirin (5-acetylsalicylic acid), azodisal sodium, carboheterocyclic acids, carprofen, chlorambucil, diclophenac, fenbufen, fenclofenac, fenoprofen, flufenamic acid, flurbiprofen, fluprofen, furosemide, gold sodium thiomalate, ibuprofen, indomethacin, indoprofen, ketoprofen, lonazolac, loxoprofen, meclofenamic acid, mefanamic acid, melphalan, naproxen, penicillamine, phenylacetic acids, proprionic acids, salicylic acids, salazosulfapyridine, sulindac, tolmetin, a pyrazolone butazone propazone NTHE, meloxicam, oxicams, piroxicam, feldene, piroxicam beta cyclodextran, tenoxicam. etodolac, and oxaprozin), an inhibitor of HER-2/neu, RNAi therapy, GM-CSF, monoclonal antibodies (e.g., anti-Her-2/neu antibodies, anti-CEA antibodies, A33 (HB 8779), 100- 210 (HB 11764) and 100-310 (HB 11028)), erbitux, vectibix, hormonal therapy, pyrimidineamines, camptothecin derivatives (e.g., CPT- 11), folinic acid (FA), Gemcitabine, Ara-C, platinum-based chemotherapeutics such as cisplatin, carboplatin and oxaliplatin, a cGMP-specific

phosphodiesterase inhibitor, or any combination thereof. In one embodiment the additional therapeutic treatment is a combination of 5-FU, leucovorin and oxaliplatin (FOLFOX). In one embodiment, the additional therapeutic treatment is a combination of 5-FU, irinotecan and leucovorin (IFL). In one embodiment, the additional agent is eribtux. In one embodiment, the additional agent is vectibix. In yet another embodiment, the additional agent is a VEGF receptor inhibitor. Non-limiting examples of VEGF receptor inhibitors include aflibercept, sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib, and pazopanib. The dosages for any of these therapies are known in the art and can be adjusted with combination therapy accordingly.

[00328] In one embodiment, the cancer is pancreatic cancer and the one or more additional therapeutic treatment is a combination of therapeutic treatments is surgery, radiation therapy (RT), Fluorouracil (5-FU) and RT, systemic therapy, stenting, Gemcitabine (GEMZAR®), Gemcitabine and RT, Cetuximab, erlotinib (TARCEVA®), chemoradiation, or any combination thereof. In yet another embodiment, the additional agent is a VEGF receptor inhibitor. Non-limiting examples of VEGF receptor inhibitors include aflibercept, sunitinib (SUTENT®), sorafenib (NEXAVAR®), axitinib, and pazopanib.

[00329] Subjects can be assessed with respect to symptoms at one or more multiple time points including prior to, during, and after treatment regimens. Treatment can result in improving the subject's condition and can be assessed by determining if one or more of the following factors has occurred: decreased tumor size, decreased cell proliferation, decreased numbers of cells, decreased neovascularization, increased apoptosis, or decreased survival of at least a portion of the cells comprising the cell proliferative disorder. One or more of these occurrences may, in some cases, result in partial or total elimination of the cancer and prolongation of survival of the subject. Alternatively, for terminal stage cancers, treatment may result in stasis of disease, better quality of life and/or prolongation of survival.

IV. Functional Assays

[00330] Compositions described herein can be assessed in a variety of in vitro, in vivo and ex vivo assays. Any suitable assay known to one of skill in the art can be used to monitor such effects. Several such techniques are described herein.

Assaying for Signaling and Function

[00331] The chimeric antibodies can be assessed with respect to stimulating cancer immunity and endothelial cell proliferation. Binding of anti-endoglin antibodies to HUVECs does not prevent subsequent binding of TGF-β to HUVECs. Thus, direct suppression of the endothelial cell growth by endoglin antibodies represents one of the underlying mechanisms by which tumor-suppressive effects are observed in vivo. In another embodiment, the antibodies can be assessed with respect to blocking angiogenesis by preventing Smadl/5/8 phosphorylation and/or signaling. CD105 participates in the promotion of angiogenesis through signaling of the TGF-p/ALKl, which in turn involves the decrease and/or blockage of the phosphorylation of Smad2/3 proteins. In yet another embodiment, the antibodies can be assessed with respect to blocking angiogenesis by enhancing Smad2/3 phosphorylation and/or signaling.

[00332] Methods and techniques to assay the blocking or inhibitory effect of the antibodies provided herein on the TGF-p/ALKl signaling pathway and/or the phosphorylation of Smadl/5 include, but are not limited to, known molecular techniques. By way of example, western blotting with antibodies specific to any of the proteins in the TGF-p/ALK5 or TGF-p/ALKl pathways can be used to determine the inhibitory and/or stimulatory effect of the anti-endoglin antibodies disclosed herein on the TGF-p/ALK5 or TGF-p/ALKl pathways. Similarly, detection of mRNA or regulation of the mRNA for the proteins involved in the TGF-p/ALK5 or TGF-p/ALKl pathways can be used to assay the inhibitory and/or stimulatory effect of the antibodies disclosed herein. Additional methods for the assaying cell signaling for the TGF-p/ALK5 or TGF-p/ALKl pathways are known in the art and are contemplated herein.

[00333] Activity of the anti-endoglin antibodies disclosed herein can be assessed using art recognized assays by, for example, binding assays such ELIS As, competitive ELISAs, surface plasmon resonance, and effect on HUVEC cells as described in more detail below.

Syngeneic Mouse Models

[00334] Syngeneic mouse models {e.g., a BALB/c or C57BL/6 mouse models) can also be utilized to assess tumor growth and inhibition thereof by the antibodies or described herein as exemplified by, for example, Tsujie et al, Int. J. Oncology, 29: 1087-1094 (2006).

Chimeric Mice

[00335] Another assay measures angiogenesis in a chimeric mouse:human mouse model and is referred to as the chimeric mouse assay. The assay has been described in detail by others, and further has been described herein to measure angiogenesis, neovascularization, and regression of tumor tissues. See, Yan, et al. (1993) J. Clin. Invest., 91 :986-996.

[00336] The chimeric mouse assay is a useful assay model for in vivo angiogenesis because the transplanted skin grafts closely resemble normal human skin histologically and

neovascularization of whole tissue is occurring wherein actual human blood vessels are growing from the grafted human skin into the human tumor tissue on the surface of the grafted human skin. The origin of the neovascularization into the human graft can be demonstrated by

immunohistochemical staining of the neovasculature with human-specific endothelial cell markers.

[00337] The chimeric mouse assay demonstrates regression of neovascularization based on both the amount and extent of regression of new vessel growth. Furthermore, it is easy to monitor effects on the growth of any tissue transplanted upon the grafted skin, such as a tumor tissue.

Finally, the assay is useful because there is an internal control for toxicity in the assay system. The chimeric mouse is exposed to any test reagent, and therefore the health of the mouse is an indication of toxicity. Other animal models described herein and known in the art can also be utilized in the methods described herein.

Additional Assays

[00338] Other assays known in the art can also be used to test the effect of the compositions described herein such as, for example, those described in the examples below.

Packages and Kits

[00339] In still further embodiments, the present application concerns kits for use with the compounds described above. Antibodies that preferentially bind to endoglin and antibodies that preferentially bind to PD-1 and/or PD-Ll can be provided in a kit. The kits can include one or more suitable containers for housing the agents, in liquid and/or solid form.

[00340] The containers of the kits will generally include at least one vial, test tube, flask, ampoule, bottle, syringe and/or other container, into which the at least one reagent can be placed, and/or preferably, suitably aliquoted. The kits can include a means for containing at least one fusion protein, detectable moiety, reporter molecule, and/or any other reagent containers in close confinement for commercial sale. Such containers may include injection and/or blow-molded plastic containers into which the desired vials are retained. Kits can also include printed material for use of the materials in the kit.

[00341] Packages and kits can additionally include one or more buffering agents, one or more preservatives, one or more stabilizing agents, or a combination thereof in each formulation. Each component of the kit can be enclosed within an individual container and all of the various containers can be within a single package. Kits can be designed for cold storage or room

temperature storage.

[00342] Additionally, the preparations can contain stabilizers to increase the shelf-life of the kits and include, for example, bovine serum albumin (BSA). Where the compositions are lyophilized, the kit can contain further preparations of solutions to reconstitute the lyophilized preparations. Acceptable reconstitution solutions are well known in the art and include, for example, pharmaceutically acceptable phosphate buffered saline (PBS). [00343] Additionally, the packages or kits provided herein can further include any of the other moieties provided herein such as, for example, one or more reporter molecules and/or one or more detectable moieties/agents.

[00344] Packages and kits can further include one or more components for an assay, such as, for example, an ELISA assay. Samples to be tested in this application include, for example, blood, plasma, tissue/tumor sections and secretions, urine, lymph, and products thereof. Packages and kits can further include one or more components for collection of a sample (e.g., a syringe, a cup, a swab, etc.).

[00345] Packages and kits can further include one or more means to administer the agent, for example, one or more syringes. Syringes, in some instances, can be pre-filled with an agent or separately from one or more agents included in the package or kit.

[00346] Packages and kits can further include a label specifying, for example, a product description, mode of administration and/or indication of treatment. Packages provided herein can include any of the compositions as described herein. The package can further include a label for treating various forms of cancer and their metastases.

[00347] The term "packaging material" refers to a physical structure housing the components of the kit. The packaging material can maintain the components sterilely and can be made of material commonly used for such purposes (e.g., paper, corrugated fiber, glass, plastic, foil, ampules, etc.). The label or packaging insert can include appropriate written instructions. Kits, therefore, can additionally include labels or instructions for using the kit components in any method described herein. A kit can include a compound in a pack, or dispenser together with instructions for administering the compound in a method described herein.

[00348] In still further embodiments, a kit comprises reagents for the detection of PD-1, PD-

Ll, and/or CD105expression levels in a sample of tumor cells from a subject to be treated; and a dose or doses an inhibitor, including but not limited to antibodies described herein, in a variety of dosage forms, such as capsules, caplets, gel caps, powders for suspension, etc. It is further contemplated that kits contain reagents for the detection of PD-1, PD-L1, and/or CD105expression levels in a sample of tumor cells from a subject to be treated will further comprise any of the aforementioned embodiments of the kits for co-administration of at least one additional anti-cancer agent.

[00349] Instructions can include instructions for practicing any of the methods described herein including treatment methods. Instructions can additionally include indications of a satisfactory clinical endpoint or any adverse symptoms that may occur, or additional information required by regulatory agencies such as the Food and Drug Administration for use on a human subject.

[00350] The instructions may be on "printed matter," e.g., on paper or cardboard within or affixed to the kit, or on a label affixed to the kit or packaging material, or attached to a vial or tube containing a component of the kit. Instructions may additionally be included on a computer readable medium, such as a disk (floppy diskette or hard disk), optical CD such as CD- or DVD- ROM/RAM, magnetic tape, electrical storage media such as RAM and ROM, IC tip and hybrids of these such as magnetic/optical storage media.

[00351] The embodiments of the compounds and methods of the present application are intended to be illustrative and not limiting. Modifications and variations can be made by persons skilled in the art in light of the above teachings specifically those that may pertain to alterations in the antibodies which bind endoglin surrounding the described modifications while maintaining near native functionally with respect to binding of endoglin. Therefore, it should be understood that changes may be made in the particular embodiments disclosed which are within the scope of what is described.

EXAMPLES

[00352] The application may be better understood by reference to the following non-limiting examples, which are provided as exemplary embodiments of the application. The following examples are presented in order to more fully illustrate exemplary embodiments and should in no way be construed, however, as limiting the broad scope of the application. While certain embodiments of the present application have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur; it should be understood that various alternatives to the embodiments described herein may be employed in practicing the methods described herein.

EXAMPLE 1

Inhibition of Colorectal Tumor Growth by Combinations of Chimeric Anti-Endoglin

Antibodies and Antibody to PD-1

[00353] An exemplary chimeric anti-endoglin antibody (TRC105) was studied in a syngeneic tumor model. MC38 colorectal cancer cells were implanted orthotopically in the large intestine of C57BL/6 mice prior to treatment with isotype control antibody, PD-1 antibody, anti- endoglin antibody Ml 043, anti-endoglin antibody TRC105 or the combination of anti-endoglin antibody and an anti-PD-1 antibody.

[00354] Mice were treated twice a week with either an endoglin neutralizing antibody

(M1043, lOmg/kg bodyweight or TRC105, 15mg/kg bodyweight both supplied by TRACON Pharmaceuticals, San Diego, CA, USA) or an isotype control (INVIVOMAB®, BioXcell, West Lebanon, NH, USA). For combination treatment, mice were additionally treated twice a week with either an anti-PD-1 blocking antibody (J43 lOmg/kg bodyweight; INVIVOMAB®, BioXcell, West Lebanon, NH, USA) or an isotype control antibody.

[00355] MC38 CRC tumors were grown in a subcutaneous donor C57BL/6 mouse following the injection of 5xl0⁵ tumor cells subcutaneously in both lateral sides. When tumors reached 0.5cm³, mice were sacrificed and tumors were divided into pieces of ~lmm³. These pieces were transplanted to the cecum of recipient C57BL/6 mice. Mice were weekly imaged after

intraperitoneal injection with luciferin (D-Luciferin, Synchem, Altenburg, Germany) using the IVIS Lumina (Perkin Elmer, Waltham, MA, USA). Eight days post transplantation mice were

randomized based on bioluminescent signal and treatment was started as described above. At day 36, mice were sacrificed and tumor volume was determined. Statistical analysis was performed using one-way ANOVA® and Mann-Whitney test.

[00356] The combination of TRC105 and anti-PD-1 antibody treatment inhibited tumor growth that was statistically superior to isotype control antibody treatment, to TRC105 single agent treatment, and to single agent anti-PD-1 antibody treatment.

[00357] TRC105 demonstrated superior ability to mediate ADCC of endoglin-expressing cells compared to Ml 043, which may explain its superior anti -tumor effect compared to antibody Ml 043 when combined with the anti-PD-1 antibody as shown in FIG. 1.

[00358] The experiment indicates that anti-endoglin antibody TRC105 complements the anti-

PD-1 antibody to improve anti -tumor efficacy over that seen with single agent anti-PD-1 antibody (p < 0.05).

EXAMPLE 2

Clinical Trial of Combination Therapy for Renal Cell Carcinoma with TRC105 and

Nivolumab (OPDIVO®)

[00359] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Nivolumab (OPDIVO®) in patients with renal cell carcinoma. Treatment can be indicated for patients with advanced renal cell carcinoma (RCC) who have received prior anti-cancer therapy.

[00360] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to a treatment group and about 50 - about 400 patients assigned to a placebo group.

[00361] Group I subjects are administered Nivolumab 240 mg IV q2wk infused over 1 hr.

[00362] Group II subjects are administered chimeric anti-endoglin antibody TRC105 (from about 0.1 to about 30 mg/kg IV every one to three weeks).

[00363] Group III subjects are administered chimeric anti-endoglin antibody TRC105 (from about 0.1 to about 30 mg/kg IV every one to three weeks) and administered Nivolumab 240 mg intravenously (IV) once every 2 weeks (q2wk) infused over 1 hour (hr).

[00364] Control subjects are administered a placebo intravenously.

[00365] Treatment continues until disease progression or unacceptable toxicity.

[00366] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00367] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in overall survival from about 23-27 months in the Nivolumab

(OPDIVO®) arm to about 28-32 months (or more) in the Nivolumab (OPDIVO®) plus chimeric anti-endoglin antibody arm.

[00368] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, progression free survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance. EXAMPLE 3

Clinical Trial of Combination Therapy for Non-Small Cell Lung Cancer or Metastatic Non- Small Cell Lung Cancer with TRC105 and Nivolumab (OPDIVO®)

[00369] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Nivolumab (OPDIVO®) in patients with non-small cell lung cancer or metastatic non-small cell lung cancer. Treatment can be indicated for metastatic non- small cell lung cancer (NSCLC) with progression on or after platinum-based chemotherapy.

[00370] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to a treatment group and about 50 - about 400 patients assigned to a placebo group.

[00371] Group I subjects are administered Nivolumab 240 mg IV q2wk infused over 1 hr.

[00372] Group II subjects are administered chimeric anti-endoglin antibody TRC105 (from about 0.1 to about 30 mg/kg IV every one to three weeks).

[00373] Group III subjects are administered chimeric anti-endoglin antibody TRC105 (from about 0.1 to about 30 mg/kg IV every one to three weeks) and administered Nivolumab 240 mg intravenously (IV) once every 2 weeks (q2wk) infused over 1 hour.

[00374] Control subjects are administered a placebo intravenously.

[00375] Treatment continues until disease progression or unacceptable toxicity.

[00376] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00377] Primary outcome measure: overall survival. One goal of the study is to demonstrate an increase in progression free survival from about 10-14 months in the Nivolumab (OPDIVO®) arm to about 15-19 months (or more) in the Nivolumab (OPDIVO®) plus chimeric anti-endoglin antibody arm.

[00378] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, progression free survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance. EXAMPLE 4

Clinical Trial of Combination Therapy for Melanoma (Skin Cancer) or Metastatic Melanoma with TRC105 and Nivolumab (OPDIVO®)

[00379] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC 105 with Nivolumab (OPDIVO®) in patients with melanoma or metastatic melanoma.

[00380] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to each treatment group and about 50 - about 400 patients assigned to a placebo group.

[00381] Group I subjects are administered Nivolumab at 240 mg intravenously (IV) once every 2 weeks (q2wk) infused over 1 hour; subsequent doses of nivolumab as a single agent are 240 mg IV q2wk infused over 1 hour.

[00382] Group II subjects are administered Nivolumab at 1 mg/kg IV infused over 1 hr on the same day every three weeks (q3wk) for 4 doses; subsequent doses of nivolumab as a single agent are 240 mg IV q2wk infused over 1 hour.

[00383] Group III subj ects are administered chimeric anti-endoglin antibody TRC 105 (from about 0.1 to about 30 mg/kg IV every one to three weeks).

[00384] Group IV subjects are administered chimeric anti-endoglin antibody TRC 105 (from about 0.1 to about 30 mg/kg IV every one to three weeks) and administered Nivolumab 240 mg intravenously (IV) once every 2 weeks (q2wk) infused over 1 hour; subsequent doses of nivolumab as a single agent are 240 mg IV q2wk infused over 1 hour.

[00385] Group V subjects are administered chimeric anti-endoglin antibody TRC 105 (from about 0.1 to about 30 mg/kg IV every one to three weeks) and administered Nivolumab at 1 mg/kg

IV infused over 1 hr on the same day every three weeks (q3wk) for 4 doses; subsequent doses of nivolumab as a single agent are 240 mg IV q2wk infused over 1 hour.

[00386] Treatment continues until disease progression or unacceptable toxicity.

[00387] Control subjects are administered a placebo infusion.

[00388] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00389] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in progression free survival from about 5-9 months in the Nivolumab (OPDIVO®) arm to about 10-14 months (or more) in the Nivolumab (OPDIVO®) plus chimeric anti-endoglin antibody arm.

[00390] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, overall survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance.

EXAMPLE 5

Clinical Trial of Combination Therapy for Head and Neck Cancer with TRC105 and

Nivolumab (OPDIVO®)

[00391] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Nivolumab (OPDIVO®) in patients with head and neck cancer. Treatment may be indicated for locally advanced or metastatic head and neck carcinoma in patients who have disease progression during or following platinum-containing chemotherapy, or who have disease progression within 12 months of neoadjuvant or adjuvant treatment with platinum- containing chemotherapy.

[00392] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to a treatment group and about 50 - about 400 patients assigned to a placebo group.

[00393] Group I subjects are administered Nivolumab 240 mg IV q2wk infused over 1 hr.

[00394] Group II subjects are administered chimeric anti-endoglin antibody TRC105 (from about 0.1 to about 30 mg/kg IV every one to three weeks).

[00395] Group III subjects are administered chimeric anti-endoglin antibody TRC105 (from about 0.1 to about 30 mg/kg IV every one to three weeks) and administered Nivolumab 240 mg intravenously (IV) once every 2 weeks (q2wk) infused over 1 hour (hr).

[00396] Control subjects are administered a placebo.

[00397] Treatment continues until disease progression or unacceptable toxicity.

[00398] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00399] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in overall survival from about 6-10 months in the Nivolumab (OPDIVO®) arm to about 11-15 months (or more) in the Nivolumab (OPDIVO®) plus chimeric anti-endoglin antibody arm.

[00400] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, progression free survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance.

EXAMPLE 6

Clinical Trial of Combination Therapy for Non-Small Cell Lung Cancer or Metastatic Non- Small Cell Lung Cancer with TRC105 and Pembrolizumab (KEYTRUDA®)

[00401] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Pembrolizumab (KEYTRUDA®) in patients with non-small cell lung cancer or metastatic non-small cell lung cancer, with or without the concurrent use of chemotherapy. Treatment may be indicated for the first-line treatment of patients with metastatic non-small cell lung cancer (NSCLC) whose tumors have high PD-Ll expression. Treatment may also be indicated for the treatment of patients with metastatic NSCLC whose tumors express PD-Ll (TPS >1%) as determined by an FDA-approved test, with disease progression on or after platinum- containing chemotherapy; patients with EGFR or ALK genomic tumor aberrations should have disease progression on FDA-approved therapy for these aberrations prior to receiving treatment.

[00402] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to a treatment group and about 50 - about 400 patients assigned to a placebo group.

[00403] Group I subjects are administered Pembrolizumab at 200 mg IV infusion over 30 minutes q3wk.

[00404] Group II subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks.

[00405] Group III subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks and Pembrolizumab at 200 mg IV infusion over 30 minutes over 30 minutes q3wk.

[00406] Control subjects are administered a placebo infusion.

[00407] Treatment continues until disease progression or unacceptable toxicity. [00408] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00409] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in overall survival from about 12-16 months in the Pembrolizumab (KEYTRUDA®) arm to about 17-21 months (or more) in the Pembrolizumab (KEYTRUDA®) plus chimeric anti-endoglin antibody arm.

[00410] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, progression free survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance.

EXAMPLE 7

Clinical Trial of Combination Therapy for Unresectable Melanoma or Metastatic Melanoma with TRC105 and Pembrolizumab (KEYTRUDA®)

[00411] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Pembrolizumab (KEYTRUDA®) in patients with unresectable or metastatic melanoma.

[00412] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to each treatment group and about 50 - about 400 patients assigned to a placebo group.

[00413] Group I subjects are administered Pembrolizumab at 2 mg/kg IV infusion over 30 minutes q3wk.

[00414] Group II subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks.

[00415] Group III subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks and Pembrolizumab at 2 mg/kg IV infusion over 30 minutes q3wk.

[00416] Control subjects are administered a placebo infusion.

[00417] Treatment continues until disease progression or unacceptable toxicity. [00418] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00419] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in progression free survival from about 4-8 months in the Penibrolizumab (KEYTRUDA®) arm to about 9-13 months (or more) in the Penibrolizumab ( EYTRUDA®) plus chimeric anti-endoglin antibody arm.

[00420] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, overall survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance.

EXAMPLE 8

Clinical Trial of Combination Therapy for Head & Neck Squamous Cell Carcinoma with

TRC105 and Pembrolizumab (KEYTRUDA®)

[00421] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Pembrolizumab (KEYTRUDA®) in patients with head and neck squamous cell carcinoma. Treatment may be indicated for the treatment of patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) with disease progression on or after platinum-containing chemotherapy.

[00422] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to a treatment group and about 50 - about 400 patients assigned to a placebo group.

[00423]

[00424] Group I subjects are administered Pembrolizumab at 200 mg IV infusion over 30 minutes q3wk.

[00425] Group II subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks.

[00426] Group III subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks and Pembrolizumab at 200 mg IV infusion over 30 minutes over 30 minutes q3wk.

[00427] Control subjects are administered a placebo infusion. [00428] Treatment continues until disease progression or unacceptable toxicity, or up to 24 months in patients without disease progression.

[00429] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00430] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in overall survival from about 6-10 months in the Pembrolizumab

(KEYTRUDA®) arm to about 11-15 months (or more) in the Pembrolizumab (KEYTRUDA®) plus chimeric anti-endoglin antibody arm.

[00431] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, progression free survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance.

EXAMPLE 9

Clinical Trial of Combination Therapy for Merkel Cell Carcinoma with TRC105 and

Avelumab (BAVENCIO®)

[00432] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Avelumab (BAVENCIO®) in patients with Merkel Cell

Carcinoma.

[00433] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to a treatment group and about 50 - about 400 patients assigned to a placebo group.

[00434] The trial will consist of the administration of intravenous repeating doses of chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg or placebo every one to three weeks alone, intravenous repeating doses of Avelumab (BAVENCIO®) in adults and pediatric patients aged >12 yr at about 10 mg/kg IV once every 2 weeks (q2wk), or a combination of TRC105 and Avelumab (BAVENCIO®) at the amounts described herein until progression or unacceptable toxicity. Control subjects will receive a placebo intravenously.

[00435] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows: [00436] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in progression free survival from about 9-13 months in the Avelumab (BAVENCIO®) arm to about 14-18 months (or more) in the Avelumab (BAVENCIO®) plus chimeric anti-endoglin antibody arm.

[00437] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, overall survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance.

EXAMPLE 10

Clinical Trial of Combination Therapy for Non-Small Cell Lung Cancer with TRC105 and

Atezolizumab (TECENTRIQ®)

[00438] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Atezolizumab (TECENTRIQ®) in patients with non-small cell lung cancer or metastatic non-small cell lung cancer. Treatment may be indicated for patients with metastatic non-small cell lung cancer (NSCLC) who have disease progression during or following platinum-containing chemotherapy; patients with EGFR or ALK genomic tumor aberrations should have disease progression on FDA-approved therapy for these aberrations prior to receiving

Atezolizumab (TECENTRIQ®).

[00439] Approximately about 100 - about 800 patients are enrolled, with about 50 - about 400 patients being assigned to a treatment group and about 50 - about 400 patients assigned to a placebo group.

[00440] Group I subjects are administered Atezolizumab (TECENTRIQ®) at 1200 mg IV q3wk infused over 60 min q3wk. If the first infusion is tolerated, all subsequent infusions may be administered IV over 30 minutes q3wk.

[00441] Group II subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks.

[00442] Group III subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks and Atezolizumab (TECENTRIQ®) at 1200 mg IV q3wk infused over 60 min q3wk. If the first infusion is tolerated, all subsequent infusions may be administered IV over 30 minutes q3wk.

[00443] Control subjects are administered a placebo infusion. [00444] Treatment continues until disease progression or unacceptable toxicity.

[00445] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00446] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in overall survival from about 12-16 months in the Atezolizumab

(TECENTRIQ®) arm to about 17-21 months (or more) in the Atezolizumab (TECENTRIQ®) plus chimeric anti-endoglin antibody arm.

[00447] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, progression free survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance.

EXAMPLE 11

Clinical Trial of Combination Therapy for Locally Advanced or Metastatic Urothelial Cancer with TRC105 and Atezolizumab (TECENTRIQ®)

[00448] This example describes a randomized, blinded, placebo-controlled, multicenter, study designed to provide an assessment of the safety and efficacy of combining a chimeric anti- endoglin antibody TRC105 with Atezolizumab (TECENTRIQ®) in patients with urothelial cancer. Treatment is indicated for locally advanced or metastatic urothelial carcinoma in patients who have disease progression during or following platinum-containing chemotherapy, or disease progression within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.

[00449] Approximately about 100 to about 800 patients are enrolled, with about 50 - about 400 patients being assigned to a treatment group and about 50 - about 400 patients assigned to a placebo group.

[00450] Group I subjects are administered Atezolizumab (TECENTRIQ®) at 1200 mg IV q3wk infused over 60 min q3wk. If the first infusion is tolerated, all subsequent infusions may be administered IV over 30 minutes q3wk.

[00451] Group II subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks.

[00452] Group III subjects are administered chimeric anti-endoglin antibody TRC105 at from about 0.1 to about 30 mg/kg IV every one to three weeks and Atezolizumab (TECENTRIQ®) at 1200 mg IV q3wk infused over 60 min q3wk. If the first infusion is tolerated, all subsequent infusions may be administered IV over 30 minutes q3wk.

[00453] Control subjects are administered a placebo infusion.

[00454] Treatment continues until disease progression or unacceptable toxicity.

[00455] The time frame of the study is estimated at about 6 months - about 5 years, with continued therapy for responders as indicated at the end of the initial study. Additional outcome measures are as follows:

[00456] Primary outcome measure: progression-free survival. One goal of the study is to demonstrate an increase in overall survival from about 9-13 months in the Atezolizumab

(TECENTRIQ®) arm to about 14-18 months (or more) in the Atezolizumab (TECENTRIQ®) plus chimeric anti-endoglin antibody arm.

[00457] Secondary outcome measures that can be assessed include duration of response, time to tumor progression, progression free survival, serious and non-serious adverse events. For example, a treatment may prevent progression of the tumor (i.e., stasis) or may result in an improvement where the tumor size decreases. Alternately, or in addition, other goals can be measured with respect to one or more of the following: decreased tumor burden, reduced side effects, decreased adverse reactions, and/or increased patient compliance.

EXAMPLE 12

Inhibition of Colorectal Tumor Initiation by Combinations of Chimeric Anti-Endoglin

Antibodies and Antibody to PD-1

[00458] Exemplary chimeric anti-endoglin antibodies (TRC105 and Ml 043) were studied in a chemically induced colorectal cancer model, to assess effects on early stage cancer development and growth.

[00459] C57BL/6 mice (5-6 mice per group) were injected with the alkylating agent azoxymethane (AOM), followed by 3 cycles of intestinal inflammation induced by dextran sodium sulphate in the drinking water (1 week "on" DSS, 2 week "recovery" period). At day 48 (between DSS cycle 2 and 3) treatment with isotype control antibody, PD-1 antibody (PD), anti-endoglin antibody M1043, anti-endoglin antibody TRC105 or the combination of anti-endoglin antibody and an anti-PD-1 antibody was initiated.

[00460] Mice were treated twice a week with either an endoglin neutralizing antibody (M1043, lOmg/kg bodyweight or TRC105, 15mg/kg bodyweight both generously supplied by TRACON Pharmaceuticals, San Diego, CA, USA) or an isotype control (INVIVOMAB®, BIOXCELL®, West Lebanon, ML USA). For combination treatment, mice were additionally treated twice a week with either an anti-PD-1 blocking antibody (J43 lOmg/kg bodyweight;

INVIVOMAB®, BIOXCELL®, West Lebanon, H, USA) or an isotype control antibody.

[00461] At day 84, mice were sacrificed and the number of colonic lesions was analyzed. Routine hematoxylin and eosin (H&E) histology was performed to assess histological features.

[00462] The combination of Ml 043 and anti-PD-1 antibody treatment inhibited tumor formation that was statistically superior (p < 0.05) to isotype control antibody treatment and M1043 monotherapy, and the combination of Ml 043 and anti-PDl antibody treatment exhibited a strong trend towards statistically significant superiority compared to anti-PDl treatment alone (p=0.058 by ANOVA and Mann-Whitney test; FIG. 2A).

[00463] The combination of TRC105 and anti-PD-1 antibody treatment exhibited a strong trend towards statistically significant superiority compared to anti-PDl treatment or TRC105 treatment alone (p = 0.095 by ANOVA and Mann-Whitney test; FIG. 2B).

[00464] TRC105 demonstrated superior ability to mediate ADCC of endoglin-expressing cells compared to Ml 043, which may contribute to its superior anti -tumor effect compared to antibody M1043 when combined with the anti-PD-1 antibody as shown in FIG. 2A and FIG. 2B. FIG. 2A illustrates the differences in the number of lesions upon M1043 and M1043/PD1 treatment, FIG. 2B illustrates the number of lesions including the TRC105 and TRC105/PD1 groups.

[00465] The experiment demonstrates that anti-endoglin antibody TRC105 or Ml 043 complements the anti-PD-1 antibody to improve anti-tumor efficacy in a model of early cancer growth and development.

EXAMPLE 13

Inhibition of Colorectal Tumor growth by Combinations of Chimeric Anti-Endoglin

Antibodies and Antibody to PD-1

[00466] An exemplary chimeric anti-endoglin antibody (TRC105) was studied in a syngeneic tumor model. 5xl0⁵ MC38 colorectal cancer cells were injected subcutaneously in the flank of C57BL/6 mice prior to treatment with isotype control antibody, PD-1 antibody, anti- endoglin antibody M1043, anti-endoglin antibody TRC105 or the combination of anti-endoglin antibody and an anti-PD-1 antibody. Once palpable tumors were present, treatment was initiated.

[00467] Mice were treated twice a week with either an endoglin neutralizing antibody (M1043, lOmg/kg bodyweight or TRC105, 15mg/kg bodyweight both generously supplied by TRACON Pharmaceuticals, San Diego, CA, USA) or an isotype control (INVIVOMAB®, BIOXCELL®, West Lebanon, ML USA). For combination treatment, mice were additionally treated twice a week with either an anti-PD-1 blocking antibody (J43 lOmg/kg bodyweight;

INVIVOMAB®, BIOXCELL®, West Lebanon, NH, USA) or an isotype control antibody.

[00468] MC38 CRC tumors were measured twice weekly by caliper. Mice were sacrificed when tumors reached 1500 mm³. Treatment was continued until day-60. Remaining tumor- free mice at day-80 (20 days after last TRC105/PD1 treatment) were considered cured.

[00469] The combination of TRC105 and anti-PD-1 antibody treatment increased survival of mice that was statistically superior to isotype control antibody treatment, to TRC105 single agent treatment, and to single agent anti-PD-1 antibody treatment. The combination of Ml 043 and PDl significantly improved survival compared to M1043 monotherapy. In the combination groups 30- 60% tumor free mice were observed.

[00470] TRC105 demonstrated superior ability to mediate ADCC of endoglin-expressing cells compared to M1043, which may explain its superior anti-tumor effect compared to antibody Ml 043 when combined with the anti-PD-1 antibody as shown in FIG. 3.

Log-rank (Mantel-Cox) test

Control vs. PD-1 0,0036 **

Control vs.TRC105 0,0065 **

Control vs. Ml 043 0,3741 ns

M1043 VS.M1043/PD1 0,0008 ***

PD-1 V5.M1043/PD1 0,0974 ns

TRC105 V5.TRC105/PD1 0,0022 **

PD-1 VS.TRC105/PD1 0,0234 *

[00471] The experiment indicates that anti-endoglin antibody TRC105 complements the anti-

PD-1 antibody to improve anti -tumor efficacy over that seen with single agent anti-PD-1 antibody (p < 0.05, Log-rank (Mantel-Cox test).

SEQUENCES

[00472] SEQ ID NO. 1 (TRC105 V_L: CDRs are underlined)

[00473] QIVLSQSPAILSASPGEKVTMTCRASSSVSYMHWYQQKPGSSPKPWIYATSN LASGVPVRFSGSGSGTSYSLTISRVEAEDAATYYCQQWSSNPLTFGAGTKLELK

[00474] SEQ ID NO: 2 (TRC105 C_L)

[00475] T V A AP S VFIFPP SDEQLK S GT AS V VCLLNNF YPRE AK VQ WK VDN ALQ S GNS

QES VTEQD SKD ST YSLS STLTLSKAD YEKHKVYACEVTHQGLS SP VTKSFNRGEC

[00476] SEQ ID NO: 3 (TRC105 V_H: CDRs are underlined)

[00477] EVKLEESGGGLVQPGGSMKLSCAASGFTFSDAWMDWVRQSPEKGLEWVA EIRSKASNHATYYAESVKGRFTISRDDSKSSVYLOMNSLRAEDTGIYYCTRWRRFFDSWG QGTTLTVSS

[00478] SEQ ID NO: 4 (TRC105 Cyl)

[00479] AS TKGP S VFPL AP S SK S T S GGT A ALGCL VKD YFPEP VT VS WN SGALT S GVHT

FPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPA

PELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKP

REEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTL

PPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTV

DKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK

[00480] SEQ ID NO: 5 (Variable heavy chain of humanized F(ab): F(ab)-12) EVOLVESGGGLVQPGGSLRLSCAASGYTFTNYGMNWVRQAPGKGLEWVGWINTYTGEPT

YAADFKRRFTFSLDTSKSTAYLQMNSLRAEDTAVYYCAKYPHYYGSSHWYFDVWGQGT

LVTVSS

[00481] SEQ ID NO: 6 (Variable heavy chain of humlll: human consensus framework for heavy subgroup III)

[00482] EVQLVESGGGLVQPGGSLRLSCAASGFTFSSYAMSWVRQAPGKGLEWVSVI SGDGGSTYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARGFDYWGQGTLVT

vss

[00483] SEQ ID NO: 7 (Variable light chain of humanized F(ab): F(ab)-12)

[00484] DIOMTOSPSSLSASVGDRVTITCSASQDISNYLNWYQQKPGKAPKVLIYFTSS

LHSGVPSRFSGSGSGTDFTLTISSLOPEDFATYYCQQYSTVPWTFGQGTKVEIKR

[00485] SEQ ID NO: 8 (Variable light chain of humKl: human consensus framework for kappa subgroup I)

[00486] DIQMTQSPSSLSASVGDRVTITCRASQSISNYLAWYQQKPGKAPKLLIYAASS

LESGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQYNSLPWTFGQGTKVEIKR

[00487] SEQ ID NO: 9 (6x His tag): His His His His His His

[00488] SEQ ID NO: 10 (human PD-1; GenBank deposit GI: 167857792)

[00489] MQIPQAPWPVVWAVLQLGWRPGWFLDSPDRPWNPPTFSPALLVVTEGDNA

TFTCSFSNTSESFVLNWYRMSPSNQTDKLAAFPEDRSQPGQDCRFRVTQLPNGRDFHMSV

VRARRNDSGTYLCGAISLAPKAQIKESLRAELRVTERRAEVPTAHPSPSPRPAGQFQTLVV

GVVGGLLGSL VLL VW VL AVIC SRAARGTIGARRTGQPLKEDP S AVP VF S VD YGELDFQWR

EKTPEPPVPCVPEQTEYATIVFPSGMGTSSPARRGSADGPRSAQPLRPEDGHCSWPL

[00490] SEQ ID NO: 11 (human PD-L1 precursor; UniProtKB/Swiss-Prot: Q9NZQ7.1)

[00491] MRIFAVFIFMTYWHLLNAFTVTVPKDLYVVEYGSNMTIECKFPVEKQLDLA

ALIVYWEMEDKNIIQFVHGEEDLKVQHSSYRQRARLLKDQLSLGNAALQITDVKLQDAGV

YRCMISYGGADYKRITVKVNAPYNKINQRILVVDPVTSEHELTCQAEGYPKAEVIWTSSDH

Q VL S GKTTTTNSKREEKLFN VT S TLRINTTTNEIF YC TFRRLDPEENHT AEL VIPELPL AHPP

NERTHLVILGAILLCLGVALTFIFRLRKGRMMDVKKCGIQDTNSKKQSDTHLEET

[00492] VL CDR1 : RASSSVSYMH (SEQ ID NO: 12; Synthetic peptide)

[00493] VL CDR2: ATSNLAS (SEQ ID NO: 13; Synthetic peptide)

[00494] VL CDR3 : QQWSSNPLT (SEQ ID NO: 14; Synthetic peptide)

[00495] VH CDR1 : DAWMD (SEQ ID NO: 15; Synthetic peptide)

[00496] VH CDR2: EIRSKASNHATYYAESVKG (SEQ ID NO: 16; Synthetic peptide)

[00497] VH CDR3 : WRRFFDS (SEQ ID NO: 17; Synthetic peptide) [00498] SEQ ID NO: 18 Synthetic VH1 A polypeptide

[00499] Glu Val Gin Leu Val Glu Ser Gly Gly Gly Leu Val Lys Pro Gly Gly Ser Leu Arg

Leu Ser Cys Ala Ala Ser Gly Phe Thr Phe Ser Asp Ala Trp Met Asp Trp Val Arg Gin Ala Pro Gly Lys Gly Leu Glu Trp Val Ala Glu lie Arg Ser Lys Ala Ser Asn His Ala Thr Tyr Tyr Ala Glu Ser Val Lys Gly Arg Phe Thr He Ser Arg Asp Asp Ser Lys Asn Thr Leu Tyr Leu Gin Met Asn Ser Leu Lys Thr Glu Asp Thr Ala Val Tyr Tyr Cys Thr Arg Trp Arg Arg Phe Phe Asp Ser Trp Gly Gin Gly Thr Leu Val Thr Val Ser Ser

[00500] SEQ ID NO: 19 Synthetic VH1A2 polypeptide

[00501] Glu Val Gin Leu Val Glu Ser Gly Gly Gly Leu Val Lys Pro Gly Gly Ser Leu Arg

Leu Ser Cys Ala Ala Ser Gly Phe Thr Phe Ser Asp Ala Trp Met Asp Trp Val Arg Gin Ala Pro Gly Lys Gly Leu Glu Trp Val Gly Glu Ala Arg Ser Lys Ala Ser Asn His Ala Thr Tyr Tyr Ala Glu Ser Val Lys Gly Arg Phe Thr He Ser Arg Asp Asp Ser Lys Asn Thr Leu Tyr Leu Gin Met Asn Ser Leu Lys Thr Glu Asp Thr Ala Val Tyr Tyr Cys Thr Arg Trp Arg Arg Phe Phe Asp Ser Trp Gly Gin Gly Thr Leu Val Thr Val Ser Ser

[00502] SEQ ID NO: 20 Synthetic VH1Q polypeptide

[00503] Glu Val Gin Leu Val Glu Ser Gly Gly Gly Leu Val Lys Pro Gly Gly Ser Leu Arg

Leu Ser Cys Ala Ala Ser Gly Phe Thr Phe Ser Asp Ala Trp Met Asp Trp Val Arg Gin Ala Pro Gly Lys Gly Leu Glu Trp Val Gly Glu lie Arg Ser Gin Ala Ser Asn His Ala Thr Tyr Tyr Ala Glu Ser Val Lys Gly Arg Phe Thr He Ser Arg Asp Asp Ser Lys Asn Thr Leu Tyr Leu Gin Met Asn Ser Leu Lys Thr Glu Asp Thr Ala Val Tyr Tyr Cys Thr Arg Trp Arg Arg Phe Phe Asp Ser Trp Gly Gin Gly Thr Leu Val Thr Val Ser Ser

[00504] SEQ ID NO: 21 Synthetic VH1R polypeptide

[00505] Glu Val Gin Leu Val Glu Ser Gly Gly Gly Leu Val Lys Pro Gly Gly Ser Leu Arg

Leu Ser Cys Ala Ala Ser Gly Phe Thr Phe Ser Asp Ala Trp Met Asp Trp Val Arg Gin Ala Pro Gly Lys Gly Leu Glu Trp Val Gly Glu He Arg Ser Arg Ala Ser Asn His Ala Thr Tyr Tyr Ala Glu Ser Val Lys Gly Arg Phe Thr He Ser Arg Asp Asp Ser Lys Asn Thr Leu Tyr Leu Gin Met Asn Ser Leu Lys Thr Glu Asp Thr Ala Val Tyr Tyr Cys Thr Arg Trp Arg Arg Phe Phe Asp Ser Trp Gly Gin Gly Thr Leu Val Thr Val Ser Ser

[00506] SEQ ID NO: 22 Synthetic VH1 S polypeptide

[00507] Glu Val Gin Leu Val Glu Ser Gly Gly Gly Leu Val Lys Pro Gly Gly Ser Leu Arg

Leu Ser Cys Ala Ala Ser Gly Phe Thr Phe Ser Asp Ala Trp Met Asp Trp Val Arg Gin Ala Pro Gly Lys Gly Leu Glu Trp Val Ser Glu He Arg Ser Lys Ala Ser Asn His Ala Thr Tyr Tyr Ala Glu Ser Val Lys Gly Arg Phe Thr He Ser Arg Asp Asp Ser Lys Asn Thr Leu Tyr Leu Gin Met Asn Ser Leu Lys Thr Glu Asp Thr Ala Val Tyr Tyr Cys Thr Arg Trp Arg Arg Phe Phe Asp Ser Trp Gly Gin Gly Thr Leu Val Thr Val Ser Ser

[00508] SEQ ID NO: 23 Synthetic VK1AA polypeptide

[00509] Asp lie Gin Met Thr Gin Ser Pro Ser Ser Leu Ser Ala Ser Val Gly Asp Arg Ala Thr lie Thr Cys Arg Ala Ser Ser Ser Val Ser Tyr Met His Trp Tyr Gin Gin Lys Pro Gly Lys Ala Pro Lys Pro Trp Ala Tyr Ala Thr Ser Asn Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser Gly Ser Gly Thr Asp Tyr Thr Leu Thr He Ser Ser Leu Gin Pro Glu Asp Phe Ala Thr Tyr Tyr Cys Gin Gin Trp Ser Ser Asn Pro Leu Thr Phe Gly Gly Gly Thr Lys Val Glu He Lys

[00510] SEQ ID NO: 24 Synthetic VK2AA polypeptide

[00511] Asp lie Gin Leu Thr Gin Ser Pro Ser Ser Leu Ser Ala Ser Val Gly Asp Arg Ala Thr

He Thr Cys Arg Ala Ser Ser Ser Val Ser Tyr Met His Trp Tyr Gin Gin Lys Pro Gly Lys Ala Pro Lys Pro Trp Ala Tyr Ala Thr Ser Asn Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser Gly Ser Gly Thr Asp Tyr Thr Leu Thr He Ser Ser Leu Gin Pro Glu Asp Phe Ala Thr Tyr Tyr Cys Gin Gin Trp Ser Ser Asn Pro Leu Thr Phe Gly Gly Gly Thr Lys Val Glu He Lys

[00512] SEQ ID NO: 25 Synthetic VK2AS polypeptide

[00513] Asp He Gin Leu Thr Gin Ser Pro Ser Ser Leu Ser Ala Ser Val Gly Asp Arg Ala Thr

He Thr Cys Arg Ala Ser Ser Ser Val Ser Tyr Met His Trp Tyr Gin Gin Lys Pro Gly Lys Ala Pro Lys Pro Trp He Tyr Ala Ser Ser Asn Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser Gly Ser Gly Thr Asp Tyr Thr Leu Thr He Ser Ser Leu Gin Pro Glu Asp Phe Ala Thr Tyr Tyr Cys Gin Gin Trp Ser Ser Asn Pro Leu Thr Phe Gly Gly Gly Thr Lys Val Glu He Lys

[00514] SEQ ID NO: 26 Synthetic VK2SA polypeptide

[00515] Asp He Gin Leu Thr Gin Ser Pro Ser Ser Leu Ser Ala Ser Val Gly Asp Arg Val Thr

He Ser Cys Arg Ala Ser Ser Ser Val Ser Tyr Met His Trp Tyr Gin Gin Lys Pro Gly Lys Ala Pro Lys Pro Trp Ala Tyr Ala Thr Ser Asn Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser Gly Ser Gly Thr Asp Tyr Thr Leu Thr He Ser Ser Leu Gin Pro Glu Asp Phe Ala Thr Tyr Tyr Cys Gin Gin Trp Ser Ser Asn Pro Leu Thr Phe Gly Gly Gly Thr Lys Val Glu He Lys

[00516] SEQ ID NO: 27 Synthetic VK2SS polypeptide

[00517] Asp He Gin Leu Thr Gin Ser Pro Ser Ser Leu Ser Ala Ser Val Gly Asp Arg Val Thr

He Ser Cys Arg Ala Ser Ser Ser Val Ser Tyr Met His Trp Tyr Gin Gin Lys Pro Gly Lys Ala Pro Lys Pro Trp He Tyr Ala Ser Ser Asn Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser Gly Ser Gly Thr Asp Tyr Thr Leu Thr He Ser Ser Leu Gin Pro Glu Asp Phe Ala Thr Tyr Tyr Cys Gin Gin Trp Ser Ser Asn Pro Leu Thr Phe Gly Gly Gly Thr Lys Val Glu He Lys

[00518] SEQ ID NO: 28 Synthetic VK1 SS polypeptide [00519] Asp lie Gin Met Thr Gin Ser Pro Ser Ser Leu Ser Ala Ser Val Gly Asp Arg Val Thr lie Ser Cys Arg Ala Ser Ser Ser Val Ser Tyr Met His Trp Tyr Gin Gin Lys Pro Gly Lys Ala Pro Lys Pro Trp He Tyr Ala Ser Ser Asn Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser Gly Ser Gly Thr Asp Tyr Thr Leu Thr He Ser Ser Leu Gin Pro Glu Asp Phe Ala Thr Tyr Tyr Cys Gin Gin Trp Ser Ser Asn Pro Leu Thr Phe Gly Gly Gly Thr Lys Val Glu He Lys

[00520] SEQ ID NO: 29 Synthetic VK1 AS polypeptide

[00521] Asp He Gin Met Thr Gin Ser Pro Ser Ser Leu Ser Ala Ser Val Gly Asp Arg Ala Thr

He Thr Cys Arg Ala Ser Ser Ser Val Ser Tyr Met His Trp Tyr Gin Gin Lys Pro Gly Lys Ala Pro Lys Pro Trp He Tyr Ala Ser Ser Asn Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser Gly Ser Gly Thr Asp Tyr Thr Leu Thr He Ser Ser Leu Gin Pro Glu Asp Phe Ala Thr Tyr Tyr Cys Gin Gin Trp Ser Ser Asn Pro Leu Thr Phe Gly Gly Gly Thr Lys Val Glu He Lys

[00522] SEQ ID NO: 30 Synthetic VK1 SA polypeptide

[00523] Asp He Gin Met Thr Gin Ser Pro Ser Ser Leu Ser Ala Ser Val Gly Asp Arg Val Thr

He Ser Cys Arg Ala Ser Ser Ser Val Ser Tyr Met His Trp Tyr Gin Gin Lys Pro Gly Lys Ala Pro Lys Pro Trp Ala Tyr Ala Thr Ser Asn Leu Ala Ser Gly Val Pro Ser Arg Phe Ser Gly Ser Gly Ser Gly Thr Asp Tyr Thr Leu Thr He Ser Ser Leu Gin Pro Glu Asp Phe Ala Thr Tyr Tyr Cys Gin Gin Trp Ser Ser Asn Pro Leu Thr Phe Gly Gly Gly Thr Lys Val Glu He Lys

[00524] Aspects of the embodiments described herein may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present disclosure is therefore to be considered as in all aspects illustrated and not restrictive, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A method of treating a cancer or a metastasis thereof in a subject in need thereof, comprising administering to the subject an anti-endoglin antibody or an antigen-binding fragment thereof, an anti-PD-1 antibody or an antigen-binding fragment thereof, and/or anti-PD-Ll antibody or an antigen-binding fragment thereof.

2. The method of claim 1, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a monoclonal antibody, a chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a humanized antibody, a deimmunized antibody, a human antibody, or a combination thereof; wherein the anti-PD-1 antibody or an antigen-binding fragment thereof comprises a monoclonal antibody, a chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a humanized antibody, a deimmunized antibody, a human antibody, or a combination thereof; and/or wherein the anti-PD- Ll antibody or an antigen-binding fragment thereof comprises a monoclonal antibody, a chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a humanized antibody, a deimmunized antibody, a human antibody, or a combination thereof.

3. The method of claim 2, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a chimeric antibody or an antigen-binding fragment thereof.

4. The method of claim 3, wherein the chimeric anti-endoglin antibody or an antigen- binding fragment thereof, comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 1 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 3.

5. The method of claim 4, wherein the chimeric anti-endoglin antibody further comprises a light chain constant region having an amino acid sequence set forth as SEQ ID NO: 2 and a constant region having an amino acid sequence set forth as SEQ ID NO: 4.

6. The method of claim 2, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a humanized antibody, a deimmunized antibody, or a humanized and a deimmunized antibody, or an antigen-binding fragment of any thereof.

7. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

8. The method of claim 6, wherein the anti-endoglin antibody or the antigen -binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

9. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

10. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18.

11. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

12. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18.

13. The method of claim 6, wherein the anti-endoglin antibody or the antigen -binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

14. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

15. The method of claim 6, wherein the anti-endoglin antibody or the antigen -binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22.

16. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18.

17. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

18. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22.

19. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 26 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

20. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

21. The method of claim 6, wherein the anti-endoglin antibody or the antigen -binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

22. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

23. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22.

24. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18.

25. The method of claim 6, wherein the anti-endoglin antibody or the antigen -binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

26. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

27. The method of claim 6, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

28. The method of any one of claims 1-27, wherein the antibodies or antigen binding fragments thereof are formulated in one or more pharmaceutical compositions that comprise one or more pharmaceutically acceptable excipients or carriers.

29. The method of any one of claims 1-28, wherein the anti-endoglin antibody comprises a therapeutic label, a diagnostic label, or a therapeutic label and a diagnostic label.

30. The method of any one of claims 1-29, wherein the anti-PD-1 or anti-PD-Ll antibody comprises a therapeutic label, a diagnostic label, or a therapeutic label and a diagnostic label.

31. The method of any one of claims 1-30, wherein the cancer or the metastasis thereof comprises a solid tumor or a semi-solid tumor.

32. The method of any one of claims 1-31, wherein the cancer or the metastasis thereof comprises an epithelial based tumor.

33. The method of any one of claims 1-32, wherein the cancer or the metastasis thereof is selected from the group consisting of a kidney cancer, a lung cancer, melanoma, a head and neck cancer, a Merkel cell carcinoma, a urothelial cancer, a breast cancer, a pancreatic cancer, an ovarian cancer, a uterine cancer, a colorectal cancer, a prostate cancer, a bladder cancer, a brain cancer, a liver cancer, a sarcoma, a myeloma, a lymphoma, and a combination thereof.

34. The method of claim 33, wherein the cancer or the metastasis thereof comprises the kidney cancer that comprises a renal cell carcinoma or a metastasis thereof.

35. The method of claim 33, wherein the cancer or the metastasis thereof comprises the lung cancer that comprises a primary non-small cell lung cancer or a metastatic non-small cell lung cancer.

36. The method of claim 33, wherein the cancer or the metastasis thereof comprises the melanoma that comprises a primary melanoma, an unresectable melanoma or a metastatic melanoma.

37. The method of claim 33, wherein the cancer or the metastasis thereof comprises the head and neck cancer that comprises a head and neck squamous cell carcinoma, or a metastasis thereof.

38. The method of claim 33, wherein the cancer or the metastasis thereof comprises the urothelial cancer that comprises a primary urothelial cancer, a locally advanced urothelial cancer or a metastatic urothelial cancer.

39. The method of any one of claims 1-38, wherein the anti-endoglin antibody or antigen-binding fragment thereof is administered to the subject in an amount of about 0.01 mg/kg, about 0.05 mg/kg, about 0.1 mg/kg, about 0.5 mg/kg, about 1.0 mg/kg, about 5.0 mg/kg, about 10.0 mg/kg, about 20.0 mg/kg, about 30.0 mg/kg, about 40.0 mg/kg, about 50.0 mg/kg, about 60.0 mg/kg, about 70.0 mg/kg, about 80.0 mg/kg, about 90.0 mg/kg, about 100.0 mg/kg, about 125.0 mg/kg, about 150.0 mg/kg, about 175.0 mg/kg, or about 200.0 mg/kg.

40. The method of any one of claims 1-39, wherein the anti-endoglin antibody or antigen-binding fragment thereof is administered to the subject intravenously or intravitreally.

41. The method of any one of claims 1-40, wherein the anti-PD-1 antibody or antigen- binding fragment thereof and/or the anti-PD-Ll antibody or antigen-binding fragment thereof is administered to the subject intravenously or intravitreally.

42. The method of any one of claims 1-41, wherein the anti-endoglin antibody, the anti- PD-1 antibody, and/or the anti-PD-Ll antibody or antigen-binding fragment or any thereof are administered to the subject sequentially or simultaneously.

43. The method of any one of claims 1-41, wherein the anti-endoglin antibody, the anti- PD-1 antibody, and/or the anti-PD-Ll antibody, or the antigen-binding fragment or any thereof are administered to the subject separately.

44. The method of any one of claims 1-41, wherein the anti-endoglin antibody, the anti- PD-1 antibody, and/or the anti-PD-Ll antibody, or the antigen-binding fragment or any thereof are administered to the subject at the same site.

45. The method of any one of claims 1-41, wherein the anti-endoglin antibody, the anti- PD-1 antibody, and/or the anti-PD-Ll antibody, or the antigen-binding fragment or any thereof are administered to the subject at different sites.

46. The method of any one of claims 1-45, wherein the anti-PD-Ll antibody comprises Pembrolizumab.

47. The method of any one of claims 1-45, wherein the anti-PD-Ll antibody comprises BMS-936559.

48. The method of any one of claims 1-45, wherein the anti-PD-Ll antibody comprises Avelumab.

49. The method of any one of claims 1-45, wherein the anti-PD-Ll antibody comprises Atezolizumab.

50. The method of any one of the claims 1-45, wherein the anti-PD-1 antibody comprises nivolumab.

51. The method of any one of the claims 1-45, wherein the anti-PD-1 antibody comprises Pidilizumab.

52. The method of any one of the claims 1-45, wherein the anti-PD-1 antibody comprises PDR001.

53. A combination of an anti-endoglin antibody or an antigen-binding fragment thereof, and an anti-PD-1 antibody or an antigen-binding fragment, and/or an anti-PD-Ll antibody or an antigen-binding fragment thereof, for use in treating cancer or a metastasis thereof in a subject in need thereof by separate, simultaneous or sequential administration.

54. The combination for use of claim 53, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a monoclonal antibody, a chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a humanized antibody, a deimmunized antibody, a human antibody, or a combination thereof; wherein the anti-PD-1 antibody or an antigen-binding fragment thereof comprises a monoclonal antibody, a chimeric antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a humanized antibody, a deimmunized antibody, a human antibody, or a combination thereof; and/or wherein the anti-PD-Ll antibody or an antigen-binding fragment thereof comprises a chimeric a monoclonal antibody, an antibody, a bispecific antibody, a multispecific antibody, a heteroconjugate antibody, a humanized antibody, a deimmunized antibody, a human antibody, or a combination thereof.

55. The combination for use of claim 54, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a chimeric antibody or antigen-binding fragment thereof.

56. The combination for use of claim 55, wherein the chimeric anti-endoglin antibody or an antigen-binding fragment thereof, comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 1 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 3.

57. The combination for use of claim 56, wherein the chimeric anti-endoglin antibody further comprises a light chain constant region having an amino acid sequence set forth as SEQ ID NO: 2 and a constant region having an amino acid sequence set forth as SEQ ID NO: 4.

58. The combination for use of claim 54, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a humanized antibody, a deimmunized antibody, or a humanized and a deimmunized antibody.

59. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

60. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

61. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

62. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18.

63. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

64. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18.

65. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

66. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

67. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 24 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22.

68. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18.

69. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

70. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 25 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22.

71. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 26 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

72. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

73. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

74. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

75. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 27 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 22.

76. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 18.

77. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 19.

78. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 20.

79. The combination for use of claim 58, wherein the anti-endoglin antibody or the antigen-binding fragment thereof comprises a light chain variable region having an amino acid sequence set forth as SEQ ID NO: 23 and a heavy chain variable region having an amino acid sequence set forth as SEQ ID NO: 21.

80. The combination for use of claim 58, wherein each antibody or antigen-binding fragment thereof is formulated in a pharmaceutical composition that comprises one or more pharmaceutically acceptable excipients or carriers.

81. The combination for use of any one of claims 53-80, wherein the anti-endoglin antibody or antigen-binding fragment thereof comprises a therapeutic label, a diagnostic label, or a therapeutic label and a diagnostic label.

82. The combination for use of any one of claims 53-81, wherein the anti-PD-1 antibody or antigen-binding fragment thereof or the anti-PD-Ll antibody or antigen-binding fragment thereof comprises a therapeutic label, a diagnostic label, or a therapeutic label and a diagnostic label.

83. The combination for use of any one of claims 53-82, wherein the cancer or the metastasis thereof comprises a solid tumor or a semi-solid tumor.

84. The combination for use of any one of claims 53-82, wherein the cancer or the metastasis thereof comprises an epithelial based tumor.

85. The combination for use of any one of claims 53-84, wherein the cancer or the metastasis thereof is selected from the group consisting of a kidney cancer, a lung cancer, melanoma, a head and neck cancer, a Merkel cell carcinoma, a urothelial cancer, a breast cancer, a pancreatic cancer, an ovarian cancer, a uterine cancer, a colorectal cancer, a prostate cancer, a bladder cancer, a liver cancer, a brain cancer, a sarcoma, a myeloma, a lymphoma, and a combination thereof.

86. The combination for use of claim 85, wherein the cancer or the metastasis thereof comprises the kidney cancer that comprises a renal cell carcinoma or a metastasis thereof.

87. The combination for use of claim 85, wherein the cancer or the metastasis thereof comprises the lung cancer that comprises a primary non-small cell lung cancer or a metastatic non- small cell lung cancer.

88. The combination for use of claim 85, wherein the cancer or the metastasis thereof comprises the melanoma that comprises a primary melanoma, an unresectable melanoma or a metastatic melanoma.

89. The combination for use of claim 85, wherein the cancer or the metastasis thereof comprises the head and neck cancer that comprises a head and neck squamous cell carcinoma or a metastasis thereof.

90. The combination for use of claim 85, wherein the cancer or the metastasis thereof comprises the urothelial cancer that comprises a primary urothelial cancer, a locally advanced urothelial cancer or a metastatic urothelial cancer.

91. The combination for use of any one of claims 53-90, wherein the anti-endoglin antibody or antigen-binding fragment thereof is formulated for administration to the subject in an amount of about 0.01 mg/kg, about 0.05 mg/kg, about 0.1 mg/kg, about 0.5 mg/kg, about 1.0 mg/kg, about 5.0 mg/kg, about 10.0 mg/kg, about 20.0 mg/kg, about 30.0 mg/kg, about 40.0 mg/kg, about 50.0 mg/kg, about 60.0 mg/kg, about 70.0 mg/kg, about 80.0 mg/kg, about 90.0 mg/kg, about 100.0 mg/kg, about 125.0 mg/kg, about 150.0 mg/kg, about 175.0 mg/kg, or about 200.0 mg/kg.

92. The combination for use of any one of claims 53-91, that is formulated for intravenous administration.

93. The combination for use of any one of claims 53-91, that is formulated for intravitreal administration.

94. The combination for use of any one of claims 53-93, wherein the anti-PD-Ll antibody comprises Pembrolizumab.

95. The combination for use of any one of claims 53-93, wherein the anti-PD-Ll antibody comprises BMS-936559.

96. The combination for use of any one of claims 53-93, wherein the anti-PD-Ll antibody comprises Avelumab.

97. The combination for use of any one of claims 53-93, wherein the anti-PD-Ll antibody comprises Atezolizumab.

98. The combination for use of any one of the claims 53-93, wherein the anti-PD-1 antibody comprises nivolumab.

99. The combination for use of any one of the claims 53-93, wherein the anti-PD-1 antibody comprises Pidilizumab.

100. The combination for use of any one of the claims 53-93, wherein the anti-PD-1 antibody comprises PDR001.

101. An anti-endoglin antibody or an antigen-binding fragment thereof for use in the treatment of cancer or a metastasis thereof by separate, simultaneous or sequential administration with an anti-PD-1 antibody or an antigen-binding fragment thereof and/or an anti-PD-Ll antibody or an antigen-binding fragment thereof.

102. An anti-PD-1 antibody or an antigen-binding fragment thereof, and/or an anti-PD-Ll antibody or an antigen-binding fragment thereof, for use in the treatment of cancer or a metastasis thereof by separate, simultaneous or sequential administration with an anti-endoglin antibody or an antigen-binding fragment thereof.