Prolactin receptor (PRLR)-specific antibody and uses thereof

Abstract

The present disclosure provides antibodies or antigen-binding fragments thereof specific for prolactin receptor (PRLR). Such antibodies or antigen-binding fragments can be used in many pharmaceutical applications, for example, as anti-cancer agents and / or immune modulators. The present disclosure also concerns methods of making the antibodies or antigen-binding fragments described herein as well as compositions comprising such antibodies or antigen-binding fragments. The present disclosure further relates to nucleic acid molecules encoding such antibodies or antigen-binding fragments. In addition, the present disclosure provides therapeutic and / or diagnostic uses of such antibodies or antigen-binding fragments.

Description

PROLACTIN RECEPTOR (PRLR)-SPECIFIC ANTIBODY AND USES THEREOFI. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority to US Provisional Patent Application No. 63 / 653,329, filed May 30, 2024, the contents of which are incorporated herein by reference in its entirety for all purposes.IL SEQUENCE LISTING

[0002] The instant application contains a Sequence Listing which has been submitted electronically in XML format and is hereby incorporated by reference in its entirety. Said XML copy, created on May 28, 2025, is named “01363-0001-00PCT.xml” and is 346,802 bytes in size.III. INTRODUCTION AND SUMMARY

[0003] The present disclosure provides antibodies or antigen-binding fragments thereof specific for prolactin receptor (PRLR) and compositions comprising such antibodies or antigenbinding fragments. Such antibodies or antigen-binding fragments can be used in many therapeutic applications, for example, cancer immunotherapy.

[0004] Prolactin receptor (PRLR) is a type I cytokine receptor with a single transmembrane domain. The Prolactin (PRL) binding induces JAK2 association on its cytoplasmic domain that leads to downstream activation of multiple pathways including STAT3, STAT5, PI3K, AKT, and ERK (Standing et al, Front Endocrinol (Lausanne), 2022. 13: 1112987). PRLR signaling plays a major role in numerous biological functions, primarily in mammary gland development and lactation. PRL signaling is upregulated in many cancers including breast, prostate, ovarian, colon, pancreas, and liver cancers and leads to increased cell proliferation and migration (Touraine et al., J Clin Endocrinol Metab, 1998. 83(2): 667-74; Reynold et al., Endocrinology, 1997. 138(12): 5555-60; Gill et al., J Clin Pathol, 2001. 54(12): 956-60). Thus, PRLR-PRL signaling has been an attractive target for cancer immunotherapy. For example, humanized anti-PRLR antibody could inhibit the binding of PRL and its receptor PRLR, which subsequently inhibits tumor cell proliferation (Damiano et al., Cancer Ther, 2013. 12(3): p. 295-305; Agarwal et al., Oncologist, 2016. 21(5): 535-6). An anti-PRLR antibody-drug conjugate (ADC) had shown significant PRLR- specific antitumor activity against breast cancer (Kelly et al., Mol Cancer Ther, 2017. 16(7): 1299- 1311).

[0005] The present disclosure provides, among other things, novel antibodies and antigenbinding fragments thereof that bind PRLR.

[0006] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 6.

[0007] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 11, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 12, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 13, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 14, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 15, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 16.

[0008] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 21, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 22, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 23, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 24, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 25, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 26.

[0009] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 31, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 32, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 33, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 34, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 35, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 36.

[0010] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 41, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 42, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 43, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 44, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 45, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 46.

[0011] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 51, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 52, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 53, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 54, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 55, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 56.

[0012] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 61, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 62, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 63, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 64, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 65, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 66.

[0013] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 71, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 72, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 73, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 74, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 75, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 76.

[0014] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 81, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO:82, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 83, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 84, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 85, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 86.

[0015] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 91; (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 92, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 93, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 94, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 95, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 96.

[0016] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 101, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 102, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 103, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 104, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 105, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 106.

[0017] In some embodiments, the antibody or antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 111, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 112, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 113, and a VL comprising (d) CDR-L1 comprising the amino acid sequence of SEQ ID NO: 114, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 115, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 116.

[0018] In some embodiments, the multispecific antigen-binding protein provided herein comprises (1) the antibody or the antigen-binding fragment thereof disclosed herein; and (2) a second binding domain that that binds human CD3. In some embodiments of the multispecific antigen-binding protein provided herei, wherein the antibody or the antigen-binding fragment thereof comprises: (1) a first antigen binding domain that specifically binds human PRLR comprising a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the aminoacid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 6; and (2) a second antigen binding domain that binds human CD3. In some embodiments, the multispecific antigenbinding protein is a bispecific antibody.

[0019] In some embodiments, an antibody-drug conjugate is provided in which the antibody-drug conjugate comprises the antibody or antigen-binding fragment thereof or the multispecific antigen-binding protein provided herein; and a drug.

[0020] In some embodiments, an isolated nucleic acid molecule is provided in which the isolated nucleic acid molecule comprises a nucleotide sequence encoding the antibody or antigenbinding fragment thereof or the multispecific antigen-binding protein provided herein.

[0021] In some embodiments, a method of treating a cancer in a subject is provided, in which the method comprises administering to the subject a therapeutically effective amount of the antibody or antigen-binding fragment thereof, the multispecific antigen-binding protein, the antibody-drug conjugate, or the pharmaceutical composition provided herein.IV. DEFINITIONS

[0022] The following list defines terms, phrases, and abbreviations used throughout the instant specification. All terms listed and defined herein are intended to encompass all grammatical forms. The term “or” is used in an inclusive sense, i.e., equivalent to “and / or,” unless the context clearly indicates otherwise. When “about” is present before the first value of a series, it is understood to modify each value in the series.

[0023] As used herein, unless otherwise specified, “PRLR” means human PRLR. Human PRLR means a full-length protein defined by UniProt P16471, a mature form thereof, an isoform thereof, a fragment thereof, or a variant thereof. Human PRLR is encoded by the PRLR gene. PRLR is also known as secreted prolactin binding protein, RI-PRLR, HPRL, and MF AB, which terms may be used interchangeably herein. In some particular embodiments, PRLR of non-human species, e.g., cynomolgus PRLR or mouse PRLR, is used.

[0024] As used herein, “binding affinity” describes the ability of a biomolecule (e.g., a polypeptide or a protein) of the disclosure (e.g., an antibody or antigen-binding fragment thereof, a fusion protein, or any other peptide or protein) to bind a selected target (and form a complex). Binding affinity is measured by a number of methods known to those skilled in the art including, but not limited to, fluorescence titration, enzyme-linked immunosorbent assay (ELISA)-based assays, including direct and competitive ELISA, calorimetric methods, such as isothermal titration calorimetry (ITC), and surface plasmon resonance (SPR). These methods are well-established in the art and some examples of such methods are further described herein. Binding affinity is thereby reported as a value of the dissociation constant (KD), half maximal effective concentration (ECso), or half maximal inhibitory concentration (IC50) measured using such methods. A lower KD, EC50, or IC50 value reflects better (higher) binding ability (affinity). Accordingly, the binding affinities of two biomolecules toward a selected target can be measured and compared. When comparing the binding affinities of two biomolecules toward the selected target, the term “comparable to”, “about the same,” “substantially the same” or “substantially similar” means one biomolecule has a binding affinity reported as a KD, an EC50, or an IC50 value that is identical or similar to that of another molecule within the experimental variability of the binding affinity measurement. In some embodiments, “comparable to”, “about the same,” “substantially the same” or “substantially similar” relate to a value that is within 50% deviation to a given reference value. In some embodiments, “comparable to”, “about the same,” “substantially the same” or “substantially similar” relate to a value that is within 20% deviation or within 10% deviation to a given reference value. The experimental variability of the binding affinity measurement is dependent upon the specific method used and is known to those skilled in the art.

[0025] As used herein, the term “substantially” may also refer to the qualitative condition of exhibiting total or near-total extent or degree of a characteristic or property of interest. One of ordinary skill in the biological arts will understand that biological and chemical phenomena rarely, if ever, go to completion and / or proceed to completeness or achieve or avoid an absolute result. The term “substantially” is therefore used herein to capture the potential lack of completeness inherent in many biological and chemical phenomena.

[0026] As used herein, the term “detect”, “detection”, “detectable”, or “detecting” is understood both on a quantitative and a qualitative level, as well as a combination thereof. It thus includes quantitative, semi -quantitative, and qualitative measurements performed on a biomolecule of the disclosure.

[0027] As used herein, “detectable affinity” generally means the binding ability between a biomolecule and its target, reported by a KD, ECSO, or IC50 value, is at most about 10'5M or lower. A binding affinity, reported by a KD, EC50, or IC50 value, higher than 10'5M is generally no longer measurable with common methods such as ELISA and SPR and is therefore of secondary importance. In some embodiment, “detectable affinity” may refer to a KD value of about 10'5M or lower as determined by ELISA or SPR.

[0028] As used herein, “specific for”, “specific binding”, “specifically bind”, or “binding specificity” relates to the ability of a biomolecule to discriminate between the desired target (for example, PRLR) and one or more reference targets. It is understood that such specificity is not an absolute but a relative property and can be determined, for example, by means of SPR, western blots, ELISA, fluorescence activated cell sorting (FACS), radioimmunoassay (RIA), electrochemiluminescence (ECL), immunoradiometric assay (IRMA), ImmunoHistoChemistry (IHC), and peptide scans.

[0029] When used herein in the context of a biomolecule, such as an antibody, an antigenbinding fragment thereof, or a fusion protein, of the present disclosure that binds to PRLR, the term “specific for”, “specific binding”, “specifically bind”, or “binding specificity” means that the biomolecule binds to, reacts with, or is directed against PRLR, as described herein, but does not substantially bind another protein. The term “another protein” includes any proteins that are not PRLR nor proteins closely related to or being homologous to PRLR. However, PRLR from species other than human and fragments and / or variants of PRLR do not fall under the term “another protein.” The term “does not substantially bind” means that a biomolecule of the present disclosure binds another protein with lower binding affinity than PRLR, i.e., shows a cross-reactivity of less than 30%, optionally less than 20, 10, 9, 8, 7, 6, or 5 %. Whether the biomolecule specifically reacts as defined herein above can easily be tested, inter alia, by comparing the reaction of a biomolecule of the present disclosure with PRLR and the reaction of said biomolecule with (an)other protein(s).

[0030] As used herein, a “mutant” or a “mutated” entity (whether protein or nucleic acid), refers to the exchange, deletion, or insertion of one or more amino acids or nucleotides, compared to the naturally occurring (wild-type) protein or nucleic acid. Said term also includes fragments of a mutein as described herein. In some embodiments, a PRLR mutant, as described herein, has a LCDR1 region, wherein at least one amino acid located within said LCDR1 region has been mutated as compared to the native sequence PRLR.

[0031] As used herein, the term “variant” relates to derivatives of a protein or polypeptide that include mutations, for example by substitutions, deletions, insertions, and / or chemical modifications of an amino acid sequence or nucleotide sequence. In some embodiments, such mutations and / or chemical modifications do not reduce the functionality of the protein or peptide. Such substitutions may be conservative, i.e., an amino acid residue is replaced with a chemically similar amino acid residue. Examples of conservative substitutions are the replacements among the members of the following groups: 1) alanine, serine, threonine, and valine; 2) aspartic acid, glutamic acid, glutamine, asparagine, and histidine; 3) arginine, lysine, glutamine, asparagine, and histidine; 4) isoleucine, leucine, methionine, valine, alanine, phenylalanine, threonine, and proline; and 5) isoleucine, leucine, methionine, phenylalanine, tyrosine, and tryptophan. Such variants include proteins or polypeptides, wherein one or more amino acids have been substituted by their respective D-stereoi somers or by amino acids other than the naturally occurring 20 amino acids, such as, for example, ornithine, hydroxyproline, citrulline, homoserine, hydroxylysine, norvaline. Such variants also include, for instance, proteins or polypeptides in which one or more amino acid residues are added or deleted at the N- and / or C-terminus. Generally, a variant has at least about 50%, 60%, 70%, 75%, 80%, 85%, 90%, 92%, 95% or at least about 98% amino acid sequence identity with the native sequence protein or polypeptide. A variant preferably retains the biological activity, e.g., binding the same target, of the protein or polypeptide it is derived from.

[0032] The term “variant”, as used herein with respect to an antibody or an antigen-binding fragment thereof relates to an antibody or an antigen-binding fragment thereof of the disclosure, wherein the sequence has mutations, including substitutions, deletions, insertions, and / or chemical modifications. A variant of an antibody or an antigen-binding fragment thereof as described herein retains the biological activity, e.g., binding to PRLR, of the antibody or antigen-binding fragment thereof from which it is derived. Generally, a variant of an antibody or an antigen-binding fragment thereof has at least about 50%, 60%, 70%, 75%, 80%, 85%, 90%, 92%, 95%, or at least about 98% amino acid sequence identity with the antibody or antigen-binding fragment thereof from which it is derived.

[0033] As used herein, the term “sequence identity” or “identity” denotes a property of sequences that measures their similarity or relationship. The term “sequence identity” or “identity” as used in the present disclosure means the percentage of pair-wise identical residues - following (homologous) alignment of a sequence of a protein or polypeptide of the disclosure with a sequence in question - with respect to the number of residues in the longer of these two sequences.Sequence identity is measured by dividing the number of identical amino acid residues by the total number of residues and multiplying the product by 100.

[0034] As used herein, the term “sequence homology” or “homology” has its usual meaning, and a homologous amino acid includes identical amino acids as well as amino acids which are regarded to be conservative substitutions at equivalent positions in the linear amino acid sequence of a protein or polypeptide of the disclosure.

[0035] A skilled artisan will recognize available computer programs, for example BLAST (Altschul et al., Nucleic Acids Res, 1997), BLAST2 (Altschul et al., J Mol Biol, 1990), and Smith- Waterman (Smith and Waterman, J Mol Biol, 1981), for determining sequence homology or sequence identity using standard parameters. The percentage of sequence homology or sequence identity can, for example, be determined herein using the program BLASTP, version 2.2.5 (November 16, 2002; (Altschul et al., Nucleic Acids Res, 1997). In some embodiments, the percentage of homology is based on the alignment of the entire protein or polypeptide sequences (matrix: BLOSUM 62; gap costs: 11.1; cutoff value set to 10'3) including the propeptide sequences, preferably using the wild-type protein scaffold as reference in a pairwise comparison. It is calculated as the percentage of numbers of “positives” (homologous amino acids) indicated as result in the BLASTP program output divided by the total number of amino acids selected by the program for the alignment.

[0036] As used interchangeably herein, the terms “conjugate”, “conjugation”, “fuse”, “fusion”, or “linked” refer to the joining together of two or more subunits, through all forms of covalent or non-covalent linkage, by means including, but not limited to, genetic fusion, chemical conjugation, coupling through a linker or a cross-linking agent, and non-covalent association.

[0037] The term “fusion polypeptide” or “fusion protein” as used herein refers to a polypeptide or protein comprising two or more subunits. In some embodiments, a fusion protein as described herein comprises two or more subunits, at least one of these subunits being capable of specifically binding to PRLR. Within the fusion protein, these subunits may be linked by covalent or non-covalent linkage. In some cases, the fusion protein is a translational fusion between the two or more subunits. The translational fusion may be generated by genetically engineering the coding sequence for one subunit in a reading frame with the coding sequence of a further subunit. Both subunits may be interspersed by a nucleotide sequence encoding a linker. However, the subunits of a fusion protein of the present disclosure may also be linked throughchemical conjugation. The subunits forming the fusion protein are typically linked to each other as follows: C-terminus of one subunit to N-terminus of another subunit, or C-terminus of one subunit to C-terminus of another subunit, or N-terminus of one subunit to N-terminus of another subunit, or N-terminus of one subunit to C-terminus of another subunit. The subunits of the fusion protein can be linked in any order and may include more than one of any of the constituent subunits. If one or more of the subunits are part of a protein (complex) that consists of more than one polypeptide chain, the term “fusion protein” may also refer to the protein comprising the fused sequences and all other polypeptide chain(s) of the protein (complex). As an illustrative example, where a full-length immunoglobulin / antibody is fused to a lipocalin mutein via a heavy or light chain of the immunoglobulin / antibody, the term “fusion protein” may refer to the single polypeptide chain comprising the lipocalin mutein and the heavy or light chain of the immunoglobulin / antibody. The term “fusion protein” may also refer to the entire immunoglobulin / antibody (both light and heavy chains) and the lipocalin mutein fused to one or both of its heavy and / or light chains.

[0038] As used herein, the term “subunit” of a fusion protein disclosed herein refers to a single protein or a separate polypeptide chain, which can form a stable folded structure by itself and may define a unique function of providing a binding motif towards a target. In some embodiments, a preferred subunit of the disclosure is an antibody, such as a full-length antibody, or an antigen-binding domain / fragment thereof.

[0039] A “linker” that may be comprised by a fusion protein of the present disclosure joins together two or more subunits of a fusion protein as described herein.

[0040] A “sample” is defined as a biological sample taken from any subject. Biological samples include, but are not limited to, blood, serum, urine, feces, semen, or tissue, including tumor tissue.

[0041] A “subject” is a vertebrate; in some embodiments, a subject is a mammal. The term “mammal” is used herein to refer to any animal classified as a mammal, including, without limitation, humans, domestic and farm animals, and zoo, sports, or pet animals, such as sheep, dogs, horses, cats, cows, rats, pigs, apes such as cynomolgus monkeys, to name only a few illustrative examples. In some embodiments, the “mammal” used herein is human.

[0042] An “effective amount” is an amount sufficient to yield beneficial or desired results. An effective amount can be administered in one or more individual administrations or doses.

[0043] As used herein, “antibody” includes whole antibodies or any antigen-binding fragment (i.e., “antigen-binding portion” or “antigen-binding domain”) or single chain thereof. The terms “antibody” and “immunoglobulin” can be and are used interchangeably herein. A whole antibody refers to a glycoprotein comprising at least two heavy chains (HCs) and two light chains (LCs) inter-connected by disulfide bonds. Each heavy chain is comprised of a heavy chain variable domain / region (VH or HCVR) and a heavy chain constant region (CH). The heavy chain constant region is comprised of three domains, Cm, Cm and CH3. Each light chain is comprised of a light chain variable domain / region (VL or LCVR) and a light chain constant region (CL). The light chain constant region is comprised of one domain, CL. The VH and VL regions can be further subdivided into regions of hypervariability, termed complementarity determining regions (CDRs), interspersed with regions that are more conserved, termed framework regions (FRs). Each VH and VL is composed of three CDRs and four FRs, arranged in the following order from the aminoterminus to the carboxy -terminus: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The variable regions of the heavy and light chains contain a binding domain that interacts with an antigen (for example, PRLR). The constant regions of the antibodies may optionally mediate the binding of the immunoglobulin to host tissues or factors, including various cells of the immune system (e.g., effector cells) and the first component (Clq) of the classical complement system.

[0044] As used herein, “antigen-binding fragment” (also referred to as “antigen-binding domain”) of an antibody refers to one or more fragments of an antibody that retain the ability to specifically bind to an antigen (e.g., PRLR). It has been shown that the antigen-binding function of an antibody can be performed by fragments of a full-length antibody. Examples of binding fragments encompassed within the term “antigen-binding fragment” of an antibody include (i) a Fab fragment consisting of the VH, VL, CL and Cm domains; (ii) a F(ab')2 fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fab' fragment consisting of the VH, VL, CL and CHI domains and the region between the Cm and Cm domains; (iv) an Fd fragment consisting of the VH and Cm domains; (v) a single-chain Fv fragment consisting of the VH and VL domains of a single arm of an antibody, (vi) a dAb fragment (Ward et al., Nature, 1989) consisting of a VH domain; (vii) an isolated complementarity determining region (CDR) or a combination of two or more isolated CDRs which may optionally be joined by a synthetic linker; (viii) a “diabody” comprising the VH and VL connected in the same polypeptide chain using a short linker (see, e.g., patent documents EP 404,097; WO 93 / 11161; and Holliger et al., Proc Natl Acad Set USA, 1993); and (ix) a “domain antibody fragment” containing only the VH or VL, where in some instances two or more VH regions are covalently joined. Throughout the present disclosureand claims, the term “CDR-H1” and “HCDR1” are used interchangeably; the term “CDR-H2” and “HCDR2” are used interchangeably; the term “CDR-H3” and “HCDR3” are used interchangeably; the term “CDR-L1” and “LCDR1” are used interchangeably; the term “CDR-L2” and “LCDR2” are used interchangeably; and the term “CDR-L3” and “LCDR3” are used interchangeably.

[0045] Antibodies may be polyclonal or monoclonal; xenogeneic, allogeneic, or syngeneic; or modified forms thereof (e.g., humanized, chimeric, or multispecific). Antibodies may also be fully human.

[0046] As used herein, “framework” or “FR” refers to the variable domain residues other than the hypervariable region (CDR) residues.

[0047] “Fragment crystallizable region” or “Fc region” refers to the C-terminal region of an immunoglobulin heavy chain, including native-sequence Fc regions and variant Fc regions. Although the boundaries of the Fc region of an immunoglobulin heavy chain might vary, the human IgG heavy-chain Fc region is usually defined to stretch from an amino acid residue at position Cys226, or from Pro230, to the carboxyl-terminus thereof numbering according to EU index of Kabat (Johnson and Wu, Nucleic Acids Res, 2000). The C-terminal lysine (residue 447 according to EU index of Kabat) of the Fc region may be removed, for example, during production or purification of the antibody, or by recombinantly engineering the nucleic acid encoding a heavy chain of the antibody. Accordingly, a composition of intact antibodies may comprise antibody populations with all K447 residues removed, antibody populations with no K447 residues removed, and antibody populations having a mixture of antibodies with and without the K447 residue. Suitable native- sequence Fc regions for use in the antibodies of the disclosure include human IgGl, IgG2 (IgG2A, IgG2B), IgG3, and IgG4.

[0048] “Fc receptor” or “FcR” refers to a receptor that binds to the Fc region of an antibody.

[0049] As used herein, “isolated antibody” refers to an antibody that is substantially free of its natural environment. For instance, an isolated antibody is substantially free of cellular material and other proteins from the cell or tissue source from which it is derived. An “isolated antibody” further refers to an antibody that is substantially free of other antibodies having different antigenic specificities. In the present case, an isolated antibody that binds specifically PRLR is substantially free of antibodies that specifically bind antigens other than PRLR. However, anisolated antibody that specifically binds PRLR may have cross-reactivity to other antigens, such as PRLR molecules from other species.

[0050] As used herein, “monoclonal antibody” refers 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.

[0051] The term “therapeutic agent” or “therapeutically active agent”, as used herein, refers to an agent which is therapeutically useful. A therapeutic agent may be any agent for the prevention, amelioration, or treatment of a disease, a physiological condition, a symptom, or for the evaluation or diagnosis thereof.

[0052] As used herein, “human antibody” includes antibodies having variable regions in which both the framework and CDR regions are derived from human germline immunoglobulin sequences. Furthermore, if the antibody contains a constant region, the constant region is also derived from human germline immunoglobulin sequences. The human antibodies of the disclosure may include amino acid residues not encoded by human germline 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.V. BRIEF DESCRIPTION OF DRAWINGS

[0053] FIG. 1 shows binding of the selected anti-PRLR clones to PRLR ectodomain analyzed by ELISA.

[0054] FIGS. 2A-2D show cell surface binding of the PRLR antibodies. Cell surface binding was further studied with flow cytometry after staining T47D cells with ELISA-positive antibodies (FIGS. 2A-2B). The five purified antibodies (PRLR_n-5, PRLR_n-7, PRLR_n-8, PRLR_n-10, and PRLR_n-l 1) were found to specifically bind to PRLR-positive T47D cells (FIG. 2C), but not to PRLR-negative Freestyle 293 cells (FIG. 2D).

[0055] FIGS. 3A-3F show binding affinities of PRLR antibodies analyzed by Octet. The antibody probes were simultaneously submerged in wells containing a serial concentration of PRLR antigen at 0 nM, 3.125 nM, 6.25 nM, 12.5 nM, 25 nM, 50 nM, and 100 nM for 600 seconds, then followed by 300 seconds of dissociation in the kinetic buffer. FIGS. 3 A-3B show the bindingresponse of the five antibodies (PRLR_n-5, PRLR_n-7, PRLR_n-8, PRLR_n-10, and PRLR n- 11) (FIGS. 3A-3E respectively). FIG. 3F shows the dissociation constant (KD) is estimated by fitting to the 1 : 1 binding model (F).

[0056] FIGS. 4A-4F show results of epitope binning experiments (assessment of competitive binding of antibody pairs) for each of the PRLR antibodies. Bindings of PRLR_n-5 (FIG. 4 A), PRLR_n-7 (FIG. 4B), PRLR_n-8 (FIG. 4C), PRLR_n-10 (FIG. 4D), and PRLR_n-l l (FIG. 4E) to the PRLR antigen in the presence of competition from each of the other four antibodies are indicated by arrows. The binning results are summarized in FIG. 4F.

[0057] FIGS. 5A-5F show T cell activation activity of the PRLR antibodies evaluated in the HSA-bispecific format. FIG. 5A shows the design of an exemplary HSA-based bispecific format. FIG. 5B shows HSA-based bispecific fusion proteins purified and qualified by SDS- PAGE. FIG. 5C shows SEC profiles of the purified PRLR-HSA fusion proteins to evaluate the aggregation status of each protein. FIG. 5D shows principle of the T cell activation assay in which the bispecific molecule recruits and engages T cells by simultaneous binding to CD3 of TCR and PRLR on the target cell. FIGS. 5E and 5F show the results of the T cell activation assay with T47D cells (FIG. 5E) and their corresponding EC50s (FIG. 5F).

[0058] FIGS. 6A-6B show alignments of antibody PRLR_n-8 IGHV and IGKV sequences with their closest germline counterpart. FIG. 6A shows the PRLR_n-8 IGHV sequence (SEQ ID NO: 7) aligned with IGHV1-69*O1 (SEQ ID NO: 138). FIG. 6B shows the PRLR_n-8 IGKV sequence (SEQ ID NO: 8) aligned with IGKV2-28*01 (SEQ ID NO: 139). IMGT-defined frameworks (FRs) and complementary determined regions (CDRs) are labeled.

[0059] FIGS. 7A-7E show affinity maturation of PRLR_n-8. FIG. 7A shows clones identified from LCDR1 libraries. Underlined are LCDR1 sequences subjected to mutagenesis. FIGS. 7B-7E shows affinities of converted IgGs measured by Octet.

[0060] FIG. 8 A (SEQ ID NOS: 381 - 383) shows redesign of PRLR_n-8 LCDR1 library with mutations from PRLR-4B6 LCDR1.

[0061] FIG. 8B shows clones identified from the LCDR1 library that were converted to the IgG-[L]-hOKT3 format and were expressed in Freestyle 293 cells. The expression titers were measured by Octet.

[0062] FIGS. 9A-9D show T cell activation mediated by PRLR bsAbs. FIG 9A shows aschematic diagram of PRLR bsAb in which human 0KT3 scFv is fused to the C-termini of light chain. FIGS. 9B and 9C show T cell activation of PRLR bsAbs in the presence and absence, respectively, of T47D cells. FIG. 9D shows their corresponding EC50 values .

[0063] FIGS. 10A-10E show cytotoxicity of PRLR bsAbs analyzed by the KILR cytotoxicity assay. Principle of the KILR cytotoxicity assay (FIG. 10A). The engineered T47D cells expressing ePL were assayed in the presence of PBMCs and PRLR bsAbs (FIGS. 10B-10E). PBMCs from two donors (FIGS. 10B-10C and FIGS. 10D-10E, respectively) were used in the assay. Samples allocated on the two assay plates were plotted separately.

[0064] FIGS. 11A-11E shows binding kinetics of the PRLR bispecific antibodies of PRLR-529 (FIG. 11 A), PRLR-619 (FIG. 1 IB), PRLR-621 (FIG. 11C), and LFA102 (FIG. 1 ID) in the IgG-[L]-hOKT3 format measured by BLI using GatorBio Prime. FIG. HE shows the corresponding IgG used for bsAb and the kinetic parameters of the bsAbs with the titers of bsAbs transiently expressed in Expi-CHO cells.

[0065] FIG. 12 shows pharmacokinetic analysis of PRLR bsAbs (PRLR-619 and PRLR- 621).

[0066] FIGS. 13A-13D show inhibition of tumor growth by PRLR bsAbs in a mouse cografting model. FIG. 13A shows study design and schedule of T47D / huPBMCs co-grafting model. Tumor volume (FIG. 13B) and mouse body weight (FIG. 13C) were measured throughout the study. Digital images of stripped tumors (FIG. 13D). Statistical analysis was based on one-tailed t-test. *P < 0.05, **P < 0.01, and ***P < 0.001.

[0067] FIGS. 14A-14D show inhibition of tumor growth by PRLR bsAbs in T47D tumor model with huPBMCs delivered intravenously. FIG. 14A shows study design and schedule of the mouse model (A). Mouse body weight (FIG. 14B) and tumor volume (FIG. 14C) were measured throughout the study, images of stripped tumors (FIG. 14D). Statistical analysis was based on one- tailed t-test. *P < 0.05, **P < 0.01, and ***P < 0.001.VI. DETAILED DESCRIPTION OF THE DISCLOSURE

[0068] As is described herein, in one aspect, the present disclosure provides antibodies or antigen-binding fragments thereof that bind PRLR. Such anti -PRLR antibodies or antigen-binding fragments thereof can be used by themselves as antibody therapeutics, conjugated to a therapeutic agent to generate an antibody-drug conjugate, included as part of a bispecific or multispecificantibody, or included as part of a fusion molecule. In certain embodiments, the antibody or antigen-binding fragment is incorporated into a fusion molecule that includes a binding domain that binds a different target than PRLR.

[0069] For example, as described in greater detail below, in some embodiments, the antibody or antigen-binding fragment is incorporated into a fusion molecule that can bind both PRLR and CD3. The use of the anti -PRLR antibodies or antigen-binding fragments as provided herein in fusion proteins, for example those that target both PRLR and CD3 can be utilized to bridge TCR / CD3 effector cells with PRLR-expressing tumor cells located in the tumor microenvironment, as shown in exemplary FIG. 5D. The anti-PRLR antibodies and antigenbinding fragments provided herein can be used to generate fusion proteins directed to other targets to achieve similar effects.

[0070] In other aspects, the present disclosure provides methods and useful applications of the anti- PRLR antibodies and antigen binding fragments thereof that are provided herein. The disclosure also provides methods of making PRLR-binding antibodies or antigen-binding fragments thereof described herein as well as compositions comprising such proteins. PRLR- binding antibodies or antigen-binding fragments thereof of the disclosure as well as compositions thereof may be used in methods of detecting PRLR in a sample, or in methods of binding of PRLR in a subject. No such antibodies or antigen-binding fragments thereof having these features attendant to the uses provided by present disclosure have been previously described.A. Exemplary antibodies or antigen-binding fragments thereof specific for PRLR

[0071] In some embodiments, the antibody or antigen-binding fragment thereof that bindsPRLR provided herein comprises:1) a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 6;2) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 11, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 12, and (c) CDR-H3comprising the amino acid sequence of SEQ ID NO: 13, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 14, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 15, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 16; ) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 21, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 22, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 23, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 24, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 25, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 26; ) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 31, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 32, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 33, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 34, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 35, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 36; ) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 41, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 42, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 43, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 44, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 45, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 46; ) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 51, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 52, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 53, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 54, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 55, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 56; ) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 61, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 62, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 63, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 64, (e) CDR-L2 comprising theamino acid sequence of SEQ ID NO: 65, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 66;8) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 71, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 72, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 73, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 74, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 75, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 76;9) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 81, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 82, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 83, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 84, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 85, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 86;10) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 91; (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 92, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 93, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 94, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 95, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 96;11) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 101, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 102, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 103, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 104, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 105, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 106;12) a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 111, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 112, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 113, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 114, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 115, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 116.

[0072] In some embodiments, an antibody or an antigen-binding fragment thereof that bindsPRLR provided herein comprises: a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 6.

[0073] In some embodiments, an antibody or an antigen-binding fragment thereof that binds PRLR provided herein comprises: a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 6.

[0074] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises:1) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 7, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 8;2) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 17, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 18;3) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%,at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 27, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 28;) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 37, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 38;) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 47, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 48;) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 57, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 58;) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 67, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 68;) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 77, anda VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 78;9) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 87, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 88;10) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 97, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 98.11) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 107, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 108; or12) a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 117, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 118.

[0075] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 7, and aVL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 8.

[0076] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 7, and a VL comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to any one of SEQ ID NOs: 131-135:

[0077] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises:1) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of any one of SEQ ID NOs: 8 and 131-135;2) a VH comprising the amino acid sequence of SEQ ID NO: 17, and a VL comprising the amino acid sequence of SEQ ID NO: 18;3) a VH comprising the amino acid sequence of SEQ ID NO: 27, and a VL comprising the amino acid sequence of SEQ ID NO: 28;4) a VH comprising the amino acid sequence of SEQ ID NO: 37, and a VL comprising the amino acid sequence of SEQ ID NO: 38;5) a VH comprising the amino acid sequence of SEQ ID NO: 47, and a VL comprising the amino acid sequence of SEQ ID NO: 48;6) a VH comprising the amino acid sequence of SEQ ID NO: 57, and a VL comprising the amino acid sequence of SEQ ID NO: 58;7) a VH comprising the amino acid sequence of SEQ ID NO: 67, and a VL comprising the amino acid sequence of SEQ ID NO: 68;8) a VH comprising the amino acid sequence of SEQ ID NO: 77, and a VL comprising the amino acid sequence of SEQ ID NO: 78;9) a VH comprising the amino acid sequence of SEQ ID NO: 87, and a VL comprising the amino acid sequence of SEQ ID NO: 88;10) a VH comprising the amino acid sequence of SEQ ID NO: 97, and a VL comprising the amino acid sequence of SEQ ID NO: 98;11) a VH comprising the amino acid sequence of SEQ ID NO: 107, and a VL comprising the amino acid sequence of SEQ ID NO: 108; or12) a VH comprising the amino acid sequence of SEQ ID NO: 117, and a VL comprising the amino acid sequence of SEQ ID NO: 118.

[0078] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of any one of SEQ ID NOs: 8 and 131-135.

[0079] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises: a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of any one of SEQ ID NOs: 131-135.

[0080] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises:1) a heavy chain (HC) comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 9, and a light chain (LC) comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 10;2) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 19, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 20;3) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 29, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 30;) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 39, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 40; ) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 49, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 50; ) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 59, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 60; ) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 69, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 70; ) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 79, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 80; or ) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, atleast 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 89, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 90;10) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 99, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 100; or11) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 109, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 110; or12) a HC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 119, and a LC comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 120.

[0081] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises: a heavy chain (HC) comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 9, and a light chain (LC) comprising an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 10.

[0082] In some embodiments, the antibody or the antigen-binding fragment thereof thatbinds PRLR provided herein comprises:1) a heavy chain (HC) comprising the amino acid sequence of SEQ ID NO: 9, and a light chain (LC) comprising the amino acid sequence of any one of SEQ ID NOs: 10 and 141-145;2) a HC comprising the amino acid sequence of SEQ ID NO: 19, and a LC comprising the amino acid sequence of SEQ ID NO: 20;3) a HC comprising the amino acid sequence of SEQ ID NO: 29, and a LC comprising the amino acid sequence of SEQ ID NO: 30;4) a HC comprising the amino acid sequence of SEQ ID NO: 39, and a LC comprising the amino acid sequence of SEQ ID NO: 40;5) a HC comprising the amino acid sequence of SEQ ID NO: 49, and a LC comprising the amino acid sequence of SEQ ID NO: 50;6) a HC comprising the amino acid sequence of SEQ ID NO: 59, and a LC comprising the amino acid sequence of SEQ ID NO: 60;7) a HC comprising the amino acid sequence of SEQ ID NO: 69, and a LC comprising the amino acid sequence of SEQ ID NO: 70;8) a HC comprising the amino acid sequence of SEQ ID NO: 79, and a LC comprising the amino acid sequence of SEQ ID NO: 80;9) a HC comprising the amino acid sequence of SEQ ID NO: 89, and a LC comprising the amino acid sequence of SEQ ID NO: 90;10) a HC comprising the amino acid sequence of SEQ ID NO: 99, and a LC comprising the amino acid sequence of SEQ ID NO: 100;11) a HC comprising the amino acid sequence of SEQ ID NO: 109, and a LC comprising the amino acid sequence of SEQ ID NO: 110; or12) a HC comprising the amino acid sequence of SEQ ID NO: 119, and a LC comprising the amino acid sequence of SEQ ID NO: 120.

[0083] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein comprises: a heavy chain (HC) comprising the amino acid sequence of SEQ ID NO: 9, and a light chain (LC) comprising the amino acid sequence of any one of SEQ ID NOs: 10 and 141-145.

[0084] In some embodiments, an antibody or an antigen-binding fragment thereof that binds PRLR is provided, wherein the antibody or the antigen-binding fragment thereof competes forbinding with PRLR with any one of the antibodies or antigen-binding fragments thereof disclosed herein. In some embodiments, the antibody or antigen-binding fragment thereof provided herein blocks prolactin-mediated signaling in cells expressing PRLR. In some such embodiments, the antibody that binds PRLR provided herein is a monoclonal antibody. In some embodiments, the antibody is monoclonal. In some embodiments, the antibody is a fully human antibody. In some such embodiments, the antibody that binds PRLR provided herein is a humanized or chimeric antibody. In some such embodiments, the antibody is an IgGl, IgG2, IgG3, or IgG4 antibody. In some embodiments, the antibody is an antigen-binding fragment. In some embodiments, the antibody fragment is a Fab, a Fab’, a F(ab’)2, a scFv, or a diabody. In some embodiments, the antibody is a multispecific antibody. In some embodiments, the antibody is a bispecific antibody.

[0085] In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 100 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 50 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 75 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 25 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 20 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 15 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 10 nM or less. In some embodiments, the antibody or the antigenbinding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 5 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 4 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 3 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 2.5 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 2 nM or less. In some embodiments, the antibody or the antigenbinding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 1.5 nM or less. In some embodiments, the antibody or the antigen-binding fragment thereof that binds PRLR provided herein binds PRLR with a KD value of 1 nM or less.

[0086] In some embodiments, the present disclosure encompasses a fusion protein comprising the antibody or antigen binding fragment thereof that specifically binds to PRLR disclosed herein.

[0087] In some embodiments, the present disclosure encompasses a composition comprising a provided fusion protein for inducing a localized lymphocyte response in the vicinity of PRLR-positive tumor cells. Accordingly, in some embodiments, the present disclosure provides methods of inducing a localized lymphocyte response in the vicinity of PRLR-positive tumor cells, comprising applying one or more fusion proteins of the disclosure or of one or more compositions comprising such fusion proteins.

[0088] For example, in some embodiments, the fusion protein is provided as a multispecific antigen-binding protein that can bind to both PRLR and CD3. The use of the anti- PRLR antibodies or antigen-binding fragments as provided herein in fusion proteins, for example those that target both PRLR and CD3 can be utilized to bridge TCR / CD3 effector cells with PRLR- expressing tumor cells located in the tumor microenvironment, as shown in exemplary FIG. 5D. The anti-PRLR antibodies and antigen-binding fragments provided herein can be used to generate fusion proteins directed to other targets to achieve similar effects.

[0089] For example, in some embodiments of the multispecific antigen-binding protein disclosed herein, the antibody or the antigen-binding fragment thereof comprises: (1) a first antigen binding domain that specifically binds human PRLR comprising a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR- H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 121-130, 136, and 137, (e) CDR- L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 6; and (2) a second antigen binding domain that that binds human CD3. In some embodiments of the multi specific antigen-binding protein described herein, the first antigen binding domain comprises a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising an amino acid sequence of any one of SEQ ID NOs: 131, 132, 133, 134, and 135.

[0090] In some embodiments of the multi specific antigen-binding protein described herein, wherein the second antigen binding domain comprises a humanized OKT3 (hOKT3) scFv. In someembodiments, the second antigen binding domain comprises SEQ ID NO: 153.

[0091] In some embodiments of the multi specific antigen-binding protein described herein, a peptide linker is provided between the first and second antigen binding domain. In some embodiments, the peptide linker comprises SEQ ID NO: 154. In some embodiments of the multispecific antigen-binding protein described herein, the multispecific antigen-binding protein provided herein comprise a polypeptide, from N terminal to C terminal, (1) a light chain of the first antigen binding domain comprising SEQ ID NO: 132 or 134, (2) a peptide linker, and (3) the second antigen binding domain comprising SEQ ID NO: 153. In further embodiments, the polypeptide comprises an amino acid sequence at least 95%, 96%, 97%, 98%, 99%, or 100 % identical to any one of SEQ ID NOs: 146-150. In some embodiments, the polypeptide comprises an amino acid sequence at least 95%, 96%, 97%, 98%, 99%, or 100 % identical to SEQ ID NO: 147 or 149. In some embodiments, the polypeptide comprises SEQ ID NO: 147 or 149.

[0092] In some embodiments, CDR sequences disclosed herein are defined according to the Kabat numbering scheme as described in Kabat et al. (1991), “Sequences of Proteins of Immunological Interest,” 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD. In some embodiments, CDR sequences disclosed herein are defined according to the IMGT method as described in Lefranc, M.-P., The Immunologist, 7, 132-136 (1999).

[0093] Antibodies specifically binding to PRLR as included in fusion proteins of the disclosure may comprise an Fc part which allows for extending the in vivo half-life of the bispecific binding molecule of the disclosure. In some embodiments, such Fc part is preferably from human origin, more preferably a human Fc part of an IgGl or lgG4 antibody, even more preferably an engineered human Fc part of an IgGl or lgG4 with activating or silencing effector functions. In some embodiments, silencing effector functions may be preferred over activating effector functions. In some embodiments, such an Fc part is an engineered to silence effector functions with mutation(s) at positions 297 and / or 322, numbering according to EU index of Kabat (Johnson and Wu, Nucleic Acids Res, 2000). In some embodiments, mutations in positions N297 and K322 of a provided anti-PRLR antibody may be introduced to silence effector functions. Numbering for these potential mutations is according to the EU index of Kabat (Shields et al., J Biol ('hem, 2001). In some embodiments, the provided PRLR antibody has an engineered IgGl backbone with double mutations N297G and K322A.

[0094] Various techniques for the production of antibodies and antigen-binding fragmentsthereof are well known in the art and described, e.g., in Altshuler et al. (2010). Thus, for example, polyclonal antibodies can be obtained from the blood of an animal following immunization with an antigen in mixture with additives and adjuvants and monoclonal antibodies can be produced by any technique which provides antibodies produced by continuous cell line cultures. Examples of such techniques are described, e.g., Harlow and Lane (1999), (1988), and include the hybridoma technique originally described by Kohler and Milstein, 1975, the trioma technique, the human B cell hybridoma technique (see e.g., Li et al., Proc Natl Acad Sci USA, 2006; Kozbor and Roder, Immunol Today, 1983) and the EBV-hybridoma technique to produce human monoclonal antibodies (Cole et al., Cancer Res, 1984). Furthermore, recombinant antibodies may be obtained from monoclonal antibodies or can be prepared de novo using various display methods such as phage, ribosomal, mRNA, or cell display. In some embodiments, a suitable system for the expression of the recombinant (humanized) antibodies or fragments thereof may be selected from, for example, bacteria, yeast, insects, mammalian cell lines or transgenic animals or plants (see, e.g., US Patent No. 6,080,560; Holliger and Hudson, Nat Biotechnol, 2005). Further, techniques described for the production of single chain antibodies (see, inter alia, US Patent No. 4,946,778) can be adapted to produce single chain antibodies specific for the target of the present disclosure. Surface plasmon resonance as employed in the BIAcore system can be used to increase the efficiency of phage antibodies.B. Immunoconjugates of antibodies or antigen-binding fragments thereof

[0095] The antibodies or antigen-binding fragments thereof provided herein can be conjugated to cytotoxic or cytostatic moieties (including pharmaceutically compatible salts thereof) to form immunoconjugates, such as an antibody drug conjugate (ADC).

[0096] Exemplary suitable moieties for conjugation to the antibodies or antigen-binding fragments thereof include, but are not limited to, cytotoxic agents (e.g., chemotherapeutic agents), prodrug converting enzymes, radioactive isotopes or compounds, or toxins (these moieties being collectively referred to as a therapeutic agent). For example, an antibody or antigen-binding fragment thereof can be conjugated to a cytotoxic agent such as a chemotherapeutic agent, or a toxin (e.g., a cytostatic or cytocidal agent such as, for example, abrin, ricin A, pseudomonas exotoxin, or diphtheria toxin). Examples of useful classes of cytotoxic agents include, for example, tubulin inhibitors, DNA minor groove binders, and DNA alkylating agents. Exemplary cytotoxic agents include, for example, auristatins, maytansinoids (e.g., DM1, DM2, DM3, DM4), camptothecins, calicheamicins, duocarmycins, etoposides, taxanes, benzodiazepines (e.g.,pyrrolo[l,4]benzodiazepines, indolinobenzodiazepines, and oxazolidinobenzodiazepines) and vinca alkaloids. In some embodiments, the cytotoxic agent is an auristatin- or maytansine-based cytotoxic agent.

[0097] In one embodiment, an antibody or antigen-binding fragment thereof is conjugated to a pro-drug converting enzyme. The pro-drug converting enzyme can be recombinantly fused to the antibody or antigen-binding fragment thereof or chemically conjugated thereto using known methods. Exemplary pro-drug converting enzymes are carboxypeptidase G2, P-glucuronidase, penicillin-V-amidase, penicillin-G-amidase, [3-lactamase, P-glucosidase, nitroreductase and carboxypeptidase A.

[0098] Techniques for conjugating therapeutic agents to antibodies or antigen-binding fragments thereof are well-known. (See, e.g., Alley et al., Current Opinion in Chemical Biology 2010 14: 1-9; Senter, Cancer J., 2008, 14(3): 154- 169.) The therapeutic agent can be conjugated in a manner that reduces its activity unless it is cleaved off the antibody or antigen-binding fragment thereof (e.g., by hydrolysis, by proteolytic degradation, or by a cleaving agent). In some aspects, the therapeutic agent is attached to the antibody or antigen-binding fragment thereof with a cleavable linker that is sensitive to cleavage in the intracellular environment of the PRLR- expressing cancer cell but is not substantially sensitive to the extracellular environment, such that the immunoconjugate is cleaved from the antibody or antigen-binding fragment thereof when it is internalized by the PRLR-expressing cancer cell (e.g., in the endosomal or, for example by virtue of pH sensitivity or protease sensitivity, in the lysosomal environment or in the caveolear environment). In some aspects, the therapeutic agent can also be attached to the antibody or antigen-binding fragment thereof with a non-cleavable linker.

[0099] Typically, the immunoconjugate comprises a linker region between the therapeutic agent and the antibody or antigen-binding fragment thereof. The linker generally is cleavable under intracellular conditions, such that cleavage of the linker releases the therapeutic agent from the antibody or antigen-binding fragment thereof in the intracellular environment (e.g., within a lysosome or endosome or caveolea). The linker can be, e.g., a peptidyl linker that is cleaved by an intracellular peptidase or protease enzyme, including a lysosomal or endosomal protease. Cleaving agents can include cathepsins B and D and plasmin (see, e.g., Dubowchik and Walker, Pharm. Therapeutics 83:67-123, 1999). Most typical are peptidyl linkers that are cleavable by enzymes that are present in PRLR-expressing cells. For example, a peptidyl linker that is cleavable by the thiol-dependent protease cathepsin-B, which is highly expressed in cancerous tissue, can be used(e.g., a linker comprising a Phe-Leu or a Val-Cit peptide).

[0100] The cleavable linker can be pH-sensitive, i.e., sensitive to hydrolysis at certain pH values. Typically, the pH-sensitive linker is hydrolyzable under acidic conditions. For example, an acid-labile linker that is hydrolyzable in the lysosome (e.g., a hydrazone, semicarbazone, thiosemicarbazone, cis-aconitic amide, orthoester, acetal, ketal, or the like) can be used. (See, e.g., U.S. Patent Nos. 5,122,368; 5,824,805; 5,622,929; Dubowchik and Walker, Pharm. Therapeutics 83:67-123, 1999; Neville et al., Biol. Chem. 264: 14653-14661, 1989.) Such linkers are relatively stable under neutral pH conditions, such as those in the blood, but are unstable at below pH 5.5 or 5.0, the approximate pH of the lysosome.

[0101] Other linkers are cleavable under reducing conditions (e.g., a disulfide linker). Disulfide linkers include those that can be formed using SATA (N-succinimidyl-S- acetylthioacetate), SPDP (N-succinimidyl-3-(2-pyridyldithio)propionate), SPDB (N- succinimidyl-3-(2-pyridyldithio)butyrate) and SMPT (N-succinimidyl-oxycarbonyl-alpha- methyl-alpha-(2-pyridyl-dithio)toluene), SPDB and SMPT. (See, e.g., Thorpe et al., Cancer Res. 47:5924-5931, 1987; Wawrzynczak et al., In Immunoconjugates: Antibody Conjugates in Radioimagery and Therapy of Cancer (C. W. Vogel ed., Oxford U. Press, 1987. See also U.S. Patent No. 4,880,935.)

[0102] The linker can also be a malonate linker (Johnson et al., Anticancer Res. 15: 1387- 93, 1995), a maleimidobenzoyl linker (Lau et al., Bioorg-Med-Chem. 3: 1299-1304, 1995), or a 3’- N-amide analog (Lau et al., Bioorg-Med-Chem. 3: 1305-12, 1995).

[0103] In other embodiments, the linker is a non-cleavable linker, such as an maleimido- alkylene- or maleimide-aryl linker that is directly attached to the therapeutic agent and released by proteolytic degradation of the antibody or antigen-binding fragment thereof.

[0104] Typically, the linker is not substantially sensitive to the extracellular environment, meaning that no more than about 20%, typically no more than about 15%, more typically no more than about 10%, and even more typically no more than about 5%, no more than about 3%, or no more than about 1% of the linkers in a sample of the immunoconjugate is cleaved when the immunoconjugate is present in an extracellular environment (e.g., in plasma). Whether a linker is not substantially sensitive to the extracellular environment can be determined, for example, by incubating independently with plasma both (a) the immunoconjugate (the “immunoconjugate sample”) and (b) an equal molar amount of unconjugated antibody or antigen-binding fragmentthereof or therapeutic agent (the “control sample”) for a predetermined time period (e.g., 2, 4, 8, 16, or 24 hours) and then comparing the amount of unconjugated antibody or antigen-binding fragment thereof or therapeutic agent present in the immunoconjugate sample with that present in control sample, as measured, for example, by high performance liquid chromatography.

[0105] The linker can also promote cellular internalization. The linker can promote cellular internalization when conjugated to the therapeutic agent (i.e., in the milieu of the linker-therapeutic agent moiety of the immunoconjugate or immunoconjugate derivate as described herein). Alternatively, the linker can promote cellular internalization when conjugated to both the therapeutic agent and the antibody or antigen-binding fragment thereof (i.e., in the milieu of the immunoconjugate as described herein).

[0106] Exemplary immunoconjugates include auristatin-based conjugates, meaning that the drug component is an auristatin drug. Auristatins bind tubulin, have been shown to interfere with microtubule dynamics and nuclear and cellular division, and have anticancer activity. Typically, the auristatin based antibody-drug conjugate comprises a linker between the auristatin drug and the antibody or antigen-binding fragment thereof. The linker can be, for example, a cleavable linker (e.g., a peptidyl linker) or a non-cleavable linker (e.g., linker released by degradation of the antibody). The auristatin can be auristatin E or a derivative thereof. Exemplary auristatins include monomethyl auristatin-E (MMAE) and monomethyl auristatin-F (MMAF). The syntheses of such auristatin based conjugates are known in the art, e.g., Chen H et al., Tubulin Inhibitor-Based Antibody -Drug Conjugates for Cancer Therapy. Molecules. 2017 Aug 1 ;22(8): 1281, the content of which is herein incorporated by reference.C. Exemplary uses and applications of antibodies or antigen-binding fragments thereof specific for PRLR, or of immunoconjugates of antibodies or antigen-binding fragments thereof

[0107] In some aspects, the present disclosure provides diagnostic and / or analytical kits comprising one or more antibodies, antigen-binding fragments thereof, or immunoconjugates of antibodies, or antigen-binding fragments thereof, according to the present disclosure.

[0108] In addition to their use in diagnostics, in yet another aspect, the disclosure contemplates pharmaceutical compositions comprising one or more antibodies, antigen-binding fragments thereof, or immunoconjugates of antibodies, or antigen-binding fragments thereof, of the present disclosure and a pharmaceutically acceptable excipient.

[0109] Furthermore, in some embodiments, the presently disclosed antibodies, antigenbinding fragments thereof, or immunoconjugates of antibodies, or antigen-binding fragments thereof, may be used in therapy, e.g., as anti-tumor and / or anti-infection agents and / or immune modulators. In some embodiments, the presently disclosed antibodies, antigen-binding fragments thereof, or immunoconjugates of antibodies, or antigen-binding fragments thereof, may be used in the manufacture of a medicament, e.g., a medicament for the treatment of cancer, including PRLR- positive cancer (e.g., breast cancer). In some embodiments, antibodies, antigen-binding fragments thereof, or immunoconjugates of antibodies, or antigen-binding fragments thereof, of the present disclosure are envisaged to be used in a method of prevention, amelioration, or treatment of human diseases, such as a cancer, including PRLR-positive cancer (e.g., breast cancer). Accordingly, also provided are methods of preventing, ameliorating, or treating human diseases, such as cancer, including PRLR-positive cancer (e.g., breast cancer)., in a subject in need thereof, comprising administering to said subject a therapeutically effective amount of one or more antibodies, antigenbinding fragments thereof, or immunoconjugates of antibodies or antigen-binding fragments thereof of the disclosure or one or more compositions comprising such antibodies, antigen-binding fragments thereof, or immunoconjugates of antibodies or antigen-binding fragments thereof. In some embodiments, the cancer is PRLR-positive cancer (e.g., breast cancer).

[0110] Examples of cancers that may be treated using the antibodies, antigen-binding fragments thereof, or immunoconjugates of antibodies or antigen-binding fragments thereof of the present disclosure include breast cancer, bladder cancer, uterine cancer, cervical cancer, ovarian cancer, prostate cancer, testicular cancer, esophageal cancer, gastrointestinal cancer, gastric cancer, pancreatic cancer, colorectal cancer, colon cancer, kidney cancer, clear cell renal carcinoma, head and neck cancer, lung cancer, lung adenocarcinoma, stomach cancer, germ cell cancer, bone cancer, liver cancer, thyroid cancer, skin cancer, melanoma, neoplasm of the central nervous system, mesothelioma, lymphoma, leukemia, chronic lymphocytic leukemia, diffuse large B cell lymphoma, follicular lymphoma, Hodgkin lymphoma, myeloma, or sarcoma. In some embodiments, the cancer includes breast cancer, prostate cancer, gastrointestinal cancer, kidney cancer, lung cancer, liver cancer, endometrial cancer, ovarian cancer, and colorectal cancer. In some embodiments, the cancer includes breast cancer. In some embodiments, cancer includes metastatic cancers.

[0111] In some embodiments, fusion proteins of the disclosure may simultaneously target tumor cells where PRLR is expressed and activate lymphocytes of the host immune systemadjacent to such tumor cells. In some embodiments, fusion proteins of the present disclosure may increase targeted anti-tumor T cell activity, enhance anti-tumor immunity and, and / or have a direct inhibiting effect on tumor growth, thereby producing synergistic anti-tumor results. In some embodiments, fusion proteins of the present disclosure may activate immune responses in a tumor microenvironment. In some embodiments, fusion proteins of the disclosure may reduce side effects of effector lymphocytes towards healthy cells, i.e., off-target toxicity, for example, via locally inhibiting oncogene activity and / or inducing lymphocyte activation.

[0112] In some embodiments, the present disclosure encompasses the use of a fusion protein of the disclosure, or a composition comprising a provided fusion protein, for inducing a localized lymphocyte response in the vicinity of PRLR-positive tumor cells. Accordingly, in some embodiments, the present disclosure provides methods of inducing a localized lymphocyte response in the vicinity of PRLR-positive tumor cells, comprising applying one or more fusion proteins of the disclosure or of one or more compositions comprising such fusion proteins.

[0113] For example, in some embodiments, the fusion protein is provided that can bind to both PRLR and CD3. The use of the anti-PRLR antibodies or antigen-binding fragments as provided herein in fusion proteins, for example those that target both PRLR and CD3 can be utilized to bridge TCR / CD3 effector cells with PRLR-expressing tumor cells located in the tumor microenvironment, as shown in the exemplary schematic in FIG. 5D. The anti-PRLR antibodies and antigen-binding fragments provided herein can be used to generate fusion proteins directed to other targets to achieve similar effects.D. Production of exemplary provided antibodies or antigen-binding fragments thereof specific for PRLR

[0114] In some embodiments, the present disclosure provides nucleic acid molecules (e.g., DNA or RNA) that include nucleotide sequences encoding the presently disclosed antibodies or antigen-binding fragments thereof. In some embodiments, the disclosure encompasses a vector containing a provided nucleic acid molecule. Since the degeneracy of the genetic code permits substitutions of certain codons by other codons specifying the same amino acid, the disclosure is not limited to a specific nucleic acid molecule encoding an antibody or antigen-binding fragment thereof as described herein, rather, encompassing all nucleic acid molecules that include nucleotide sequences encoding a functional antibody or antigen-binding fragment thereof. In this regard, the present disclosure also relates to nucleotide sequences encoding provided antibodies or antigen-binding fragments thereof. In some embodiments, the disclosure encompasses a host cell containing a provided nucleic acid molecule or vector.

[0115] Accordingly, the present disclosure encompasses an isolated polynucleotide encoding the antibody or antigen binding fragment thereof that specifically binds to PRLR disclosed herein. In some embodiments, the polynucleotide encodes (i) the heavy chain, (ii) the light chain, or (iii) the heavy chain and the light chain of the antibody or the antigen-binding fragment thereof described herein. In some embodiments, the polynucleotide comprises a nucleotide sequence of any one of SEQ ID NOs: 201-325. In some embodiments, the polynucleotide comprises one or more nucleotide sequences selected from SEQ ID NOs: 201-325.

[0116] In some embodiments, the polynucleotide encodes a multispecific antigen binding protein described herein. For example, in some embodiments, the polynucleotide encoding the multispecific antigen binding protein comprises a first nucleic acid encoding the first antigen binding domain that specifically binds PRLR, and a second nucleic acid encoding the second antigen binding domain that specifically binds CD3.

[0117] In some embodiments, the polynucleotide encoding the multispecific antigen binding protein disclosed herein comprises (1) a nucleic acid sequence encoding a heavy chain variable region of the first antigen binding domain disclosed herein that is at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO: 277; and / or (2) a nucleic acid sequence encoding a light chain variable region of the first antigen binding domain disclosed herein that is at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to any one of SEQ ID NOs: 321-325; and / or (3) a nucleic acid sequence encoding the second antigen binding domain that is at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO: 163. In some embodiments, the nucleic acid sequence encoding a light chain variable region of the first antigen binding domain disclosed herein comprises the nucleic acid sequence of SEQ ID NO: 322 or 324.

[0118] In some embodiments of the polynucleotide encoding the multispecific antigen binding protein disclosed herein, the nucleic acid encoding the second antigen binding domain comprises a nucleic acid sequence at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO: 163. In some embodiments, the nucleic acid sequence encoding the heavy chain variable region of the first antigen binding domain disclosed herein comprises SEQ ID NO: 277 and the nucleic acid sequence encoding the light chain variable regionof the first antigen binding domain comprises SEQ ID NO: 322 or 324, and the nucleic acid encoding the second antigen binding domain comprises SEQ ID NO: 163.

[0119] In some embodiments, the nucleic acid molecule is operably linked to a regulatory sequence to allow expression of said nucleic acid molecule.

[0120] A nucleic acid molecule, such as DNA, is referred to as “capable of expressing a nucleic acid molecule” or “able to allow expression of a nucleotide sequence” if it includes sequence elements that contain information regarding to transcriptional and / or translational regulation, and such sequences are “operably linked” to the nucleotide sequence encoding the protein. An operable linkage is a linkage in which the regulatory sequence elements and the sequence to be expressed are connected in a way that enables gene expression. The precise nature of the regulatory regions necessary for gene expression may vary among species, but in general these regions include a promoter, which, in prokaryotes, contains both the promoter per se, i.e., DNA elements directing the initiation of transcription, as well as DNA elements which, when transcribed into RNA, will signal the initiation of translation. Such promoter regions normally include 5’ non-coding sequences involved in initiation of transcription and translation, such as the -35 / - 10 boxes and the Shine-Dalgamo element in prokaryotes or the TATA box, CAAT sequences, and 5 ’-capping elements in eukaryotes. These regions can also include enhancer or repressor elements as well as translated signal and leader sequences for targeting the native protein to a specific compartment of a host cell.

[0121] In addition, 3’ non-coding sequences may contain regulatory elements involved in transcriptional termination, polyadenylation or the like. If, however, these termination sequences are not satisfactorily functional in a particular host cell, then they may be substituted with signals functional in that cell.

[0122] A nucleic acid molecule of the disclosure may be “operably linked” to one or more regulatory sequences, such as a promoter sequence, to allow expression of this nucleic acid molecule. In some embodiments, a nucleic acid molecule of the disclosure includes a promoter sequence and a transcriptional termination sequence. Suitable prokaryotic promoters are, for example, the tet promoter, the lacUV5 promoter or the T7 promoter. Examples of promoters useful for expression in eukaryotic cells are the SV40 promoter or the CMV promoter.

[0123] In some embodiments, nucleic acid molecules disclosed herein can also be part of a vector or any other kind of cloning vehicle, such as a plasmid, a phagemid, a phage, abaculovirus, a cosmid or an artificial chromosome.

[0124] In some embodiments, a provided nucleic acid molecule may be included in a phagemid. As used in this context, a phagemid vector denotes a vector encoding the intergenic region of a temperate phage, such as Ml 3 or fl, or a functional part thereof fused to the cDNA of interest. For example, in some embodiments, after superinfection of bacterial host cells with such a provided phagemid vector and an appropriate helper phage (e.g., M13K07, VCS-M13 or R408) intact phage particles are produced, thereby enabling physical coupling of the encoded heterologous cDNA to its corresponding polypeptide displayed on the phage surface (Lowman, Annu Rev Biophys Biomol Struct, 1997, Rodi and Makowski, Curr Opin Biolechnol, 1999).

[0125] In accordance with various embodiments, cloning vehicles can include, aside from the regulatory sequences described above and a nucleic acid sequence encoding an antibody or antigen-binding fragment thereof as described herein, replication and control sequences derived from a species compatible with the host cell that is used for expression as well as selection markers conferring a selectable phenotype on transformed or transfected cells. Large numbers of suitable cloning vectors are known in the art and are commercially available.

[0126] The disclosure also relates, in some embodiments, to methods for the production of antibodies or antigen-binding fragments thereof of the disclosure starting from a nucleic acid coding for an antibody or antigen-binding fragment thereof or any subunit(s) therein using genetic engineering methods. In some embodiments, a provided method can be carried out in vivo, wherein a provided antibody or antigen-binding fragment thereof can, for example, be produced in a bacterial or eukaryotic host organism, and then isolated from this host organism or its culture. It is also possible to produce an antibody or antigen-binding fragment thereof of the disclosure in vitro, for example, using an in vitro translation system.

[0127] When producing an antibody or antigen-binding fragment thereof in vivo, a nucleic acid encoding such antibody or antigen-binding fragment thereof may be introduced into a suitable bacterial or eukaryotic host organism using recombinant DN A technology well known in the art. In some embodiments, a DNA molecule encoding an antibody or antigen-binding fragment thereof as described herein, and in particular a cloning vector containing the coding sequence of such an antibody or antigen-binding fragment thereof can be transformed into a host cell capable of expressing the gene. Transformation can be performed using standard techniques. Thus, the disclosure is also directed to host cells containing a nucleic acid molecule as disclosed herein.

[0128] In some embodiments, transformed host cells may be cultured under conditions suitable for expression of the nucleotide sequence encoding an antibody or antigen-binding fragment thereof of the disclosure. In some embodiments, host cells can be prokaryotic, such as Escherichia coli (E. coli) or Bacillus suhlilis. or eukaryotic, such as Saccharomyces cerevisiae. Pichia pastoris, SF9 or High5 insect cells, immortalized mammalian cell lines (e.g., HeLa cells or CHO cells) or primary mammalian cells.

[0129] In some embodiments, it is also possible to produce an antibody or antigen-binding fragment thereof of the disclosure in the cytosol of a host cell, preferably E. coli. In this case, a provided antibody or antigen-binding fragment thereof can either be directly obtained in a soluble and folded state or recovered in the form of inclusion bodies, followed by renaturation in vitro. A further option is the use of specific host strains having an oxidizing intracellular milieu, which may thus allow the formation of disulfide bonds in the cytosol (Venturi et al., J Mol Biol, 2002).

[0130] In some embodiments, the antibody, or antigen-binding fragment thereof, of the disclosure as described herein may be not necessarily generated or produced, in whole or in part, via use of genetic engineering. Rather, such protein can also be obtained by any of the many conventional and well-known techniques such as plain organic synthesis strategies, solid phase- assisted synthesis techniques, commercially available automated synthesizers, or by in vitro transcription and translation. It is, for example, possible that promising antibodies or antigenbinding fragments thereof are identified using molecular modeling, synthesized in vitro, and investigated for the binding activity for the target(s) of interest. Methods for the solid phase and / or solution phase synthesis of proteins are well known in the art (see, e.g., Bruckdorfer et al., Curr Pharm Biotechnol, 2004).

[0131] In some embodiments, an antibody, or antigen-binding fragment thereof, of the disclosure may be produced by in vitro transcription / translation employing well-established methods known to those skilled in the art.

[0132] In some further embodiments, the antibodies or antigen-binding fragments thereof as described herein may also be prepared by conventional recombinant techniques alone or in combination with conventional synthetic techniques.

[0133] The skilled worker will appreciate methods useful to prepare antibodies or antigenbinding fragments thereof contemplated by the present disclosure but whose protein or nucleic acid sequences are not explicitly disclosed herein. As an overview, such modifications of theamino acid sequence include, e.g., directed mutagenesis of single amino acid positions to simplify sub-cloning of a protein gene or its parts by incorporating cleavage sites for certain restriction enzymes. Also, these mutations can be incorporated to further improve the affinity of an antibody or antigen-binding fragment thereof for its target(s) (e.g., PRLR). Furthermore, mutations can be introduced to modulate one or more characteristics of the protein such as to improve folding stability, serum stability, protein resistance or water solubility or to reduce aggregation tendency, if necessary.

[0134] Additional objects, advantages, and features of this disclosure will become apparent to those skilled in the art upon examination of the following Examples and the attached Figures, which are not intended to be limiting. Thus, it should be understood that although the present disclosure is specifically disclosed by exemplary embodiments and optional features, modification and variation of the disclosures embodied therein herein disclosed may be resorted to by those skilled in the art and that such modifications and variations are considered to be within the scope of this disclosure.VII. EXAMPLES

[0135] The following examples are provided to illustrate certain disclosed embodiments and are not to be construed as limiting the scope of this disclosure in any way.Example 1. Phage display and selection on cells

[0136] Phage display was carried out to search for antibodies that can bind to cell surface prolactin receptor (PRLR). In the first and third round of panning, biotinylated PRLR ectodomain (PRR-H52Ha, Acrobiosystems) were coupled to the streptavidin magnetic beads (ThermoFisher, Cat. No. 11205D). The beads were then incubated with a naive scFv library made from human PBMC mRNA. The unbound phage was washed away using PBST. The bound phage was eluted in 0.1 N HC1 and was immediately neutralized with 1 M Tris-HCl, pH 8.0. In the second round of panning, T47D cells were used to enrich phages for cell surface PRLR binding. The phage from the first round of panning was gently laid on the top of T47D cells and incubated on ice for 30 minutes. The unbound phage was washed away with ice-cold PBS (3x). The bound phage was eluted by treating cells with trypsin.

[0137] After three rounds of panning, 48 clones were randomly picked for phage ELISA and the top 12 clones were selected for IgG conversion (see Table of Sequences). ELISA wasperformed by loading culture media containing transiently expressed the IgG constructs in Freestyle 293 cells onto a plate coated with PRLR ectodomain. Binding signals were detected with the anti-human Fc-HRP / TMB system. 11 out of 12 antibodies were found to be capable of binding to the PRLR ectodomain by ELISA (FIG. 1).

[0138] To further verify cell surface binding, flow cytometry were carried out by staining T47D cells with ELISA positive antibodies. Five antibodies were found to specifically bind to T47D cells, but not to PRLR-negative Freestyle 293 cells (FIGS. 2A-D). The five antibodies were PRLR_n-5, PRLR_n-7, PRLR_n-8, PRLR_n-10, and PRLR_n-l 1.Example 2. Binding affinities of PRLR antibodies

[0139] Binding affinities of the five PRLR antibodies were evaluated using Octet. In brief, the anti-human Fc probes were loaded with testing antibodies at 2.5 mg / mL. Then, the loaded probes were dipped into the antigen wells to initiate association for 600 seconds. A serial concentration of PRLR antigen from 0 nM to 100 nM (0 nM, 3.125 nM, 6.25 nM, 12.5 nM, 25 nM, 50 nM, and 100 nM) was prepared in parallel. Dissociation for 300 seconds was initiated by transferring probes into the kinetic buffer.

[0140] The binding response of the five antibodies (PRLR_n-5, PRLR_n-7, PRLR_n-8, PRLR_n-10, and PRLR_n-l l) is shown in FIG. 3A-3E, respectively. The binding response was fitted with 1 : 1 binding mode and the KDS were estimated in the range of single to double digit nanomolar concentrations (FIG. 3F).Example 3. Epitope binning of PRLR antibodies

[0141] The epitopes of the five PRLR antibodies were analyzed by a cross-competition binning experiment where competitive binding of antibody pairs is assessed. In brief, 1 pg / mL His-tagged PRLR ectodomain was loaded onto an anti-His (HIS2) probe. The loaded probe was dipped into the first well containing 2.5 pg / mL of a testing IgG to initiate Phae I association. The probe was then dipped into a second well to initiate phase II association. The second well contained a mixture of the testing IgG and a second competing antibody IgG at the same concentration of 2.5 pg / ml, respectively.

[0142] For example, as shown in FIG. 4A, the probe loaded with His-PRLR antigen was first dipped into the PRLR_n-5 well. When the probe was then transferred into the second well containing PRLR_n-5 plus any one of other four antibodies, more binding signals were observedcompared to the well containing 2x concentration of PRLR_n-5. The results suggest that the PRLR_n-5 epitope is different from any of other antibodies. In contrast, the epitope for PRLR n- 8 was shown very close to the epitope of PRLR_n-7 or PRLR_n-l l as dipping the PRLR_n-8 probe into the well containing either PRLR_n-7 or PRLR_n-l l did not produce signals stronger than PRLR_n-8 alone (FIG 4B, 4C, and 4E). The binning results are summarized in FIG. 4F in which PRLR_n-5 and PRLR_n-10 belong to different bins, whereas PRLR_n-7, PRLR_n-8, and PRLR_n-l 1 belong to a closely related bin.Example 4. T cell activation activity of PRLR antibodies in an HSA-based bispecific format

[0143] To evaluate applicability of the five PRLR antibodies in directing T cells against tumor cells, an HSA-based bispecific format in which humanized OKT3 (hOKT3) scFv was fused to the C-terminus of human serum albumin (HSA) and anti-PRLR scFv was fused to the N- terminus of HSA was prepared. The HSA-hOKT3 fusion without anti-PRLR scFv was used as a control (FIG. 5 A). The HSA-based bispecific fusion proteins were expressed in Freestyle 293 cells and were purified and qualified by SDS-PAGE under non-reduced and reduced conditions using protein L columns (FIG. 5B).

[0144] The bioactivities of these molecules were assayed with an engineered Jurkat cell line expressing a luciferase reporter that is driven by an NF AT -response element. When these cells were exposed to an anti-TCR / CD3 stimulus, receptor-mediated signaling induced luminescence via activation of nuclear transcription factors. The assay was performed by incubating Jurkat cells with the HSA-based bispecific molecule in the absence and presence of T47D cells. SEC profiles of the purified PRLR-HSA fusion proteins were generated to evaluate the aggregation status of each protein (FIG. 5C). PRLR-HSA bispecific molecules evaluated by the T cell activation assay with T47D cells are shown in FIG. 5E and their corresponding EC50s are listed in FIG. 5F.Example 5. Affinity maturation of PRLR_n-8

[0145] First, PRLR_n-8 variable sequences were analyzed for affinity maturation using IMGT / V-Quest online tool. The PRLR_n-8 heavy chain variable sequence (IGHV) is identical to human IGHV1 -69*01, whereas the PRLR_n-8 light chain variable sequence (IGKV) is identical to human IGKV2-28*01 except one amino acid at the N-terminus (FIGS. 6A-6B). A total of 14 libraries were constructed to search for hot spots for affinity maturation. Each library generally targeted 4-5 amino acids among IMGT-defined CDR sequences (See Table 1). For library construction, a pair of 5’ phosphorylated primers were used to amplify the whole phagemid. Theforward primer was synthesized as degenerate oligonucleotides to randomly mutagenize the targeted amino acid sequence (Table 1). The PCR product was then self-ligated and electroporated into TGI electrocompetent cells. The transformed cells were then infected with M13KO7 helper phage to rescue the phagemid with its scFv gene and displayed one or more copies of scFv at their tips. The average diversity of the libraries was around IxlO8. The libraries belonging to the same CDR were usually panned together except for HCDR3 libraries.Table 1. Primer sequences used for constructing mutagenesis libraries targeting PRLR_n-8 CDRs

[0146] Three sequences (PRLR-1C11, PRLR-4B6, and PRLR-4H2) were recovered from the LCDR1 library with better ELISA signals (FIG. 7A, 1C11, 4B6 and 4H2). No sequence was recovered from other libraries. The three sequences were subsequently incorporated into IgGs, were expressed in Freestyle 293 cells, and were purified up to 99% of purity. Affinities of the three new antibodies were measured using Octet (FIGS. 7B-7E). The affinity of PRLR 4B6 wasimproved by approximately 3-fold, which was mainly contributed by a slower off-rate (FIG. 7A).Example 6. Improvement of expression titers of PRLR-4B6

[0147] To further explore LCDR1, an additional library was constructed by targeting more residues (FIG. 8A). This library was focused on three amino acids at the N-terminus of LCDR1 that had not been probed by the previous libraries while retaining the beneficial mutations of PRLR-4B6. After three rounds of panning, top 9 clones were selected for further evaluation based on phage ELISA. The titers of these clones in the IgG-[L]-hOKT3 format were surveyed by expressing in 12.5 mL Freestyle 293 cells (FIG. 8B). Four (4) clones (PRLR-619, PRLR-620, PRLR-621, PRLR-622 in IgG-[L]-hOKT3 format, see Table 2 for sequences) were selected for further development.

[0148] Table 2 shows the mutant clones selected from LCDR1 mutagenesis libraries for making bispecific antibodies in the IgG-[L]-hOKT3 format. Each light chain is paired with the same heavy chain containing VH_n-8 variable sequence (SEQ ID NO:7).TABLE 2.Example 7. The IgG-[L]-hOKT3 bispecific format

[0149] Even though an HSA-based bispecific format was made to redirect T cells against tumor cells (FIG. 5A), the HSA-based bispecific format was significantly less effective compared to the IgG-based bispecific format (data not shown). The IgG-based format was first reported by Sanitch et al., Sci Transl Med, 2020. 12(534) in which hOKT3 scFv was fused to the C-terminus of the light chain of an anti-GD2 antibody via a flexible linker. Besides, double mutations N297G and K322A were introduced in Fc to eliminate effector and complement functions (FIG. 9A). Five PRLR bispecific antibodies in IgG-[L]-hOKT3 format were constructed. Also, a bispecific antibody with LFA102, a neutralization antibody against PRLR from Norvatis (Damiano et al., Cancer Ther, 2013. 12(3): 295-305) was constructed, in the same format for comparison. Once again, T cell activation assay (shown in FIG. 5D) was used to analyze PRLR IgG-[L]-hOKT3 bispecific molecules in the presence and absence of T47D cells (FIGS. 9B and 9C). All five PRLR bsAbs showed similar activities to LFA102-[L]-hOKT3 bsAb in activating NF AT T cells (FIG. 9D).

[0150] To further evaluate anti-tumor activities of PRLR bispecific molecules, the KILR cytotoxicity assay was developed based on DiscoverX’s enzyme fragment complementation technology. The technology is based on two recombinant beta-galactosidase (P-gal) fragments that are inactive separately but active when combined. The active P-gal can hydrolyze its substrate to produce chemiluminescence signal (FIG. 10A). The ePL protein is a small fragment of P-gal enzyme with no activity when expressed alone in target cells. Upon lysis of target cells, the ePL protein is released into the medium and can be detected by adding the large P -gal fragment and substrate. The engineered T47D cells constitutively expressing ePL were assayed in the presence of PBMCs and PRLR bsAbs (FIGS. 10B-10E). PBMCs from two donors (FIGS. 10B-10C and FIGS. 10D-10E, respectively) were used in the assay. Samples allocated on the two assay plates were plotted separately. When assayed in the presence of a PRLR bsAb and human PBMCs, theePL would be released into the culture medium which could be detected by adding the large enzyme fragment, or enzyme acceptor, and substrate (FIG. 10A). The T47D / KILR cell line was generated by stable transfection of the KILR gene encoding for the small fragment ePL.Example 8. Binding affinities of PRLR-[L]-hOKT3 bispecific antibodies

[0151] Binding affinities of PRLR bsAbs in the IgG-[L]-hOKT3 format were measured using GatorBio’s BLI technology. PRLR bsAbs were transiently expressed in ExpiCHO cells using ThermoFisher’s expression kit (Cat. No. A29133) and were purified over 98% purity. As shown in FIGS. 11 A-l ID, KD of PRLR-529 was estimated to be 4.14 nM using 1 : 1 fitting model. This number is close to the KD measured previously in the IgG format (FIG. 7), suggesting that conversion of this antibody to the IgG-[L]-hOKT3 format does not cause any affinity attrition. The two bsAbs (PRLR-619 and PRLR-621) selected from the LCDR1 modification library did not show any improvement in affinity but significant improvement in expression titers when expressed in ExpiCHO cells (FIG. 1 IE).Example 9. Pharmacokinetics of PRLR-[L]-hOKT3 bispecific antibodies

[0152] Pharmacokinetic (PK) studies were performed in BALB / c male mice. A single dose of 5 mg / kg of PRLR-619 or PRLR-621 were injected intravenously into BALB / c mice (5 mg / kg, n = 5 / group). Blood samples were collected at 15 minutes, 6 hours, 1, 2, 4, 7, 10, 15, 21, and 28 days. Plasma antibody concentrations were assayed by ELISA in which human PRLR protein (ACRO Biosystems) was immobilized. PK parameters were determined with a noncompartmental analysis model using Pksolver.

[0153] As shown in FIGS. 12A-12B, both PRLR-619 and PRLR-621 showed a favorable PK profile with a half-life of 8.73 days and 5.16 days, respectively. The maximum serum concentration (Cmax) was 45.61 mg / mL for PRLR-619 and 57.93 mg / mL for PRLR-621. The area under the curve (AUC) and the total clearance (CL) were similar for PRLR-619 and PRLR-621 (FIG. 12B).Example 10. Anti-tumor effects of PRLR-[L]-hOKT3 bispecific antibodies in mouse cografting model

[0154] The in vivo anti -turn or activity of PRLR-619 and PRL-621 was evaluated in the T47D / PBMCs co-grafting mouse model (FIG. 13 A). 6-week-old female NOD / SCID mice (Charles River Laboratories) were implanted subcutaneously with 17[3-estradiol pellets (0.72 mg per pellet, 60-day release, Innovative Research of America). After 1 week, the mixture of IxlO7T47D cells and 2.5xl06PBMCs in matrigel (Corning) were injected subcutaneously. The mice were divided into five groups based on body weight and administered intravenously with a vehicle control (PBS), LFA102 1+1, LFA102-[L]-hOKT3, and PRLR-619, and PRLR-621 according to the schedule shown in FIG. 13A. LFA102 1+1 is referred to as the bispecific molecule with one arm binding to PRLR (LFA102 arm) and the other arm binding to CD3 (hOKT3 arm). The two half molecules harboring either F405L mutation or F409R mutation in the Fc region were expressed separately and were assembled via Fab-arm exchange (Labrijn et al., PNAS, 2013. 110(13): 5145-50; Labrijn et al., Nat Protoc, 2014. 9(10): 2450-63).

[0155] Tumor volume (FIG. 13B) and mouse body weight (FIG. 13C) were measured throughout the study. Mouse weight and tumor dimensions (length and width) were recorded twice a week, and tumor volume was estimated by (length x width x width) / 2. As shown in FIG. 13B, all four bispecific molecules showed significant inhibition of tumor growth compared to the vehicle control. Digital images of stripped tumors are shown in FIG. 13D. These results are consistent with the in vitro results of T cell activation and cytotoxicity assays.Example 11. Anti-tumor effects of PRLR-[L]-hOKT3 bispecific antibodies in a mouse model with PBMCs delivered from periphery after tumor establishment

[0156] In this model, PBMCs were not co-grafted with tumor cells, but were delivered from periphery 9 days after grafting T47D cells (FIG. 14A). Since PBMCs are recruited from periphery to the tumor sites, this setting is more in line with the microenvironment of solid tumors. In this experiment, PRLR-619 was tested at 0.2 mg / kg, 1 mg / kg, and 5 mg / kg. As shown in FIG. 14C, a dose-dependent inhibition of tumor growth was observed between 0.2 mg / kg and 1 mg / kg. Throughout the study, mouse body weight was not affected by any treatment (FIG. 14B). At the endpoint, tumors were stripped and imaged (FIG. 14D).

[0157] Embodiments illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present embodiments have been specifically disclosed by preferred embodiments and optional features, equivalents, modificationsand variations thereof may be resorted to by those skilled in the art, and that such equivalents, modifications and variations are considered to be within the scope of this invention. All patents, patent applications, textbooks and (peer-reviewed) publications described herein are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. Each of the narrower species and subgeneric groupings falling within the generic disclosure also forms part of the invention. This includes the generic description of the invention with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein. In addition, where features are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. Further embodiments will become apparent from the following claims.VIII. TABLE OF SEQUENCES

Claims

What is Claimed is:

1. An isolated antibody or an isolated antigen-binding fragment thereof that binds prolactin receptor (PRLR), wherein the antibody or the antigen-binding fragment thereof comprises: a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 6; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 11, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 12, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 13, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 14, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 15, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 16; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 21, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 22, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 23, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 24, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 25, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 26; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 31, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 32, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 33, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 34, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 35, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 36; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 41, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 42, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 43, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 44, (e) CDR-L2 comprising theamino acid sequence of SEQ ID NO: 45, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 46; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 51, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 52, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 53, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 54, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 55, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 56; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 61, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 62, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 63, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 64, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 65, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 66; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 71, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 72, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 73, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 74, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 75, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 76; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 81, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 82, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 83, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 84, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 85, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 86; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 91; (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 92, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 93, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 94, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 95, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 96;a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 101, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 102, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 103, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 104, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 105, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 106; a VH comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 111, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 112, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 113, and a VL comprising (d) CDR- L1 comprising the amino acid sequence of SEQ ID NO: 114, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 115, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO:

116. The antibody or the antigen-binding fragment thereof of claim 1, wherein the antibody or the antigen-binding fragment thereof comprises: a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO:

6. The antibody or the antigen-binding fragment thereof of claim 1 or 2, wherein the antibody or the antigen-binding fragment thereof comprises: a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO:

6. The antibody or the antigen-binding fragment thereof of any one of claims 1-3, wherein the antibody or the antigen-binding fragment thereof comprises: a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 7, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 8;a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 17, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 18; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 27, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 28; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 37, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 38; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 47, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 48; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 57, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 58; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 67, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 68; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 77, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 78; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 87, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 88; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 97, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 98; a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 107, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 108; or a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 117, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 118.The antibody or the antigen-binding fragment thereof of any one of claims 1-4, wherein the antibody or the antigen-binding fragment thereof comprises: a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 7, and a VL comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO:

8. The antibody or the antigen-binding fragment thereof of claim 1-5, wherein the antibody or the antigen-binding fragment thereof comprises: a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of any one of SEQ ID NOs: 8 and 131-135; a VH comprising the amino acid sequence of SEQ ID NO: 17, and a VL comprising the amino acid sequence of SEQ ID NO: 18; a VH comprising the amino acid sequence of SEQ ID NO: 27, and a VL comprising the amino acid sequence of SEQ ID NO: 28; a VH comprising the amino acid sequence of SEQ ID NO: 37, and a VL comprising the amino acid sequence of SEQ ID NO: 38; a VH comprising the amino acid sequence of SEQ ID NO: 47, and a VL comprising the amino acid sequence of SEQ ID NO: 48; a VH comprising the amino acid sequence of SEQ ID NO: 57, and a VL comprising the amino acid sequence of SEQ ID NO: 58; a VH comprising the amino acid sequence of SEQ ID NO: 67, and a VL comprising the amino acid sequence of SEQ ID NO: 68; a VH comprising the amino acid sequence of SEQ ID NO: 77, and a VL comprising the amino acid sequence of SEQ ID NO: 78; a VH comprising the amino acid sequence of SEQ ID NO: 87, and a VL comprising the amino acid sequence of SEQ ID NO: 88; a VH comprising the amino acid sequence of SEQ ID NO: 97, and a VL comprising the amino acid sequence of SEQ ID NO: 98; a VH comprising the amino acid sequence of SEQ ID NO: 107, and a VL comprising the amino acid sequence of SEQ ID NO: 108; or a VH comprising the amino acid sequence of SEQ ID NO: 117, and a VL comprising the amino acid sequence of SEQ ID NO:

118. The antibody or the antigen-binding fragment thereof of any one of claims 1-6, wherein the antibody or the antigen-binding fragment thereof comprises: a VH comprising the amino acidsequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of any one of SEQ ID NOs: 8 and 131-135. The antibody or the antigen-binding fragment thereof of claim 7, wherein the VL comprises the amino acid sequence of SEQ ID NO:

8. The antibody or the antigen-binding fragment thereof of claim 7, wherein the VL comprises the amino acid sequence of SEQ ID NO:

131. The antibody or the antigen-binding fragment thereof of claim 7, wherein the VL comprises the amino acid sequence of SEQ ID NO:

132. The antibody or the antigen-binding fragment thereof of claim 7, wherein the VL comprises the amino acid sequence of SEQ ID NO:

133. The antibody or the antigen-binding fragment thereof of claim 7, wherein the VL comprises the amino acid sequence of SEQ ID NO:

134. The antibody or the antigen-binding fragment thereof of claim 7, wherein the VL comprises the amino acid sequence of SEQ ID NO:

135. The antibody or the antigen-binding fragment thereof of any one of claims 1-13, comprising a heavy chain (HC) comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 9, and a light chain (LC) comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 10; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 19, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 20; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 29, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 30; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 39, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 40; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 49, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 50; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 59, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 60;a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 69, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 70; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 79, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 80; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 89, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 90; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 99, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 100; a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 109, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 110; or a HC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 119, and a LC comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO:

120. The antibody or the antigen-binding fragment thereof of any one of claims 1-14, wherein the antibody or the antigen-binding fragment thereof comprises: a heavy chain (HC) comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 9, and a light chain (LC) comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO:

10. The antibody or the antigen-binding fragment thereof of any one of claims 1-15, comprising a heavy chain (HC) comprising the amino acid sequence of SEQ ID NO: 9, and a light chain (LC) comprising the amino acid sequence of any one of SEQ ID NOs: 10 and 141-145; a HC comprising the amino acid sequence of SEQ ID NO: 19, and a LC comprising the amino acid sequence of SEQ ID NO: 20; a HC comprising the amino acid sequence of SEQ ID NO: 29, and a LC comprising the amino acid sequence of SEQ ID NO: 30; a HC comprising the amino acid sequence of SEQ ID NO: 39, and a LC comprising the amino acid sequence of SEQ ID NO: 40;a HC comprising the amino acid sequence of SEQ ID NO: 49, and a LC comprising the amino acid sequence of SEQ ID NO: 50; a HC comprising the amino acid sequence of SEQ ID NO: 59, and a LC comprising the amino acid sequence of SEQ ID NO: 60; a HC comprising the amino acid sequence of SEQ ID NO: 69, and a LC comprising the amino acid sequence of SEQ ID NO: 70; a HC comprising the amino acid sequence of SEQ ID NO: 79, and a LC comprising the amino acid sequence of SEQ ID NO: 80; a HC comprising the amino acid sequence of SEQ ID NO: 89, and a LC comprising the amino acid sequence of SEQ ID NO: 90; a HC comprising the amino acid sequence of SEQ ID NO: 99, and a LC comprising the amino acid sequence of SEQ ID NO: 100; a HC comprising the amino acid sequence of SEQ ID NO: 109, and a LC comprising the amino acid sequence of SEQ ID NO: 110; or a HC comprising the amino acid sequence of SEQ ID NO: 119, and a LC comprising the amino acid sequence of SEQ ID NO:

120. The antibody or the antigen-binding fragment thereof of any one of claims 1-16, comprising a heavy chain (HC) comprising the amino acid sequence of SEQ ID NO: 9, and a light chain (LC) comprising the amino acid sequence of any one of SEQ ID NOs: 10 and 141-145. An isolated antibody or an isolated antigen-binding fragment thereof comprising: a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO:

6. The antibody or the antigen-binding fragment thereof of claim 18, wherein the antibody or the antigen-binding fragment thereof comprises: a VH comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 7, and a VL comprising an amino acid sequence having at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ ID NO:

8. The antibody or the antigen-binding fragment thereof of claim 19, wherein the VL comprises the amino acid sequence of any one of SEQ ID NOs: 8 and 131-135.The antibody or the antigen-binding fragment thereof of any one of claims 18-20, comprising a heavy chain (HC) comprising an amino acid sequence having at least 95% sequence identity to SEQ ID NO: 9, and a light chain (LC) comprising an amino acid sequence having at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO:

10. The antibody or the antigen-binding fragment thereof of claim 21, wherein the light chain (LC) comprises the amino acid sequence of any one of SEQ ID NO: 10 and 141-145. The antibody or the antigen-binding fragment thereof of any one of claims 1-22, wherein the antibody or the antigen-binding fragment thereof binds PRLR with a KD value of 100 nM or less. The antibody or the antigen-binding fragment thereof of any one of claims 1-23, wherein the antibody blocks prolactin-mediated signaling in cells expressing PRLR. The antibody or the antigen-binding fragment thereof of any one of claims 1-24, wherein the antibody is monoclonal. The antibody or the antigen-binding fragment thereof of any one of claims 1-25, wherein the antibody is a fully human antibody. The antibody or the antigen-binding fragment thereof of any one of claims 1-26, wherein the antibody is a humanized or chimeric antibody. The antibody or the antigen-binding fragment thereof of any one of claims 1-27, wherein the antibody is an IgGl, IgG2, IgG3, or IgG4 antibody. The antibody or the antigen-binding fragment thereof of any one of claims 1-28, wherein the antibody fragment is a Fab, a Fab’, a F(ab’)2, a scFv, or a diabody. The antibody or the antigen-binding fragment thereof of any one of claims 1-29, wherein the antibody is a multispecific antibody. The antibody or the antigen-binding fragment thereof of any one of claims 1-30, wherein the antibody is a bispecific antibody. A multispecific antigen-binding protein, comprising (1) the antibody or the antigen-binding fragment thereof according to any one of claims 1-31; and (2) a second binding domain that that binds human CD3. A multispecific antigen-binding protein, wherein the antibody or the antigen-binding fragment thereof comprises:(1) a first antigen binding domain that specifically binds human PRLR comprising a heavy chain variable domain (VH) comprising (a) CDR-H1 comprising the amino acid sequence ofSEQ ID NO: 1, (b) CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2, and (c) CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3, and a light chain variable domain (VL) comprising (d) CDR-L1 comprising the amino acid sequence of any one of SEQ ID NOs: 121-130, 136, and 137, (e) CDR-L2 comprising the amino acid sequence of SEQ ID NO: 5, and (f) CDR-L3 comprising the amino acid sequence of SEQ ID NO: 6; and (2) a second antigen binding domain that binds human CD3. The multispecific antigen-binding protein of claim 32 or 33, wherein the multispecific antigenbinding protein is a bispecific antibody. The multispecific antigen-binding protein of any one of claims 32-34, wherein: the first antigen binding domain comprises a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising an amino acid sequence of any one of SEQ ID NOs: 131, 132, 133, 134, and 135. The multispecific antigen-binding protein of any one of claims 32-35, wherein a heavy chain (HC) comprises the amino acid sequence of SEQ ID NO: 9, and a light chain (LC) comprises an amino acid sequence of any one of SEQ ID NO: 141-145. The multispecific antigen-binding protein of any one of claims 32-36, wherein the VH comprises the amino acid sequence of SEQ ID NO: 7, and the VH comprises an amino acid sequence of any one of SEQ ID NO: 132 or 134. The multispecific antigen-binding protein of any one of claims 32-37, wherein the HC comprises the amino acid sequence of SEQ ID NO: 9, and the LC comprises an amino acid sequence of any one of SEQ ID NO: 142 or 144. The multispecific antigen-binding protein of any one of claims 32-38, wherein the second antigen binding domain comprises a humanized OKT3 (hOKT3) scFv. The multispecific antigen-binding protein of any one of claims 32-39, wherein the second antigen binding domain comprises SEQ ID NO:

153. The multispecific antigen-binding protein of any one of claims 32-40, comprising a peptide linker between the first and second antigen binding domain. The multispecific antigen-binding protein of any one of claims 32-41, comprising a polypeptide comprising, from N terminal to C terminal, (1) a light chain of the first antigen binding domain comprising SEQ ID NO: 132 or 134, (2) a peptide linker, and (3) the second antigen binding domain comprising SEQ ID NO: 153, optionally the polypeptide comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100 % identical to any one of SEQ ID NOs: 146-150.The multispecific antigen-binding protein of any one of claims 41 or 42, wherein the peptide linker comprises SEQ ID NO:

154. An antibody-drug conjugate comprising an antibody or antigen-binding fragment thereof of any one of claims 1-43 or the multispecific antigen-binding protein of any one of claims 32- 43; and a drug. The antibody-drug conjugate of claim 44, wherein the antibody-drug conjugate is an immunoconj ugate . The antibody-drug conjugate of claim 44 or 45, wherein the immunoconjugate comprises an antibody or antigen-binding fragment thereof of any one of claims 1-44 or the multispecific antigen-binding protein of any one of claims 32-43; and a cytotoxic agent. The antibody-drug conjugate of claim 46, wherein the cytotoxic agent is an auristatin. The antibody-drug conjugate of claim 47, wherein the cytotoxic agent is monomethyl auristatin E (MMAE). The antibody-drug conjugate of claim 47, wherein the cytotoxic agent is monomethyl auristatin F (MMAF). The antibody-drug conjugate of claims 44-49, wherein the antibody-drug conjugate further comprises a linker between the antibody or antigen binding domain and the drug. The antibody-drug conjugate of claim 50, wherein the linker is cleavable. The antibody-drug conjugate of claim 50, wherein the linker is non-cleavable. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof of any one of claims 1-43, the multispecific antigen-binding protein of any one of claims 32- 43, and the antibody-drug conjugate of any one of claims 44-52, and a pharmaceutically acceptable excipient. An isolated polynucleotide that encodes (i) the heavy chain of the antibody of any one of claims 1-31; (ii) the light chain of the antibody of any one of claims 1-31; or (iii) the heavy chain and the light chain of the antibody of any one of claims 1-31. An isolated nucleic acid molecule comprising a nucleotide sequence encoding the antibody or the antigen-binding fragment thereof of any one of claims 1-31 or the multispecific antigenbinding protein of any one of claims 32-43. The isolated polynucleotide of claim 54 or 55, wherein the polynucleotide comprises a nucleotide sequence selected from SEQ ID NOs: 201-325. The isolated polynucleotide of any one of claims 54-56, comprising (1) a nucleic acid sequence encoding a heavy chain variable region of the first antigen binding domain that is at least 95%,at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO: 277; and / or (2) a nucleic acid encoding a light chain variable region of the first antigen binding domain that is at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to any one of SEQ ID NOs: 321-325; and / or (3) a nucleic acid sequence encoding the second antigen binding domain that is at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO:

163. The isolated polynucleotide of claim 57, wherein the nucleic acid sequence encoding the heavy chain variable region of the first antigen binding domain disclosed herein comprises SEQ ID NO: 277 and the nucleic acid sequence encoding the light chain variable region of the first antigen binding domain comprises SEQ ID NO: 322 or 324, and the nucleic acid encoding the second antigen binding domain comprises SEQ ID NO:

163. The isolated polynucleotide of any one of claims 54-58, wherein the nucleic acid molecule is operably linked to a regulatory sequence to allow expression of said nucleic acid molecule. A vector comprising the polynucleotide of any one of claims 54-59. An isolated host cell comprising the isolated polynucleotide of any one of claims 54-59, or the vector of claim 60. An isolated host cell that expresses the antibody or the antigen-binding fragment thereof of any one of claims 1-31 or the multispecific antigen-binding protein of any one of claims 32- 43. A host cell comprising a polynucleotide comprising a nucleotide sequence encoding the antibody or the antigen-binding fragment thereof of any one of claims 1-31 or the multispecific antigen-binding protein of any one of claims 32-43. The host cell of claim 62 or 63, wherein the polynucleotide is a vector. The host cell of any one of claims 62-64, wherein the host cell is a prokaryotic cell or a eukaryotic cell. A method of producing the antibody or the antigen-binding fragment thereof of any one of claims 1-31 or the multispecific antigen-binding protein of any one of claims 32-44, the method comprising incubating the host cell of any one of claims 63-65 under conditions suitable to produce the antibody or antigen-binding fragment thereof or the multispecific antigen-binding protein. The method of claim 66, further comprising isolating the antibody or the antigen-binding fragment thereof or the multispecific antigen-binding protein.A kit comprising: the antibody or antigen-binding fragment thereof of any one of claims 1-31, the multispecific antigen-binding protein of any one of claims 32-43, and the antibody-drug conjugate of any one of claims 44-52, or the pharmaceutical composition of claim 53; and an additional therapeutic agent. The kit of claim 68, wherein the additional therapeutic is an anti-cancer agent. The kit of claim 68 or 69, wherein the additional therapeutic agent is an antibody. The kit of any one of claims 68-70, wherein the additional therapeutic agent is an antagonist or an inhibitor of a T cell coinhibitor; an agonist of a T cell coactivator; an immune stimulatory cytokine; or SGN-2FF. A method for inhibiting or attenuating tumor growth, the method comprising administering a therapeutically effective amount of the antibody or antigen-binding fragment thereof of any one of claims 1-31, the multispecific antigen-binding protein of any one of claims 32-43, the antibody-drug conjugate of any one of claims 44-52, or the pharmaceutical composition of claim 53, to a subject afflicted with a tumor. A method for inhibiting or attenuating tumor growth in a subject, the method comprising administering to the subject a therapeutically effective amount of the antibody or antigenbinding fragment thereof of any one of claims 1-31, and an additional therapeutic agent, wherein the second therapeutic agent is an antibody or antigen- binding fragment thereof that specifically binds CD3. A method for inhibiting or attenuating tumor growth in a subject, the method comprising administering to the subject a therapeutically effective amount of the antibody or antigenbinding fragment thereof of any one of claims 1-31, the multispecific antigen-binding protein of any one of claims 32-43, the antibody-drug conjugate of any one of claims 44-52, or the pharmaceutical composition of claim 53, and a second therapeutic agent, wherein the second therapeutic agent is a chemotherapeutic agent. A method of treating a cancer in a subject, comprising administering to the subject a therapeutically effective amount of the antibody or antigen-binding fragment thereof of any one of claims 1-31, the multispecific antigen-binding protein of any one of claims 32-43, the antibody-drug conjugate of any one of claims 44-52, or the pharmaceutical composition of claim 53. The method of claim 75, wherein the cancer is breast cancer, bladder cancer, uterine cancer, cervical cancer, ovarian cancer, prostate cancer, testicular cancer, esophageal cancer, gastrointestinal cancer, gastric cancer, pancreatic cancer, colorectal cancer, colon cancer,kidney cancer, clear cell renal carcinoma, head and neck cancer, lung cancer, lung adenocarcinoma, stomach cancer, germ cell cancer, bone cancer, liver cancer, thyroid cancer, skin cancer, melanoma, neoplasm of the central nervous system, mesothelioma, lymphoma, leukemia, chronic lymphocytic leukemia, diffuse large B cell lymphoma, follicular lymphoma, Hodgkin lymphoma, myeloma, or sarcoma. The method of claim 75, wherein the cancer is breast cancer, prostate cancer, gastrointestinal cancer, kidney cancer, lung cancer, liver cancer, endometrial cancer, ovarian cancer or colorectal cancer. The method of claim 75, wherein the cancer is breast cancer. The method of any one of claims 75-78, further comprising administering to the subject a therapeutically effective amount of an additional therapeutic agent. The method of claim 79 wherein the additional therapeutic is an anti-cancer agent. The method of claim 79 or 80, wherein the additional therapeutic agent is an antibody. The method of any one of claims 79-81, wherein the additional therapeutic agent is an antagonist or an inhibitor of a T cell coinhibitor; an agonist of a T cell coactivator; an immune stimulatory cytokine; or SGN-2FF. The antibody or antigen-binding fragment thereof of any one of claims 1-31, the multispecific antigen-binding protein of any one of claims 32-43, the antibody-drug conjugate of any one of claims 44-52, or the pharmaceutical composition of claim 53, for use as a medicament. The antibody or antigen-binding fragment thereof of any one of claims 1-31, the multispecific antigen-binding protein of any one of claims 32-43, the antibody-drug conjugate of any one of claims 44-52, or the pharmaceutical composition of claim 53, for use in treating a cancer. Use of the antibody or antigen-binding fragment thereof of any one of claims 1-31, the multispecific antigen-binding protein of any one of claims 32-43, the antibody-drug conjugate of any one of claims 44-52, or the pharmaceutical composition of claim 53, in the manufacture of a medicament for treating a cancer. The use of claim 84 or 85, wherein the cancer is breast cancer, bladder cancer, uterine cancer, cervical cancer, ovarian cancer, prostate cancer, testicular cancer, esophageal cancer, gastrointestinal cancer, gastric cancer, pancreatic cancer, colorectal cancer, colon cancer, kidney cancer, clear cell renal carcinoma, head and neck cancer, lung cancer, lung adenocarcinoma, stomach cancer, germ cell cancer, bone cancer, liver cancer, thyroid cancer,skin cancer, melanoma, neoplasm of the central nervous system, mesothelioma, lymphoma, leukemia, chronic lymphocytic leukemia, diffuse large B cell lymphoma, follicular lymphoma, Hodgkin lymphoma, myeloma, or sarcoma. The use of claim 84 or 85, wherein the cancer is breast cancer.

Images