WO2021058729A1

WO2021058729A1 - Anti-müllerian inhibiting substance type i receptor antibodies and uses thereof

Info

Publication number: WO2021058729A1
Application number: PCT/EP2020/076882
Authority: WO
Inventors: André Pelegrin; Bruno Robert; Pierre Martineau; Maeva CHAUVIN; Myriam CHENTOUF
Original assignee: Institut National de la Sante et de la Recherche Medicale INSERM; Universite de Montpellier; Institut Regional du Cancer de Montpellier
Current assignee: Institut National de la Sante et de la Recherche Medicale INSERM; Universite de Montpellier; Institut Regional du Cancer de Montpellier
Priority date: 2019-09-27
Filing date: 2020-09-25
Publication date: 2021-04-01
Anticipated expiration: 2022-03-27

Abstract

The present disclosure relates to anti-mullerian inhibiting substance type 1 receptor (MISRI) antibodies and uses thereof in particular in the therapeutic field. The application also relates to bispecific antibody targeting MISRI and MISRII and their uses in the treatment of MISRI or MISRII positive cancer. In particular, the disclosure describes 2 anti-ALK2 (activin-like kinase-2) and 2 anti-ALK3 antibodies and used them to design original BsAbs directed against MISRII and ALK2 or ALK3. These BsAbs induced apoptosis and decreased clonogenic survival in COV434-MISRII and SKOV3- MISRII cell lines. These results were confirmed in tumor cells isolated from ascites samples of three patients with ovarian carcinoma.

Description

ANTI-MULLERIAN INHIBITING SUBSTANCE TYPE I RECEPTOR ANTIBODIES

AND USES THEREOF

FIELD OF THE INVENTION:

The present invention relates to anti-miillerian inhibiting substance type I receptor (MISRI) antibodies and uses thereof in particular in the therapeutic field and more particular in the treatment of MIS or MISRII positive cancer.

BACKGROUND OF THE INVENTION:

Miillerian Inhibiting Substance (MIS) is a member of the TGFp family, and acts by binding to its specific receptor (MIS type II receptor; MISRII) that recruits type I receptors (MISRI: ALK2, ALK3 and ALK6). MISRI phosphorylation induces SMAD 1/5/8 phosphorylation and their migration into the nucleus where through SMAD4, they regulate different responsive genes, depending on the target tissue (di Clemente et al, 2010; Josso and Clemente, 2003). Preclinical in vitro and in vivo findings as well as data from clinical samples (Bakkum-Gamez et al, 2008; Masiakos et al, 1999; Meirelles et al, 2012; Pepin et al, 2015; Renaud et al, 2005; Wei et al., 2010) have demonstrated that MISRII and the MIS/MISRII signaling pathway are potential therapeutic targets in gynecological tumors, and particularly in ovarian carcinoma (reviewed in (Kim et al., 2014)). Moreover, Beck TN et al. showed that in lung cancer, MIS/MISRII signaling regulates epithelial-mesenchymal transition (EMT) and promotes cell survival/proliferation (Beck et al., 2016). They suggested that MIS/MISRII signaling role in EMT regulation was important for chemoresistance. Furthermore, the MIS/MISRII signaling pathway has recently been shown to be implicated in colorectal cancers in which (i) the MIS gene is upregulated (Pellatt et al., 2018), and (ii) high MIS RNA expression is an unfavorable prognostic factor (n= 597 patients with a follow-up of more than 12 years) (Uhlen et al., 2017). This signaling cascade could be targeted using recombinant MIS or anti- MISRII antibodies. However, the use of recombinant MIS has been hampered by the difficulties linked to the production of sufficient amounts of bioactive MIS and to its delivery at the tumor site (Donahoe et al., 2003). Recently, Pepin et al. described an original production strategy and an alternative delivery approach using gene therapy (not yet in clinical phase) (Pepin et al., 2013, 2015). Among anti-MISRII antibodies (Salhi et al., 2004) and antibody fragments (Yuan et al., 2006, 2008), the monoclonal antibody (MAb) 12G4 and its humanized version have been extensively evaluated in preclinical studies (Bougherara et al., 2017; Estupina et al., 2017; Gill et al., 2017; Kersual et al., 2014), and the humanized antibody (GM-102 or murlentamab) is now tested in clinical trials (NCT02978755, NCT03799731). The mechanism of action of the glyco-engineered murlentamab involves antibody-dependent cell-mediated cytotoxicity and antibody-dependent cell phagocytosis, but almost no apoptosis, suggesting that the effect is not directly related to the MIS signaling pathway (Bougherara et al., 2017; Estupina et al., 2017). Indeed, in MISRII-positive cancer cells, MIS inhibits proliferation and induces apoptosis.

To understand why the MIS signaling pathway is not implicated in the mechanisms of action of this anti-MISRII MAb, the inventors analyzed the role of the three MISRI (ALK2, ALK3 and ALK6) in ovarian carcinoma cell lines and carcinoma cells isolated from ascites samples of patients with ovarian carcinoma. Indeed, although ALK2, ALK3 and ALK6 roles in several cell types have been studied during development and in other physiological conditions (Belville et al., 2005; Clarke et al., 2001; Josso et al., 1998; Orvis et al., 2008; Sedes et al., 2013; Visser et al., 2001; Zhan et al., 2006), few data are available in cancer. Basal et al. demonstrated that MISRII, ALK2, ALK3 and ALK6 are expressed in epithelial ovarian cancer (immunohistochemistry analysis of 262 samples), but did not assess their specific role (Basal et al, 2016).

Herein, the inventors found that ALK2 and ALK3 are the two main MISRI used for MIS signaling in four ovarian cancer cell lines (derived from two epithelial ovarian tumors and from two sex cord-stromal tumors, including one granulosa cell tumor), and that they have a differential role according to MIS concentration. The inventors demonstrate that ALK2 and ALK3 are the two main MISRIs involved in MIS signaling at low and high MIS concentrations, respectively. This observation opens the way to innovative therapeutic approaches using bispecific antibodies targeting MISRII and ALK2 or ALK3 in order to induce cancer cell apoptosis.

The inventors developed the first monoclonal antibody against miillerian inhibiting substance type II receptor (MISRII) (12G4) and demonstrated its therapeutic potential in ovarian cancers (Kersual N et al, 2014). The humanized version of this antibody, 3C23K, has confirmed its interest in monotherapy and in combination with platinum-based chemotherapy (Estupina P et al, 2017., Bougherara H et al, 2017.). The success of therapeutic antibodies and their limits (36) led to the development of second-generation antibodies: antibodies with optimized Fc such as 3C23K (Kersual N et al, 2014., Romain et al, 2014.), antibody-drug conjugates (Wong et al, 2014.) and bispecific anticoproteins (BsAbs) ( Spiess C and al, 2015).

SUMMARY OF THE INVENTION: The inventors demonstrate that ALK2 and ALK3 are the two main MISRIs involved in MIS signaling at low and high MIS concentrations, respectively.

Herein, the inventors have selected and produced bispecific antibodies (BsAb) targeting both AMHRII and Alk2, and AMHRII and Alk3. They constructed these BsAbs in order to confer a greater affinity for the AMHRII receptor (12G4) since it targets specifically the ligand and is the marker of ovarian cancers cell.

Thus, the present invention relates to anti-miillerian inhibiting substance type I receptor (MISRI) antibodies and uses thereof in particular in the therapeutic field and more particular in the treatment of gynecological cancer, lung cancer or colorectal cancer. More particularly, the present invention also relates to bispecific antibody targeting MISRI and miillerian inhibiting substance type II receptor MISRII and their uses in the treatment of gynecological cancer, lung cancer or colorectal cancer.

DETAILED DESCRIPTION OF THE INVENTION:

The present invention relates to anti-miillerian inhibiting substance type I receptor (MISRI) antibodies and uses thereof in particular in the therapeutic field and more particular in the treatment of gynecological cancer, lung cancer or colorectal cancer. The present invention also relates to bispecific antibody targeting MISRI and miillerian inhibiting substance type II receptor MISRII and their uses in the treatment of gynecological cancer, lung cancer or colorectal cancer.

Definition

As used herein, the term “miillerian inhibiting substance” or “MIS”, also known as “anti-miillerian hormone” or “AMH”, has its general meaning in the art and refers to a glycoprotein hormone structurally related to inhibin and activin from the transforming growth factor beta (TGFP) superfamily, which play a key roles in growth differentiation and folliculogenesis. MIS is a 140 kDa dimeric glycoprotein that is encoded by AMH gene on human chromosome 19p 13.3. Its entrez reference is 268 and its Uniprot reference is P03971. The MIS acts by binding to its specific MIS type II receptor (MISRII or AMHR2) that recruits type I receptor (MISRI or AMHRl).

As used herein, the term “miillerian inhibiting substance type II receptor” or “MISRII”, also known as “AMHR2” has its general meaning in the art. The MISRII is encoded by the AMHR2 gene on human chromosome 12ql 3.13. Its entrez reference is 269 and its Uniprot reference is Q 16671.

As used herein, the term “mullerian inhibiting substance type I receptor” or ‘MISRF also known as “AMHR1” has its general meaning in the art. ALK2, ALK3 and ALK6 are the three variants of MISRI. The phosphorylation of MISRI induces SMAD 1/5/8 phosphorylation and regulate through SMAD4 different responsive gene, depending on the target tissue.

As used herein, the term “ALK2” for ” activing receptor-like kinase 2”, also known as “activing A receptor type I”, has its general meaning in the art and refers to a protein encoded by the AVCR1 gene on human chromosome 2q24.1. Its entrez reference is 90 and its Uniprot reference is Q04771.

As used herein, the tern “ALK3” also known as “activing receptor-like kinase 3”, also known as “bone morphogenetic protein receptor type 1A” (BMPR-1A), has its general meaning in the art and refers to a protein encoded by the BMPR1A gene on human chromosome 10q23.2. Its entrez reference is 657 and its Uniprot reference is P36894.

As used herein, the term “ALK6” for “activing receptor-like kinase 6”, also known as “bone morphogenetic protein receptor type- IB”, has its general meaning in the art and refers to a protein encoded by the BMPR1B gene on human chromosome 4q22.3. Its entrez reference is 658 and its Uniprot reference is 000238.

As used herein the term "antibody" or "immunoglobulin" have the same meaning, and will be used equally in the present invention. The term "antibody" as used herein refers to immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, i.e., molecules that contain an antigen binding site that immunospecifically binds an antigen. As such, the term antibody encompasses not only whole antibody molecules, but also antibody fragments as well as variants (including derivatives) of antibodies and antibody fragments. In natural antibodies, two heavy chains are linked to each other by disulfide bonds and each heavy chain is linked to a light chain by a disulfide bond. There are two types of light chain, lambda (1) and kappa (k). There are five main heavy chain classes (or isotypes) which determine the functional activity of an antibody molecule: IgM, IgD, IgG, IgA and IgE. Each chain contains distinct sequence domains. The light chain includes two domains, a variable domain (VL) and a constant domain (CL). The heavy chain includes four domains, a variable domain (VET) and three constant domains (CHI, CH2 and CH3, collectively referred to as CH). The variable regions of both light (VL) and heavy (VH) chains determine binding recognition and specificity to the antigen. The constant region domains of the light (CL) and heavy (CH) chains confer important biological properties such as antibody chain association, secretion, trans-placental mobility, complement binding, and binding to Fc receptors (FcR). The Fv fragment is the N-terminal part of the Fab fragment of an immunoglobulin and consists of the variable portions of one light chain and one heavy chain. The specificity of the antibody resides in the structural complementarity between the antibody combining site and the antigenic determinant. Antibody combining sites are made up of residues that are primarily from the hypervariable or complementarity determining regions (CDRs). Occasionally, residues from nonhypervariable or framework regions (FR) can participate to the antibody binding site or influence the overall domain structure and hence the combining site. Complementarity Determining Regions or CDRs refer to amino acid sequences which together define the binding affinity and specificity of the natural Fv region of a native immunoglobulin binding site. The light and heavy chains of an immunoglobulin each have three CDRs, designated L-CDR1, L- CDR2, L- CDR3 and H-CDR1, H-CDR2, H-CDR3, respectively. An antigen-binding site, therefore, typically includes six CDRs, comprising the CDR set from each of a heavy and a light chain V region. Framework Regions (FRs) refer to amino acid sequences interposed between CDRs.

In the context of the invention, the amino acid residues of the antibody of the invention are numbered according to the IMGT numbering system. The IMGT unique numbering has been defined to compare the variable domains whatever the antigen receptor, the chain type, or the species (Lefranc M.-P., "Unique database numbering system for immunogenetic analysis" Immunology Today, 18, 509 (1997) ; Lefranc M.-P., "The IMGT unique numbering for Immunoglobulins, T cell receptors and Ig-like domains" The Immunologist, 7, 132-136 (1999).; Lefranc, M.-P., Pommie, C., Ruiz, M., Giudicelli, V., Foulquier, E., Truong, L., Thouvenin- Contet, V. and Lefranc, G., "IMGT unique numbering for immunoglobulin and T cell receptor variable domains and Ig superfamily V-like domains" Dev. Comp. Immunol., 27, 55-77 (2003).). In the IMGT unique numbering, the conserved amino acids always have the same position, for instance cysteine 23, tryptophan 41, hydrophobic amino acid 89, cysteine 104, phenylalanine or tryptophan 118. The IMGT unique numbering provides a standardized delimitation of the framework regions (FR1-IMGT: positions 1 to 26, FR2-IMGT: 39 to 55, FR3-IMGT: 66 to 104 and FR4-IMGT: 118 to 128) and of the complementarity determining regions: CDR 1 -IMGT: 27 to 38, CDR2-IMGT : 56 to 65 and CDR3-IMGT: 105 to 117. If the CDR3-IMGT length is less than 13 amino acids, gaps are created from the top of the loop, in the following order 111, 112, 110, 113, 109, 114, etc. If the CDR3-IMGT length is more than 13 amino acids, additional positions are created between positions 111 and 112 at the top of the CDR3-IMGT loop in the following order 112.1,111.1, 112.2, 111.2, 112.3, 111.3, etc. (http://www.imgt.org/IMGTScientificChart/Nomenclature/IMGT-FRCDRdefmition.html).

As used herein, the term “amino acid sequence” has its general meaning and is a sequence of amino acids that confers to a protein its primary structure. According to the invention, the amino acid sequence may be modified with one, two or three conservative amino acid substitutions, without appreciable loss of interactive binding capacity. By “conservative amino acid substitution”, it is meant that an amino acid can be replaced with another amino acid having a similar side chain. Families of amino acid having similar side chains have been defined in the art, including basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., glycine, cysteine, alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta- branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine).

According to the invention a first amino acid sequence having at least 70% of identity with a second amino acid sequence means that the first sequence has 70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81; 82; 83; 84; 85; 86; 87; 88; 89; 90; 91; 92; 93; 94; 95; 96; 97; 98; or 99% of identity with the second amino acid sequence. Amino acid sequence identity is typically determined using a suitable sequence alignment algorithm and default parameters, such as BLAST P (Karlin and Altschul, 1990).

According to the meaning of the present invention, the “identity” is calculated by comparing two aligned sequences in a comparison window. The sequence alignment allows determining the number of positions (nucleotides or amino acids) in common for the two sequences in the comparison window. The number of positions in common is therefore divided by the total number of positions in the comparison window and multiplied by 100 to obtain the identity percentage. The determination of the identity percentage of sequence can be made manually or thanks to well-known computer programs.

As used herein, the terms “purified” and “isolated” relate to the antibodies or polypeptides of the invention and mean that the antibodies or polypeptides is present in the substantial absence of other biologic macromolecules of the same type. The term “purified” as used here means preferably that at least 75 % in weight, more preferably at least 85% in weight, even more preferably at least 95% in weight, and the more preferably at least 98% in weight of antibody, compared to the total weight of macromolecules present. As used herein, the term “specificity” refers to the ability of an antibody to detectably bind an epitope presented on an antigen, such as MISRI or MISRII, while having relatively little detectable reactivity with non-MISRI or non-MISRII proteins. Specificity can be relatively determined by binding or competitive binding assays, using, e.g., Biacore instruments, as described elsewhere herein. Specificity can be exhibited by, e.g., an about 10:1, about 20:1, about 50:1, about 100:1, 10.000:1 or greater ratio of affinity/avidity in binding to the specific antigen versus nonspecific binding to other irrelevant molecules (in this case the specific antigen is MISRI or MISRII).

The term “affinity”, as used herein, means the strength of the binding of an antibody to an epitope. The affinity of an antibody is given by the dissociation constant Kd, defined as [Ab] ^x [Ag] / [Ab-Ag], where [Ab-Ag] is the molar concentration of the antibody-antigen complex, [Ab] is the molar concentration of the unbound antibody and [Ag] is the molar concentration of the unbound antigen. The affinity constant Ka is defined by 1/Kd. Preferred methods for determining the affinity of mAbs can be found in Harlow, et al., Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1988), Coligan et al, eds., Current Protocols in Immunology, Greene Publishing Assoc and Wiley Interscience, N.Y., (1992, 1993), and Muller, Meth. Enzymol. 92:589-601 (1983), which references are entirely incorporated herein by reference. One preferred and standard method well known in the art for determining the affinity of mAbs is the use of Biacore instruments. Other methods such as Scatchard plot using radioactive antibody or MIS, or ELISA can be used to determine this affinity or to evaluate it by an EC50.

As used herein, the terms "monoclonal antibody", "monoclonal Ab", "monoclonal antibody composition", "mAb", or the like, as used herein refer to a preparation of antibody molecules of single molecular composition. A monoclonal antibody composition displays a single binding specificity and affinity for a particular epitope.

As used herein, the terms "bispecific antibody", "bispecific Ab", "BAb", or the like, as used herein refer to an antibody that comprises one or two antigen(s) binding site (Fab) directed against a first antigen and one or two further binding site(s) directed against a second antigen.

As used herein, the term “antigen-binding site” correspond to the arms of the Y -shaped structure, which consist each of the complete light chain paired with the VH and CHI domains of the heavy chain, and are called the Fab fragments (for Fragment antigen binding).

As used herein, the term "nucleic acid molecule" has its general meaning in the art and refers to a DNA or RNA molecule. The sequences of interest in the present application are indicated in the following Table 1 :

Monoclonal Antibodies

The present invention provides for anti-MISRI antibodies, particularly in a purified form or in an isolated form. Therefore, the inventors relates to an isolated anti-mullerian inhibiting substance type I receptor (MISRI) antibody comprising:

(a) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 1; a H-CDR2 having a sequence set forth as SEQ ID NO:2; a H-CDR3 having a sequence set forth as SEQ ID NO:3; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:4; a L-CDR2 having a sequence set forth as SEQ ID NO: 5; a L-CDR3 having a sequence set forth as SEQ ID NO: 6 (“2C1 derivative”); or

(b) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 9; a H-CDR2 having a sequence set forth as SEQ ID NO: 10; a H-CDR3 having a sequence set forth as SEQ ID NO: 11; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO: 12; a L- CDR2 having a sequence set forth as SEQ ID NO: 13; a L-CDR3 having a sequence set forth as SEQ ID NO: 14 (“2F9 derivative”); or

(c) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 17; a H-CDR2 having a sequence set forth as SEQ ID NO: 18; a H-CDR3 having a sequence set forth as SEQ ID NO: 19; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:20; a L- CDR2 having a sequence set forth as SEQ ID NO:21; a L-CDR3 having a sequence set forth as SEQ ID NO:22 (“3H6 derivative”); or

(d) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:25; a H-CDR2 having a sequence set forth as SEQ ID NO:26; a H-CDR3 having a sequence set forth as SEQ ID NO:27; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:28; a L- CDR2 having a sequence set forth as SEQ ID NO:29; a L-CDR3 having a sequence set forth as SEQ ID NO:30 (“3D7 derivative”).

The present invention thus provides antibodies comprising functional variants of the VL region, VH region, or one or more CDRs of 2C1, 2F9, 3D7, 3H6. A functional variant of a VL, VH, or CDR used in the context of a monoclonal antibody of the present invention still allows the antibody to retain at least a substantial proportion (at least about 50%, 60%, 70%, 80%, 90%, 95% or more) of the affmity/avidity and/or the specificity/selectivity of the parent antibody (i.e. [Ab name] antibody) and in some cases such a monoclonal antibody of the present invention may be associated with greater affinity, selectivity and/or specificity than the parent Ab. Such variants can be obtained by a number of affinity maturation protocols including mutating the CDRs (Yang et al, J. Mol. Biol., 254, 392-403, 1995), chain shuffling (Marks et al, Bio/Technology, 10, 779-783, 1992), use of mutator strains of E. coli (Low et al, J. Mol. Biol., 250, 359-368, 1996), DNA shuffling (Patten et al, Curr. Opin. Biotechnol, 8, 724-733, 1997), phage display (Thompson et al., J. Mol. Biol., 256, 77-88, 1996) and sexual PCR (Crameri et al, Nature, 391, 288-291, 1998). Vaughan et al. (supra) discusses these methods of affinity maturation. Such functional variants typically retain significant sequence identity to the parent Ab. The sequence of CDR variants may differ from the sequence of the CDR of the parent antibody sequences through mostly conservative substitutions; for instance at least about 35%, about 50% or more, about 60% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, (e.g., about 65-95%, such as about 92%, 93% or 94%) of the substitutions in the variant are conservative amino acid residue replacements. The sequences of CDR variants may differ from the sequence of the CDRs of the parent antibody sequences through mostly conservative substitutions; for instance at least 10, such as at least 9, 8, 7, 6, 5, 4, 3, 2 or 1 of the substitutions in the variant are conservative amino acid residue replacements. In the context of the present invention, conservative substitutions may be defined by substitutions within the classes of amino acids reflected as follows: Aliphatic residues I, L, V, and M Cycloalkenyl-associated residues F, H, W, and Y Hydrophobic residues A, C, F, G, H, I, L, M, R, T, V, W, and Y Negatively charged residues D and E Polar residues C, D, E, H, K, N, Q, R, S, and T Positively charged residues H, K, and R Small residues A, C, D, G, N, P, S, T, and V Very small residues A, G, and S

Residues involved in turn A, C, D, E, G, H, K, N, Q, R, S, P, and formation T Flexible residues Q, T, K, S, G, P, D, E, and R

More conservative substitutions groupings include: valine-leucine-isoleucine, phenylalanine-tyrosine, lysine-arginine, alanine-valine, and asparagine-glutamine. Conservation in terms of hydropathic/hydrophilic properties and residue weight/size also is substantially retained in a variant CDR as compared to a CDR of the antibody of the invention, e.g 2C1, 2F9, 3H6, 3D7, 2C1-12G4, 2F9-12G4, 3H6-12G4 or 3D7-12G4.The importance of the hydropathic amino acid index in conferring interactive biologic function on a protein is generally understood in the art. It is accepted that the relative hydropathic character of the amino acid contributes to the secondary structure of the resultant protein, which in turn defines the interaction of the protein with other molecules, for example, enzymes, substrates, receptors, DNA, antibodies, antigens, and the like. Each amino acid has been assigned a hydropathic index on the basis of their hydrophobicity and charge characteristics these are: isoleucine (+4.5); valine (+4.2); leucine (+3.8) ; phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (-0.4); threonine (-0.7); serine (-0.8); tryptophane (-0.9); tyrosine (-1.3); proline (-1.6); histidine (-3.2); glutamate (-3.5); glutamine (-3.5); aspartate (-3.5); asparagine (- 3.5); lysine (-3.9); and arginine (-4.5). The retention of similar residues may also or alternatively be measured by a similarity score, as determined by use of a BLAST program (e.g., BLAST 2.2.8 available through the NCBI using standard settings BLOSUM62, Open Gap= 1 1 and Extended Gap= 1). Suitable variants typically exhibit at least about 70% of identity to the parent peptide.

Thus, in some embodiment, the isolated anti-MISRI antibody comprises: (a) a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO:7; and a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO: 8 (“2C1 derivative”); or

(b) a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO: 15; and a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO: 16 (“2F9 derivative”); or

(c) a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO:23; and a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO:24 (“3H6 derivative”); or

(d) a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO: 31 ; and a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO:32 (“3D7 derivative”).

In some embodiment, the isolated anti-MISRI antibody comprises:

(a) - a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO:7 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 1; a H-CDR2 having a sequence set forth as SEQ ID NO:2; a H-CDR3 having a sequence set forth as SEQ ID NO:3; and

- a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO:8 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:4; a H-CDR2 having a sequence set forth as SEQ ID NO:5; a H-CDR3 having a sequence set forth as SEQ ID NO: 6 (“2C1 derivative”); or

(b) - a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO: 15 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 9; a H-CDR2 having a sequence set forth as SEQ ID NO: 10; a H-CDR3 having a sequence set forth as SEQ ID NO: 11; and

- a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO: 16 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 12; a H-CDR2 having a sequence set forth as SEQ ID NO: 13; a H-CDR3 having a sequence set forth as SEQ ID NO: 14 (“2F9 derivative”); or

(c) - a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO:23 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 17; a H-CDR2 having a sequence set forth as SEQ ID NO: 18; a H-CDR3 having a sequence set forth as SEQ ID NO: 19; and - a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO:24 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:20; a H-CDR2 having a sequence set forth as SEQ ID NO:21; a H-CDR3 having a sequence set forth as SEQ ID NO:22 (“3H6 derivative”); or

(d) - a variable heavy chain having at least 70% identity with a sequence set forth as

SEQ ID NO:31 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:25; a H-CDR2 having a sequence set forth as SEQ ID NO:26; a H-CDR3 having a sequence set forth as SEQ ID NO:27; and

- a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO:32 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:28; a H-CDR2 having a sequence set forth as SEQ ID NO:29; a H-CDR3 having a sequence set forth as SEQ ID NO:30 (“3D7 derivative”).

In some embodiment, the isolated anti-MISRI antibody comprises:

(a) a variable heavy chain having a sequence set forth as SEQ ID NO: 7; and a variable light chain having a sequence set forth as SEQ ID NO: 8 (“20 derivative”); or

(b) a variable heavy chain having a sequence set forth as SEQ ID NO: 15; and a variable light chain having a sequence set forth as SEQ ID NO: 16 (“2F9 derivative”); or

(c) a variable heavy chain having a sequence set forth as SEQ ID NO:23; and a variable light chain having a sequence set forth as SEQ ID NO:24 (“3H6 derivative”); or

(d) a variable heavy chain having a sequence set forth as SEQ ID NO:31; and a variable light chain having a sequence set forth as SEQ ID NO:32 (“3D7 derivative”).

The antibodies of the present invention are produced by any technique known in the art, such as, without limitation, any chemical, biological, genetic or enzymatic technique, either alone or in combination. Typically, knowing the amino acid sequence of the desired sequence, one skilled in the art can readily produce said antibodies, by standard techniques for production of polypeptides. For instance, they can be synthesized using well-known solid phase method, preferably using a commercially available peptide synthesis apparatus (such as that made by Applied Biosystems, Foster City, California) and following the manufacturer’s instructions. Alternatively, antibodies of the present invention can be synthesized by recombinant DNA techniques well-known in the art. For example, antibodies can be obtained as DNA expression products after incorporation of DNA sequences encoding the antibodies into expression vectors and introduction of such vectors into suitable eukaryotic or prokaryotic hosts that will express the desired antibodies, from which they can be later isolated using well-known techniques.

In some embodiment, the antibody of the invention is a monoclonal antibody.

In another embodiment, the monoclonal antibody of the invention is a humanized antibody. In particular, in said humanized antibody, the variable domain comprises human acceptor frameworks regions, and optionally human constant domain where present, and non human donor CDRs, such as mouse CDRs.

According to the invention, the term "humanized antibody" refers to an antibody having variable region framework and constant regions from a human antibody but retains the CDRs of a previous non-human antibody.

The humanized antibody of the present invention may be produced by obtaining nucleic acid sequences encoding CDR domains, as previously described, constructing a humanized antibody expression vector by inserting them into an expression vector for animal cell having genes encoding (i) a heavy chain constant region identical to that of a human antibody and (ii) a light chain constant region identical to that of a human antibody, and expressing the genes by introducing the expression vector into an animal cell. The humanized antibody expression vector may be either of a type in which a gene encoding an antibody heavy chain and a gene encoding an antibody light chain exists on separate vectors or of a type in which both genes exist on the same vector (tandem type). In respect of easiness of construction of a humanized antibody expression vector, easiness of introduction into animal cells, and balance between the expression levels of antibody H and L chains in animal cells, humanized antibody expression vector of the tandem type is preferred. Examples of tandem type humanized antibody expression vector include pKANTEX93 (WO 97/10354), pEE18 and the like. Methods for producing humanized antibodies based on conventional recombinant DNA and gene transfection techniques are well known in the art (See, e. g., Riechmann L. et al. 1988; Neuberger MS. et al. 1985). Antibodies can be humanized using a variety of techniques known in the art including, for example, CDR-grafting (EP 239,400; PCT publication WO91/09967; U.S. Pat. Nos. 5,225,539; 5,530,101; and 5,585,089), veneering or resurfacing (EP 592,106; EP 519,596; Padlan EA (1991); Studnicka GM et al. (1994); Roguska MA. et al. (1994)), and chain shuffling (U.S. Pat. No.5, 565, 332). The general recombinant DNA technology for preparation of such antibodies is also known (see European Patent Application EP 125023 and International Patent Application WO 96/02576).

In some embodiments the monoclonal antibody of the invention is a human antibody. As used herein the term "human antibody is intended to include antibodies having variable and constant regions derived from human immunoglobulin sequences. The human antibodies of the present invention may include amino acid residues not encoded by human immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo). However, the term "human antibody", as used herein, is not intended to include antibodies in which CDR sequences derived from the germline of another mammalian species, such as a mouse, have been grafted onto human framework sequences.

Human antibodies can be produced using various techniques known in the art. Human antibodies are described generally in van Dijk and van de Winkel, cur. Opin. Pharmacol. 5; 368-74 (2001) and Lonberg, cur. Opin. Immunol. 20; 450-459 (2008). Human antibodies may be prepared by administering an immunogen to a transgenic animal that has been modified to produce intact human antibodies or intact antibodies with human variable regions in response to antigenic challenge. Such animals typically contain all or a portion of the human immunoglobulin loci, or which are present extrachromosomally or integrated randomly into the animal’s chromosomes. In such transgenic mice, the endogenous immunoglobulin loci have generally been inactivated. For review of methods for obtaining human antibodies from transgenic animals, see Lonberg, Nat.Biotech. 23; 1117-1125 (2005). See also, e.g., U.S. Patent Nos. 6,075,181 and 6,150,584 describing XENOMOUSE™ technology; U.S. Patent No. 5,770,429 describing HUMAB^® technology; U.S. Patent No. 7,041,870 describing K-M MOUSE^® technology, and U.S. Patent Application publication No. US 2007/0061900, describing VELOCIMOUSE^® technology. Human variable regions from intact antibodies generated by such animals may be further modified, e.g., by combining with a different human constant region Human antibodies can also be made by hybridoma-based methods. Human myeloma and mouse-human heteromyeloma cell lines for the production of human monoclonal antibodies have been described. (See, e.g., Kozbor J. Immunol., 13: 3001 (1984); Brodeur et al, Monoclonal Antibody Production Techniques and Applications, pp. 51-63 (Marcel Dekker, Inc., New York, 1987); and Boerner et al., J. Immunol., 147: 86(1991).) Human antibodies generated via human B-cell hybridoma technology are also described in Li et al, Proc. Natl. Acad. Sci. USA, 103:3557-3562 (2006). Additional methods include those described, for example, in U.S. Patent No. 7,189,826 (describing production of monoclonal human igM antibodies from hybridoma cell lines) and Ni, Xiandai Mianyixue, 26(4):265-268 (2006) (describing human-human hybridomas). Human hybridoma technology (Trioma technology) is also described in Vollmers and Brandlein,, Histology and Histopathology, 20(3): 927-937 (2005) and Vollmers and Brandlein, Methods and Findings in Experimental and Clinical Pharmacology, 27(3): 185-91 (2005). Fully human antibodies can also be derived from phage- display libraries (as disclosed in Hoogenboom et al., 1991, J. Mol. Biol. 227:381; and Marks et al, 1991, J. Mol. Biol. 222:581). Phage display techniques mimic immune selection through the display of antibody repertoires on the surface of filamentous bacteriophage, and subsequent selection of phage by their binding to an antigen of choice. One such technique is described in PCT publication No. WO 99/10494. Human antibodies described herein can also be prepared using SCID mice into which human immune cells have been reconstituted such that a human antibody response can be generated upon immunization. Such mice are described in, for example, U.S. Patent Nos. 5,476,996 and 5,698,767 to Wilson et al.

In one embodiment, the antibody of the invention is an antigen binding fragment selected from the group consisting of a Fab, a F(ab’)2, a single domain antibody, a ScFv, a Sc(Fv)2, a diabody, a triabody, a tetrabody, an unibody, a minibody, a maxibody, a small modular immunopharmaceutical (SMIP), minimal recognition units consisting of the amino acid residues that mimic the hypervariable region of an antibody as an isolated complementary determining region (CDR), and fragments which comprise or consist of: the VL as well as amino acid sequence having at least 70% of identity with sequence selected from the group consisting of SEQ ID NO:7, SEQ ID NO: 16, SEQ ID NO:25 and SEQ ID NO:34; or the VH chains as well as amino acid sequence having at least 70% of identity with sequence selected from the group consisting of SEQ ID NO:8, SEQ ID NO: 17, SEQ ID NO:26 and SEQ ID NO:35.

The term “antigen binding fragment” of an antibody, as used herein, refers to one or more fragments of an intact antibody that retain the ability to specifically binds to a given antigen (e.g., MISRI). Antigen binding functions of an antibody can be performed by fragments of an intact antibody. Examples of binding fragments encompassed within the term antigen binding fragment of an antibody include a Fab fragment, a monovalent fragment consisting of the VL,VH,CL and CHI domains; a Fab’ fragment, a monovalent fragment consisting of the VL,VH,CL,CH1 domains and hinge region; a F(ab’)2 fragment, a bivalent fragment comprising two Fab’ fragments linked by a disulfide bridge at the hinge region; an Fd fragment consisting of VH domains of a single arm of an antibody; a single domain antibody (sdAb) fragment (Ward et al, 1989 Nature 341:544-546), which consists of a VH domain or a VL domain; and an isolated complementary determining region (CDR). Furthermore, although the two domains of the Fv fragment, VL and VH, are coded for by separate genes, they can be joined, using recombinant methods, by an artificial peptide linker that enables them to be made as a single protein chain in which the VL and VH regions pair to form monovalent molecules (known as single chain Fv (ScFv); see, e.g., Bird et ah, 1989 Science 242:423-426; and Huston et ah, 1988 proc. Natl. Acad. Sci. 85:5879-5883). "dsFv" is a VH::VL heterodimer stabilised by a disulfide bond. Divalent and multivalent antibody fragments can form either spontaneously by association of monovalent scFvs, or can be generated by coupling monovalent scFvs by a peptide linker, such as divalent sc(Fv)2. Such single chain antibodies include one or more antigen binding portions or fragments of an antibody. These antibody fragments are obtained using conventional techniques known to those skilled in the art, and the fragments are screened for utility in the same manner as are intact antibodies. A unibody is another type of antibody fragment lacking the hinge region of IgG4 antibodies. The deletion of the hinge region results in a molecule that is essentially half the size of traditional IgG4 antibodies and has a univalent binding region rather than the bivalent binding region of IgG4 antibodies. Antigen binding fragments can be incorporated into single domain antibodies, SMTP, maxibodies, minibodies, intrabodies, diabodies, triabodies and tetrabodies (see, e.g., Hollinger and Hudson, 2005, Nature Biotechnology, 23, 9, 1126-1136). The term "diabodies" “tribodies” or “tetrabodies” refers to small antibody fragments with multivalent antigen-binding sites (2, 3 or four), which fragments comprise a heavy-chain variable domain (VH) connected to a light-chain variable domain (VL) in the same polypeptide chain (VH-VL). By using a linker that is too short to allow pairing between the two domains on the same chain, the domains are forced to pair with the complementary domains of another chain and create two antigen-binding sites. Antigen binding fragments can be incorporated into single chain molecules comprising a pair of tandem Fv segments (VH-CHl-VH-CHl) which, together with complementary light chain polypeptides, form a pair of antigen binding regions (Zapata et al, 1995 Protein Eng. 8(10); 1057-1062 and U.S. Pat. No. 5,641,870).

The Fab of the present invention can be obtained by treating an antibody which specifically reacts with MISRI with a protease, papaine. Also, the Fab can be produced by inserting DNA encoding Fab of the antibody into a vector for prokaryotic expression system, or for eukaryotic expression system, and introducing the vector into a procaryote or eucaryote (as appropriate) to express the Fab.

The F(ab')2 of the present invention can be obtained treating an antibody which specifically reacts with MISRI with a protease, pepsin. Also, the F(ab')2 can be produced by binding Fab' described below via a thioether bond or a disulfide bond. The Fab' of the present invention can be obtained treating F(ab')2 which specifically reacts with MISRI with a reducing agent, dithiothreitol. Also, the Fab' can be produced by inserting DNA encoding Fab' fragment of the antibody into an expression vector for prokaryote, or an expression vector for eukaryote, and introducing the vector into a prokaryote or eukaryote (as appropriate) to perform its expression.

The scFv of the present invention can be produced by obtaining cDNA encoding the VH and VL domains as previously described, constructing DNA encoding scFv, inserting the DNA into an expression vector for prokaryote, or an expression vector for eukaryote, and then introducing the expression vector into a prokaryote or eukaryote (as appropriate) to express the scFv. To generate a humanized scFv fragment, a well-known technology called CDR grafting may be used, which involves selecting the complementary determining regions (CDRs) from a donor scFv fragment, and grafting them onto a human scFv fragment framework of known three dimensional structure (see, e. g., W098/45322; WO 87/02671; US5,859,205; US5,585,089; US4,816,567; EP0173494).

Domain Antibodies (dAbs) are the smallest functional binding units of antibodies - molecular weight approximately 13 kDa - and correspond to the variable regions of either the heavy (VH) or light (VL) chains of antibodies. Further details on domain antibodies and methods of their production are found in US 6,291,158; 6,582,915; 6,593,081; 6,172,197; and 6,696,245; US 2004/0110941; EP 1433846, 0368684 and 0616640; WO 2005/035572, 2004/101790, 2004/081026, 2004/058821, 2004/003019 and 2003/002609, each of which is herein incorporated by reference in its entirety.

UniBodies are another antibody fragment technology, based upon the removal of the hinge region of IgG4 antibodies. The deletion of the hinge region results in a molecule that is essentially half the size of a traditional IgG4 antibody and has a univalent binding region rather than a bivalent binding region. Furthermore, because UniBodies are about smaller, they may show better distribution over larger solid tumors with potentially advantageous efficacy. Further details on UniBodies may be obtained by reference to WO 2007/059782, which is incorporated by reference in its entirety.

A further aspect to the invention refers to a cross-competing antibody which cross- competes for binding MISRI with the antibody of the invention.

In some embodiment, the cross-competing antibody of the present invention cross- competes for binding MISRI with the antibody comprising: (a) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 1; a H-CDR2 having a sequence set forth as SEQ ID NO:2; a H-CDR3 having a sequence set forth as SEQ ID NO:3; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:4; a L-CDR2 having a sequence set forth as SEQ ID NO: 5; a L-CDR3 having a sequence set forth as SEQ ID NO: 6 (“2C1 derivative”); or

(b) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 9; a H-CDR2 having a sequence set forth as SEQ ID NO: 10; a H-CDR3 having a sequence set forth as SEQ ID NO: 11; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO: 12; a L-CDR2 having a sequence set forth as SEQ ID NO: 13; a L-CDR3 having a sequence set forth as SEQ ID NO: 14 (“2F9 derivative”); or

(c) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 17; a H-CDR2 having a sequence set forth as SEQ ID NO: 18; a H-CDR3 having a sequence set forth as SEQ ID NO: 19; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:20; a L-CDR2 having a sequence set forth as SEQ IDNO:21; aL-CDR3 having a sequence set forth as SEQ IDNO:22 (“3H6 derivative”); or

(d) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:25; a H-CDR2 having a sequence set forth as SEQ ID NO:26; a H-CDR3 having a sequence set forth as SEQ ID NO:27; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:28; a L-CDR2 having a sequence set forth as SEQ ID NO:29; a L-CDR3 having a sequence set forth as SEQ ID NO:30 (“3D7 derivative”).

In some embodiment, the cross-competing antibody of the present invention cross- competes for binding MISRI with the antibody comprising

(d) a variable heavy chain having a sequence set forth as SEQ ID NO:31; and a variable light chain having a sequence set forth as SEQ ID NO:32 (“3D7 derivative”). As used herein, the term “cross-competes” refers to antibodies which share the ability to bind to a specific region of an antigen. In the present disclosure the antibody that “cross- competes" has the ability to interfere with the binding of another antibody for the antigen in a standard competitive binding assay. Such antibody may, according to non-limiting theory, bind to the same or a related or nearby (e.g., a structurally similar or spatially proximal) epitope as the antibody with which it competes. Cross-competition is present if antibody A reduces binding of antibody B at least by 60%, specifically at least by 70% and more specifically at least by 80% and vice versa in comparison to the positive control which lacks one of said antibodies. As the skilled artisan appreciates competition may be assessed in different assay set-ups. One suitable assay involves the use of the Biacore technology (e.g., by using the BIAcore 3000 instrument (Biacore, Uppsala, Sweden)), which can measure the extent of interactions using surface plasmon resonance technology. Another assay for measuring cross competition uses an ELISA-based approach. Furthermore, a high throughput process for "binning" antibodies based upon their cross-competition is described in International Patent Application No. WO2003/48731.

Engineered antibodies of the invention include those in which modifications have been made to framework residues within VH and/or VL, e.g. to improve the properties of the antibody. Typically such framework modifications are made to decrease the immunogenicity of the antibody. For example, one approach is to "backmutate" one or more framework residues to the corresponding germline sequence. More specifically, an antibody that has undergone somatic mutation may contain framework residues that differ from the germline sequence from which the antibody is derived. Such residues can be identified by comparing the antibody framework sequences to the germline sequences from which the antibody is derived. To return the framework region sequences to their germline configuration, the somatic mutations can be "backmutated" to the germline sequence by, for example, site-directed mutagenesis or PCR- mediated mutagenesis. Such "backmutated" antibodies are also intended to be encompassed by the invention. Another type of framework modification involves mutating one or more residues within the framework region, or even within one or more CDR regions, to remove T cell - epitopes to thereby reduce the potential immunogenicity of the antibody. This approach is also referred to as "deimmunization" and is described in further detail in U.S. Patent Publication No. 20030153043 by Carr et al.

In some embodiments, the glycosylation of an antibody is modified. Glycosylation can be altered to, for example, increase the affinity of the antibody for the antigen. Such carbohydrate modifications can be accomplished by, for example, altering one or more sites of glycosylation within the antibody sequence. For example, one or more amino acid substitutions can be made that result in elimination of one or more variable region framework glycosylation sites to thereby eliminate glycosylation at that site. Such aglycosylation may increase the affinity of the antibody for antigen. Such an approach is described in further detail in U. S. Patent Nos. 5,714,350 and 6,350,861 by Co et al.

In some embodiments, some mutations are made to the amino acids localized in aggregation “hotspots” within and near the first CDR (CDR1) to decrease the antibodies susceptibility to aggregation (see Joseph M. Perchiacca et al., Proteins 2011; 79:2637-2647).

In another embodiment, the antibody is modified to increase its biological half-life. Various approaches are possible. For example, one or more of the following mutations can be introduced: T252L, T254S, T256F, as described in U.S. Patent No. 6,277,375 by Ward. Alternatively, to increase the biological half-life, the antibody can be altered within the CHI or CL region to contain a salvage receptor binding epitope taken from two loops of a CH2 domain of an Fc region of an IgG, as described in U.S. Patent Nos. 5,869,046 and 6,121 ,022 by Presta et al. Antibodies with increased half-lives and improved binding to the neonatal Fc receptor (FcRn), which is responsible for the transfer of maternal IgGs to the foetus (Guyer et al, J. Immunol. 117:587 (1976) and Kim et al, J. immunol. 24:249 (1994)), are described in US2005/0014934A1 (Hinton et al). Those antibodies comprise an Fc region with one or more substitutions therein which improve binding of the Fc region to FcRn. Such Fc variants include those with substitutions at one or more of Fc region residues: 238, 256, 265, 272, 286, 303, 305, 307, 311,312, 317, 340, 356, 360, 362, 376, 378, 380, 382, 413, 424, or 434, e.g., substitutions ofFc region residue 434 (US Patent No. 7,371,826).

Another modification of the antibodies herein that is contemplated by the invention is pegylation. An antibody can be pegylated to, for example, increase the biological (e.g., serum) half-life of the antibody. To pegylate an antibody, the antibody, or fragment thereof, typically is reacted with polyethylene glycol (PEG), such as a reactive ester or aldehyde derivative of PEG, under conditions in which one or more PEG groups become attached to the antibody or antibody fragment. The pegylation can be carried out by an acylation reaction or an alkylation reaction with a reactive PEG molecule (or an analogous reactive water-soluble polymer). As used herein, the term "polyethylene glycol" is intended to encompass any of the forms of PEG that have been used to derivatize other proteins, such as mono (Cl- CIO) alkoxy- or aryloxy- polyethylene glycol or polyethylene glycol-maleimide. In certain embodiments, the antibody to be pegylated is an aglycosylated antibody. Methods for pegylating proteins are known in the art and can be applied to the antibodies of the invention. See for example, EP0154316 by Nishimura et al. and EP0401384 by Ishikawa et al.

Another modification of the antibodies that is contemplated by the invention is a conjugate or a protein fusion of at least the antigen-binding region of the antibody of the invention to serum protein, such as human serum albumin or a fragment thereof to increase half-life of the resulting molecule. Such approach is for example described in Ballance et al. EP0322094. Another possibility is a fusion of at least the antigen-binding region of the antibody of the invention to proteins capable of binding to serum proteins, such human serum albumin to increase half-life of the resulting molecule. Such approach is for example described in Nygren et al, EP 0 486 525.

Polysialytion is another technology, which uses the natural polymer polysialic acid (PSA) to prolong the active life and improve the stability of therapeutic peptides and proteins. PSA is a polymer of sialic acid (a sugar). When used for protein and therapeutic peptide drug delivery, polysialic acid provides a protective microenvironment on conjugation. This increases the active life of the therapeutic protein in the circulation and prevents it from being recognized by the immune system. The PSA polymer is naturally found in the human body. It was adopted by certain bacteria which evolved over millions of years to coat their walls with it. These naturally polysialylated bacteria were then able, by virtue of molecular mimicry, to foil the body's defense system. PSA, nature's ultimate stealth technology, can be easily produced from such bacteria in large quantities and with predetermined physical characteristics. Bacterial PSA is completely non-immunogenic, even when coupled to proteins, as it is chemically identical to PSA in the human body.

Another technology includes the use of hydroxy ethyl starch ("HES") derivatives linked to antibodies. HES is a modified natural polymer derived from waxy maize starch and can be metabolized by the body's enzymes. HES solutions are usually administered to substitute deficient blood volume and to improve the rheological properties of the blood. Hesylation of an antibody enables the prolongation of the circulation half-life by increasing the stability of the molecule, as well as by reducing renal clearance, resulting in an increased biological activity. By varying different parameters, such as the molecular weight of HES, a wide range of HES antibody conjugates can be customized.

Multispecific antibody of the invention

Based on their findings on MIS signaling and their knowledge of bispecific antibodies (BsAbs), the inventors constructed bispecific antibodies (BsAbs) in order to confer a greater affinity for the MISRII receptor since it targets specifically the ligand and is the marker of ovarian cancers cell. They demonstrate that targeting of MISRII and Alk3 would be pro- apoptotic if the Alk3 antibody is agonist of this pathway or pro-proliferative if it is antagonist. Alk2 being more involved in cell survival, it would be necessary, in the BsAb targeting of MISRII and ALK2, to have an anti-Alk2 antagonist antibody to lead to cell death.

Thus, a further aspect of the invention refers to a multispecific antibody comprising a first antigen-binding site from an anti-MISRI monoclonal antibody and at least one second antigen binding site.

In some embodiment, the multispecific antibody of the invention is a bispecific antibody.

In some embodiment, the second antigen is mullerian inhibiting substance type II receptor (MISRII).

Thus, the present invention refers to a bispecific antibody comprising a first Fab from an anti-MISRI antibody and a second Fab from an anti-MISRII antibody.

In some embodiment, the bispecific antibody has a stronger affinity with MISRII than

MISRI.

Thus, in some embodiment, the bispecific antibody comprises a first Fab from an anti- MISRI antibody and a second Fab from an anti-MISRII antibody, wherein the bispecific antibody has a stronger affinity for MISRII than MISRI.

In the present invention, “stronger affinity” means at least a two times greater affinity.

According to the invention, a bispecific antibody having a stronger affinity with MISRII than MISRI means that the bispecific antibody bind in the first place and specifically with MISRII before to bind MISRI in order to ensure a specific targeting on AMHRII positive cells and to limit the binding on ALK2 positives and/or ALK3 positives cells which are MISRII negatives. Indeed, MISRII is the tumor specific receptor whereas ALK2/ALK3 are expressed in many different cell types.

In some embodiment, the anti-MISRI antibody is an anti-ALK2 antagonist antibody or an ALK3 agonist antibody.

In some embodiment, the anti-MISRI antibody is an anti-ALK2 antagonist monoclonal antibody or an ALK3 agonist monoclonal antibody. In some embodiment, the bispecific antibody comprises a first Fab from an anti-ALK2 antagonist monoclonal antibody and a second Fab from an anti-MISRII antibody, wherein the bispecific antibody has a stronger affinity for MISRII than ALK2.

In some embodiment, the bispecific antibody comprises a first Fab from an ALK3 agonist monoclonal antibody and a second Fab from an anti-MISRII antibody, wherein the bispecific antibody has a stronger affinity for MISRII than ALK3.

In some embodiment, the bispecific antibody comprises a first Fab from an anti-MISRI antibody of the invention and a second Fab from an anti-MISRII antibody, wherein the bispecific antibody has a stronger affinity for MISRII than MISRI.

In some embodiment, the bispecific antibody comprises a first Fab from the anti-MISRI antibody selected from the group consisting in 2C1, 2F9, 3D7, 3H6 and their derivatives as described above; and a second Fab from an anti-MISRII antibody, wherein the bispecific antibody has a stronger affinity for MISRII than MISRI.

In some embodiment, the second Fab comprises a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:33; a H-CDR2 having a sequence set forth as SEQ ID NO:34; a H-CDR3 having a sequence set forth as SEQ ID NO:35; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO: 36; a L-CDR2 having a sequence set forth as SEQ ID NO: 37; a L- CDR3 having a sequence set forth as SEQ ID NO:38.

Thus, in some embodiment the bispecific antibody comprises a first Fab from the anti- MISRI antibody selected from the group consisting in 2C1, 2F9, 3D7, 3H6 and their derivatives as described above; and a second Fab comprising a H-CDR1 having a sequence set forth as SEQ ID NO:33; a H-CDR2 having a sequence set forth as SEQ ID NO:34; a H-CDR3 having a sequence set forth as SEQ ID NO:35; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO: 36; a L-CDR2 having a sequence set forth as SEQ ID NO: 37; a L-CDR3 having a sequence set forth as SEQ ID NO: 38, wherein the bispecific antibody has a stronger affinity for MISRII than MISRI.

In some embodiment, the second Fab comprises a) a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO:39, wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:33; a H-CDR2 having a sequence set forth as SEQ ID NO:34; a H-CDR3 having a sequence set forth as SEQ ID NO:35; and b) a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO:40 wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 36; a H-CDR2 having a sequence set forth as SEQ ID NO: 37; a H-CDR3 having a sequence set forth as SEQ ID NO:38.

In some embodiment, the second Fab comprises a variable heavy chain having a sequence set forth as SEQ ID NO: 39; and a variable light chain having a sequence set forth as SEQ ID NO:40

Exemplary formats for the multispecific antibody molecules of the invention include, but are not limited to (i) two antibodies cross-linked by chemical heteroconjugation, one with a specificity to MISRI and another with a specificity to a second antigen, e.g MISRII; (ii) a single antibody that comprises two different antigen-binding regions; (iii) a single-chain antibody that comprises two different antigen-binding regions, e.g., two scFvs linked in tandem by an extra peptide linker; (iv) a dual-variable-domain antibody (DVD-Ig), where each light chain and heavy chain contains two variable domains in tandem through a short peptide linkage (Wu et ak, Generation and Characterization of a Dual Variable Domain Immunoglobulin (DVD-Ig™) Molecule, In : Antibody Engineering, Springer Berlin Heidelberg (2010)); (v) a chemically-linked bispecific (Fab')2 fragment; (vi) a Tandab, which is a fusion of two single chain diabodies resulting in a tetravalent bispecific antibody that has two binding sites for each of the target antigens; (vii) a flexibody, which is a combination of scFvs with a diabody resulting in a multivalent molecule; (viii) a so called "dock and lock" molecule, based on the "dimerization and docking domain" in Protein Kinase A, which, when applied to Fabs, can yield a trivalent bispecific binding protein consisting of two identical Fab fragments linked to a different Fab fragment; (ix) a so-called Scorpion molecule, comprising, e.g., two scFvs fused to both termini of a human Fab-arm; and (x) a diabody. Another exemplary format for bispecific antibodies is IgG-like molecules with complementary CH3 domains to force heterodimerization. Such molecules can be prepared using known technologies, such as, e.g., those known as Triomab/Quadroma (Trion Pharma/Fresenius Biotech), Knob-into-Hole (Genentech), CrossMAb (Roche) and electrostatically-matched (Amgen), LUZ-Y (Genentech), Strand Exchange Engineered Domain body (SEEDbody)(EMD Serono), Biclonic (Merus) and DuoBody (Genmab A/S) technologies.

In some embodiments, the bispecific antibody is obtained or obtainable via a controlled Fab-arm exchange, typically using DuoBody technology. In vitro methods for producing bispecific antibodies by controlled Fab-arm exchange have been described in W02008119353 and WO 2011131746 (both by Genmab A/S). In one exemplary method, described in WO 2008119353, a bispecific antibody is formed by "Fab-arm" or "half- molecule" exchange (swapping of a heavy chain and attached light chain) between two monospecific antibodies, both comprising IgG4-like CH3 regions, upon incubation under reducing conditions. The resulting product is a bispecific antibody having two Fab arms which may comprise different sequences. In another exemplary method, described in WO 2011131746, bispecific antibodies of the present invention are prepared by a method comprising the following steps, wherein at least one of the first and second antibodies is the antibody of the present invention : a) providing a first antibody comprising an Fc region of an immunoglobulin, said Fc region comprising a first CH3 region; b) providing a second antibody comprising an Fc region of an immunoglobulin, said Fc region comprising a second CH3 region; wherein the sequences of said first and second CH3 regions are different and are such that the heterodimeric interaction between said first and second CH3 regions is stronger than each of the homodimeric interactions of said first and second CH3 regions; c) incubating said first antibody together with said second antibody under reducing conditions; and d) obtaining said bispecific antibody, wherein the first antibody is the antibody of the present invention and the second antibody has a different binding specificity, or vice versa. The reducing conditions may, for example, be provided by adding a reducing agent, e.g. selected from 2-mercaptoethylamine, dithiothreitol and tris(2- carboxyethyl)phosphine. Step d) may further comprise restoring the conditions to become non reducing or less reducing, for example by removal of a reducing agent, e.g. by desalting. Preferably, the sequences of the first and second CH3 regions are different, comprising only a few, fairly conservative, asymmetrical mutations, such that the heterodimeric interaction between said first and second CH3 regions is stronger than each of the homodimeric interactions of said first and second CH3 regions. More details on these interactions and how they can be achieved are provided in WO 2011131746, which is hereby incorporated by reference in its entirety. The following are exemplary embodiments of combinations of such assymetrical mutations, optionally wherein one or both Fc-regions are of the IgGl isotype.

In some embodiments, the first Fc region has an amino acid substitution at a position selected from the group consisting of: 366, 368, 370, 399, 405, 407 and 409, and the second Fc region has an amino acid substitution at a position selected from the group consisting of: 366, 368, 370, 399, 405, 407 and 409, and wherein the first and second Fc regions are not substituted in the same positions.

In some embodiments, the first Fc region has an amino acid substitution at position 405, and said second Fc region has an amino acid substitution at a position selected from the group consisting of: 366, 368, 370, 399, 407 and 409, optionally 409. In some embodiments, the first Fc region has an amino acid substitution at position 409, and said second Fc region has an amino acid substitution at a position selected from the group consisting of: 366, 368, 370, 399, 405, and 407, optionally 405 or 368.

In some embodiments, both the first and second Fc regions are of the IgGl isotype, with the first Fc region having a Leu at position 405, and the second Fc region having an Arg at position 409.

In some embodiments, the bispecific antibody is obtained or obtainable via a methods that maintains natural Fab structures of both original mAbs as well as full human Fc, described in Golay et al, 2016 (Golay et al, Design and Validation of a Novel Generic Platform for the Production of Tetravalent IgGl-like Bispecific Antibodies. J Immunol. 2016) and W02013005194.

In some embodiment, the bispecific antibodies of the present invention comprises Fab fragments having mutations at the interface of the CHI and CL domains, said mutations preventing heavy chain/light chain mispairing.

In some embodiment, the CHI domain of the Fab fragments has mutations selected from the group consisting in: substitution of the threonine residue at position 192 with a glutamic acid residue; substitution of the leucine residue at position 143 with a glutamine residue and substitution of the serine residue at position 188; substitution of the leucine residue at position 124 with an alanine residue and substitution of the leucine residue at position 143 with a glutamic acid residue; and substitution of the valine residue at position 190 with an alanine residue.

In some embodiment, the CL domain of the Fab fragments has mutations selected from the group consisting in: substitution asparagine residue at position 137 with a lysine residue and substitution of the serine residue at position 114 with an alanine residue; substitution of the valine residue at position 133 with a threonine residue and substitution of the serine residue at position 176 with an valine residue; substitution of the valine residue at position 133 with a tryptophane residue; and substitution of the leucine residue at position 135 with a tryptophane residue and substitution of the asparagine residue at position 137 with an alanine residue.

In some embodiment, the bispecific antibodies of the present invention comprises Fab fragments having mutations at the interface of the CHI and CL domains, said mutations preventing heavy chain/light chain mispairing and said Fab fragments being tandemly arranged in any order, the C-terminal end of the CHI domain of the first Fab fragment being linked to the N-terminal end of the VH domain of the following Fab fragment through a polypeptide linker. Generally, said polypeptide linker should have a length of at least 20, preferably at least 25, and still more preferably at least 30, and up to 80, preferably up to 60, and still more preferably up to 40 amino-acids.

Advantageously, said polypeptide linker comprises all or part of the sequence of the hinge region of one or more immunoglobulin(s) selected among IgA, IgG, and IgD.

In some embodiment, the polypeptide linker has a length of at least 20 amino-acids.

In some embodiment, the bi specific antibody of the invention has an immunoglobulin like structure.

Nucleic acids , vectors , recombinant host cells and uses thereof

As an alternative to automated peptide synthesis, recombinant DNA technology may be employed wherein a nucleotide sequence which encodes a protein of choice is inserted into an expression vector, transformed or transfected into an appropriate host cell and cultivated under conditions suitable for expression as described herein below. Recombinant methods are especially preferred for producing longer polypeptides.

A variety of expression vector/host systems may be utilized to contain and express the peptide or protein coding sequence. These include but are not limited to microorganisms such as bacteria transformed with recombinant bacteriophage, plasmid or cosmid DNA expression vectors; yeast transformed with yeast expression vectors (Giga-Hama et al., 1999); insect cell systems infected with virus expression vectors (e.g., baculovirus, see Ghosh et al., 2002); plant cell systems transfected with virus expression vectors (e.g., cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV) or transformed with bacterial expression vectors (e.g., Ti or pBR322 plasmid; see e.g., Babe et al., 2000); or animal cell systems. Those of skill in the art are aware of various techniques for optimizing mammalian expression of proteins, see e.g., Kaufman, 2000; Colosimo et al., 2000. Mammalian cells that are useful in recombinant protein productions include but are not limited to VERO cells, HeLa cells, Chinese hamster ovary (CHO) cell lines, COS cells (such as COS-7), W138, BHK, HepG2, 3T3, RIN, MDCK, A549, PC12, K562 and 293 cells. Exemplary protocols for the recombinant expression of the peptide substrates or fusion polypeptides in bacteria, yeast and other invertebrates are known to those of skill in the art and a briefly described herein below. Mammalian host systems for the expression of recombinant proteins also are well known to those of skill in the art. Host cell strains may be chosen for a particular ability to process the expressed protein or produce certain post-translation modifications that will be useful in providing protein activity. Such modifications of the polypeptide include, but are not limited to, acetylation, carboxylation, glycosylation, phosphorylation, lipidation and acylation. Post-translational processing which cleaves a "prepro" form of the protein may also be important for correct insertion, folding and/or function. Different host cells such as CHO, HeLa, MDCK, 293, WI38, and the like have specific cellular machinery and characteristic mechanisms for such post-translational activities and may be chosen to ensure the correct modification and processing of the introduced, foreign protein.

In the recombinant production of the antibodies and polypeptides of the invention, it would be necessary to employ vectors comprising polynucleotide molecules for encoding the antibodies and polypeptides of the invention. Methods of preparing such vectors as well as producing host cells transformed with such vectors are well known to those skilled in the art.

Accordingly, a further object of the invention relates to a nucleic acid molecule encoding an antibody according to the invention. More particularly the nucleic acid molecule encodes a heavy chain or a light chain of an antibody of the present invention.

Typically, said nucleic acid is a DNA or RNA molecule, which may be included in any suitable vector, such as a plasmid, cosmid, episome, artificial chromosome, phage or a viral vector.As used herein, the terms "vector", "cloning vector" and "expression vector" mean the vehicle by which a DNA or RNA sequence (e.g. a foreign gene) can be introduced into a host cell, so as to transform the host and promote expression (e.g. transcription and translation) of the introduced sequence. So, a further aspect of the invention relates to a vector comprising a nucleic acid of the invention. Such vectors may comprise regulatory elements, such as a promoter, enhancer, terminator and the like, to cause or direct expression of said antibody upon administration to a subject. Examples of promoters and enhancers used in the expression vector for animal cell include early promoter and enhancer of SV40 (Mizukami T. et al. 1987), LTR promoter and enhancer of Moloney mouse leukemia virus (Kuwana Y et al. 1987), promoter (Mason JO et al. 1985) and enhancer (Gillies SD et al. 1983) of immunoglobulin H chain and the like. Any expression vector for animal cell can be used, so long as a gene encoding the human antibody C region can be inserted and expressed. Examples of suitable vectors include pAGE107 (Miyaji H et al. 1990), pAGE103 (Mizukami T et al. 1987), pHSG274 (Brady G et al. 1984), pKCR (O'Hare K et al. 1981), pSGl beta d2-4-(Miyaji H et al. 1990) and the like. Other examples of plasmids include replicating plasmids comprising an origin of replication, or integrative plasmids, such as for instance pUC, pcDNA, pBR, and the like. Other examples of viral vector include adenoviral, retroviral, herpes virus and AAV vectors. Such recombinant viruses may be produced by techniques known in the art, such as by transfecting packaging cells or by transient transfection with helper plasmids or viruses. Typical examples of virus packaging cells include PA317 cells, PsiCRIP cells, GPenv+ cells, 293 cells, etc. Detailed protocols for producing such replication-defective recombinant viruses may be found for instance in WO 95/14785, WO 96/22378, US 5,882,877, US 6,013,516, US 4,861,719, US 5,278,056 and WO 94/19478.

The choice of a suitable expression vector for expression of the antibodies of the invention will of course depend upon the specific host cell to be used, and is within the skill of the ordinary artisan. Expression requires that appropriate signals be provided in the vectors, such as enhancers/promoters from both viral and mammalian sources that may be used to drive expression of the nucleic acids of interest in host cells. Usually, the nucleic acid being expressed is under transcriptional control of a promoter. A "promoter" refers to a DNA sequence recognized by the synthetic machinery of the cell, or introduced synthetic machinery, required to initiate the specific transcription of a gene. Nucleotide sequences are operably linked when the regulatory sequence functionally relates to the DNA encoding the protein of interest (e.g., a monoclonal antibody). Thus, a promoter nucleotide sequence is operably linked to a given DNA sequence if the promoter nucleotide sequence directs the transcription of the sequence.

A further aspect of the invention relates to a host cell which has been transfected, infected or transformed by a nucleic acid and/or a vector according to the invention.

The term "transformation" means the introduction of a "foreign" (i.e. extrinsic or extracellular) gene, DNA or RNA sequence to a host cell, so that the host cell will express the introduced gene or sequence to produce a desired substance, typically a protein or enzyme coded by the introduced gene or sequence. A host cell that receives and expresses introduced DNA or RNA has been "transformed".

The nucleic acids of the invention may be used to produce an antibody of the present invention in a suitable expression system. The term "expression system" means a host cell and compatible vector under suitable conditions, e.g. for the expression of a protein coded for by foreign DNA carried by the vector and introduced to the host cell. Common expression systems include E. coli host cells and plasmid vectors, insect host cells and Baculovirus vectors, and mammalian host cells and vectors. Other examples of host cells include, without limitation, prokaryotic cells (such as bacteria) and eukaryotic cells (such as yeast cells, mammalian cells, insect cells, plant cells, etc.). Specific examples include E.coli, Kluyveromyces or Saccharomyces yeasts, mammalian cell lines (e.g., Vero cells, CHO cells, 3T3 cells, COS cells, etc.) as well as primary or established mammalian cell cultures (e.g., produced from lymphoblasts, fibroblasts, embryonic cells, epithelial cells, nervous cells, adipocytes, etc.). Examples also include mouse SP2/0-Agl4 cell (ATCC CRL1581), mouse P3X63-Ag8.653 cell (ATCC CRL1580), CHO cell in which a dihydrofolate reductase gene (hereinafter referred to as "DHFR gene") is defective (Urlaub G et al; 1980), rat YB2/3HL.P2.G11.16Ag.20 cell (ATCC CRL1662, hereinafter referred to as "YB2/0 cell"), and the like. The present invention also relates to a method of producing a recombinant host cell expressing an antibody according to the invention, said method comprising the steps of: (i) introducing in vitro or ex vivo a recombinant nucleic acid or a vector as described above into a competent host cell, (ii) culturing in vitro or ex vivo the recombinant host cell obtained and (iii), optionally, selecting the cells which express and/or secrete said antibody. Such recombinant host cells can be used for the production of antibodies of the present invention.

Antibodies of the present invention are suitably separated from the culture medium by conventional immunoglobulin purification procedures such as, for example, protein A- Sepharose, hydroxylapatite chromatography, gel electrophoresis, dialysis, or affinity chromatography.

Therapeutic methods and uses

The antibodies (monovalent or bispecific) of the invention are used as antagonist of ALK2 or as agonist of ALK3. The antibodies of the invention are particularly suitable for the treatment of MIS or MISRII positive cancer in a subject in need thereof.

Thus, the present invention relates to the bi specific antibody of the invention for use in the treatment of MIS or MISRII positive cancer in a subject in need thereof.

In other word, the invention refers to a method of treating MIS or MISRII positive cancer in a subject in need thereof, comprising administrating to said subject a therapeutically effective amount of the bi specific antibody of the invention.

As used herein, the term “subject” refers to any mammal, such as rodent, a feline, a canine, a primate or human. In some embodiment of the invention, the subject refers to any subject afflicted with or susceptible to be afflicted with gynecological cancer, lung cancer or colorectal cancer. Particularly, in preferred embodiment, the subject is a human afflicted with or susceptible to be afflicted with gynecological cancer, lung cancer or colorectal cancer.

As used herein, the term "treatment" or "treating" refer to both prophylactic or preventive treatment as well as curative or disease modifying treatment, including treatment of subjects at risk of contracting the disease or suspected to have contracted the disease as well as subjects who are ill or have been diagnosed as suffering from a disease or medical condition, and includes suppression of clinical relapse. The treatment may be administered to a subject having a medical disorder or who ultimately may acquire the disorder, in order to prevent, cure, delay the onset of, reduce the severity of, or ameliorate one or more symptoms of a disorder or recurring disorder, or in order to prolong the survival of a subject beyond that expected in the absence of such treatment. By "therapeutic regimen" is meant the pattern of treatment of an illness, e.g., the pattern of dosing used during therapy. A therapeutic regimen may include an induction regimen and a maintenance regimen. The phrase "induction regimen" or "induction period" refers to a therapeutic regimen (or the portion of a therapeutic regimen) that is used for the initial treatment of a disease. The general goal of an induction regimen is to provide a high level of drug to a subject during the initial period of a treatment regimen. An induction regimen may employ (in part or in whole) a "loading regimen", which may include administering a greater dose of the drug than a physician would employ during a maintenance regimen, administering a drug more frequently than a physician would administer the drug during a maintenance regimen, or both. The phrase "maintenance regimen" or "maintenance period" refers to a therapeutic regimen (or the portion of a therapeutic regimen) that is used for the maintenance of a subject during treatment of an illness, e.g., to keep the subject in remission for long periods of time (months or years). A maintenance regimen may employ continuous therapy (e.g., administering a drug at a regular intervals, e.g., weekly, monthly, yearly, etc.) or intermittent therapy (e.g., interrupted treatment, intermittent treatment, treatment at relapse, or treatment upon achievement of a particular predetermined criteria [e.g., pain, disease manifestation, etc.]).

As used herein “the MIS or MISRII positive cancer” refers to cancer which express the MIS. In some embodiment, the MIS or MISRII positive cancer is selected from the group consisting of breast cancer, prostate cancer, lung cancer, colorectal cancer or gynecological cancer (see Kim et al, 2014).

In particular embodiment, the MIS or MISRII positive cancer treated by the antibodies and the polypeptides of the invention is a lung cancer, colorectal cancer or gynecological cancer.

As used herein, the term “lung cancer”, also known as “lung carcinoma” includes the well-accepted medical definition that defines lung cancer as a medical condition characterized by uncontrolled cell growth in tissues of the lung. The main types of lung cancer are lung carcinoid tumor, small-cell lung carcinoma (SCLC) and non-small-cell lung carcinoma (NSCLC) such as squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. Additionally, the term “lung cancer” includes all types of lung cancer at all stages of progression. The staging system most often used for lung cancer is the American Joint Committee on Cancer (AJCC) TNM system which is based on the size of the tumor, the spread to nearby lymph nodes and the spread (metastasis) to distant sites. As used herein, the term “colorectal cancer” or “CRC” includes the well-accepted medical definition that defines colorectal cancer as a medical condition characterized by cancer of cells of the intestinal tract below the small intestine (i.e., the large intestine (colon), including the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum). Additionally, as used herein, the term “colorectal cancer” also further includes medical conditions, which are characterized by cancer of cells of the duodenum and small intestine (jejunum and ileum). Additionally, the term “colorectal cancer” includes all types of colorectal cancer at all stages of progression. The earliest stage colorectal cancers are called stage 0 (a very early and superficial cancer), and then range from stage I through IV. In stage IV of colorectal cancer, also known as metastatic colorectal, the cancer has spread beyond the colon or rectum to distant organs, such as the liver or lungs. The staging system most often used for CRC is the American Joint Committee on Cancer (AJCC) TNM system which is based on the size of the tumor, the spread to nearby lymph nodes and the spread (metastasis) to distant sites.

As used herein, the term “gynecological cancer” has its general meaning in the art and refers to cancer that develop in woman’s reproductive tract. The types of gynecological cancers are cervical cancer, uterine cancer also known as womb cancer or endometrial cancer, ovarian cancer, vaginal cancer, vulvar cancer, primary peritoneal cancer, gestational trophoblastic disease and fallopian tube cancer. Cervical cancer occurs when the cells of the cervix grow abnormally and invade other tissues and organs of the body and include squamous cell carcinoma; adenocarcinoma; adenosquamous carcinoma; small cell carcinoma: neuroendocrine tumor; glassy cell carcinoma; villoglandular adenocarcinoma; cervical melanoma and cervical lymphoma. Uterine refer to any types of cancer which occur in the uterus and include endometrial carcinoma such as endometrial adenocarcinoma, endometrial adenosquamous carcinoma, papillary serous carcinoma, uterine clear-cell carcinoma, mucinous carcinoma of endometrium, mucinous adenocarcinoma of endometrium and endometrial squamous cell carcinoma; transitional cell carcinoma of the endometrium; endometrial stromal sarcomas; malignant mixed mullerian tumors; uterine fibroma; and uterine sarcoma such as uterine carcinosarcoma, uterine adenosarcoma and uterine leiomyosarcomas. Vaginal cancer is a rare cancer occurring in vagina and include vaginal squamous cell carcinoma; vaginal melanoma; and vaginal sarcoma. Vulvar cancer is a type of cancer that occurs on the outer surface area of the female genitalia and include vulvar squamous cell carcinoma; vulvar melanoma; vulvar basal cell carcinoma; Bartholin gland carcinoma; vulvar adenocarcinoma and vulvar sarcoma. Ovarian cancer is a cancer that forms in or on an ovary and include: ovarian epithelial tumors such as ovarian mucinous carcinoma, high-grade serous carcinoma, ovarian endometrioid carcinoma, ovarian clear-cell carcinoma, ovarian low malignant potential tumors and primary peritoneal carcinoma; germ cell tumors such as teratomas, dysgerminoma ovarian germ cell cancer, choriocarcinoma tumors and endodermal sinus tumors; sex-cord stromal tumors such as granulosa cell tumors, granulosa-theca tumors, ovarian fibroma, leydic cell tumors, sertoli cell tumors, sertoli-leydig tumors and gynandroblastoma; ovarian sarcoma such as ovarian carcinosarcomas, ovarian adenosarcomas, ovarian leiomyosarcomas and ovarian fibrosarcomas; krukenberg tumors; and ovarian cysts.

In some embodiment, the MIS or MISRII positive cancer treated by the antibodies and the polypeptides of the invention is a gynecological cancer.

In some embodiment, the MIS or MISRII positive cancer treated by the antibodies and the polypeptides of the invention is an ovarian cancer.

In some embodiment, the bispecific antibody of the invention can be administered in combination with a classical treatment of gynecological cancer, lung cancer or colorectal cancer.

Thus, the invention also refers to i) an bispecific antibody of the invention, and ii) a classical treatment of cancer for use in the treatment of gynecological cancer, lung cancer or colorectal cancer.

As used herein, the term “classical treatment” refers to any compound, natural or synthetic, used for the treatment of MIS or MISRII positive cancer.

In a particular embodiment, the classical treatment refers to radiation therapy, immunotherapy or chemotherapy.

According to the invention, compound used for the classical treatment of MIS or MISRII positive cancer may be selected in the group consisting in: EGFR inhibitor such as cetuximab, panitumumab, bevacizumab and ramucirumab; kinase inhibitor such as erlotinib, gefitinib afatinib, regorafenib and larotrectinib; immune checkpoint inhibitor; chemotherapeutic agent and radiotherapeutics agent.

As used herein, the term “chemotherapy” refers to cancer treatment that uses one or more chemotherapeutic agents.

As used herein, the term "chemotherapeutic agent" refers to chemical compounds that are effective in inhibiting tumor growth. Examples of chemotherapeutic agents include alkylating agents such as thiotepa and cyclosphosphamide; alkyl sulfonates such as busulfan, improsulfan and piposulfan; aziridines such as benzodopa, carboquone, meturedopa, and uredopa; ethylenimines and methylamelamines including altretamine, triethylenemelamine, trietylenephosphoramide, triethylenethiophosphaorarnide and trimethylolomelamine; acetogenins (especially bullatacin and bullatacinone); a camptothecin (including the synthetic analogue topotecan and irinotecan); bryostatin; cally statin; CC-1065 (including its adozelesin, carzelesin and bizelesin synthetic analogues); cryptophycins (particularly cryptophycin 1 and cryptophycin 8); dolastatin; duocarmycin (including the synthetic analogues, KW-2189 and CBI-TMI); eleutherobin; pancratistatin; a sarcodictyin; spongistatin; nitrogen mustards such as chlorambucil, chlomaphazine, cholophosphamide, estrarnustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimus tine, trofosfamide, uracil mustard; nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, ranimustine; antibiotics such as the enediyne antibiotics (e.g. calicheamicin, especially calicheamicin (11 and calicheamicin 211, see, e.g., Agnew Chem Inti. Ed. Engl. 33: 183-186 (1994); dynemicin, including dynemicin A; an esperamicin; as well as neocarzinostatin chromophore and related chromoprotein enediyne antiobiotic chromomophores), aclacinomysins, actinomycin, authramycin, azaserine, bleomycins, cactinomycin, carabicin, canninomycin, carzinophilin, chromomycins, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, doxorubicin (including morpholino- doxorubicin, cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin and deoxydoxorubicin), epirubicin, esorubicin, idanrbicin, marcellomycin, mitomycins, mycophenolic acid, nogalarnycin, olivomycins, peplomycin, potfiromycin, puromycin, quelamycin, rodorubicin, streptomgrin, streptozocin, tubercidin, ubenimex, zinostatin, zorubicin; anti-metabolites such as methotrexate and 5-fluorouracil (5-FU); folic acid analogues such as denopterin, methotrexate, pteropterin, trimetrexate; purine analogs such as fludarabine, 6-mercaptopurine, thiamiprine, thioguanine; pyrimidine analogs such as ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, trifluridine, tipiracil, enocitabine, floxuridine, 5-FU; androgens such as calusterone, dromostanolone propionate, epitiostanol, mepitiostane, testolactone; anti- adrenals such as aminoglutethimide, mitotane, trilostane; folic acid replenisher such as frolinic acid; aceglatone; aldophospharnide glycoside; aminolevulinic acid; amsacrine; bestrabucil; bisantrene; edatraxate; defo famine; demecolcine; diaziquone; elfornithine; elliptinium acetate; an epothilone; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidamine; maytansinoids such as maytansine and ansamitocins; mitoguazone; mitoxantrone; mopidamol; nitracrine; pento statin; phenamet; pirarubicin; podophyllinic acid; 2-ethylhydrazide; procarbazine; PSK®; razoxane; rhizoxin; sizofiran; spirogennanium; tenuazonic acid; triaziquone; 2, 2', 2"- trichlorotriethylarnine; trichothecenes (especially T-2 toxin, verracurin A, roridinA and anguidine); urethan; vindesine; dacarbazine; mannomustine; mitobromtol; mitolactol; pipobroman; gacytosine; arabinoside ("Ara-C"); cyclophosphamide; thiotepa; taxoids, e.g. paclitaxel (TAXOL®, Bristol-Myers Squibb Oncology, Princeton, N.].) and doxetaxel (TAXOTERE®, Rhone-Poulenc Rorer, Antony, France); chlorambucil; gemcitabine; 6- thioguanine; mercaptopurine; methotrexate; platinum analogs such as cisp latin and carbop latin; vinblastine; platinum such as oxaliplatin, cisplatin and carbloplatin; etoposide (VP- 16); ifosfamide; mitomycin C; mitoxantrone; vincristine; vinorelbine; navelbine; novantrone; teniposide; daunomycin; aminopterin; xeloda; ibandronate; CPT-1 1 ; topoisomerase inhibitor RFS 2000; difluoromethylornithine (DMFO); retinoic acid; capecitabine; ziv-aflibercept; and pharmaceutically acceptable salts, acids or derivatives of any of the above. Also included in this definition are antihormonal agents that act to regulate or inhibit honnone action on tumors such as anti-estrogens including for example tamoxifen, raloxifene, aromatase inhibiting 4(5)-imidazoles, 4-hydroxytamoxifen, trioxifene, keoxifene, LY117018, onapristone, and toremifene (Fareston); and anti-androgens such as flutamide, nilutamide, bicalutamide, leuprolide, and goserelin; and pharmaceutically acceptable salts, acids or derivatives of any of the above.

"Pharmaceutically" or "pharmaceutically acceptable" refers to molecular entities and compositions that do not produce an adverse, allergic or other untoward reaction when administered to a mammal, especially a human, as appropriate. A pharmaceutically acceptable carrier or excipient refers to a non-toxic solid, semi-solid or liquid filler, diluent, encapsulating material or formulation auxiliary of any type

As used herein, the term “radiation therapy” has its general meaning in the art and refers the treatment of MIS or MISRII positive cancer with ionizing radiation. Ionizing radiation deposits energy that injures or destroys cells in the area being treated (the target tissue) by damaging their genetic material, making it impossible for these cells to continue to grow. One type of radiation therapy commonly used involves photons, e.g. X-rays. Depending on the amount of energy they possess, the rays can be used to destroy cancer cells on the surface of or deeper in the body. The higher the energy of the x-ray beam, the deeper the x-rays can go into the target tissue. Linear accelerators and betatrons produce x-rays of increasingly greater energy. The use of machines to focus radiation (such as x-rays) on a colorectal cancer site is called external beam radiation therapy. Gamma rays are another form of photons used in radiation therapy. Gamma rays are produced spontaneously as certain elements (such as radium, uranium, and cobalt 60) release radiation as they decompose, or decay. In some embodiments, the radiation therapy is external radiation therapy. Examples of external radiation therapy include, but are not limited to, conventional external beam radiation therapy; three-dimensional conformal radiation therapy (3D-CRT), which delivers shaped beams to closely fit the shape of a tumor from different directions; intensity modulated radiation therapy (IMRT), e.g., helical tomotherapy, which shapes the radiation beams to closely fit the shape of a tumor and also alters the radiation dose according to the shape of the tumor; conformal proton beam radiation therapy; image-guided radiation therapy (IGRT), which combines scanning and radiation technologies to provide real time images of a tumor to guide the radiation treatment; intraoperative radiation therapy (IORT), which delivers radiation directly to a tumor during surgery; stereotactic radiosurgery, which delivers a large, precise radiation dose to a small tumor area in a single session; hyperfractionated radiation therapy, e.g., continuous hyperfractionated accelerated radiation therapy (CHART), in which more than one treatment (fraction) of radiation therapy are given to a subject per day; and hypofractionated radiation therapy, in which larger doses of radiation therapy per fraction is given but fewer fractions.

As used herein, the term "immune checkpoint inhibitor" refers to molecules that totally or partially reduce, inhibit, interfere with or modulate one or more immune checkpoint proteins.

As used herein, the term "immune checkpoint protein" has its general meaning in the art and refers to a molecule that is expressed by T cells in that either turn up a signal (stimulatory checkpoint molecules) or turn down a signal (inhibitory checkpoint molecules).

Examples of stimulatory checkpoint include CD27 CD28 CD40, CD 122, CD 137, 0X40, GITR, and ICOS. Examples of inhibitory checkpoint molecules include A2AR, B7-H3, B7-H4, BTLA, CTLA-4, CD277, IDO, KIR, PD-1, PD-L1, LAG-3, TIM-3 and VISTA.

According to the invention, the MIS inhibitors and the classical treatment can be used as a combined treatment.

As used herein, the terms “combined treatment”, “combined therapy” or “therapy combination” refer to a treatment that uses more than one medication. The combined therapy may be dual therapy or bi-therapy. The medications used in the combined treatment according to the invention are administered to the subject simultaneously, separately or sequentially.

As used herein, a “therapeutically effective amount” is intended for a minimal amount of active agent which is necessary to impart therapeutic benefit to a patient. For example, a “therapeutically effective amount of the active agent” to a patient is an amount of the active agent that induces, ameliorates or causes an improvement in the pathological symptoms, disease progression, or physical conditions associated with the disease affecting the patient.

As used herein the terms "administering" or "administration" refer to the act of injecting or otherwise physically delivering a substance as it exists outside the body (e.g.the antibody of the invention) into the subject, such as by mucosal, intradermal, intravenous, subcutaneous, intramuscular delivery and/or any other method of physical delivery described herein or known in the art. When a disease, or a symptom thereof, is being treated, administration of the substance typically occurs after the onset of the disease or symptoms thereof. When a disease or symptoms thereof, are being prevented, administration of the substance typically occurs before the onset of the disease or symptoms thereof.

Pharmaceutical compositions and kits of the invention

Typically the antibodies (monoclonal or bispecific) of the invention may be combined with pharmaceutically acceptable excipients, and optionally sustained-release matrices, such as biodegradable polymers, to form phamaceutical compositions. Thus, the antibodies and polypeptides of the invention is administered to the subject in the form of a pharmaceutical composition.

In the pharmaceutical compositions of the present invention for oral, sublingual, subcutaneous, intramuscular, intravenous, transdermal, local or rectal administration, the active principle, alone or in combination with another active principle, can be administered in a unit administration form, as a mixture with conventional pharmaceutical supports, to animals and human beings. Suitable unit administration forms comprise oral-route forms such as tablets, gel capsules, powders, granules and oral suspensions or solutions, sublingual and buccal administration forms, aerosols, implants, subcutaneous, transdermal, topical, intraperitoneal, intramuscular, intravenous, subdermal, transdermal, intrathecal and intranasal administration forms and rectal administration forms.

Preferably, the pharmaceutical compositions contain vehicles which are pharmaceutically acceptable for a formulation capable of being injected. These may be in particular isotonic, sterile, saline solutions (monosodium or disodium phosphate, sodium, potassium, calcium or magnesium chloride and the like or mixtures of such salts), or dry, especially freeze-dried compositions which upon addition, depending on the case, of sterilized water or physiological saline, permit the constitution of injectable solutions.

The pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions; formulations including sesame oil, peanut oil or aqueous propylene glycol; and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. In all cases, the form must be sterile and must be fluid to the extent that easy syringability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms, such as bacteria and fungi. Solutions comprising inhibitors of the invention as free base or pharmacologically acceptable salts can be prepared in water suitably mixed with a surfactant, such as hydroxypropylcellulose. Dispersions can also be prepared in glycerol, liquid polyethylene glycols, and mixtures thereof and in oils. Under ordinary conditions of storage and use, these preparations contain a preservative to prevent the growth of microorganisms.

The inhibitor of the invention can be formulated into a composition in a neutral or salt form. Pharmaceutically acceptable salts include the acid addition salts (formed with the free amino groups of the protein) and which are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, oxalic, tartaric, mandelic, and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium, or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, histidine, procaine and the like.

The carrier can also be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyethylene glycol, and the like), suitable mixtures thereof, and vegetables oils. The proper 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. The prevention of the action of microorganisms can be brought about by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars or sodium chloride. Prolonged absorption of the injectable compositions can be brought about by the use in the compositions of agents delaying absorption, for example, aluminium monostearate and gelatin.

Sterile injectable solutions are prepared by incorporating the active compounds in the required amount in the appropriate solvent with several of the other ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the various sterilized active ingredients into a sterile vehicle which contains the 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 preferred methods of preparation are vacuum-drying and freeze-drying techniques which yield a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.

Upon formulation, solutions will be administered in a manner compatible with the dosage formulation and in such amount as is therapeutically effective. The formulations are easily administered in a variety of dosage forms, such as the type of injectable solutions described above, but drug release capsules and the like can also be employed.

For parenteral administration in an aqueous solution, for example, the solution should be suitably buffered if necessary and the liquid diluent first rendered isotonic with sufficient saline or glucose. These particular aqueous solutions are especially suitable for intravenous, intramuscular, subcutaneous and intraperitoneal administration. In this connection, sterile aqueous media which can be employed will be known to those of skill in the art in light of the present disclosure. Some variation in dosage will necessarily occur depending on the condition of the subject being treated. The person responsible for administration will, in any event, determine the appropriate dose for the individual subject.

In addition to the inhibitors of the invention formulated for parenteral administration, such as intravenous or intramuscular injection, other pharmaceutically acceptable forms include, e.g. tablets or other solids for oral administration; liposomal formulations; time release capsules; and any other form currently used.

Pharmaceutical compositions of the invention may include any further agent which is used in the prevention or treatment of MIS or MISRII positive cancer in a subject in need thereof.

In some embodiment, the MIS or MISRII positive cancer is selected in the group consisting of gynecological cancer, lung cancer or colorectal cancer.

In one embodiment, said additional active agents may be contained in the same composition or administrated separately.

In another embodiment, the pharmaceutical composition of the invention relates to combined preparation for simultaneous, separate or sequential use in the treatment of gynecological cancer, lung cancer or colorectal cancer in a subject in need thereof.

Finally, the invention also provides kits comprising at least one single domain antibody or polypeptide of the invention. Kits containing an anti-MISRI antibody or polypeptide of the invention find use in therapeutic methods.

The invention will be further illustrated by the following figures and examples. However, these examples and figures should not be interpreted in any way as limiting the scope of the present invention.

FIGURE: Figure 1: Graphical abstract of the differential involvement of ALK2 and ALK3 depending on miillerian inhibiting substance (MIS) concentration in ovarian carcinomas and of the therapeutic strategy accordingly.

Figure 2: Incubation with recombinant AMH (LR-AMH) modulates ALK2 and ALK3 expression in COV434-AMHRII, SKOV3-AMHRII, OVCAR8 and KGN ovarian cancer cells. Western blot analysis of AMH signaling (phosphorylated SMAD1/5), ALK2 and ALK3 expression, apoptosis induction (cleaved caspase 3 and PARP), and AKT phosphorylation after incubation with 1.6 and 25 nM LR-AMH for 6 hours. Data were quantified with ImageJ, and expressed as fold change relative to control (no LR-AMH). (A) COV434-AMHRII cells, (B) SKO V 3 - AMHRII cells, (C) OVCAR8 cells and (D) KGN cells.

Figure 3: Analysis of the binding of the anti-ALK2 (A) and anti-ALK3 (B) antibodies on their respective antigen. Binding was analyzed by ELISA on recombinant receptors using IgG (left panel) or BsAb (right panel). Binding of all the BsAbs was also performed on AMHRII (C). EC50 was calculated for all experiments.

Figure 4: Effect of the differents BsAb on apoptosis induction (A) and clonogenic survival (B). Apoptosis initiation (caspase 3/7 activity) was analyzed after incubation with 333 nM BsAb or 12G4 MAbs for 24 hours and 48 hours of COV434-MISRII or SKOV3-MISRII cells, respectively (A). Clonogenic survival in COV434-MISRII cells (direct clone counting) and in SKOV3-MISRII (estimated from OD after cell lysis) after incubation for 11 days with 333 nM of the different BsAb. The anti-MISRII Mab 12G4 was used as control. Results are expressed as ratios to non-treated cells (B).

Figure 5: Effect of BsAbs on cells isolated from ascites in patients with ovarian cancers. Cell growth inhibition (cell confluence measured with the Celigo Imaging System) after incubation or not (NT) with 25 nM of MIS (AMH) or 333 nM of the antibody 12G4 or the BsAbs MSRII-ALK3 : 12G4-3D7 and 12G4-3H6 for 48 hours.

Figure 6: The anti-AMHRII-ALK2 BsAb 12G4-2F9 slows growth of COV434- AMHRII cell xenografts in vivo. Nude mice bearing COV434-MISRII cell-derived tumors were treated with 17 mg/kg of anti-AMHRII-CD5 (control BsAb targeting AMHRII and CD5), A. anti- AMHRII- ALK2 (12G4-2C1 and 12G4-2F9) and B. anti- AMHRII- ALK3 (12G4-3D7 and 12G4-3H6) BsAbs, or vehicle (NaCl) twice per week for 4 weeks. Tumor growth curves (mean and SEM); *p < 0.05; **p < 0.01.

EXAMPLE:

Material & Methods Cell lines

The human COV434 (sex cord-stromal tumor) (Chan-Penebre et al., 2017; Zhang et al., 2000) and KGN (granulosa cell tumor) (Nishi et al, 2001) cell lines were kind gifts from Dr. PI Schrier (Department of Clinical Oncology, Leiden University Medical Center, Nederland) and Dr T Yanase (Kyushu University, Fukuoka, Japan), respectively. The human epithelial ovarian cancer cell lines SKOV3 and NIH-OVCAR8 were from ATCC (ATCC® HTB-77) and from the Division of Cancer Treatment and Diagnosis, NCI, Frederick, MD, USA, respectively.. Cells were grown in DMEM F12 medium without red phenol containing 10% heat-inactivated fetal bovine serum (FBS). COV434-MISRII and SKOV3-MISRII cells were supplemented with 0.33 mg/ml geneticin (InvivoGen, ant-gn-1). Cells were grown at 37°C in a humidified atmosphere with 5% C02, and medium was replaced twice per week. Cells were harvested with 0.5 mg/ml trypsin/0.2mg/ml EDTA. All culture media and supplements were purchased from Life Technologies. Inc. (Gibco BRL). The HEK293K cells, used for antibody production by the GenAc platform at IRCM, were grown in DMEM F12 with phenol red containing 10% heat-inactivated FBS.

The COV434-MISRII and SKOV3-MISRII cell lines were generated by transfection of the cDNA encoding full-length human MISRII (Kersual et al., 2014). The cDNA coding for full-length human MISRII in the pCMV6 plasmid was a generous gift by J Teixeira (Pediatric Surgical Research Laboratories, Massachusetts General Hospital, Harvard Medical School). MISRII cDNA was first subcloned in the pcDNA3.1.myc-His vector (Invitrogen) using the EcoRI and Xhol restriction sites (enzymes from New England BioLabs), and then, using the EcoRI and Sail sites, in the pIRESl-EGFP vector, a kind gift from F Poulat (IGH-UPR1142 CNRS). Twenty- four hours before transfection, COV434 cells were seeded in 10 cm cell culture dishes at 80% of confluence. The MISRII construct was transfected using the Fugene transfection kit according to the manufacturer’s protocol. After 48h, transfection medium was replaced with fresh medium containing 0.5 mg/ml geneticin and was then changed twice/week for two weeks. Then, cells were harvested and sorted using a FACSAria cytometer (Becton Dickinson) in 96-well plates. For each cell line, a clone that strongly expressed MISRII was selected and designed as COV434-MISRII and SKOV3-MISRII.

Primary tumor cells from patients ascites

Ascites samples from two patients with ovarian cancer were obtained from the “Institut Cancer Montpellier, ICM” according to the French laws and after their informed consent. These two patients were selected because they never received any chemotherapy and were waiting for surgical intervention at the ICM - Val d’Aurelle Hospital. Freshly obtained ascites were aliquoted in 50 ml conical centrifuge tubes and spun at 1300 rpm for 5 min. Cell pellets were re-suspended in ammonium-chloride-potassium buffer (ACK lysis buffer: NH4C1 150nM; KHC03 lOnM; Na2EDTA 0. InM) to lyse red blood cells (RBC) on ice for 5 min. The process was repeated until RBC lysis was complete. Then, cell pellets were plated on 150 mm cell culture dishes with 20 ml DMEM F12-Glutamax (Gibco) and 10% FBS. The same day, 100,000 cells were harvested to assess MISRII expression by FACS. Cells were then plated in DMEM F12/10% FBS for 30 minutes to rapidly eliminate adherent fibroblasts (O Donnell et al., 2014). Non-adherent cells were transferred in new dishes with DMEM F 12/10% FBS. Low-passage cells were used for experiments or frozen in liquid nitrogen.

Mullerian Inhibiting Substance (MIS) production and assay

The active recombinant MIS (LRMIS), described in the work by D Pepin et al. (Pepin et al, 2013, 2015) was used in our study. It contains (i) the 24 AA leader sequence of albumin instead of the MIS leader sequence to increase production and secretion, and (ii) the RARR/S furin/kex2 consensus site instead of the native MIS RAQR/S sequence at position 423-428 to improve cleavage. MIS dosages were performed using the Elecsys® AMH (Anti-Mullerian Hormone) assay from Roche. All experiments involving LRMIS were performed in culture medium containing 1% FBS because bovine MIS can signal through human MISRII (Cate et al, 1986). In these experimental conditions, endogenous MIS concentration ranged from 5 to 10 pM in fresh medium to about 10 to 15 pM after 5 days of cell culture. To determine endogenous MIS concentration in cell culture supernatants, one million cells were plated in 100 mm cell culture dishes in 10 ml DMEM F 12/ 1 % FBS. Every 24h, 300 mΐ of medium was removed for MIS dosage.

Anti-ALK2 and anti-ALK3 antibodies development and production

Anti-ALK2 scFv antibodies 2C1 and 2F9, and anti-ALK3 scFv 3D7 and 3H6 antibodies were selected from two series of scFv obtained by phage display from the human scFv phage display library Husc I (Philibert et al, 2007; Robin and Martineau, 2012) after sequential panning using ALK2 and ALK3 recombinant protein (637-AR, 2406-BR R&D system), respectively. Antibodies were first expressed in the human IgGl format.

Human IgGl were produced in HEK293T cells (ATCC CRL1573). HEK293T cells were grown in 150 mm2 dishes up to 70% confluence. A 1:1 mixture of 30 pg of plasmid encoding the different antibodies and 240 pg of the transfection agent polyethylenimine PEI (Poly science) was kept at room temperature for 10 minutes, and then added to the cells for 6 hours. Then, the transfection medium was replaced by DMEM without FBS. Five days later, supernatant was collected and diluted (1:1) with 40 mM sodium phosphate buffer, pH 8, filtered through a 0.22gm filter and purified on a 1 ml protein A column for 24 hours. Antibodies were eluted at acidic pH (glycine pH 3), and immediately stabilized with Tris buffer, pH 9. Centricons filters with a cut-off of 50 kDa were used to concentrate the antibody in PBS. Two hundreds ml of cell culture provided about 1 mg of purified antibody.

BsAb constructs and production

The variable domains of the anti-MISRII Mab 12G4 were introduced in position 2 of the BsAb format described by Golay et al (J Immunol, 2016) and the variable domains of the anti-ALK2 and anti-ALK3 Mabs, 2C1, 2F9, 3D7 and 3H6 were introduced in position 1 of the same BsAb format. Four BsAbs were thus generated : 12G4-2C1, 12G4-2F9, 12G4-3D7 and 12G4-3H6. BsAbs were produced in HEK293T cells according the protocol used for human IgG.

Western blot analysis

Cells were washed with PBS and scrapped immediately in RIPA lysis buffer (Santa Cruz) that included 200 mM PMSF solution, 100 mM sodium orthovanadate solution, and protease inhibitor cocktail. The protein concentration was determined using the BCA assay protein quantitation kit (Interchim). Cell extracts were heated at 95°C for 5 min, separated (50 pg proteins/well) on 10% SDS-PAGE in reducing conditions (5% 2P-mercaptoethanol), and transferred to PVDF membranes (Biorad). Membranes were saturated in Tris-buffered saline, containing 0.1% Tween 20 and 5% non-fat dry milk, and probed with the relevant primary antibodies at RT for 1 h. After washing, peroxidase-conjugated IgG secondary antibodies were added (1/10,000) at RT for 1 h. After washing, antibody-antigen interactions were detected using a chemiluminescent substrate (Merck). To verify equal loading, immunoblots were also probed with an anti-GAPDH monoclonal antibody (Cell Signaling).

MIS pathway analysis

Cells were cultured in DMEM F 12/ 1 % FBS medium overnight, and then incubated with LRMIS (0-25 nM) at 37°C for 6 hours. Western blotting was performed using anti- phosphorylated SMAD 1/5, anti-phosphorylated ART, anti-cleaved caspase 3, anti-cleaved PARP, and anti-GAPDH primary antibodies (1:1.000; Cell Signaling), anti-ALK2, and anti- ALK3 antibodies (lpg/ml; R&D system) at 4°C overnight, followed by anti-rabbit and anti goat IgG HRP secondary antibodies (1 : 10.000; Sigma) at room temperature for 1 hour.

Clonosenic survival

Cells were plated in 24-well plates (50 cells/well) in DMEM F 12/ 1 % FBS medium overnight. LRMIS (0-25 nM) or the anti-MIS Mab B10 ( 333 nM) were then added for 11 days of culture. For COV434-MISRII cells, which grow as clearly individualized clones, colonies were fixed with a methanol/acetic acid solution (3:1) at 4°C for 20min, stained with 10% Giemsa, and counted. For SKOV3-MISRII, OVCAR8, KGN cells and cells from patient’s ascites, the number of clones was estimated from the confluence area, determined using the Celigo Imaging System after cell staining with Hoechst 33342 trihydrochloride (Invitrogen H1399, 0.25 pg/ml for 15 min).

Apoptosis assays

Apoptosis initiation was measured using the Caspase-Glos-3/7 assay (Promega). Cells were plated on white 96-well plates and incubated with LRMIS (0 - 25nM) for 6 hours. Upon addition of the proluminescent caspase-3/7 DEVD-aminoluciferin substrate, caspase-3/7 generated free aminoluciferin that, consumed by luciferase, produced a luminescent signal proportional to the caspase-3/7 activity. The luminescent signal was quantified 30 min after substrate addition with a PHERASTAR microplate reader.

For a more complete analysis of apoptosis, the Annexin V-FITC Apoptosis Detection Kit (Beckman Coulter IM3614) was used. Approximately 100,000 cells per well were seeded in 24-well plates and incubated or not with 50 pg/ml Mab B10, 25 nM LRMIS, or 150 nM staurosporin (positive control) for 24 h. Adherent and detached cells were collected and centrifuged at 900 rpm for 5 min. After washes with PBS, cells were stained with 130 pi of a mixture containing 10 pi FITC-labeled annexin V and 20 pi 7AAD in 100 mΐ annexin buffer on ice in the dark for 15min. After addition of 400 mΐ annexin buffer, fluorescence signal data were acquired by flow cytometry within 30 min, and data were analyzed with the Kaluza Flow Analysis software (Beckman Coulter).

Cell Viability Assay

For cell viability/proliferation testing, the CellTiter 96 AQueous One Solution Cell Proliferation Assay system (Promega) was used according to the manufacturer’s instructions. Five thousand cells were plated in each well of a 96-well plate and cultured in 50 mΐ DMEM F 12/ 1 % FBS medium overnight. Cells were then incubated with LRMIS (0 - 25nM) or the anti- MIS B10 antibody (0 - 333 nM ) for 3 days. Then, 10 mΐ of CellTiter 96 AQueous One Solution reagent was added per well, and plates were incubated in humidified 5% C02 atmosphere until the positive control wells became brown (from 1 to 2 h, depending on the cell line). Then, absorbance was measured at 490 nm using a PHERASTAR microplate reader. Three replicate wells were used for each condition.

ELISA assay

ELISA was used to determine the EC50 of all IgG and BsAb. Recombinant Human BMPR-IA/ALK-3 Fc, Activin RIA/ALK-2 Fc, MIS RII Fc Chimera (637-AR, 2406-BR, 4749- MR R&D system respectively) were coated on a 96 wells high protein-binding capacity plate (Nunc MaxiSorp) overnight. Then, the plate was washed 3 times and saturated with a PBS - Tween 0.01% - BSA 2% solution during 2 hours. After each step, the plate was washed 3 times with PBS-Tween 0.01%. Then, BsAb or Mab (333 - 0 nM) or was added and incubated for lh30 at 37°C. The secondary anti-Fc human peroxidase (HRP) antibody was incubated for 30 min and the substrate enzyme (Thermofisher TMB) was added. Absorbance was read at 450 nm after stopping the enzymatic reaction by the addition of sulfuric acid.

In vivo studies using ovarian cancer cell xenografts

All animal experiments were performed in compliance with the guidelines of the French government and the Inserm’s regulations (agreement D34-172-27). Athymic nude Hsd female mice (6-8 week-old) (ENVIGO, France) were used. At day 0 (DO), 7.106 human COV434- AMHRII cells in BD Matrigel (ratio 1:1), in a volume of 150m1, were subcutaneously (s.c.) grafted onto the right flank. At D14, when tumor volume reached 80-100mm³, mice were randomized (n=8-10 mice/group) and treatments (BsAbs at 17 mg/kg or saline solution) were administered by intraperitoneal (i.p.) injection twice per week for 4 weeks. Tumor dimensions were measured with a caliper once per week, and tumor volumes were calculated using the formula: D1 x D2 x D3/2. Tumor growth inhibition was calculated as T/C % = [(median tumor volume of treated group at day X)/(median tumor volume of control group at day X)] ^c 100.

Statistical Analysis

Statistical analyses concerning differences in caspase-3/7 activity and cell viability/proliferation were performed with the Prism software and ANOVA (Tukey's Multiple Comparison Test).

A linear mixed regression model was used to determine the relationship between tumor growth and number of days post-graft. The fixed part of the model included variables corresponding to the number of days post-graft and the different groups. Interaction terms were built into the model. Random intercept and random slope were included to take into account the time effect. The coefficients of the model were estimated by maximum likelihood and considered significant at the 0.05 level. Statistical analyses were carried out using the STATA 16.0 software (StataCorp, College Station, TX).

Results

In ovarian cancer cells, MIS modulates ALK2 and ALK3 expression

We investigated MIS effect on MISRII, ALK2, ALK3 and ALK6 expression in four MISRII-positive ovarian cancer cell lines: COV434-MISRII (sex cord stromal tumor), SKOV3- MISRII (epithelial cancer), OVCAR8 (epithelial cancer), and KGN (granulosa cell tumor). Immunofluorescence (IF) analysis showed that MISRII and ALK2 were clearly expressed in all four cell lines in basal condition (1% FBS corresponding to 10 pM AMH), and their expression was not modulated by incubation with 25 nM LR-MIS for 90 min (Figure 3A). ALK3 expression was not detectable by IF in basal condition, but was induced by MIS addition (data not shown) in all four cell lines. ALK6 was not detectable in both experimental conditions.

Then, to determine the role of ALK2 and ALK3, we assessed their expression and that of MIS signaling proteins by western blotting in basal conditions and after incubation with LR- MIS (1.6 to 25 nM) for 6 hours. In these conditions in all four cell lines (Figures 2A-D show data quantification of WB at 1.6 and 25 nM AMH), ALK2 basal expression decreased upon incubation with LR-MIS and was almost undetectable in the presence of 6.25 or 12.5 nM LR- MIS. Conversely, ALK3 expression increased upon LR-MIS exposure. Moreover, SMAD1/5 phosphorylation and caspase 3 and PARP cleavages increased in parallel with ALK3 expression (Data not shown).

To analyze the involvement of non-SMAD pathways in AMH signaling (Beck et al., 2016; Zhang, 2017), we monitored ART phosphorylation and found that it decreased upon incubation with LR-MIS, as observed for ALK2 expression (Figure 2A-D). These results confirmed that in ovarian carcinoma cells, ALK3 is the major MISRI in MIS signaling through the SMAD pathway for inducing apoptosis (starting around 6 nM of LR-MIS). ALK2 is expressed in basal conditions (around 10 pM MIS) and then its expression is reduced upon incubation with LR-MIS.

Anti-ALK2 and anti-ALK3 antibodies development and chacterization

Based on the differential expression of ALK2 and ALK3 upon MIS concentration and in order to exploit these data in a therapeutic perspective, we produced 2 MAbs directed against ALK2 and 2 MAbs directed against ALK3. They were isolated from the human scFv phage display library Husc I (Philibert et al, 2007; Robin and Martineau, 2012) after panning on ALK2 or ALK3 extra-cellular domains. First, we characterized their affinity for ALK2 or ALK3 by ELISA as IgG (Figure 3A and 3B). Clones 2C1 and 2F9 exhibited an EC50 of 54.96 and 159.4 nM, respectively, against ALK2. Clones 3H6 and 3D7 exhibited an EC50 of 1.379 and 59.85 nM, respectively, against ALK2.

Anti-MISRII/ALK2 and anti-MISRII/ALK3 bispecific antibodies development and chacterization

In order to confer a tumor specificity to our anti-ALK2 or anti-ALK3 antibodies, we included them in a bispecific construct according to Golay et al. (Golay et al., 2016). Their affinities were estimated by ELISA and, interestingly, there were found very close to those of the parental MAbs (Figure 3A and 3B). The affinities of all BsAbs against MISRII were in the same range from 0.3099 to 0.5854 nM (Figure 3C).

The anti-MISRII/ALK2 and anti-MISRII/ALK3 BsAb induce apoptosis and reduce clonosenic survival in ovarian cancer cells

Apoptosis initiation (caspase 3/7 activity) was analyzed after incubation with 333 nM BsAb or 12G4 MAb for 24 hours and 48 hours of COV434-MISRII or SKOV3-MISRII cells, respectively. BsAbs 12G4-3D7 and 12G4-3H6 induced apoptosis initiation on COV434- MISRII cells and 12G4-2C1 and 12G4-2F9 induced it on SKOV3-MISRII cells. In the 2 cases, this effect was clearly enhanced as compared to those of the anti-MISRII Mab 12G4 (Figure 4A). The 4 BsAbs were even more active in a clonogenic survival assay since 12G4-3D7 and 12G4-3H6 inhibited COV434-MISRII cells survival by 75% (Figure 4B)

The anti-MISRII/ALK2 and anti-MISRII/ ALK3 BsAb reduce clonosenic survival in cells isolated from ascites inpatients with ovarian cancers

Finally, we assessed anti-MISRII/ ALK3 BsAb effect in primary cancer cells isolated from ascites samples of three patients with ovarian cancer. These patients were awaiting surgical intervention and had never received chemotherapy. Like in the COV434-MISRII cell line, 12G4-3D7 and 12G4-3H6 inhibited cell growth (estimated by the confluence area) by 20% to 50% (patient 2 and 3, respectively) (Figure 5). Despite the limited number of samples, these results highlight the potential translational perspective of orienting MIS signaling pathway thanks to anti-MISRII/MISRI BsAbs.

The anti-AMHRII-ALK2 BsAb 12G4-2F9 reduces the growth of COV434-AMHRII cell xenografts in vivo

To evaluate the in vivo anti-tumor activity of our anti-AMHRII-AMHRI BsAbs, we treated mice with established COV434-AMHRII cell xenografts (8 to 10 mice/group) with either the two anti-AMHRII-ALK2 BsAbs (12G4-2C1, 12G4-2F9), the two anti-AMHRII- ALK3 BsAbs (12G4-3D7, 12G4-3H6), vehicle control (NaCl), or a control BsAb against AMHRII and CD5 (12G4-CD5) (Loisel et al. 2011; Golay et al. 2016). This BsAb against AMHRII and CD5 (12G4-CD5) was used as a control with retained antigen recognition to AMHRII but a lack of binding to ALK2 and ALK3, instead targeting the second paratope to an irrelevant antigen (CD5). Mice received 17 mg/kg of BsAb (molar equivalent to 10 mg/kg for MAbs) by i.p. injection twice per week for 4 weeks. Treatment started at D14 after tumor grafting (average tumor volume of 85 mm³, no difference among the six groups). At D31, when tumors reached 1,500 mm³ in three mice of the saline vehicle group (mean±SEM = 1180±201 mm³), the mean tumor volume was smaller in the antibody-treated groups, including in mice treated with the control BsAb 12G4-CD5 suggesting baseline efficacy by the anti-AMHRII Fab alone (709±110 mm³). Tumor volume of mice treated with the anti-AMHRII-ALK3 BsAbs 12G4-3D7 and 12G4-3H6, or the anti-AMHRII-ALK2 BsAbs 12G4-2C1 (671±92.3 mm³, 669±111.8 mm³, and 620±102 mm³, respectively) were not not significantly different from the control anti-AMHRII BsAb 12G4-CD5 (Fig 6A and 6B). However, mice treated with the AMHRII-ALK2 12G4-2F9 BsAb had a significantly smaller tumors than those treated with the control BsAb 12G4-CD5 (484±95 mm³). In agreement, the T/C% ratios of the 12G4-2C1 and 12G4-2F9 BsAbs were 52% and 41%, respectively. Throughout the experiment, tumor growth was significantly lower in antibody-treated mice than in the vehicle group (from p=0.018 between vehicle and 12G4-3D7 to p=0.001 between vehicle and 12G4-CD5, 12G4-2C1 or 12G4-3H6) (Fig. 6A and 6B). However, only tumor growth in 12G4-2F9-treated mice was statistically different from that of the 12G4-CD5 group (p=0.048).

Discussion

Here, using two ovarian cancer cell lines (COV434-MISRII and SKOV3-MISRII), we found that ALK3 is the favorite MISRI for MIS signaling and apoptosis induction. In four ovarian cancer cell lines (COV434-MISR.il, SKOV3-MISRII, OVCAR8 and KGN), we showed that ALK2 and ALK3 are modulated by incubation with LRMIS, and that ALK3 is preferentially expressed when high doses of LRMIS are used to induce apoptosis (Figures 2A, 2B, 2C and 2D)

Based on these observations, we developed 2 anti-ALK2 and 2 anti-ALK3 antibodies and used them to design original BsAbs directed against MISRII and ALK2 or ALK3. These BsAbs induced apoptosis and decreased clonogenic survival in COV434-MISRII and SKOV3- MISRII cell lines. These results were confirmed in tumor cells isolated from ascites samples of three patients with ovarian carcinoma.

For the first time to our knowledge, BsAbs directed against heterodimeric receptors are designed and used to modulate cell signaling. The MIS/MISRII signaling axe involving a ligand specific receptor (MISRII) and different ligand non specific ones (ALK2, ALK3 and ALK6) is particularly adapted to this strategy. All other receptors with such a structure could be targeted by BsAbs using the same strategy.

In our BsAbs, the relative affinity of the anti-AMHRII Fab (mean EC50 = 0.34 nM) compared with that of the anti-ALK Fab corresponded to a 1/100 ratio for the MAbs 2C1, 2F9 and 3D7 (EC50 from 26 to 85 nM) and to a 1/10 ratio for the MAb 3H6 (EC50 about 2 nM). These affinity differences and the BsAb design ensure a tumor specificity through AMHRII as the first step of the binding, and then a potential signaling through ALK2 or ALK3 binding. Interestingly, the BsAb with the highest affinity ratio and thus the lowest anti-ALK affinity (12G4-2F9) was the most efficient in vivo.

In vivo, all BsAbs reduced COV434-AMHRII tumor growth compared with vehicle. The BsAb 12G4-2F9 was the most efficient with T/C% of 41% (59% growth inhibition) and 68% (32% growth inhibition) compared with vehicle and with the BsAb targeting only AMHRII (12G4-CD5), respectively. The stronger anti-tumor growth effect of anti-AMHRII- ALK2 BsAbs compared with anti-AMHRII-ALK3 BsAbs is in line with our finding that ALK2 is mainly expressed at physiological endogenous AMH concentrations and ALK3 at supraphysiological AMH concentrations. Indeed, no exogenous AMH was added in the in vivo experiments. Alternatively, as ALK3 is mostly implicated in apoptosis induction, an anti-ALK3 MAb or an anti-AMHRII-ALK3 BsAb would have to be agonistic to reduce tumor growth. Agonist antibodies are rarely obtained unless specific and complex screening strategies are employed.

Our original observation that ALK2 and ALK3 have opposite roles in AMH signaling in ovarian cancer cells furthers our understanding of the involvement of this hormone in cancer and opens the way to develop new anti-cancer strategies. Our findings constitute proof of concept that BsAbs targeting AMHRII- ALK2 and AMHRII- ALK3 can inhibit tumor growth in models of ovarian cancer, and may have enhanced efficacy compared to those targeted at AMHRII alone, which is all the more remarkable considering these experiments were carried out in cells overexpressing AMHRII. This strategy offers an alternative to or might complement the use of recombinant AMH to induce cancer cell apoptosis (22, 23).

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Claims

CLAIMS :

1. An isolated anti-miillerian inhibiting substance type I receptors (MISRI) antibody comprising :

(a) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 1; a H-CDR2 having a sequence set forth as SEQ ID NO:2; a H-CDR3 having a sequence set forth as SEQ ID NO:3; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:4; a L-CDR2 having a sequence set forth as SEQ ID NO: 5; a L-CDR3 having a sequence set forth as SEQ ID NO: 6; or

(b) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 9; a H-CDR2 having a sequence set forth as SEQ ID NO: 10; a H-CDR3 having a sequence set forth as SEQ ID NO: 11; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO: 12; a L-CDR2 having a sequence set forth as SEQ ID NO: 13; a L-CDR3 having a sequence set forth as SEQ ID NO: 14; or

(c) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO: 17; a H-CDR2 having a sequence set forth as SEQ ID NO: 18; a H-CDR3 having a sequence set forth as SEQ ID NO: 19; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:20; a L-CDR2 having a sequence set forth as SEQ ID NO:21; a L-CDR3 having a sequence set forth as SEQ ID NO:22; or

(d) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:25; a H-CDR2 having a sequence set forth as SEQ ID NO:26; a H-CDR3 having a sequence set forth as SEQ ID NO:27; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:28; a L-CDR2 having a sequence set forth as SEQ ID NO:29; a L-CDR3 having a sequence set forth as SEQ ID NO:30.

2. The isolated anti-MISRI antibody according to claim 1 comprising:

(a) a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO:7; and a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO: 8 (“2C1 derivative”); or (b) a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO: 15; and a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO: 16 (“2F9 derivative”); or

(d) a variable heavy chain having at least 70% identity with a sequence set forth as SEQ ID NO:31 ; and a variable light chain having at least 70% identity with a sequence set forth as SEQ ID NO:32 (“3D7 derivative”).

3. The isolated anti-MISRI antibody according to claim 1 comprising:

4. A bispecific antibody comprising a) a first antigen-binding site (Fab) from an anti-mullerian inhibiting substance type II receptor antibody (MISRII) and b) a second Fab from an anti-mullerian inhibiting substance type I receptor (MISRI) antibody, wherein the bispecific antibody has a stronger affinity for MISRII than MISRI.

5. A bispecific antibody according to claim 4, wherein the bispecific antibody have at least a two times greater affinity for MISRII than MISRI.

6. A bispecific antibody according to claim 4, wherein the bispecific antibody bind in the first place and specifically with MISRII before to bind MISRI in order to ensure a specific targeting on AMHRII positive cells and to limit the binding on ALK2 positives and/or ALK3 positives cells which are MISRII negatives.

7. A bispecific antibody according to claims 4 to 6, wherein the anti-MISRI antibody is an anti-ALK2 antagonist antibody or an ALK3 agonist antibody

8. A bispecific antibody according to claim 4 to 6, wherein the anti-MISRI antibody is an antibody according to claims 1 to 3.

9. A bispecific antibody according to claims 4 to 8, wherein the second Fab from an anti-MISRII antibody comprises a) a heavy chain wherein the variable domain comprises a H-CDR1 having a sequence set forth as SEQ ID NO:33; a H-CDR2 having a sequence set forth as SEQ ID NO:34; a H-CDR3 having a sequence set forth as SEQ ID NO:35; and a light chain wherein the variable domain comprises a L-CDR1 having a sequence set forth as SEQ ID NO:36; a L-CDR2 having a sequence set forth as SEQ ID NO:37; a L-CDR3 having a sequence set forth as SEQ ID NO:38.

10. A bispecific antibody according to claim 9, wherein the second Fab from anti- MISRII antibody comprises a variable heavy chain having a sequence set forth as SEQ ID NO:39 and a variable light chain having a sequence set forth as SEQ ID NO:40.

11. A nucleic acid molecule encoding the anti-MISRI antibody of claim 1 and/or the bispecific antibody of claims 4 to 10.

12. A vector that comprises the nucleic acid of claim 11.

13. A host cell which has been transfected, infected or transformed by the nucleic acid of claim 11 and/or the vector of claim 12.

14. A pharmaceutical composition comprising the anti-MISRI antibody of claim 1 and/or the bispecific antibody of claims 4 to 10.

15. A method of treating gynecological cancer, lung cancer or colorectal cancer in a subject in need thereof, comprising administrating to said subject a therapeutically effective amount of the anti-MISRI antibody of claim 1 and/or the bi specific antibody of claims 4 to 10.