Bispecific CD16-Binding Molecules and Their Use in the Treatment of Disease

This application claims priority to U.S. Patent Appln. Ser. No. 62/597,800 (filed on Dec. 12, 2017; pending), which application is herein incorporated by reference in its entirety.

This application includes one or more Sequence Listings pursuant to 37 C.F.R. 1.821 et seq., which are disclosed in computer-readable media (file name: 1301_0153PCT_Sequence_Listing_ST25.txt, created on Dec. 4, 2018, and having a size of 276,384 bytes), which file is herein incorporated by reference in its entirety.

The present invention is directed to molecules (e.g., an antibody, a diabody, an scFv, an antibody, a TandAb, etc.) capable of binding an epitope of human CD16 (a “CD16 Binding Molecule”). The present invention is further directed to CD16 Binding Molecules that are capable of binding an epitope of human CD16 and one or more epitope(s) of a Disease Antigen (“DA”) (e.g., a “CD16 x DA Binding Molecule”). The present invention is particularly directed to such CD16 x DA Binding Molecules that are antibodies, or that comprise an Epitope Binding Domain thereof, or are diabodies (including DART® diabodies), bispecific antibodies, TandAbs, other multispecific binding molecules (e.g., trivalent TRIDENT™ molecules), etc. The invention particularly concerns CD16 x DA Binding Molecules that are capable of binding a Disease Antigen that is a Cancer Antigen or a Pathogen-Associated Antigen in addition to being able to bind CD16. The invention particularly concerns the use of such CD16 and CD16 x DA Binding Molecules in the treatment of cancer and pathogen-associated diseases. The present invention is also directed to pharmaceutical compositions that comprise such molecule(s).

The mammalian immune system serves as a defense against a variety of conditions, including, e.g., injury, infection and neoplasia. The efficiency with which humans and other mammals develop an immunological response to pathogens, foreign substances and cancer antigens rests on two characteristics: the exquisite specificity of the immune response for antigen recognition, and the immunological memory that allows for faster and more vigorous responses upon re-activation with the same antigen (Portolés, P. et al. (2009) “The TCR/CD3 Complex: Opening the Gate to Successful Vaccination,” Current Pharmaceutical Design 15:3290-3300; Guy, C. S. et al. (2009) “Organization of Proximal Signal Initiation at the TCR:CD3 Complex,” Immunol Rev. 232(1):7-21; Topalian, S. L. et al. (2015) “Immune Checkpoint Blockade: A Common Denominator Approach to Cancer Therapy,” Cancer Cell 27:450-461).

In healthy individuals, the immune system is in a quiescent state, inhibited by a repertoire of diverse inhibitory receptors and receptor ligands. Upon recognition of a cancer antigen, microbial pathogen, or an allergen, an array of activating receptors and receptor ligands are triggered to induce the activation of the immune system. Such activation leads to the activation of macrophages, Natural Killer (NK) cells and antigen-specific, cytotoxic, T-cells, and promotes the release of various cytokines, all of which act to counter the perceived threat to the health of the subject (Dong, C. et al. (2003) “Immune Regulation by Novel Costimulatory Molecules,” Immunolog. Res. 28(1):39-48; Viglietta, V. et al. (2007) “Modulating Co-Stimulation,” Neurotherapeutics 4:666-675; Korman, A. J. et al. (2007) “Checkpoint Blockade in Cancer Immunotherapy,” Adv. Immunol. 90:297-339). The immune system is capable of returning to its normal quiescent state when the countervailing inhibitory immune signals outweigh the activating immune signals.

Thus, the disease state of cancer (and indeed the disease states of infectious diseases) may be considered to reflect a failure to adequately activate a subject's immune system. Such failure may reflect an inadequate presentation of activating immune signals, or it may reflect an inadequate ability to alleviate inhibitory immune signals in the subject. In some instances, researchers have determined that cancer cells can co-opt the immune system to evade being detected by the immune system (Topalian, S. L. et al. (2015) “Immune Checkpoint Blockade: A Common Denominator Approach to Cancer Therapy,” Cancer Cell 27:450-461).

Among the receptors involved in the activation of the immune system are the Fc Receptors:CD16, CD32 and CD64. These Fc receptors are found on the surfaces of multiple types of immune system cells (e.g., B lymphocytes, follicular dendritic cells, natural killer cells, macrophages, neutrophils, eosinophils, basophils and mast cells). Such receptors have an “extracellular” portion (which is thus capable of ligating to an Fc Domain), a “transmembrane” portion (which extends through the cellular membrane), and a “cytoplasmic” portion (positioned inside the cell). Multiple types of FcγRs have been identified: CD16A (FcγRIIIA), CD16B (FcγRIIIB), CD32A (FcγRIIA), CD32B (FcγRIIB), and CD64 (FcγRI). These receptors bind the Fc portion of IgG antibodies, thereby triggering the transduction of activating or inhibitory signals to the immune system.

CD16 is a generic name for the activating Fc receptors, FcγRIIIA (CD16A) and FcγRIIIB (CD16B). These receptors bind the Fc portion of IgG antibodies, thereby triggering the release of cytokines. If such antibodies are bound to a Disease Antigen that is expressed on the surface of a cell (e.g., a cancer cell, pathogen-infected cell, etc.), then such release mediates the killing of the targeted cell.

CD16A is expressed by Natural Killer (NK) cells and tissue macrophages that bind aggregated but not monomeric human IgG (Selvaraj, P. et al. (2004) “Functional Regulation Of Human Neutrophil Fc Gamma Receptors,” Immunol Res. 29(1-3):219-230; Peltz, G. A. et al. (1989) “Human Fc Gamma RIII: Cloning, Expression, And Identification Of The Chromosomal Locus Of Two Fc Receptors For IgG,” Proc. Natl. Acad. Sci. (U.S.A.) 86(3):1013-1017; Bachanova, V. et al. (2014) “NK Cells In Therapy Of Cancer,” Crit. Rev. Oncog. 19(1-2): 133-141; Miller, J. S. (2013) “Therapeutic Applications: Natural Killer Cells In The Clinic,” Hematology Am. Soc. Hematol. Educ. Program. 2013:247-253; Youinou, P. et al. (2002) “Pathogenic Effects Of Anti-Fc Gamma Receptor IIIB (CD16) On Polymorphonuclear Neutrophils In Non-Organ-Specific Autoimmune Diseases,” Autoimmun Rev. 1(1-2):13-19; Peipp, M. et al. (2002) “Bispecific Antibodies Targeting Cancer Cells,” Biochem. Soc. Trans. 30(4):507-511; Unkeless, J. C. et al. (1995) “Function Of Human Fc Gamma RIIA And Fc Gamma RIIIB,” Semin. Immunol. 7(1):37-44).

The expression of CD16A by Natural Killer (NK) cells has particular relevance to the present invention, since such cells release cytokines when their CD16 molecules bind to the Fc Domain of an antibody. Thus, when a natural antibody binds to a Disease Antigen of a target cell, its Fc Domain can be recognized by a CD16 molecule of a Natural Killer cell, which then mediates the killing of the target cell. Since such killing is antibody-dependent, it is termed antibody-dependent cell-mediated cytotoxicity (ADCC). ADCC thus depends on a prior antibody response, and, as stated, requires the presence and participation of an FcγR-expressing effector cell (typically natural killer (NK) cells, but also macrophages, neutrophils and eosinophils). CD16A signals ADCC through interactions with the CD ξ protein of NK cells, and signals macrophage-mediated killing through interactions with macrophage FcγR chains.

CD16A possesses two major polymorphic forms, F158 and V158, which differ by possessing a phenylalanine or a valine at residue 158 (shown as residue 160 of the extracellular domain of CD16A (FIG. 7), which corresponds to residue 176 of the full-length protein (Wu, J. et al. (1997) “A Novel Polymorphism of FcγRIIIa (CD16) Alters Receptor Function and Predisposes to Autoimmune Disease,” J. Clin.Invest. 100(5):1059-1070; Ravetch, J. V. et al. (1989) “Alternative Membrane Forms Of FcγRIII(CD16) On Human Natural Killer Cells And Neutrophils,” J. Exper. Med. 170:481-497; Koene, H. R. et al. (1997) “FcγRIIIa-158V/F Polymorphism Influences the Binding of IgG by Natural Killer Cell FcγRIIIa, Independently of the FcγRIIIa-48L/R/H Phenotype,” Blood, 90(3):1109-1114; van Sorge, N. M. (2003) “FcgammaR Polymorphisms: Implications For Function, Disease Susceptibility And Immunotherapy,” Tissue Antigens 61(3):189-202; Fijen, C. A. (2000) “The Role Of Fcgamma Receptor Polymorphisms And C3 In The Immune Defence Against Neisseria Meningitidis In Complement-Deficient Individuals,” Clin. Exp. Immunol. 120(2):338-345). 50% of Caucasians are homozygous for the phenylalanine polymorphism (F158/F158), whereas 39% of Caucasians are heterozygous for this polymorphism (F158/V158) and 11% of Caucasians are homozygous for the valine polymorphism (V158/V158).

CD16B is expressed on neutrophils, and is anchored to glycophosphatidylinositol (“GPI-anchored”) (Meknache, N. et al. (2009) “Human Basophils Express The Glycosylphosphatidylinositol-Anchored Low Affinity IgG Receptor FcgammaRIIIB (CD16B),” J. Immunol. 182(4):2542-2550 Fernandes, M. J. et al. (2006) “CD16b Associates With High-Density, Detergent-Resistant Membranes In Human Neutrophils,” Biochem. J. 393(Pt 1):351-359; Selvaraj, P. et al. (2004) “Functional Regulation Of Human Neutrophil Fc Gamma Receptors,” Immunol Res. 29(1-3):219-230; Unkeless, J. C. et al. (1995) “Function Of Human Fc Gamma RIIA And Fc Gamma RIIIB,” Semin. Immunol. 7(1):37-44). Although thought to be a decoy receptor, it can also transmit signals (Fernandes, M. J. (2005) “Signaling Through CD16b In Human Neutrophils Involves The Tec Family Of Tyrosine Kinases,” J. Leukoc. Biol. 78(2):524-532), and is downregulated/cleaved by ADAM17 after cell activation (Wang, Y. et al. (2013) “ADAM17 Cleaves CD16b (FcγRIIIb) In Human Neutrophils,” Biochim. Biophys. Acta 1833(3):680-685; Guo, S. et al. (2012) “Role of ADAM10 and ADAM17 in CD16b Shedding Mediated By Different Stimulators,” Chin. Med. Sci. J. 27(2):73-79).

CD16B possesses two major polymorphic forms, NA1 and NA2, which exhibit different binding affinities for IgG1 and IgG3 subclasses (Bournazos, S. et al. (2010) “Fcγ Receptor IIIb (CD16b) Polymorphisms Are Associated With Susceptibility To Idiopathic Pulmonary Fibrosis,” Lung 188(6):475-481; van Sorge, N. M. (2003) “FcgammaR Polymorphisms: Implications For Function, Disease Susceptibility And Immunotherapy,” Tissue Antigens 61(3):189-202). 13% of Caucasians and 16% of Indians are homozygous for the NA1 polymorphism (NA1/NA1), whereas 55% of Caucasians and 28% of Indians are heterozygous for this polymorphism (NA1/NA2) and 32% of Caucasians and 55% of Indians are homozygous for the NA2 polymorphism (NA2/NA2). The alignment of human CD16A and CD16B allotypes is shown in FIG. 7.

CD32A (FcγRIIA) (Brandsma, A. M. (2015) “Fc Receptor Inside-Out Signaling And Possible Impact On Antibody Therapy,” Immunol Rev. 268(1):74-87; van Sorge, N. M. et al. (2003) “FcgammaR Polymorphisms: Implications For Function, Disease Susceptibility And Immunotherapy,” Tissue Antigens 61(3):189-202; Selvaraj, P. et al. (2004) “Functional Regulation Of Human Neutrophil Fc Gamma Receptors,” Immunol. Res. 29(1-3):219-230) and CD64 (FcγRI) (Lu, S. et al. (2015) “Structural Mechanism Of High Affinity FcγRI recognition Of Immunoglobulin G,” Immunol. Rev. 268(1):192-200; Swisher, J. F. et al. (2015) “The Many Faces Of FcγRI: Implications For Therapeutic Antibody Function,” Immunol. Rev. 268(1):160-174; Thepen, T. et al. (2009) “Fcgamma Receptor 1 (CD64), A Target Beyond Cancer,” Curr. Pharm. Des. 15(23):2712-2718; Rouard, H. et al. (1997) “Fc Receptors As Targets For Immunotherapy,” Int. Rev. Immunol. 16(1-2):147-185) are activating Fc receptors that are expressed on macrophages, neutrophils, eosinophils and dendritic cells (and for CD32A, also on platelets and Langerhan cells). In contrast, CD32B (FcγRIIB) is an inhibiting Fc receptor on B lymphocytes (macrophages, neutrophils, and eosinophils) (Stopforth, R. J. et al. (2016) “Regulation of Monoclonal Antibody Immunotherapy by FcγRIIB,” J. Clin. Immunol. [2016 Feb. 27 Epub], pp. 1-7; Bruhns, P. et al. (2009) “Specificity And Affinity Of Human Fcgamma Receptors And Their Polymorphic Variants For Human IgG Subclasses,” Blood. 113(16):3716-3725; White, A. L. et al. (2014) “FcγRIIB As A Key Determinant Of Agonistic Antibody Efficacy,” Curr. Top. Microbiol. Immunol. 382:355-372; Selvaraj, P. et al. (2004) “Functional Regulation Of Human Neutrophil Fc Gamma Receptors,” Immunol. Res. 29(1-3):219-230).

The ability of the different FcγRs to mediate diametrically opposing functions reflects their structural differences, and in particular whether the FcγR possesses an immunoreceptor tyrosine-based activation motif (“ITAM”) or an immunoreceptor tyrosine-based inhibitory motif (“ITIM”). The recruitment of different cytoplasmic enzymes to these structures dictates the outcome of the FcγR-mediated cellular responses. ITAM-containing FcγRs include FcγRT, FcγRIIA, FcγRIIIA, and activate the immune system when bound to Fc Domains (e.g., aggregated Fc Domains present in an immune complex). FcγRIIB is the only currently known natural ITIM-containing FcγR; it acts to dampen or inhibit the immune system when bound to aggregated Fc Domains.

Although natural IgG antibodies directed to an epitope of a particular Disease Antigen possess Fc Domains that can interact with CD16 molecules to activate a subject's immune response, in the case of many diseases and many subjects, such immune system activation is not sufficient to provide an effective therapy for the disease. Thus, despite prior advances in identifying the molecules involved in mammalian immune responses, a need remains for improved therapies for treating cancers and infectious diseases. The CD16-Binding Molecules of the present invention, and particularly, the CD16 x DA Binding Molecules of the present invention that comprise a CD16 Binding Domain and a Binding Domain specific for a Disease Antigen expressed on a target cell are capable of co-localizing CD16-expressing cells to the site(s) of cells expressing the Disease Antigen. Such co-localization enhances the ADCC-mediated killing of target cells by increasing the likelihood that an Fc portion of an antibody directed against an epitope of the Disease Antigen will bind to a CD16-expressing effector cell and, via such Fc-CD16 interaction, trigger immune system activation and the release of cytokines against the target cell. Thus, the present invention is directed to improving the activation of a subject's immune response to a Disease antigen and other goals.

The present invention is directed to molecules (e.g., an antibody, a diabody, an scFv, an antibody, a TandAb, etc.) capable of binding an epitope of human CD16 (a “CD16 Binding Molecule”). The present invention is further directed to CD16 Binding Molecules that are capable of binding an epitope of human CD16 and one or more epitope(s) of a Disease Antigen (“DA”) (e.g., a “CD16 x DA Binding Molecule”). The present invention is particularly directed to such CD16 x DA Binding Molecules that are antibodies, or that comprise an Epitope Binding Domain thereof, or are diabodies (including DART® diabodies), bispecific antibodies, TandAbs, other multispecific binding molecules (e.g., trivalent TRIDENT™ molecules), etc. The invention particularly concerns CD16 x DA Binding Molecules that are capable of binding a Disease Antigen that is a Cancer Antigen or a Pathogen-Associated Antigen in addition to being able to bind CD16. The invention particularly concerns the use of such CD16 and CD16 x DA Binding Molecules in the treatment of cancer and pathogen-associated diseases. The present invention is also directed to pharmaceutical compositions that comprise such molecule(s).

In detail, the invention provides a CD16 x Disease Antigen (CD16 x DA) Binding Molecule comprising a CD16 Binding Domain capable of binding an epitope of CD16 and also a Disease Antigen-Binding Domain capable of binding an epitope of a Disease Antigen, wherein the CD16 Binding Domain comprises one or more of:

• (I) (A) a CDR_H1 Domain comprising the amino acid sequence of SEQ ID NO:66;
  • (B) a CDR_H2 Domain comprising the amino acid sequence of SEQ ID NO:67;
  • (C) a CDR_H3 Domain comprising the amino acid sequence of SEQ ID NO:68 or SEQ ID NO:60;
  • (D) a CDR_L1 Domain comprising the amino acid sequence of SEQ ID NO:69 or SEQ ID NO:74;
  • (E) a CDR_L2 Domain comprising the amino acid sequence of SEQ ID NO:70; and
  • (F) a CDR_L3 Domain comprising the amino acid sequence of SEQ ID NO:71 or SEQ ID NO:61;
• (II) (A) a CDR_H1 Domain comprising the amino acid sequence of SEQ ID NO:77;
  • (B) a CDR_H2 Domain comprising the amino acid sequence of SEQ ID NO:78;
  • (C) a CDR_H3 Domain comprising the amino acid sequence of SEQ ID NO:79;
  • (D) a CDR_L1 Domain comprising the amino acid sequence of SEQ ID NO:80;
  • (E) a CDR_L2 Domain comprising the amino acid sequence of SEQ ID NO:81; and
  • (F) a CDR_L3 Domain comprising the amino acid sequence of SEQ ID NO:82;
• (III) a VH Domain comprising the amino acid sequence of SEQ ID NO:72, SEQ ID NO:83, SEQ ID NO:84, or SEQ ID NO:58;
• (IV) a VL Domain comprising the amino acid sequence of SEQ ID NO:73, SEQ ID NO:85, or SEQ ID NO:59;
• (V) a VH Domain comprising the amino acid sequence of SEQ ID NO:72 and a VL Domain comprising the amino acid sequence of SEQ ID NO:73; and
• (VI) a VH Domain comprising the amino acid sequence of SEQ ID NO:83 or SEQ ID NO:84 and a VL Domain comprising the amino acid sequence of SEQ ID NO:85
• (VII) a VH Domain comprising the amino acid sequence of SEQ ID NO:58 and a VL Domain comprising the amino acid sequence of SEQ ID NO:73;
• (VIII) a VH Domain comprising the amino acid sequence of SEQ ID NO:72 and a VL Domain comprising the amino acid sequence of SEQ ID NO:59; and
• (IX) a VH Domain comprising the amino acid sequence of SEQ ID NO:58 and a VL Domain comprising the amino acid sequence of SEQ ID NO:59.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecule, wherein the Molecule is a bispecific antibody, a bispecific diabody, a bispecific TandAb, a bispecific trivalent molecule, or a bispecific CAR.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Molecule is capable of binding more than one Disease Antigen and/or more than one epitope of CD16.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the CD16 Binding Domain comprises:

• • (A) a CDR_H1 Domain comprising the amino acid sequence of SEQ ID NO:66;
  • (B) a CDR_H2 Domain comprising the amino acid sequence of SEQ ID NO:67;
  • (C) a CDR_H3 Domain comprising the amino acid sequence of SEQ ID NO:68, or SEQ ID NO:60;
  • (D) a CDR_L1 Domain comprising the amino acid sequence of SEQ ID NO:69 or SEQ ID NO:74;
  • (E) a CDR_L2 Domain comprising the amino acid sequence of SEQ ID NO:70; and
  • (F) a CDR_L3 Domain comprising the amino acid sequence of SEQ ID NO:71, or SEQ ID NO:61.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the CD16 Binding Domain comprises:

• • (A) a VH Domain comprising the amino acid sequence of SEQ ID NO:72, or SEQ ID NO:58;
  • (B) a VL Domain comprising the amino acid sequence of SEQ ID NO:73, or SEQ ID NO:59; or
  • (C) a VH Domain comprising the amino acid sequence of SEQ ID NO:72 and a VL Domain comprising the amino acid sequence of SEQ ID NO:73
  • (D) a VH Domain comprising the amino acid sequence of SEQ ID NO:58 and a VL Domain comprising the amino acid sequence of SEQ ID NO:73;
  • (E) a VH Domain comprising the amino acid sequence of SEQ ID NO:72 and a VL Domain comprising the amino acid sequence of SEQ ID NO:59; or
  • (F) a VH Domain comprising the amino acid sequence of SEQ ID NO:58 and a VL Domain comprising the amino acid sequence of SEQ ID NO:59.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the CD16 Binding Domain comprises:

• • (A) a CDR_H1 Domain comprising the amino acid sequence of SEQ ID NO:77;
  • (B) a CDR_H2 Domain comprising the amino acid sequence of SEQ ID NO:78;
  • (C) a CDR_H3 Domain comprising the amino acid sequence of SEQ ID NO:79;
  • (D) a CDR_L1 Domain comprising the amino acid sequence of SEQ ID NO:80;
  • (E) a CDR_L2 Domain comprising the amino acid sequence of SEQ ID NO:81; and
  • (F) a CDR_L3 Domain comprising the amino acid sequence of SEQ ID NO:82.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the CD16 Binding Domain comprises:

• • (A) a VH Domain comprising the amino acid sequence of SEQ ID NO:83, or SEQ ID NO:84;
  • (B) a VL Domain comprising the amino acid sequence of or SEQ ID NO:85; or
  • (C) a VH Domain comprising the amino acid sequence of SEQ ID NO:83 or SEQ ID NO:84 and a VL Domain comprising the amino acid sequence of SEQ ID NO:85.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Disease Antigen is a Cancer Antigen and the disease is cancer.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the cancer is selected from the group consisting of adrenal cancer, bladder cancer, breast cancer, colorectal cancer, gastric cancer, glioblastoma, kidney cancer, non-small-cell lung cancer, acute lymphocytic leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, chronic myeloid leukemia, hairy cell leukemia, Burkett's lymphoma, diffuse large B cell lymphoma, follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, non-Hodgkin's lymphoma, small lymphocytic lymphoma, multiple myeloma, melanoma, ovarian cancer, pancreatic cancer, prostate cancer, skin cancer, renal cell carcinoma, testicular cancer, and uterine cancer.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Cancer Antigen is selected from the group consisting of the Cancer Antigens: 19.9, 4.2, A33, ADAM-9, AH6, ALCAM, B1, B7-H3, BAGE, beta-catenin, blood group ALe^b/Le^y, Burkitt's lymphoma antigen-38.13, C14, CA125, Carboxypeptidase M, CD5, CD19, CD20, CD22, CD23, CD25, CD27, CD28, CD33, CD36, CD40/CD154, CD45, CD56, CD46, CD52, CD56, CD79a/CD79b, CD103, CD123, CD317, CDK4, CEA, CEACAM5/CEACAM6, CO17-1A, CO-43, CO-514, CTA-1, CTLA-4, Cytokeratin 8, D1.1, Di56-22, DR5, E₁series, EGFR, an Ephrin receptor, EphA2, Erb, GAGE, a GD2/GD3/GM2 ganglioside, GICA 19-9, gp100, Gp37, gp75, gpA33, HER2/neu, HMFG, human papillomavirus-E6/human papillomavirus-E7, HMW-MAA, I antigen, IL13Rα2, Integrin (36, JAM-3, KID3, KID31, KS 1/4 pan-carcinoma antigen, L6,L20, LEA, LUCA-2, M1:22:25:8, M18, M39, MAGE, MART, mesothelin, MUC-1, MUM-1, Myl, N-acetylglucosaminyltransferase, neoglycoprotein, NS-10, OFA-1, OFA-2, Oncostatin M, p15, p97, PEM, PEMA, PIPA, PSA, PSMA, prostatic acid phosphate, R₂₄, ROR1, a sphingolipid, SSEA-1, SSEA-3, SSEA-4, sTn, the T cell receptor derived peptide, T₅A₇, TAG-72, TL5, TNF-receptor, TNF-γ receptor, TRA-1-85, a Transferrin Receptor, 5T4, TSTA, VEGF, a VEGF Receptor, VEP8, VEP9, VIM-D5, and Y hapten, Le^y.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Disease Antigen is 5T4, B7-H3, CEACAM5/CEACAM6, CD19, CD123, EGRF, EphA2, HER2/neu, IL13Rα2 or VEGF.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Disease Antigen is a Pathogen-Associated Antigen.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Pathogen-Associated Antigen is selected from the group consisting of the Pathogen-Associated Antigens: Herpes Simplex Virus infected cell protein (ICP)47, Herpes Simplex Virus gD, Epstein-Barr Virus LMP-1, Epstein-Barr Virus LMP-2A, Epstein-Barr Virus LMP-2B, Human Immunodeficiency Virus gp160, Human Immunodeficiency Virus gp120, Human Immunodeficiency Virus gp41, etc.), Human Papillomavirus E6, Human Papillomavirus E7, human T-cell leukemia virus gp64, human T-cell leukemia virus gp46, and human T-cell leukemia virus gp21.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Disease Antigen is an HIV env antigen.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the molecule is:

• • (A) a diabody, said diabody being a covalently bonded complex that comprises two, or three, four or five polypeptide chains; or
  • (B) a trivalent binding molecule, said trivalent binding molecule being a covalently bonded complex that comprises three, four or five polypeptide chains, or
  • (C) a bispecific antibody.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the molecule comprises an Fc Region.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Fc Region, is of the IgG1, IgG2, IgG3, or IgG4 isotype.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules, wherein the Fc Region is a variant Fc Region that comprises:

• • (A) one or more amino acid modifications that reduces the affinity of the variant Fc Region for an FcγR; and/or
  • (B) one or more amino acid modifications that enhances the serum half-life of the variant Fc Region.

The invention additionally concerns the embodiment of such CD16 x Disease Antigen Binding Molecules:

• • (A) said modifications that reduces the affinity of the variant Fc Region for an FcγR comprise the substitution of L234A; L235A; or L234A and L235A; and
  • (B) said modifications that that enhances the serum half-life of the variant Fc Region comprise the substitution of M252Y; M252Y and S254T; M252Y and T256E; M252Y, S254T and T256E; or K288D and H435K, wherein said numbering is that of the EU index as in Kabat.

The invention additionally concerns a CD16 Binding Molecule, that comprises:

• • (A) a CDR_H1 Domain comprising the amino acid sequence of SEQ ID NO:66;
  • (B) a CDR_H2 Domain comprising the amino acid sequence of SEQ ID NO:67;
  • (C) a CDR_H3 Domain comprising the amino acid sequence of SEQ ID NO:68, or SEQ ID NO:60;
  • (D) a CDR_L1 Domain comprising the amino acid sequence of SEQ ID NO:69 or SEQ ID NO:74;
  • (E) a CDR_L2 Domain comprising the amino acid sequence of SEQ ID NO:70; and
  • (F) a CDR_L3 Domain comprising the amino acid sequence of SEQ ID NO:71, or SEQ ID NO:61.

The invention additionally concerns the embodiment of such a CD16 Binding Molecule wherein the molecule comprises:

• • (A) a VH Domain comprising the amino acid sequence of SEQ ID NO:72, or SEQ ID NO:58;
  • (B) a VL Domain comprising the amino acid sequence of SEQ ID NO:73, or SEQ ID NO:59;
  • (C) a VH Domain comprising the amino acid sequence of SEQ ID NO:72 and a VL Domain comprising the amino acid sequence of SEQ ID NO:73; or
  • (D) a VH Domain comprising the amino acid sequence of SEQ ID NO:58 and a VL Domain comprising the amino acid sequence of SEQ ID NO:73;
  • (E) a VH Domain comprising the amino acid sequence of SEQ ID NO:72 and a VL Domain comprising the amino acid sequence of SEQ ID NO:59; or
  • (F) a VH Domain comprising the amino acid sequence of SEQ ID NO:58 and a VL Domain comprising the amino acid sequence of SEQ ID NO:59.

The invention additionally concerns a CD16 Binding Molecule that comprises:

• • (A) a CDR_H1 Domain comprising the amino acid sequence of SEQ ID NO:77;
  • (B) a CDR_H2 Domain comprising the amino acid sequence of SEQ ID NO:78;
  • (C) a CDR_H3 Domain comprising the amino acid sequence of SEQ ID NO:79;
  • (D) a CDR_L1 Domain comprising the amino acid sequence of SEQ ID NO:80;
  • (E) a CDR_L2 Domain comprising the amino acid sequence of SEQ ID NO:81; and
  • (F) a CDR_L3 Domain comprising the amino acid sequence of SEQ ID NO:82.

The invention additionally concerns the embodiment of such CD16 Binding Molecule wherein the molecule comprises:

• • (A) a VH Domain comprising the amino acid sequence of SEQ ID NO:83 or SEQ ID NO:84;
  • (B) a VL Domain comprising the amino acid sequence of or SEQ ID NO:85; or (C) a VH Domain comprising the amino acid sequence of SEQ ID NO:83 or SEQ ID NO:84 and a VL Domain comprising the amino acid sequence of SEQ ID NO:85.

The invention additionally concerns the embodiment of such CD16 Binding Molecules wherein the molecule is selected from the group consisting of: an antibody, a multispecific antibody, a Fab′ fragment, a F(ab′)2 fragment, a (Fv) fragment, a single-chain (scFv), a single-chain antibody, a disulfide-linked bispecific Fv (sdFv), a diabody, a trivalent binding molecule, and a CAR-T molecule.

The invention additionally concerns a pharmaceutical composition that comprises any of the above-described CD16 x Disease Antigen Binding Molecules, or CD16 Binding Molecules, and a pharmaceutically acceptable carrier.

The invention additionally concerns the use of the above-described pharmaceutical composition in the treatment of a disease characterized by the expression of the Disease Antigen.

The invention additionally concerns a method for the treatment of a disease characterized by the expression of the Disease Antigen, comprising administering to a subject in need thereof a therapeutically effective amount of the above-described pharmaceutical composition.

The invention additionally concerns the embodiment of such use or method wherein the CD16 x Disease Antigen Binding Molecule is capable of binding more than one Disease Antigen and/or more than one epitope of CD16.

The invention additionally concerns such use or method wherein the CD16 x Disease Antigen Binding Molecule, wherein the Disease Antigen is a Cancer Antigen, and the disease is cancer.

The invention additionally concerns such use or method wherein the cancer is selected from the group consisting of adrenal cancer, bladder cancer, breast cancer, colorectal cancer, gastric cancer, glioblastoma, kidney cancer, non-small-cell lung cancer, acute lymphocytic leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, chronic myeloid leukemia, hairy cell leukemia, Burkett's lymphoma, diffuse large B cell lymphoma, follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, non-Hodgkin's lymphoma, small lymphocytic lymphoma, multiple myeloma, melanoma, ovarian cancer, pancreatic cancer, prostate cancer, skin cancer, renal cell carcinoma, testicular cancer, and uterine cancer.

The invention additionally concerns such use or method wherein the Cancer Antigen is selected from the group consisting of the Cancer Antigens: 19.9, 4.2, A33, ADAM-9, AH6, ALCAM, B1, B7-H3, BAGE, beta-catenin, blood group ALe^b/Le^y, Burkitt's lymphoma antigen-38.13, C14, CA125, Carboxypeptidase M, CD5, CD19, CD20, CD22, CD23, CD25, CD27, CD28, CD33, CD36, CD40/CD154, CD45, CD56, CD46, CD52, CD56, CD79a/CD79b, CD103, CD123, CD317, CDK4, CEA, CEACAM5/CEACAM6, CO17-1A, CO-43, CO-514, CTA-1, CTLA-4, Cytokeratin 8, D1.1, Di56-22, DR5, E₁series, EGFR, an Ephrin receptor, EphA2, Erb, GAGE, a GD2/GD3/GM2 ganglioside, GICA 19-9, gp100, Gp37, gp75, gpA33, HER2/neu, HMFG, human papillomavirus-E6/human papillomavirus-E7, HMW-MAA, I antigen, IL13Rα2, Integrin (36, JAM-3, KID3, KID31, KS 1/4 pan-carcinoma antigen, L6,L20, LEA, LUCA-2, M1:22:25:8, M18, M39, MAGE, MART, mesothelin, MUC-1, MUM-1, Myl, N-acetylglucosaminyltransferase, neoglycoprotein, NS-10, OFA-1, OFA-2, Oncostatin M, p15, p97, PEM, PEMA, PIPA, PSA, PSMA, prostatic acid phosphate, R₂₄, ROR1, a sphingolipid, SSEA-1, SSEA-3, SSEA-4, sTn, the T cell receptor derived peptide, T5A7, TAG-72, TL5, TNF-receptor, TNF-γ receptor, TRA-1-85, a Transferrin Receptor, 5T4, TSTA, VEGF, a VEGF Receptor, VEP8, VEP9, VIM-D5, and Y hapten, Le^y.

The invention additionally concerns such use or method wherein the Disease Antigen is 5T4, B7-H3, CEACAM5/CEACAM6, CD19, CD123, EGRF, EphA2, HER2/neu, IL13Rα2 or VEGF.

The invention additionally concerns such use or method wherein the CD16 x Disease Antigen Binding Molecule, wherein the Disease Antigen is a Pathogen-Associated Antigen.

The invention additionally concerns such use or method wherein the Pathogen-Associated Antigen is selected from the group consisting of the Pathogen-Associated Antigens: Herpes Simplex Virus infected cell protein (ICP)47, Herpes Simplex Virus gD, Epstein-Barr Virus LMP-1, Epstein-Barr Virus LMP-2A, Epstein-Barr Virus LMP-2B, Human Immunodeficiency Virus gp160, Human Immunodeficiency Virus gp120, Human Immunodeficiency Virus gp41, etc.), Human Papillomavirus E6, Human Papillomavirus E7, human T-cell leukemia virus gp64, human T-cell leukemia virus gp46, and human T-cell leukemia virus gp21.

The invention additionally concerns such use or method wherein the Disease Antigen is an HIV env antigen.

The present invention is directed to molecules (e.g., an antibody, a diabody, an scFv, an antibody, a TandAb, etc.) capable of binding an epitope of human CD16 (a “CD16 Binding Molecule”). The present invention is further directed to CD16 Binding Molecules that are capable of binding an epitope of human CD16 and one or more epitope(s) of a Disease Antigen (“DA”) (e.g., a “CD16 x DA Binding Molecule”). The present invention is particularly directed to such CD16 x DA Binding Molecules that are antibodies, or that comprise an Epitope Binding Domain thereof, or are diabodies (including DART® diabodies), bispecific antibodies, TandAbs, other multispecific binding molecules (e.g., trivalent TRIDENT™ molecules), etc. The invention particularly concerns CD16 x DA Binding Molecules that are capable of binding a Disease Antigen that is a Cancer Antigen or a Pathogen-Associated Antigen in addition to being able to bind CD16. The invention particularly concerns the use of such CD16 and CD16 x DA Binding Molecules in the treatment of cancer and pathogen-associated diseases. The present invention is also directed to pharmaceutical compositions that comprise such molecule(s).

The CD16 x DA Binding Molecules of the present invention may be antibodies, or be derivable from antibodies (e.g., by fragmentation, cleavage, etc. of antibody polypeptides, or from use of the amino acid sequences of antibody molecules or of polynucleotides (or their sequences) that encode such polynucleotides, etc.).

Antibodies are immunoglobulin molecules capable of specific binding to a particular domain or moiety or conformation (an “epitope”) of a molecule, such as a carbohydrate, polynucleotide, lipid, polypeptide, etc. An epitope-containing molecule may have immunogenic activity, such that it elicits an antibody production response in an animal; such molecules are termed “antigens.” As used herein, the terms “antibody” and “antibodies” refer to monoclonal antibodies, multispecific antibodies, human antibodies, humanized antibodies, synthetic antibodies, chimeric antibodies, polyclonal antibodies, camelized antibodies, single-chain Fvs (scFv), single-chain antibodies, Fab fragments, F(ab′) fragments, disulfide-linked bispecific Fvs (sdFv), intrabodies, and Epitope Binding Domains of any of the above. Such Immunoglobulin molecules can be of any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgG₁, IgG₂, IgG₃, IgG₄, IgA₁and IgA₂) or subclass.

The term “monoclonal antibody” refers to a homogeneous antibody population wherein the monoclonal antibody is comprised of amino acids (naturally occurring or non-naturally occurring) that are involved in the selective binding of an antigen. Monoclonal antibodies are highly specific, being directed against a single epitope (or antigenic site). The term “monoclonal antibody” encompasses not only intact monoclonal antibodies and full-length monoclonal antibodies, but also fragments thereof (such as Fab, Fab′, F(ab′)₂, (Fv), single-chain (scFv), mutants thereof, fusion proteins comprising an antibody portion, humanized monoclonal antibodies, chimeric monoclonal antibodies, and any other modified configuration of the immunoglobulin molecule that comprises an antigen recognition site of the required specificity and the ability to bind to an antigen. It is not intended to be limited as regards to the source of the antibody or the manner in which it is made (e.g., by hybridoma, phage selection, recombinant expression, transgenic animals, etc.). The term includes whole immunoglobulins as well as the fragments etc. described above under the definition of “antibody.” Methods of making monoclonal antibodies are known in the art. One method which may be employed is the method of Kohler, G. et al. (1975) “Continuous Cultures Of Fused Cells Secreting Antibody Of Predefined Specificity,” Nature 256:495-497 or a modification thereof. Typically, monoclonal antibodies are developed in mice, rats or rabbits. The antibodies are produced by immunizing an animal with an immunogenic amount of cells, cell extracts, or protein preparations that contain the desired epitope. The immunogen can be, but is not limited to, primary cells, cultured cell lines, cancerous cells, proteins, peptides, nucleic acids, or tissue. Cells used for immunization may be cultured for a period of time (e.g., at least 24 hours) prior to their use as an immunogen. Cells may be used as immunogens by themselves or in combination with a non-denaturing adjuvant, such as Ribi (see, e.g., Jennings, V. M. (1995) “Review of Selected Adjuvants Used in Antibody Production,” ILAR J. 37(3):119-125). In general, cells should be kept intact and preferably viable when used as immunogens. Intact cells may allow antigens to be better detected than ruptured cells by the immunized animal. Use of denaturing or harsh adjuvants, e.g., Freund's adjuvant, may rupture cells and therefore is discouraged. The immunogen may be administered multiple times at periodic intervals such as, bi weekly, or weekly, or may be administered in such a way as to maintain viability in the animal (e.g., in a tissue recombinant). Alternatively, existing monoclonal antibodies and any other equivalent antibodies that are immunospecific for a desired pathogenic epitope can be sequenced and produced recombinantly by any means known in the art. In one embodiment, such an antibody is sequenced and the polynucleotide sequence is then cloned into a vector for expression or propagation. The sequence encoding the antibody of interest may be maintained in a vector in a host cell and the host cell can then be expanded and frozen for future use. The polynucleotide sequence of such antibodies may be used for genetic manipulation to generate the monospecific or multispecific (e.g., bispecific, trispecific and tetraspecific) molecules of the invention as well as an affinity optimized, a chimeric antibody, a humanized antibody, and/or a caninized antibody, to improve the affinity, or other characteristics of the antibody as detailed below.

Antibodies and the Binding Molecules of the present invention bind epitopes via their Binding Domains in an “immunospecific” manner. As used herein, a molecule is said to bind an epitope of another molecule in an immunospecific manner (or “immunospecifically”) if it binds or associates more frequently, more rapidly, with greater duration and/or with greater affinity with that epitope relative to alternative epitopes. For example, an antibody that immunospecifically binds to a viral epitope is an antibody that binds this viral epitope with greater affinity, avidity, more readily, and/or with greater duration than it immunospecifically binds to other viral epitopes or non-viral epitopes. It is also understood by reading this definition that, for example, an antibody (or moiety or epitope) that immunospecifically binds to a first target may or may not specifically or preferentially bind a second target. As such, “immunospecific binding” does not necessarily require (although it can include) exclusive binding. Generally, but not necessarily, reference to binding means “immunospecific” binding. Natural antibodies are capable of binding to only one epitope species (i.e., they are “monospecific”), although they can immunospecifically bind multiple copies of that species (i.e., exhibiting “bivalency” or “multivalency”). Two molecules are said to be capable of binding one another in a “physiospecific” manner, if such binding exhibits the specificity with which receptors bind their respective ligands.

The last few decades have seen a revival of interest in the therapeutic potential of antibodies, and antibodies have become one of the leading classes of biotechnology-derived drugs (Chan, C. E. et al. (2009) “The Use Of Antibodies In The Treatment Of Infectious Diseases,” Singapore Med. J. 50(7):663-666). Over 200 antibody-based drugs have been approved for use or are under development.

The basic structural unit of naturally occurring immunoglobulins (e.g., IgG) is a tetramer composed of two shorter “Light Chains” complexed with two longer “Heavy Chains” and is usually expressed as a glycoprotein of about 150,000 Da. Each chain is composed of an amino-terminal (“N-terminal”) portion that comprises a “Variable Domain” and a carboxy-terminal (“C-terminal”) portion that comprises at least one “Constant Domain.” An IgG Light Chain is composed of a single “Light Chain Variable Domain” (“VL”) and a single “Light Chain Constant Domain” (“CL”). Thus, the structure of the light chains of an IgG molecule is n-VL-CL-c (where n and c represent, respectively, the N-terminus and the C-terminus of the polypeptide). An IgG Heavy Chain is composed of a single “Heavy Chain Variable Domain” (“VH”), three “Heavy Chain Constant Domains” (“CH1,” “CH2” and “CH3”), and a “Hinge” Region (“H”), located between the CH1 and CH2 Domains. Thus, the structure of an IgG heavy chain is n-VH—CH1-H—CH2-CH3-c (where n and c represent, respectively, the N-terminus and the C-terminus of the polypeptide). The ability of an intact, unmodified antibody (e.g., an IgG antibody) to bind an epitope of an antigen depends upon the presence and sequences of the Variable Domains. Unless specifically noted, the order of domains of the protein molecules described herein is in the “N-terminal to C-terminal” direction.

A preferred CL Domain is a human IgG CL Kappa Domain. The amino acid sequence of an exemplary human CL Kappa Domain is (SEQ ID NO:1):

Alternatively, an exemplary CL Domain is a human IgG CL Lambda Domain. The amino acid sequence of an exemplary human CL Lambda Domain is (SEQ ID NO:2):

The CH1 Domains of the two Heavy Chains of an antibody complex with the antibody's Light Chain's “CL” constant region, and are attached to the Heavy Chains CH2 Domains via an intervening Hinge Domain.

An exemplary CH1 Domain is a human IgG1 CH1 Domain. The amino acid sequence of an exemplary human IgG1 CH1 Domain is (SEQ ID NO:3):

An exemplary CH1 Domain is a human IgG2 CH1 Domain. The amino acid sequence of an exemplary human IgG2 CH1 Domain is (SEQ ID NO:4):

An exemplary CH1 Domain is a human IgG3 CH1 Domain. The amino acid sequence of an exemplary human IgG3 CH1 Domain is (SEQ ID NO:5):

An exemplary CH1 Domain is a human IgG4 CH1 Domain. The amino acid sequence of an exemplary human IgG4 CH1 Domain is (SEQ ID NO:6):

One exemplary Hinge Domain is a human IgG1 Hinge Domain. The amino acid sequence of an exemplary human IgG1 Hinge Domain is (SEQ ID NO:7):

Another exemplary Hinge Domain is a human IgG2 Hinge Domain. The amino acid sequence of an exemplary human IgG2 Hinge Domain is (SEQ ID NO:8):

Another exemplary Hinge Domain is a human IgG3 Hinge Domain. The amino acid sequence of an exemplary human IgG2 Hinge Domain is (SEQ ID NO:9):

Another exemplary Hinge Domain is a human IgG4 Hinge Domain. The amino acid sequence of an exemplary human IgG4 Hinge Domain is (SEQ ID NO:10):

The CH2 and CH3 Domains of the two heavy chains interact to form the “Fc Domain” of IgG antibodies that is recognized by cellular Fc Receptors, including but not limited to Fc gamma Receptors (FcγRs). As used herein, the term “Fc Region” is used to define a C-terminal region of an IgG heavy chain. A portion of an Fc Region (including a portion that encompasses an entire Fc Region) is referred to herein as an “Fc Domain.” An Fc Region is said to be of a particular IgG isotype, class or subclass if its amino acid sequence is most homologous to that isotype relative to other IgG isotypes. In addition to their known uses in diagnostics, antibodies have been shown to be useful as therapeutic agents.

The amino acid sequence of the CH2-CH3 Domain of an exemplary human IgG1 is (SEQ ID NO:12):

The amino acid sequence of the CH2-CH3 Domain of an exemplary human IgG2 is (SEQ ID NO:13):

The amino acid sequence of the CH2-CH3 Domain of an exemplary human IgG3 is (SEQ ID NO:14):

The amino acid sequence of the CH2-CH3 Domain of an exemplary human IgG4 is (SEQ ID NO:15):

Throughout the present specification, the numbering of the residues in the constant region of an IgG heavy chain is that of the EU index as in Kabat et al., SEQUENCES OF PROTEINS OF IMMUNOLOGICAL INTEREST, 5^thEd. Public Health Service, NH1, MD (1991) (“Kabat”), expressly incorporated herein by reference. The term “EU index as in Kabat” refers to the numbering of the constant domains of human IgG1 EU antibody. Amino acids from the Variable Domains of the mature heavy and light chains of immunoglobulins are also designated by the position of an amino acid in the chain. Kabat described numerous amino acid sequences for antibodies, identified an amino acid consensus sequence for each subgroup, and assigned a residue number to each amino acid, and the CDRs are identified as defined by Kabat (it will be understood that CDR_H1 as defined by Chothia, C. & Lesk, A. M. ((1987) “Canonical Structures For The Hypervariable Regions Of Immunoglobulins,” J. Mol. Biol. 196:901-917) begins five residues earlier). Kabat's numbering scheme is extendible to antibodies not included in his compendium by aligning the antibody in question with one of the consensus sequences in Kabat by reference to conserved amino acids. This method for assigning residue numbers has become standard in the field and readily identifies amino acids at equivalent positions in different antibodies, including chimeric or humanized variants. For example, an amino acid at position 50 of a human antibody light chain occupies the equivalent position to an amino acid at position 50 of a mouse antibody light chain.

Polymorphisms have been observed at a number of different positions within antibody constant regions (e.g., Fc positions, including but not limited to positions 270, 272, 312, 315, 356, and 358 as numbered by the EU index as set forth in Kabat), and thus slight differences between the presented sequence and sequences in the prior art can exist. Polymorphic forms of human immunoglobulins have been well-characterized. At present, 18 Gm allotypes are known: G1m (1, 2, 3, 17) or G1m (a, x, f, z), G2m (23) or G2m (n), G3m (5, 6, 10, 11, 13, 14, 15, 16, 21, 24, 26, 27, 28) or G3m (b1, c3, b3, b0, b3, b4, s, t, g1, c5, u, v, g5) (Lefranc et al., “The Human IgG Subclasses: Molecular Analysis Of Structure, Function And Regulation.” Pergamon, Oxford, pp. 43-78 (1990); Lefranc, G. et al., 1979, Hum. Genet.: 50, 199-211). It is specifically contemplated that the antibodies of the present invention may incorporate any allotype, isoallotype, or haplotype of any immunoglobulin gene, and are not limited to the allotype, isoallotype or haplotype of the sequences provided herein. Furthermore, in some expression systems the C-terminal amino acid residue (bolded above) of the CH3 Domain may be post-translationally removed. Accordingly, the C-terminal residue of the CH3 Domain is an optional amino acid residue in the CD16 x DA Binding Molecules of the invention. Specifically encompassed by the instant invention are CD16 x DA Binding Molecules lacking the C-terminal residue of the CH3 Domain. Also specifically encompassed by the instant invention are such constructs comprising the C-terminal lysine residue of the CH3 Domain.

The Variable Domains of an IgG molecule consist of three “complementarity determining regions” (“CDRs”), which contain the amino acid residues of the antibody that will be in contact with the epitope, as well as intervening non-CDR segments, referred to as “framework regions” (“FRs”), which, in general maintain the structure and determine the positioning of the CDR loops so as to permit such contacting (although certain framework residues may also contact the epitope). Thus, the VL and VH Domains have the structure n-FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4-c. The amino acid sequences of the CDRs determine whether an antibody will be able to bind to a particular epitope. Interaction of an antibody light chain with an antibody heavy chain and, in particular, interaction of their VL and VH Domains, forms an epitope-binding site of the antibody.

Polypeptides that are (or may serve as) the first, second and third CDR of the Light Chain of an antibody are herein respectively designated as: CDR_L1 Domain, CDR_L2 Domain, and CDR_L3 Domain. Similarly, polypeptides that are (or may serve as) the first, second and third CDR of the Heavy Chain of an antibody are herein respectively designated as: CDR_H1 Domain, CDR_H2 Domain, and CDR_H3 Domain. Thus, the terms CDR_L1 Domain, CDR_L2 Domain, CDR_L3 Domain, CDR_H1 Domain, CDR_H2 Domain, and CDR_H3 Domain are directed to polypeptides that when incorporated into a protein cause that protein to be able to bind to a specific epitope regardless of whether such protein is an antibody having light and heavy chains or is a diabody or a single-chain binding molecule (e.g., an scFv, a BiTe, etc.), or is another type of protein.

The term “Epitope Binding Domain” denotes a fragment or portion of a binding molecule (or a polypeptide having the amino acid sequence of such a fragment or portion) that contributes to the ability of the binding molecule to immunospecifically bind to an epitope. An Epitope Binding Domain may contain a VL or VH Domain of an antibody, or any 1, 2, 3, 4, or 5 of the CDR Domains of an antibody, or may contain all 6 of the CDR Domains of an antibody and, although capable of immunospecifically binding such epitope, may exhibit an immunospecificity, affinity or selectivity towards such epitope that differs from that of such antibody. An Epitope Binding Domain may contain only part of a CDR, namely the subset of CDR residues required for binding, termed the SDRs (Kim, J. H. et al. (2012) “Humanization By CDR Grafting And Specificity-Determining Residue Grafting,” Methods Mol. Biol. 907:237-245; Kim, K. S. et al. (2010) “Construction Of A Humanized Antibody To Hepatitis B Surface Antigen By Specificity-Determining Residues (SDR)-Grafting And De Immunization,” Biochem. Biophys. Res. Commun. 396(2):231-237; Kashmiri, S. V. et al. (2005) “SDR Grafting—A New Approach To Antibody Humanization,” Methods 36(1):25-34; Gonzales, N. R. et al. (2004) “SDR Grafting Of A Murine Antibody Using Multiple Human Germline Templates To Minimize Its Immunogenicity,” Mol. Immunol. 41:863-872). Preferably, however, an Epitope Binding Domain will contain all 6 of the CDR Domains of such antibody. An Epitope Binding Domain may be a single polypeptide chain (e.g., an scFv), or may comprise two or more polypeptide chains, which may each have an amino terminus and a carboxy terminus (e.g., a diabody, a Fab fragment, an Fab₂fragment, etc.), and which may be covalently bonded to one another via a disulfide bond.

The invention also particularly encompasses Binding Molecules that comprise a VL or VH Domain of an antibody, and preferably both a VL and a VH Domain of an antibody. Preferably, such antibody is a humanized antibody. Monoclonal antibodies are typically prepared in non-human species, such as mouse or rabbit. The Variable and/or Constant Domains of such antibodies may be recognized as immunogens, thus provoking an immune response against them. Such molecules may however be “humanized” by introducing one or more amino acid substitutions in order to render such antibodies more like antibodies produced by humans. thereby reducing or eliminating their immunogenicity. The term “humanized” antibody refers to a chimeric molecule, generally prepared using recombinant techniques, having an epitope-binding site of an immunoglobulin from a non-human species and a remaining immunoglobulin structure of the molecule that is based upon the structure and/or sequence of a human immunoglobulin. The polynucleotide sequence of the variable domains of such antibodies may be used for genetic manipulation to generate such derivatives and to improve the affinity, or other characteristics of such antibodies. Application of this approach to various antibodies has been reported by LoBuglio, A. F. et al. (1989) “Mouse/Human Chimeric Monoclonal Antibody In Man: Kinetics And Immune Response,” Proc. Natl. Acad. Sci. (U.S.A.) 86:4220-4224; Sato, K. et al. (1993) Cancer Res 53:851-856. Riechmann, L. et al. (1988) “Reshaping Human Antibodies for Therapy,” Nature 332:323-327; Verhoeyen, M. et al. (1988) “Reshaping Human Antibodies: Grafting An Antilysozyme Activity,” Science 239:1534-1536; Kettleborough, C. A. et al. (1991) “Humanization Of A Mouse Monoclonal Antibody By CDR-Grafting: The Importance Of Framework Residues On Loop Conformation,” Protein Engineering 4:773-3783; Maeda, H. et al. (1991) “Construction Of Reshaped Human Antibodies With HIV-Neutralizing Activity,” Human Antibodies Hybridoma 2:124-134; Gorman, S. D. et al. (1991) “Reshaping A Therapeutic CD4 Antibody,” Proc. Natl. Acad. Sci. (U.S.A.) 88:4181-4185; Tempest, P. R. et al. (1991) “Reshaping A Human Monoclonal Antibody To Inhibit Human Respiratory Syncytial Virus Infection in vivo,” Bio/Technology 9:266-271; Co, M. S. et al. (1991) “Humanized Antibodies For Antiviral Therapy,” Proc. Natl. Acad. Sci. (U.S.A.) 88:2869-2873; Carter, P. et al. (1992) “Humanization Of An Anti-p185her2 Antibody For Human Cancer Therapy,” Proc. Natl. Acad. Sci. (U.S.A.) 89:4285-4289; and Co, M. S. et al. (1992) “Chimeric And Humanized Antibodies With Specificity For The CD33 Antigen,” J. Immunol. 148:1149-1154. In some embodiments, humanized antibodies preserve all CDR sequences (for example, a humanized mouse antibody which contains all six CDRs from the mouse antibodies). In other embodiments, humanized antibodies have one or more CDRs (one, two, three, four, five, and/or six) which differ in sequence relative to the original antibody.

The general principle in humanizing an antibody involves retaining the basic sequence of the Epitope Binding Domain of the antibody, while swapping the non-human remainder of the antibody with human antibody sequences. There are four general steps to humanize a monoclonal antibody. These are: (1) determining the nucleotide and predicted amino acid sequence of the starting antibody light and heavy variable domains (2) designing the humanized antibody or caninized antibody, i.e., deciding which antibody framework region to use during the humanizing or canonizing process (3) the actual humanizing or caninizing methodologies/techniques and (4) the transfection and expression of the humanized antibody. See, for example, U.S. Pat. Nos. 4,816,567; 5,807,715; 5,866,692; and 6,331,415.

A number of humanized antibody molecules comprising an Epitope Binding Domain derived from a non-human immunoglobulin have been described, including chimeric antibodies having rodent or modified rodent Variable Domain and their associated complementarity determining regions (CDRs) fused to human constant domains (see, for example, Winter et al. (1991) “Man-made Antibodies,” Nature 349:293-299; Lobuglio et al. (1989) “Mouse/Human Chimeric Monoclonal Antibody In Man: Kinetics And Immune Response,” Proc. Natl. Acad. Sci. (U.S.A.) 86:4220-4224 (1989), Shaw et al. (1987) “Characterization Of A Mouse/Human Chimeric Monoclonal Antibody (17-1A) To A Colon Cancer Tumor Associated Antigen,” J. Immunol. 138:4534-4538, and Brown et al. (1987) “Tumor-Specific Genetically Engineered Murine/Human Chimeric Monoclonal Antibody,” Cancer Res. 47:3577-3583). Other references describe rodent CDRs grafted into a human supporting framework region (FR) prior to fusion with an appropriate human antibody Constant Domain (see, for example, Riechmann, L. et al. (1988) “Reshaping Human Antibodies for Therapy,” Nature 332:323-327; Verhoeyen, M. et al. (1988) “Reshaping Human Antibodies: Grafting An Antilysozyme Activity,” Science 239:1534-1536; and Jones et al. (1986) “Replacing The Complementarity-Determining Regions In A Human Antibody With Those From A Mouse,” Nature 321:522-525). Another reference describes rodent CDRs supported by recombinantly veneered rodent framework regions. See, for example, European Patent Publication No. 519,596. These “humanized” molecules are designed to minimize unwanted immunological response towards rodent anti-human antibody molecules, which limits the duration and effectiveness of therapeutic applications of those moieties in human recipients. Other methods of humanizing antibodies that may also be utilized are disclosed by Daugherty et al. (1991) “Polymerase Chain Reaction Facilitates The Cloning, CDR-Grafting, And Rapid Expression Of A Murine Monoclonal Antibody Directed Against The CD18 Component Of Leukocyte Integrins,” Nucl. Acids Res. 19:2471-2476 and in U.S. Pat. Nos. 6,180,377; 6,054,297; 5,997,867; and 5,866,692. The invention particularly encompasses binding molecules (including antibodies and diabodies) that comprise a VL and/or VH Domain of a “humanized” antibody.

Notwithstanding such successes, the production of stable, functional heterodimeric, non-monospecific diabodies optimized for therapeutic use can be further improved by the careful consideration and placement of the domains employed in the polypeptide chains. The present invention is thus directed to the provision of specific polypeptides that are particularly designed to form, via covalent bonding, stable and therapeutically useful heterodimeric diabodies and heterodimeric Fc diabodies that are capable of simultaneously binding CD16 and a Disease Antigen.

As indicated above, natural antibodies are capable of binding to only one epitope species, although they can bind multiple copies of that species. The ability of an antibody to bind an epitope of an antigen depends upon the presence and amino acid sequence of the antibody's VL and VH Domains. Interaction of an antibody's Light Chain and Heavy Chain and, in particular, interaction of its VL and VH Domains forms one of the two Epitope Binding Domains of a natural antibody, such as an IgG. Natural antibodies are capable of binding only one epitope species (i.e., they are mono-specific), although they can bind multiple copies of that species (i.e., exhibiting bi-valency or multi-valency).

The functionality of antibodies can be enhanced by generating multispecific antibody-based molecules that can simultaneously bind two separate and distinct antigens (or different epitopes of the same antigen) and/or by generating antibody-based molecule having higher valency (i.e., more than two Binding Domains) for the same epitope and/or antigen.

In order to provide molecules having greater capability than natural antibodies, a wide variety of recombinant bispecific antibody formats have been developed (see, e.g., PCT Publication Nos. WO 2008/003116, WO 2009/132876, WO 2008/003103, WO 2007/146968, WO 2009/018386, WO 2012/009544, WO 2013/070565). Most of such approaches use linker peptides to fuse a further binding domain (e.g. an scFv, VL, VH, etc.) to, or within the antibody core (IgA, IgD, IgE, IgG or IgM), or to fuse multiple antibody binding portions to one another (e.g. two Fab fragments or scFv). Alternative formats use linker peptides to fuse a binding protein (e.g., an scFv, VL, VH, etc.) to a dimerization domain such as the CH2-CH3 Domain or alternative polypeptides (WO 2005/070966, WO 2006/107786A WO 2006/107617A, WO 2007/046893). Typically, such approaches involve compromises and trade-offs. For example, PCT Publication Nos. WO 2013/174873, WO 2011/133886 and WO 2010/136172 disclose that the use of linkers may cause problems in therapeutic settings, and teaches a trispecific antibody in which the CL and CH1 Domains are switched from their respective natural positions and the VL and VH Domains have been diversified (WO 2008/027236; WO 2010/108127) to allow them to bind to more than one antigen. Thus, the molecules disclosed in these documents trade binding specificity for the ability to bind additional antigen species. PCT Publication Nos. WO 2013/163427 and WO 2013/119903 disclose modifying the CH2 Domain to contain a fusion protein adduct comprising a binding domain. The document notes that the CH2 Domain likely plays only a minimal role in mediating effector function. PCT Publication Nos. WO 2010/028797, WO2010028796 and WO 2010/028795 disclose recombinant antibodies whose Fc Regions have been replaced with additional VL and VH Domains, so as to form trivalent binding molecules. PCT Publication Nos. WO 2003/025018 and WO2003012069 disclose recombinant diabodies whose individual chains contain scFv domains. PCT Publication Nos. WO 2013/006544 discloses multi-valent Fab molecules that are synthesized as a single polypeptide chain and then subjected to proteolysis to yield heterodimeric structures. Thus, the molecules disclosed in these documents trade all or some of the capability of mediating effector function for the ability to bind additional antigen species. PCT Publication Nos. WO 2014/022540, WO 2013/003652, WO 2012/162583, WO 2012/156430, WO 2011/086091, WO 2008/024188, WO 2007/024715, WO 2007/075270, WO 1998/002463, WO 1992/022583 and WO 1991/003493 disclose adding additional Binding Domains or functional groups to an antibody or an antibody portion (e.g., adding a diabody to the antibody's light chain, or adding additional VL and VH Domains to the antibody's light and heavy chains, or adding a heterologous fusion protein or chaining multiple Fab Domains to one another). Thus, the molecules disclosed in these documents trade native antibody structure for the ability to bind additional antigen species.

The binding molecules of the present invention may be Chimeric Antigen Receptors (“CARs”) that comprise a single chain variable fragment (scFv) capable of binding CD16 and a Disease Antigen. As indicated above, scFvs are made by linking Light and Heavy Chain Variable Domains together via a short linking peptide. First-generation CARs typically had the intracellular domain from the CD3 chain, which is the primary transmitter of signals from endogenous TCRs. Second-generation CARs possessed additional intracellular signaling domains from various costimulatory protein receptors (e.g., CD28, 41BB, ICOS, etc.) to the cytoplasmic tail of the CAR in order to provide additional signals to the T-cell. Third-generation CARs combine multiple signaling domains, such as CD3z-CD28-41BB or CD3z-CD28-OX40, in order to further augment potency (Tettamanti, S. et al. (2013) “Targeting Of Acute Myeloid Leukaemia By Cytokine-Induced Killer Cells Redirected With A Novel CD123-Specific Chimeric Antigen Receptor,” Br. J. Haematol. 161:389-401; Gill, S. et al. (2014) “Efficacy Against Human Acute Myeloid Leukemia And Myeloablation Of Normal Hematopoiesis In A Mouse Model Using Chimeric Antigen Receptor Modified T Cells,” Blood 123(15): 2343-2354; Mardiros, A. et al. (2013) “T Cells Expressing CD123-Specific Chimeric Antigen Receptors Exhibit Specific Cytolytic Effector Functions And Antitumor Effects Against Human Acute Myeloid Leukemia,” Blood 122:3138-3148; Pizzitola, I. et al. (2014) “Chimeric Antigen Receptors Against CD33/CD123 Antigens Efficiently Target Primary Acute Myeloid Leukemia Cells in vivo,” Leukemia doi:10.1038/leu.2014.62.

The intracellular domain of the CARs of the present invention is preferably selected from the intracellular domain of any of: 41BB-CD3ζ, b2c-CD3ζ, CD28, CD28-4-1BB-CD3ζ, CD28-CD3ζ, CD28-FcεRIγ, CD28mut-CD3ζ, CD28-OX40-CD3ζ, CD28-OX40-CD3ζ, CD3, CD4-CD3ζ, CD4-FcεRIγ, CD8-CD3ζ, FcεRIγ, FcεRIγCAIX, Heregulin-CD3ζ, IL-13-CD3ζ, or Ly49H-CD3ζ (Tettamanti, S. et al. (2013) “Targeting Of Acute Myeloid Leukaemia By Cytokine-Induced Killer Cells Redirected With A Novel CD123-Specific Chimeric Antigen Receptor,” Br. J. Haematol. 161:389-401; Gill, S. et al. (2014) “Efficacy Against Human Acute Myeloid Leukemia And Myeloablation Of Normal Hematopoiesis In A Mouse Model Using Chimeric Antigen Receptor Modified T Cells,” Blood 123(15): 2343-2354; Mardiros, A. et al. (2013) “T Cells Expressing CD123-Specific Chimeric Antigen Receptors Exhibit Specific Cytolytic Effector Functions And Antitumor Effects Against Human Acute Myeloid Leukemia,” Blood 122:3138-3148; Pizzitola, I. et al. (2014) “Chimeric Antigen Receptors Against CD33/CD123 Antigens Efficiently Target Primary Acute Myeloid Leukemia Cells in vivo,” Leukemia doi:10.1038/leu.2014.62).

The art has additionally noted the capability of producing diabodies that differ from natural antibodies in being capable of binding two or more different epitope species (i.e., exhibiting bispecificity or multispecificity in addition to bi-valency or multi-valency) (see, e.g., Holliger et al. (1993) “′Diabodies': Small Bivalent And Bispecific Antibody Fragments,” Proc. Natl. Acad. Sci. (U.S.A.) 90:6444-6448; US 2004/0058400 (Hollinger et al.); US 2004/0220388 (Mertens et al.); Alt et al. (1999) FEBS Lett. 454(1-2):90-94; Lu, D. et al. (2005) “A Fully Human Recombinant IgG-Like Bispecific Antibody To Both The Epidermal Growth Factor Receptor And The Insulin-Like Growth Factor Receptor For Enhanced Antitumor Activity,” J. Biol. Chem. 280(20):19665-19672; WO 02/02781 (Mertens et al.); Olafsen, T. et al. (2004) “Covalent Disulfide-Linked Anti-CEA Diabody Allows Site-Specific Conjugation And Radiolabeling For Tumor Targeting Applications,” Protein Eng Des Sel. 17(1):21-27; Wu, A. et al. (2001) “Multimerization Of A Chimeric Anti-CD20 Single Chain Fv-Fv Fusion Protein Is Mediated Through Variable Domain Exchange,” Protein Engineering 14(2):1025-1033; Asano et al. (2004) “A Diabody For Cancer Immunotherapy And Its Functional Enhancement By Fusion Of Human Fc Domain,” Abstract 3P-683, J. Biochem. 76(8):992; Takemura, S. et al. (2000) “Construction Of A Diabody (Small Recombinant Bispecific Antibody) Using A Refolding System,” Protein Eng. 13(8):583-588; Baeuerle, P. A. et al. (2009) “Bispecific T cell Engaging Antibodies For Cancer Therapy,” Cancer Res. 69(12):4941-4944).

The design of a diabody is based on the structure of the single-chain Variable Domain fragment (scFv), in which Light and Heavy Chain Variable Domains are linked to one another using a short linking peptide. Bird et al. (1988) (“Single-Chain Antigen-Binding Proteins,” Science 242:423-426) describes example of linking peptides which bridge approximately 3.5 nm between the carboxy terminus of one Variable Domain and the amino terminus of the other Variable Domain. Linkers of other sequences have been designed and used (Bird et al. (1988) “Single-Chain Antigen Binding Proteins,” Science 242:423-426). Linkers can in turn be modified for additional functions, such as attachment of drugs or attachment to solid supports. The single-chain variants can be produced either recombinantly or synthetically. For synthetic production of scFv, an automated synthesizer can be used. For recombinant production of scFv, a suitable plasmid containing polynucleotide that encodes the scFv can be introduced into a suitable host cell, either eukaryotic, such as yeast, plant, insect or mammalian cells, or prokaryotic, such as E. coli. Polynucleotides encoding the scFv of interest can be made by routine manipulations such as ligation of polynucleotides. The resultant scFv can be isolated using standard protein purification techniques known in the art.

The provision of non-monospecific “diabodies” provides a significant advantage over antibodies: the capacity to co-ligate and co-localize cells that express different epitopes. Bispecific diabodies thus have wide-ranging applications including therapy and immunodiagnosis. Bispecificity allows for great flexibility in the design and engineering of the diabody in various applications, providing enhanced avidity to multimeric antigens, the cross-linking of differing antigens, and directed targeting to specific cell types relying on the presence of both target antigens. Due to their bivalency, low dissociation rates and rapid clearance from the circulation (for diabodies of small size, at or below ˜50 kDa), diabody molecules known in the art have also shown particular use in the field of tumor imaging (Fitzgerald et al. (1997) “Improved Tumour Targeting By Disulphide Stabilized Diabodies Expressed In Pichia pastoris,” Protein Eng. 10:1221-1225).

The ability to produce bispecific diabodies has led to their use (in “trans”) to co-ligate two cells together, for example, by co-ligating receptors that are present on the surface of different cells (e.g., cross-linking cytotoxic T-cells to target cells, such as cancer cells or pathogen-infected cells, that express a Disease Antigen) (Staerz et al. (1985) “Hybrid Antibodies Can Target Sites For Attack By T Cells,” Nature 314:628-631, and Holliger et al. (1996) “Specific Killing Of Lymphoma Cells By Cytotoxic T-Cells Mediated By A Bispecific Diabody,” Protein Eng. 9:299-305; Marvin et al. (2005) “Recombinant Approaches To IgG-Like Bispecific Antibodies,” Acta Pharmacol. Sin. 26:649-658; Sloan et al. (2015) “Targeting HIV Reservoir in Infected CD4 T Cells by Dual-Affinity Re-targeting Molecules (DARTs) that Bind HIV Envelope and Recruit Cytotoxic T Cells,” PLoS Pathog 11(11): e1005233. doi:10.1371/journal.ppat.1005233)). Alternatively (or additionally), bispecific (or multispecific) diabodies can be used (in “cis”) to co-ligate molecules, such as receptors, etc., that are present on the surface of the same cell. Co-ligation of different cells and/or receptors is useful to modulate effector functions and/or immune cell signaling. Multispecific molecules (e.g., bispecific diabodies) comprising Epitope Binding Domains may be directed to a surface determinant of any immune cell such as CD2, CD3, CD8, CD16, TCR, NKG2D, etc., which are expressed on T lymphocytes, Natural Killer (NK) cells, Antigen-Presenting Cells or other mononuclear cells, or to a surface determinant of a B cell, such as CD19, CD20, CD22, CD30, CD37, CD40, and CD74 (Moore, P. A. et al. (2011) “Application Of Dual Affinity Retargeting Molecules To Achieve Optimal Redirected T cell Killing Of B-Cell Lymphoma,” Blood 117(17):4542-4551; Cheson, B. D. et al. (2008) “Monoclonal Antibody Therapy For B-Cell Non Hodgkin's Lymphoma,” N. Engl. J. Med. 359(6):613-626; Castillo, J. et al. (2008) “Newer Monoclonal Antibodies For Hematological Malignancies,” Exp. Hematol. 36(7):755-768). In particular, Epitope Binding Domains directed to a cell surface receptor that is present on immune effector cells, are useful in the generation of multispecific binding molecules capable of mediating redirected cell killing.

In many studies, diabody binding to effector cell determinants, e.g., Fcγ receptors (FcγR), was also found to activate the effector cell (Holliger et al. (1996) “Specific Killing Of Lymphoma Cells By Cytotoxic T cells Mediated By A Bispecific Diabody,” Protein Eng. 9:299-305; Holliger et al. (1999) “Carcinoembryonic Antigen (CEA)-Specific T cell Activation In Colon Carcinoma Induced By Anti-CD3 x Anti-CEA Bispecific Diabodies And B7 x Anti-CEA Bispecific Fusion Proteins,” Cancer Res. 59:2909-2916; WO 2006/113665; WO 2008/157379; WO 2010/080538; WO 2012/018687; WO 2012/162068). Normally, effector cell activation is triggered by the binding of an antigen-bound antibody to an effector cell via an Fc Domain-FcγR interaction; thus, in this regard, diabody molecules may exhibit Ig-like functionality independent of whether they comprise an Fc Domain (e.g., as assayed in any effector function assay known in the art or exemplified herein (e.g., ADCC assay)). By cross-linking tumor and effector cells, the diabody not only brings the effector cell within the proximity of a tumor cell but leads to effective tumor killing (see e.g., Cao et al. (2003) “Bispecific Antibody Conjugates In Therapeutics,” Adv. Drug. Deliv. Rev. 55:171-197).

However, the advantages of the above-described bispecific diabodies come at a salient cost. The formation of such non-mono-specific diabodies requires the successful assembly of two or more distinct and different polypeptides (i.e., such formation requires that the diabodies be formed through the heterodimerization of different polypeptide chain species). This fact is in contrast to mono-specific diabodies, which are formed through the homodimerization of identical polypeptide chains. Because at least two dissimilar polypeptides (i. e., two polypeptide species) must be provided in order to form a non-mono-specific diabody, and because homodimerization of such polypeptides leads to inactive molecules (Takemura, S. et al. (2000) “Construction Of A Diabody (Small Recombinant Bispecific Antibody) Using A Refolding System,” Protein Eng. 13(8):583-588), the production of such polypeptides must be accomplished in such a way as to prevent covalent bonding between polypeptides of the same species (i. e., so as to prevent homodimerization) (Takemura, S. et al. (2000) “Construction Of A Diabody (Small Recombinant Bispecific Antibody) Using A Refolding System,” Protein Eng. 13(8):583-588). The art has therefore taught the non-covalent association of such polypeptides (see, e.g., Olafsen et al. (2004) “Covalent Disulfide-Linked Anti-CEA Diabody Allows Site-Specific Conjugation And Radiolabeling For Tumor Targeting Applications,” Prot. Engr. Des. Sel. 17:21-27; Asano et al. (2004) “A Diabody For Cancer Immunotherapy And Its Functional Enhancement By Fusion Of Human Fc Domain,” Abstract 3P-683, J. Biochem. 76(8):992; Takemura, S. et al. (2000) “Construction Of A Diabody (Small Recombinant Bispecific Antibody) Using A Refolding System,” Protein Eng. 13(8):583-588; Lu, D. et al. (2005) “A Fully Human Recombinant IgG-Like Bispecific Antibody To Both The Epidermal Growth Factor Receptor And The Insulin-Like Growth Factor Receptor For Enhanced Antitumor Activity,” J. Biol. Chem. 280(20):19665-19672).

However, the art has recognized that bispecific diabodies composed of non-covalently associated polypeptides are unstable and readily dissociate into non-functional single polypeptide chain monomers (see, e.g., Lu, D. et al. (2005) “A Fully Human Recombinant IgG-Like Bispecific Antibody To Both The Epidermal Growth Factor Receptor And The Insulin-Like Growth Factor Receptor For Enhanced Antitumor Activity,” J. Biol. Chem. 280(20):19665-19672).

In the face of this challenge, the art has succeeded in developing stable, covalently bonded heterodimeric non-mono-specific diabodies, termed DART® diabodies, see, e.g., Sloan, D. D. et al. (2015) “Targeting HIV Reservoir in Infected CD4 T Cells by Dual-Affinity Re-targeting Molecules (DARTs) that Bind HIV Envelope and Recruit Cytotoxic T Cells,” PLoS Pathog. 11(11):e1005233. doi: 10.1371/journal.ppat.1005233; Al Hussaini, M. et al. (2015) “Targeting CD123 In AML Using A T-Cell Directed Dual-Affinity Re-Targeting (DART®) Platform,” Blood pii: blood-2014-05-575704; Chichili, G. R. et al. (2015) “A CD3xCD123 Bispecific DART For Redirecting Host T Cells To Myelogenous Leukemia: Preclinical Activity And Safety In Nonhuman Primates,” Sci. Transl. Med. 7(289):289ra82; Johnson, S. et al. (2010) “Effector Cell Recruitment With Novel Fv-Based Dual-Affinity Re-Targeting Protein Leads To Potent Tumor Cytolysis And In Vivo B-Cell Depletion,” J. Molec. Biol. 399(3):436-449; Veri, M. C. et al. (2010) “Therapeutic Control Of B Cell Activation Via Recruitment Of Fcgamma Receptor IIB (CD32B) Inhibitory Function With A Novel Bispecific Antibody Scaffold,” Arthritis Rheum. 62(7):1933-1943; Moore, P. A. et al. (2011) “Application Of Dual Affinity Retargeting Molecules To Achieve Optimal Redirected T cell Killing Of B-Cell Lymphoma,” Blood 117(17):4542-4551; U.S. Pat. Nos. 8,044,180; 8,133,982; 8,187,593; 8,193,318; 8,530,627; 8,669,349; 8,778,339; 8,784,808; 8,795,667; 8,802,091; 8,802,093; 8,946,387; 8,968,730; and 8,993,730; US Patent Publication Nos. 2009/0060910; 2010/0174053; 2011/0081347; 2011/0097323; 2011/0117089; 2012/0009186; 2012/0034221; 2012/0141476; 2012/0294796; 2013/0149236; 2013/0295121; 2014/0017237; and 2014/0099318; European Patent Documents No. EP 1868650; EP 2158221; EP 2247304; EP 2252631; EP 2282770; EP 2328934; EP 2376109; EP 2542256; EP 2601216; EP 2714079; EP 2714733; EP 2786762; EP 2839842; EP 2840091; and PCT Publication Nos. WO 2006/113665; WO 2008/157379; WO 2010/027797; WO 2010/033279; WO 2010/080538; WO 2011/109400; WO 2012/018687; WO 2012/162067; WO 2012/162068; WO 2014/159940; WO 2015/021089; WO 2015/026892; and WO 2015/026894). Such diabodies comprise two or more covalently complexed polypeptides and involve engineering one or more cysteine residues into each of the employed polypeptide species that permit disulfide bonds to form and thereby covalently bond one or more pairs of such polypeptide chains to one another. For example, the addition of a cysteine residue to the C-terminus of such constructs has been shown to allow disulfide bonding between the involved polypeptide chains, stabilizing the resulting diabody without interfering with the diabody's binding characteristics.

The simplest DART® diabody comprises two polypeptide chains each comprising three Domains (FIGS. 1A-1B). The first polypeptide chain comprises: (i) a Domain that comprises a binding region of a light chain variable Domain of the a first immunoglobulin (VL1), (ii) a second Domain that comprises a binding region of a heavy chain variable Domain of a second immunoglobulin (VH2), and (iii) a third Domain that serves to promote heterodimerization (a “Heterodimer-Promoting Domain”) with the second polypeptide chain and to covalently bond the first polypeptide to the second polypeptide chain of the diabody. The second polypeptide chain contains a complementary first Domain (a VL2 Domain), a complementary second Domain (a VH1 Domain) and a third Domain that complexes with the third Domain of the first polypeptide chain in order to promote heterodimerization (a “Heterodimer-Promoting Domain”) and covalent bonding with the first polypeptide chain. Such molecules are stable, potent and have the ability to simultaneously bind two or more antigens. In one embodiment, the third Domains of the first and second polypeptide chains each contain a cysteine (“©”) residue, which serves to bind the polypeptides together via a disulfide bond. The third Domain of one or both of the polypeptide chains may additionally possess the sequence of a CH2-CH3 Domain, such that complexing of the diabody polypeptides forms an Fc Domain that is capable of binding to the Fc receptor of cells (such as B lymphocytes, dendritic cells, natural killer cells, macrophages, neutrophils, eosinophils, basophils and mast cells). Many variations of such molecules have been described (see, e.g., United States Patent Publication Nos. 2013-0295121; 2010-0174053; 2007-0004909; 2009-0060910; European Patent Publication No. EP 2714079; EP 2601216; EP 2376109; EP 2158221 and PCT Publication Nos. WO 2012/162068; WO 2012/018687; WO 2010/080538; WO 2006/113665) and are provided herein. Many variations of such molecules have been described (see, e.g., United States Patent Publication Nos. 2015/0175697; 2014/0255407; 2014/0099318; 2013/0295121; 2010/0174053; 2009/0060910; 2007-0004909; European Patent Publication Nos. EP 2714079; EP 2601216; EP 2376109; EP 2158221; EP 1868650; and PCT Publication Nos. WO 2012/162068; WO 2012/018687; WO 2010/080538; WO 2006/113665), and are provided herein.

Alternative constructs are known in the art for applications where a bispecific or tetravalent molecule is desirable but an Fc is not required including, but not limited to, Bispecific T cell Engager molecules, also referred to as “BITE® antibodies” (see, e.g., PCT Publication Nos: WO 1993/11161; and WO 2004/106381) and tetravalent tandem antibodies, also referred to as “TandAbs®” (see, e.g. United States Patent Publication No: 2011-0206672; European Patent Publication No. EP 2371866, and; PCT Publication Nos. WO 1999/057150, WO 2003/025018, and WO 2013/013700). BiTEs are formed from a single polypeptide chain comprising tandem linked scFvs, while TandAbs are formed by the homo-dimerization of two identical polypeptide chains, each possessing a VH1, VL2, VH2, and VL2 Domain.

The present invention provides bispecific binding molecules that are capable of enhancing an immune response directed to the killing of a target cell (e.g., a cancer cell or a pathogen-infected cell, a pathogen, etc.) expressing a Disease Antigen. Such bispecific binding molecules are capable of binding a “First Epitope” and a “Second Epitope,” wherein one of such epitopes is an epitope of CD16 and the other of such epitopes is an epitope of a Disease Antigen (“DA”). It is irrelevant whether a particular epitope is designated as the first vs. the Second Epitope; such notation having relevance only with respect to the presence and orientation of the domains of the polypeptide chains of the binding molecules of the present invention. Thus, the bispecific molecules of the present invention comprise “VL_CD16”/“VH_CD16” Domains that are capable of binding an epitope of CD16, and “VL_DA”/“VH_DA” Domains that are capable of binding an epitope of a Disease Antigen. The instant invention particular encompasses bispecific diabodies, BiTEs, antibodies, and TandAbs produced using any of the methods provided herein.

In one embodiment, the CD16 Binding Molecules of the present invention will be bispecific diabodies and will comprise domains capable of binding both a first and a Second Epitope, but will lack an Fc Domain, and thus will be unable to bind FcγR molecules via an Fc-FcγR interaction. Such molecules are, however, able to bind to CD16 via the SDRs or CDRs of their CD16 Binding Domains. The absence of Fc domains thus serves to prevent the molecules from binding to non-CD16 FcγRs, such as the inhibitory receptor CD32B.

The first polypeptide chain of such an embodiment of bispecific diabodies preferably comprises, in the N-terminal to C-terminal direction: an N-terminus, the VL Domain of a monoclonal antibody capable of binding either the First or Second Epitope (i.e., either VL_CD16or VL_DA), a first intervening spacer peptide (Linker 1), a VH Domain of a monoclonal antibody capable of binding the epitope of the Disease Antigen (if such first polypeptide chain contains VL_CD16) or a VH Domain of a monoclonal antibody capable of binding CD16 (if such first polypeptide chain contains VL_DA), a second intervening spacer peptide (Linker 2) optionally containing a cysteine residue, a Heterodimer-Promoting Domain and a C-terminus (FIGS. 1A-1B).

The second polypeptide chain of this embodiment of bispecific diabodies comprises, in the N-terminal to C-terminal direction: an N-terminus, the VL Domain of a monoclonal antibody capable of binding the First or Second Epitope (i.e., VL_CD16or VL_DA, and being the VL Domain not selected for inclusion in the first polypeptide chain of the diabody), an intervening spacer peptide (Linker 1), a VH Domain of a monoclonal antibody capable of binding either the First or Second Epitope (i.e., VH_CD16or VH_DA, and being the VH Domain not selected for inclusion in the first polypeptide chain of the diabody), a second intervening spacer peptide (Linker 2) optionally containing a cysteine residue, a Heterodimer-Promoting Domain and a C-terminus (FIGS. 1A-1B). The employed VL and VH Domains specific for a particular epitope are preferably obtained or derived from the same monoclonal antibody. However, such domains may be derived from different monoclonal antibodies provided that they associate to form a functional Binding Domain capable of immunospecifically binding such epitope. Such different antibodies are referred to herein as being “corresponding” antibodies.

The VL Domain of the first polypeptide chain interacts with the VH Domain of the second polypeptide chain to form a first functional Epitope Binding Domain that is specific for one of the epitopes (e.g., the First Epitope). Likewise, the VL Domain of the second polypeptide chain interacts with the VH Domain of the first polypeptide chain in order to form a second functional Epitope Binding Domain that is specific for the other epitope (i.e., the Second Epitope). Thus, the selection of the VL and VH Domains of the first and second polypeptide chains is “coordinated,” such that the two polypeptide chains of the diabody collectively comprise VL and VH Domains capable of binding both the First Epitope and the Second Epitope (i.e., they collectively comprise VL_CD16/VH_CD16and VL_DA/VH_DA).

Most preferably, the length of the intervening spacer peptide (i.e., “Linker 1,” which separates such VL and VH Domains) is selected to substantially or completely prevent the VL and VH Domains of the polypeptide chain from binding one another (for example consisting of from 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9 intervening linker amino acid residues). Thus, the VL and VH Domains of the first polypeptide chain are substantially or completely incapable of binding one another. Likewise, the VL and VH Domains of the second polypeptide chain are substantially or completely incapable of binding one another. A preferred intervening spacer peptide (Linker 1) has the sequence (SEQ ID NO:16):

The length and composition of the second intervening spacer peptide (“Linker 2”) is selected based on the choice of one or more polypeptide domains that promote such dimerization (i.e., a “Heterodimer-Promoting Domain”). Typically, the second intervening spacer peptide (Linker 2) will comprise 3-20 amino acid residues. In particular, where the employed Heterodimer-Promoting Domain(s) do/does not comprise a cysteine residue a cysteine-containing second intervening spacer peptide (Linker 2) is utilized. A cysteine-containing second intervening spacer peptide (Linker 2) will contain 1, 2, 3 or more cysteines. A preferred cysteine-containing spacer peptide (Linker 2) has the sequence GGCGGG (SEQ ID NO:17). Alternatively, Linker 2 does not comprise a cysteine (e.g., GGG, GGGS (SEQ ID NO:18), LGGGSG (SEQ ID NO:19), GGGSGGGSGGG (SEQ ID NO:20), AS TKG (SEQ ID NO:21), LEPKSS (SEQ ID NO:22), APSSS (SEQ ID NO:23), etc.) and a cysteine-containing Heterodimer-Promoting Domain, as described below is used. Optionally, both a cysteine-containing Linker 2 and a cysteine-containing Heterodimer-Promoting Domain are used.

The Heterodimer-Promoting Domains may be GVEPKSC (SEQ ID NO:24) or VEPKSC (SEQ ID NO:25) or AEPKSC (SEQ ID NO:26) on one polypeptide chain and GFNRGEC (SEQ ID NO:27) or FNRGEC (SEQ ID NO:28) on the other polypeptide chain (US2007/0004909).

In a preferred embodiment, the Heterodimer-Promoting Domains will comprise tandemly repeated coil domains of opposing charge for example, an “E-coil” Heterodimer-Promoting Domain (SEQ ID NO:29: EVAALEK-EVAALEK-EVAALEK-EVAALEK), whose glutamate residues will form a negative charge at pH 7, or a “K-coil” Heterodimer-Promoting Domain (SEQ ID NO:30: KVAALKE-KVAALKE-KVAALKE KVAALKE), whose lysine residues will form a positive charge at pH 7. The presence of such charged domains promotes association between the first and second polypeptides, and thus fosters heterodimer formation. Heterodimer-Promoting Domains that comprise modifications of the above-described E-coil and K-coil sequences so as to include one or more cysteine residues may be utilized. The presence of such cysteine residues permits the coil present on one polypeptide chain to become covalently bonded to a complementary coil present on another polypeptide chain, thereby covalently bonding the polypeptide chains to one another and increasing the stability of the diabody. Examples of such particularly preferred are Heterodimer-Promoting Domains include a Modified E-Coil having the amino acid sequence EVAACEK-EVAALEK-EVAALEK-EVAALEK (SEQ ID NO:31), and a modified K-coil having the amino acid sequence KVAACKE-KVAALKE-KVAALKE-KVAALKE (SEQ ID NO:32).

As disclosed in WO 2012/018687, in order to improve the in vivo pharmacokinetic properties of diabodies, a diabody may be modified to contain a polypeptide portion of a serum-binding protein at one or more of the termini of the diabody. Most preferably, such polypeptide portion of a serum-binding protein will be installed at the C-terminus of a polypeptide chain of the diabody. Albumin is the most abundant protein in plasma and has a half-life of 19 days in humans. Albumin possesses several small molecule binding domains that permit it to non-covalently bind other proteins and thereby extend their serum half-lives. The Albumin-Binding Domain 3 (ABD3) of protein G of Streptococcus strain G148 consists of 46 amino acid residues forming a stable three-helix bundle and has broad albumin-binding specificity (Johansson, M. U. et al. (2002) “Structure, Specificity, And Mode Of Interaction For Bacterial Albumin-Binding Modules,” J. Biol. Chem. 277(10):8114-8120). Thus, a particularly preferred polypeptide portion of a serum-binding protein for improving the in vivo pharmacokinetic properties of a diabody is the Albumin-Binding Domain (ABD) from streptococcal protein G, and more preferably, the Albumin-Binding Domain 3 (ABD3) of protein G of Streptococcus strain G148 (SEQ ID NO:33):

As disclosed in WO 2012/162068 (herein incorporated by reference), “deimmunized” variants of SEQ ID NO:33 have the ability to attenuate or eliminate MHC class II binding. Based on combinational mutation results, the following combinations of substitutions are considered to be preferred substitutions for forming such a deimmunized ABD: 66D/70S+71A; 66S/70S+71A; 66S/70S+79A; 64A/65A/71A; 64A/65A/71A+66S; 64A/65A/71A+66D; 64A/65A/71A+66E; 64A/65A/79A+66S; 64A/65A/79A+66D; 64A/65A/79A+66E. Variant ABDs having the modifications L64A, I65A and D79A or the modifications N66S, T7OS and D79A. Variant deimmunized ABD having the amino acid sequence:

One embodiment of the present invention relates to multi-specific diabodies (e.g., bispecific, trispecific, tetraspecific, etc.) that comprise an Fc Domain and that are capable of simultaneously binding an epitope of CD16 and an epitope of a Disease Antigen. The Fc Domain of such molecules may be of any isotype (e.g., IgG1, IgG2, IgG3, or IgG4). The molecules may further comprise a CH1 Domain and/or a Hinge Domain. When present, the CH1 Domain and/or Hinge Domain may be of any isotype (e.g., IgG1, IgG2, IgG3, or IgG4), and is preferably of the same isotype as the desired Fc Domain.

The addition of an IgG CH2-CH3 Domain to one or both of the diabody polypeptide chains, such that the complexing of the diabody chains results in the formation of an Fc Domain, increases the biological half-life and/or alters the valency of the diabody. Such diabodies comprise, two or more polypeptide chains whose sequences permit the polypeptide chains to covalently bind each other to form a covalently associated diabody that is capable of simultaneously binding the First Epitope and the Second Epitope. Incorporating an IgG CH2-CH3 Domains onto both of the diabody polypeptides will permit a two-chain bispecific Fc Domain-containing diabody to form (FIG. 2).

Alternatively, incorporating IgG CH2-CH3 Domains onto only one of the diabody polypeptides will permit a more complex four-chain bispecific Fc Domain-containing diabody to form (FIGS. 3A-3C). FIG. 3C shows a representative four-chain diabody possessing the Constant Light (CL) Domain and the Constant Heavy CH1 Domain, however fragments of such domains as well as other polypeptides may alternatively be employed (see, e.g., FIGS. 3A and 3B, United States Patent Publication Nos. 2013-0295121; 2010-0174053 and 2009-0060910; European Patent Publication No. EP 2714079; EP 2601216; EP 2376109; EP 2158221 and PCT Publication Nos. WO 2012/162068; WO 2012/018687; WO 2010/080538). Thus, for example, in lieu of the CH1 Domain, one may employ a peptide having the amino acid sequence GVEPKSC (SEQ ID NO:24), VEPKSC (SEQ ID NO:25), or AEPKSC (SEQ ID NO:26), derived from the Hinge Domain of a human IgG, and in lieu of the CL Domain, one may employ the C-terminal 6 amino acids of the human kappa Light Chain, GFNRGEC (SEQ ID NO:27) or FNRGEC (SEQ ID NO:28). A representative peptide containing four-chain diabody is shown in FIG. 3A. Alternatively, or in addition, one may employ a peptide comprising tandem coil domains of opposing charge such as the “E-coil” helical domains

Fc Domain-containing diabody molecules of the present invention may include additional intervening spacer peptides (Linkers), generally such Linkers will be incorporated between a Heterodimer-Promoting Domain (e.g., an E-coil or K-coil) and a CH2-CH3 Domain and/or between a CH2-CH3 Domain and a Variable Domain (i.e., VH or VL). Typically, the additional Linkers will comprise 3-20 amino acid residues and may optionally contain all or a portion of an IgG Hinge Domain (preferably a cysteine-containing portion of an IgG Hinge Domain possessing 1, 2, 3 or more cysteine residues). Linkers that may be employed in the bispecific Fc Domain-containing diabody molecules of the present invention include: GGGS (SEQ ID NO:18), LGGGSG (SEQ ID NO:19), GGGSGGGSGGG (SEQ ID NO:20), AS TKG (SEQ ID NO:21), LEPKSS (SEQ ID NO:22), APSSS (SEQ ID NO:23), APSSSPME (SEQ ID NO:37), VEPKSADKTHTCPPCP (SEQ ID NO:38), LEPKSADKTHTCPPCP (SEQ ID NO:39), DKTHTCPPCP (SEQ ID NO:40), the scFv linker: GGGGSGGGGSGGGGS (SEQ ID NO:41); the “long” linker: GGGGSGGGSGGG (SEQ ID NO:42), GGC, and GGG. LEPKSS (SEQ ID NO:22) may be used in lieu of GGG or GGC for ease of cloning. Additionally, the amino acids GGG, or LEPKSS (SEQ ID NO:22) may be immediately followed by DKTHTCPPCP (SEQ ID NO:40) to form the alternate linkers: GGGDKTHTCPPCP (SEQ ID NO:43); and LEPKSSDKTHTCPPCP (SEQ ID NO:44).

Bispecific Fc Domain-containing molecules of the present invention may incorporate an IgG Hinge Domain in addition to or in place of a linker. Exemplary Hinge Domains include: EPKSCDKTHTCPPCP (SEQ ID NO:5) from IgG1, ERKCCVECPPCP (SEQ ID NO:6) from IgG2, ELKTPLGDTTHTCPRCPEPKSCDTPPPCPRCPEPKSCDTPPPCPRCPEPKS CDTPPPCPRCP (SEQ ID NO:7) from IgG3, ESKYGPPCPSCP (SEQ ID NO:8) from IgG4, and ESKYGPPCPPCP (SEQ ID NO:9) an IgG4 Hinge variant comprising a stabilizing S228P substitution (as numbered by the EU index as set forth in Kabat) to reduce strand exchange.

As provided in FIG. 3A-3C, Fc Domain-containing diabodies of the invention may comprise four chains. The first and third polypeptide chains of such a diabody contain three domains: (i) a VL1-containing Domain, (ii) a VH2-containing Domain, (iii) a Heterodimer-Promoting Domain, and (iv) a Domain containing a CH2-CH3 sequence. The second and fourth polypeptide chains contain: (i) a VL2-containing Domain, (ii) a VH1-containing Domain, and (iii) a Heterodimer-Promoting Domain, where the Heterodimer-Promoting Domains promote the dimerization of the first/third polypeptide chains with the second/fourth polypeptide chains. The VL and/or VH Domains of the third and fourth polypeptide chains, and VL and/or VH Domains of the first and second polypeptide chains may be the same or different so as to permit tetravalent binding that is either mono-specific, bispecific or tetraspecific. The notation “VL3” and “VH3” denote respectively, the Light Chain Variable Domain and Variable Heavy Chain Domain that bind a “third” epitope of such diabody. Similarly, the notation “VL4” and “VH4” denote respectively, the Light Chain Variable Domain and Variable Heavy Chain Domain that bind a “fourth” epitope of such diabody. The general structure of the polypeptide chains of a representative four-chain bispecific Fc Domain-containing diabodies of invention is provided in Table 1:

In a specific embodiment, diabodies of the present invention are bispecific, tetravalent (i.e., possess four Epitope Binding Domains), Fc-containing diabodies that are composed of four total polypeptide chains (FIGS. 3A-3C). The bispecific, tetravalent, Fc-containing diabodies of the invention comprise two First Epitope Binding Domains and two Second Epitope Binding Domains.

In a further embodiment, the Fc Domain-containing diabodies of the present invention may comprise three polypeptide chains. The first polypeptide of such a diabody contains three domains: (i) a VL1-containing Domain, (ii) a VH2-containing Domain and (iii) a Domain containing a CH2-CH3 sequence. The second polypeptide of such a diabody contains: (i) a VL2-containing Domain, (ii) a VH1-containing Domain and (iii) a Domain that promotes heterodimerization and covalent bonding with the diabody's first polypeptide chain. The third polypeptide of such a diabody comprises a CH2-CH3 sequence. Thus, the first and second polypeptide chains of such a diabody associate together to form a VL1/VH1 Epitope Binding Domain that is capable of binding either the First or Second Epitope, as well as a VL2/VH2 Epitope Binding Domain that is capable of binding the other of such epitopes. The first and second polypeptides are bonded to one another through a disulfide bond involving cysteine residues in their respective Third Domains. Notably, the first and third polypeptide chains complex with one another to form an Fc Domain that is stabilized via a disulfide bond. Such bispecific diabodies have enhanced potency. FIGS. 4A and 4B illustrate the structures of such diabodies. Such Fc Domain-containing diabodies may have either of two orientations (Table 2):

In a specific embodiment, diabodies of the present invention are bispecific, bivalent (i.e., possess two Epitope Binding Domains), Fc-containing diabodies that are composed of three total polypeptide chains (FIGS. 4A-4B). The bispecific, bivalent Fc-containing diabodies of the invention comprise one Epitope Binding Domain immunospecific for either the First or Second Epitope, as well as a VL2/VH2 Epitope Binding Domain that is capable of binding the other of such epitopes.

In a further embodiment, the Fc Domain-containing diabodies may comprise a total of five polypeptide chains. In a particular embodiment, two of the five polypeptide chains have the same amino acid sequence. The first polypeptide chain of such a diabody contains: (i) a VH1-containing Domain, (ii) a CH1-containing Domain, and (iii) a Domain containing a CH2-CH3 sequence. The first polypeptide chain may be the Heavy Chain of an antibody that contains a VH1 and a Heavy Chain constant region. The second and fifth polypeptide chains of such a diabody contain: (i) a VL1-containing Domain, and (ii) a CL-containing Domain. The second and/or fifth polypeptide chains of such a diabody may be Light Chains of an antibody that contains a VL1 complementary to the VH1 of the first/third polypeptide chain. The first, second and/or fifth polypeptide chains may be isolated from a naturally occurring antibody. Alternatively, they may be constructed recombinantly. The third polypeptide chain of such a diabody contains: (i) a VH1-containing Domain, (ii) a CH1-containing Domain, (iii) a Domain containing a CH2-CH3 sequence, (iv) a VL2-containing Domain, (v) a VH3-containing Domain and (vi) a Heterodimer-Promoting Domain, where the Heterodimer-Promoting Domains promote the dimerization of the third chain with the fourth chain. The fourth polypeptide of such diabodies contains: (i) a VL3-containing Domain, (ii) a VH2-containing Domain and (iii) a Domain that promotes heterodimerization and covalent bonding with the diabody's third polypeptide chain.

Thus, the first and second, and the third and fifth, polypeptide chains of such diabodies associate together to form two VL1/VH1 Epitope Binding Domains capable of binding a First Epitope. The third and fourth polypeptide chains of such diabodies associate together to form a VL2/VH2 Epitope Binding Domain that is capable of binding a Second Epitope, as well as a VL3/VH3 Epitope Binding Domain that is capable of binding a Third Epitope. The first and third polypeptides are bonded to one another through a disulfide bond involving cysteine residues in their respective constant regions. Notably, the first and third polypeptide chains complex with one another to form an Fc Domain. Such multispecific diabodies have enhanced potency. FIG. 5 illustrates the structure of such diabodies. It will be understood that the VL1/VH1, VL2/VH2, and VL3/VH3 Domains may be the same or different so as to permit binding that is mono-specific, bispecific or trispecific.

The VL and VH Domains of the polypeptide chains are selected so as to form VL/VH Epitope Binding Domains specific for a desired epitope. The VL/VH Epitope Binding Domains formed by the association of the polypeptide chains may be the same or different so as to permit tetravalent binding that is mono-specific, bispecific, trispecific or tetraspecific. In particular, the VL and VH Domains maybe selected such that a multivalent diabody may comprise two Binding Domains for a First Epitope and two Binding Domains for a Second Epitope, or three Binding Domains for a First Epitope and one Binding Domain for a Second Epitope, or two Binding Domains for a First Epitope, one Binding Domain for a Second Epitope and one Binding Domain for a Third Epitope (as depicted in FIG. 5). The general structure of the polypeptide chains of representative five-chain Fc Domain-containing diabodies of invention is provided in Table 3:

In a specific embodiment, diabodies of the present invention are bispecific, tetravalent (i.e., possess four Epitope Binding Domains), Fc-containing diabodies that are composed of five total polypeptide chains having two Epitope Binding Domains immunospecific for the First Epitope, and two Epitope Binding Domains specific for the Second Epitope. In another embodiment, the bispecific, tetravalent, Fc-containing diabodies of the invention comprise three Epitope Binding Domains immunospecific for the First Epitope and one Epitope Binding Domain specific for the Second Epitope. As provided above, the VL and VH Domains may be selected to permit trispecific binding. Accordingly, the invention also encompasses trispecific, tetravalent, Fc-containing diabodies. The trispecific, tetravalent, Fc-containing diabodies of the invention comprise two Epitope Binding Domains immunospecific for the First Epitope, one Epitope Binding Domain immunospecific for the Second Epitope, and one Epitope Binding Domain immunospecific for the Third Epitope.

In traditional immune function, the interaction of antibody-antigen complexes with cells of the immune system results in a wide array of responses, ranging from effector functions such as antibody-dependent cytotoxicity, mast cell degranulation, and phagocytosis to immunomodulatory signals such as regulating lymphocyte proliferation and antibody secretion. All of these interactions are initiated through the binding of the Fc Domain of antibodies or immune complexes to specialized cell surface receptors on hematopoietic cells. As discussed above, the diversity of cellular responses triggered by antibodies and immune complexes results from the structural heterogeneity of the three Fc receptors: FcγRT (CD64), FcγRII (CD32), and FcγRIII (CD16). FcγRT (CD64), FcγRIIA (CD32A) and FcγRIII (CD16) are activating (i.e., immune system enhancing) receptors; FcγRIIB (CD32B) is an inhibiting (i.e., immune system dampening) receptor. In addition, interaction with the neonatal Fc Receptor (FcRn) mediates the recycling of IgG molecules from the endosome to the cell surface and release into the blood. The amino acid sequence of exemplary wild-type IgG1 (SEQ ID NO:12), IgG2 (SEQ ID NO:13), IgG3 (SEQ ID NO:14), and IgG4 (SEQ ID NO:15) are presented above.

Modification of the Fc Domain may lead to an altered phenotype, for example altered serum half-life, altered stability, altered susceptibility to cellular enzymes or altered effector function. It may therefore be desirable to modify an Fc Domain-containing binding molecule of the present invention with respect to effector function, for example, so as to enhance the effectiveness of such molecule in treating cancer. Reduction or elimination of Fc Domain-mediated effector function is desirable in certain cases, for example in the case of antibodies whose mechanism of action involves blocking or antagonism, but not killing of the cells bearing a target antigen. Increased effector function is generally desirable when directed to undesirable cells, such as tumor and foreign cells, where the FcγRs are expressed at low levels, for example, tumor-specific B cells with low levels of FcγRIIB (e.g., non-Hodgkin's lymphoma, CLL, and Burkitt's lymphoma). Molecules of the invention possessing such conferred or altered effector function activity are useful for the treatment and/or prevention of a disease, disorder or infection in which an enhanced efficacy of effector function activity is desired.

Accordingly, in certain embodiments, the Fc Domain of the Fc Domain-containing molecules of the present invention may be an engineered variant Fc Domain. Although the Fc Domain of the bispecific Fc Domain-containing molecules of the present invention may possess the ability to bind one or more Fc receptors (e.g., FcγR(s)), more preferably such variant Fc Domain have altered binding FcγRIA (CD64), FcγRIIA (CD32A), FcγRIIB (CD32B), FcγRIIIA (CD16a) or FcγRIIIB (CD16b) (relative to the binding exhibited by a wild-type Fc Domain), e.g., will have enhanced binding an activating receptor and/or will have substantially reduced or no ability to bind inhibitory receptor(s). Thus, the Fc Domain of the Fc Domain-containing molecules of the present invention may include some or all of the CH2 Domain and/or some or all of the CH3 Domain of a complete Fc Domain, or may comprise a variant CH2 and/or a variant CH3 sequence (that may include, for example, one or more insertions and/or one or more deletions with respect to the CH2 or CH3 domains of a complete Fc Domain). Such Fc Domains may comprise non-Fc polypeptide portions, or may comprise portions of non-naturally complete Fc Domains, or may comprise non-naturally occurring orientations of CH2 and/or CH3 Domains (such as, for example, two CH2 Domains or two CH3 Domains, or in the N-terminal to C-terminal direction, a CH3 Domain linked to a CH2 Domain, etc.).

Fc Domain modifications identified as altering effector function are known in the art, including modifications that increase binding activating receptors (e.g., FcγRIIA (CD16A) and reduce binding inhibitory receptors (e.g., FcγRIIB (CD32B) (see, e.g., Stavenhagen, J. B. et al. (2007) “Fc Optimization Of Therapeutic Antibodies Enhances Their Ability To Kill Tumor Cells In Vitro And Controls Tumor Expansion In Vivo Via Low-Affinity Activating Fcgamma Receptors,” Cancer Res. 57(18):8882-8890). Table 4 lists exemplary single, double, triple, quadruple and quintuple substitutions (numbering (according to the EU index) and substitutions are relative to the amino acid sequence of SEQ ID NO:12 as presented above) of exemplary modification that increase binding activating receptors and/or reduce binding inhibitory receptors.

Exemplary variants of human IgG1 Fc Domains with reduced binding CD32B and/or increased binding CD16A contain F243L, R292P, Y300L, V305I or P396L substitutions, wherein the numbering is that of the EU index as in Kabat. These amino acid substitutions may be present in a human IgG1 Fc Domain in any combination. In one embodiment, the variant human IgG1 Fc Domain contains a F243L, R292P and Y300L substitution. In another embodiment, the variant human IgG1 Fc Domain contains a F243L, R292P, Y300L, V305I and P396L substitution.

In certain embodiments, it is preferred for the Fc Domains of the Fc Domain-containing binding molecules of the present invention to exhibit decreased (or substantially no) binding FcγRIA (CD64), FcγRIIA (CD32A), FcγRIIB (CD32B), FcγRIIIA (CD16a) or FcγRIIIB (CD16b) (relative to the binding exhibited by the wild-type IgG1 Fc Domain (SEQ ID NO:12). In a specific embodiment, the Fc Domain-containing binding molecules of the present invention comprise an IgG Fc Domain that exhibits reduced antibody-dependent cell-mediated cytotoxicity (ADCC) effector function. In a preferred embodiment, the CH2-CH3 Domains of such binding molecules include any 1, 2, 3, or 4 of the substitutions: L234A, L235A, D265A, N297Q, and N297G, wherein the numbering is that of the EU index as in Kabat. In another embodiment, the CH2-CH3 Domains contain an N297Q substitution, an N297G substitution, L234A and L235A substitutions or a D265A substitution, as these mutations abolish FcR binding. Alternatively, a CH2-CH3 Domain of a naturally occurring Fc Domain that inherently exhibits decreased (or substantially no) binding FcγRIIIA (CD16a) and/or reduced effector function (relative to the binding and effector function exhibited by the wild-type IgG1 Fc Domain (SEQ ID NO:12)) is utilized. In a specific embodiment, the Fc Domain-containing binding molecules of the present invention comprise an IgG2 Fc Domain (SEQ ID NO:13), an IgG3 Fc Domain (SEQ ID NO:14) or an IgG4 Fc Domain (SEQ ID NO:15). When an IgG4 Fc Domain is utilized, the instant invention also encompasses the introduction of a stabilizing mutation, such as the Hinge Region S228P substitution described above (see, e.g., SEQ ID NO:11). Since the N297G, N297Q, L234A, L235A and D265A substitutions abolish effector function, in circumstances in which effector function is desired, these substitutions would preferably not be employed.

A preferred IgG1 sequence for the CH2 and CH3 Domains of the Fc Domain-containing molecules of the present invention having reduced or abolished effector function will comprise the substitutions L234A/L235A (SEQ ID NO:45):

wherein X is lysine (K) or is absent.

A second preferred IgG1 sequence for the CH2 and CH3 Domains of the Fc Region-containing molecules of the present invention comprises an S442C substitution (shown underlined), so as to permit two CH3 domains to be covalently bonded to one another via a disulfide bond or to permit conjugation of a drug moiety. The amino acid sequence of such molecule is (SEQ ID NO:46):

A third preferred IgG1 sequence for the CH2 and CH3 Domains of the Fc Region-containing molecules of the present invention comprises the L234A/L235A substitutions (shown underlined) that reduce or abolish effector function and the S442C substitution (shown underlined) that permits two CH3 domains to be covalently bonded to one another via a disulfide bond or conjugation of a drug moiety. The amino acid sequence of such molecule is (SEQ ID NO:47):

The serum half-life of proteins comprising Fc Domains may be increased by increasing the binding affinity of the Fc Domain for FcRn. The term “half-life” as used herein means a pharmacokinetic property of a molecule that is a measure of the mean survival time of the molecules following their administration. Half-life can be expressed as the time required to eliminate fifty percent (50%) of a known quantity of the molecule from a subject's body (e.g., a human patient or other mammal) or a specific compartment thereof, for example, as measured in serum, i.e., circulating half-life, or in other tissues. In general, an increase in half-life results in an increase in mean residence time (MRT) in circulation for the molecule administered.

In some embodiments, the Fc Domain-containing binding molecules of the present invention comprise a variant Fc Domain that comprises at least one amino acid modification relative to a wild-type Fc Domain, such that the molecule has an increased half-life (relative to such molecule if comprising a wild-type Fc Domain). In some embodiments, the Fc Domain-containing binding molecules of the present invention comprise a variant IgG Fc Domain that comprises a half-life extending amino acid substitution at one or more positions selected from the group consisting of 238, 250, 252, 254, 256, 257, 256, 265, 272, 286, 288, 303, 305, 307, 308, 309, 311, 312, 317, 340, 356, 360, 362, 376, 378, 380, 382, 413, 424, 428, 433, 434, 435, and 436, wherein the numbering is that of the EU index as in Kabat. Numerous mutations capable of increasing the half-life of an Fc Domain-containing molecule are known in the art and include, for example M252Y, S254T, T256E, and combinations thereof. For example, see the mutations described in U.S. Pat. Nos. 6,277,375, 7,083,784; 7,217,797, 8,088,376; U.S. Publication Nos. 2002/0147311; 2007/0148164; and PCT Publication Nos. WO 98/23289; WO 2009/058492; and WO 2010/033279, which are herein incorporated by reference in their entireties.

In some embodiments, the Fc Domain-containing binding molecules of the present invention exhibiting enhanced half-life possess a variant Fc Domain comprising substitutions at two or more of Fc Domain residues 250, 252, 254, 256, 257, 288, 307, 308, 309, 311, 378, 428, 433, 434, 435 and 436. In particular, two or more substitutions selected from: T250Q, M252Y, S254T, T256E, K288D, T307Q, V308P, A378V, M428L, N434A, H435K, and Y436I, wherein the numbering is that of the EU index as in Kabat. In a specific embodiment, such molecules may possess a variant IgG Fc Domain comprising the substitution:

• • (A) M252Y, S254T and T256E;
  • (B) M252Y and S254T;
  • (C) M252Y and T256E;
  • (D) T250Q and M428L;
  • (E) T307Q and N434A;
  • (F) A378V and N434A;
  • (G) N434A and Y436I;
  • (H) V308P and N434A; or
  • (I) K288D and H435K.

In a preferred embodiment, an Fc Domain-containing CD16 x DA Binding Molecule of the present invention possesses a variant IgG Fc Region comprising any 1, 2, or 3 of the substitutions: M252Y, S254T and T256E. The invention further encompasses CD16 x DA Binding Molecules possessing variant Fc Regions comprising:

• • (A) one or more mutations which alter effector function and/or FcγR; and
  • (B) one or more mutations which extend serum half-life.

An IgG1 sequence for the CH2 and CH3 Domains of the Fc Domain-containing molecules of the present invention that provides an increased half-life (and that has a 10-fold increase in binding to both cynomolgus monkey and human FcRn) (Dall'Acqua, W. F. et al. (2006) “Properties of Human IgG1s Engineered for Enhanced Binding to the Neonatal Fc Receptor (FcRn),” J. Biol. Chem. 281(33):23514-23524) will comprise the substitutions M252Y/S254T/T256E (SEQ ID NO:48):

wherein X is lysine (K) or is absent.

An alternative IgG1 sequence for the CH2 and CH3 Domains of the Fc Domain-containing molecules of the present invention combining the reduced or abolished effector function provided by the substitutions L234A/L235A and the increased serum half-life provided by the substitutions M252Y/S254T/T256E is provided by SEQ ID NO: 49:

wherein X is lysine (K) or is absent.

A further preferred IgG1 sequence for the CH2 and CH3 Domains of the Fc Region-containing molecules of the present invention comprises the L234A/L235A substitutions (shown underlined) that reduce or abolish effector function and the M252Y, S254T and T256E substitutions (shown underlined), so as to extend the serum half-life and the S442C substitution (shown underlined), so as to permit two CH3 domains to be covalently bonded to one another via a disulfide bond or to permit conjugation of a drug moiety. The amino acid sequence of such molecule is (SEQ ID NO:50):

For certain antibodies, diabodies and trivalent binding molecules that are desired to have Fc-Domain-containing polypeptide chains of differing amino acid sequence (e.g., whose Fc Domain-containing polypeptide chains are desired to not be identical), it is desirable to reduce or prevent homodimerization from occurring between the CH2-CH3 Domains of identical chains (e.g., two first polypeptide chains or between the CH2-CH3 Domains of two third polypeptide chains). The CH2 and/or CH3 Domains of such polypeptide chains need not be identical in sequence, and advantageously are modified to foster heterodimer complexing between the two polypeptide chains. For example, an amino acid substitution (preferably a substitution with an amino acid comprising a bulky side group forming a “knob”, e.g., tryptophan) can be introduced into the CH2 or CH3 Domain such that steric interference will prevent interaction with a similarly mutated domain and will obligate the mutated domain to pair with a domain into which a complementary, or accommodating mutation has been engineered, i.e., “the hole” (e.g., a substitution with glycine). Such sets of mutations can be engineered into any pair of polypeptides comprising CH2-CH3 Domains that forms an Fc Domain to foster heterodimerization. Methods of protein engineering to favor heterodimerization over homodimerization are well-known in the art, in particular with respect to the engineering of immunoglobulin-like molecules, and are encompassed herein (see e.g., Ridgway et al. (1996) “‘Knobs-Into-Holes’ Engineering Of Antibody CH3 Domains For Heavy Chain Heterodimerization,” Protein Engr. 9:617-621, Atwell et al. (1997) “Stable Heterodimers From Remodeling The Domain Interface Of A Homodimer Using A Phage Display Library,” J. Mol. Biol. 270: 26-35, and Xie et al. (2005) “A New Format Of Bispecific Antibody: Highly Efficient Heterodimerization, Expression And Tumor Cell Lysis,” J. Immunol. Methods 296:95-101; each of which is hereby incorporated herein by reference in its entirety).

A preferred knob is created by modifying an IgG Fc Domain to contain the modification T366W. A preferred hole is created by modifying an IgG Fc Domain to contain the modification T366S, L368A and Y407V. To aid in purifying a hole-bearing polypeptide chain homodimer from the final bispecific heterodimeric Fc Domain-containing molecule, the Protein A Binding Domain of the hole-bearing CH2 and CH3 Domains of a polypeptide chain is preferably mutated by amino acid substitution at position 435 (H435R). Thus, the hole-bearing polypeptide chain homodimer will not bind protein A, whereas the bispecific heterodimer will retain its ability to bind protein A via the Protein A Binding Domain. In an alternative embodiment, the hole-bearing polypeptide chain may incorporate amino acid substitutions at positions 434 and 435 (N434A/N435K).

A preferred IgG1 amino acid sequence for the CH2 and CH3 Domains of one Fc Domain-containing polypeptide chain of an Fc Domain-containing molecule of the present invention will have the “knob-bearing” sequence (SEQ ID NO:51):

wherein X is lysine (K) or is absent.

An alternative IgG1 amino acid sequence for the CH2 and CH3 Domains of one Fc Domain-containing polypeptide chain of an Fc Domain-containing molecule of the present invention having a M252Y/S254T/T256E substitution and a “knob-bearing” sequence is SEQ ID NO:52:

wherein X is lysine (K) or is absent.

A preferred IgG1 amino acid sequence for the CH2 and CH3 Domains of the other Fc Domain-containing polypeptide chain of an Fc Domain-containing molecule of the present invention having two polypeptide chains (or the third polypeptide chain of an Fc Domain-containing molecule having three, four, or five polypeptide chains) will have the “hole-bearing” sequence (SEQ ID NO:53):

wherein X is lysine (K) or is absent.

An alternative IgG1 amino acid sequence for the CH2 and CH3 Domains of the other Fc Domain-containing polypeptide chain of an Fc Domain-containing molecule of the present invention having a M252Y/S254T/T256E substitution and a “hole-bearing” sequence is SEQ ID NO:54:

wherein X is lysine (K) or is absent.

As will be noted, the CH2-CH3 Domains of SEQ ID NO:51, SEQ ID NO:52, SEQ ID NO:53, and SEQ ID NO:54 include a substitution at position 234 with alanine and 235 with alanine, and thus form an Fc Domain exhibit decreased (or substantially no) binding FcγRIA (CD64), FcγRIIA (CD32A), FcγRIIB (CD32B), FcγRIIIA (CD16a) or FcγRIIIB (CD16b) (relative to the binding exhibited by the wild-type Fc Domain (SEQ ID NO:12). The invention also encompasses such CH2-CH3 Domains, which comprise the wild-type alanine residues, alternative and/or additional substitutions which modify effector function and/or FγR binding activity of the Fc Domain. The invention also encompasses such CH2-CH3 Domains, which further comprise one or more half-live extending amino acid substitutions. In particular, the invention encompasses such hole-bearing and such knob-bearing CH2-CH3 Domains which further comprise the M252Y/S254T/T256E.

An IgG4 amino acid sequence for the CH2 and CH3 Domains of the one Fc Domain-containing polypeptide chain of an Fc Domain-containing molecule of the present invention has enhanced serum half-life (relative to IgG1 CH2 and CH3 Domains) due to its possession of Y252/T254/E256 (SEQ ID NO:55):

wherein X is lysine (K) or is absent.

A “knob-bearing” variant of such an IgG4 CH2-CH3 amino acid sequence has the amino acid sequence of SEQ ID NO:56:

wherein X is lysine (K) or is absent.

A “hole-bearing” variant of such an IgG4 CH2-CH3 amino acid sequence has the amino acid sequence of SEQ ID NO:57:

wherein X is lysine (K) or is absent.

It is preferred that the first polypeptide chain will have a “knob-bearing” CH2-CH3 sequence, such as that of SEQ ID NO:51 or SEQ ID NO:52. However, as will be recognized, a “hole-bearing” CH2-CH3 Domain (e.g., SEQ ID NO:53 or SEQ ID NO:54) could be employed in the first polypeptide chain, in which case, a “knob-bearing” CH2-CH3 Domain (e.g., SEQ ID NO:51 or SEQ ID NO:52) would be employed in the second polypeptide chain of an Fc Domain-containing molecule of the present invention having two polypeptide chains (or in the third polypeptide chain of an Fc Domain-containing molecule having three, four, or five polypeptide chains).

In other embodiments, the invention encompasses Fc Domain-containing binding molecules comprising CH2 and/or CH3 Domains that have been engineered to favor heterodimerization over homodimerization using mutations known in the art, such as those disclosed in PCT Publication No. WO 2007/110205; WO 2011/143545; WO 2012/058768; WO 2013/06867, all of which are incorporated herein by reference in their entirety.

A further embodiment of the present invention relates to trivalent binding molecules comprising an Fc Domain capable of simultaneously binding a First Epitope, a Second Epitope and a Third Epitope, wherein at least one of such epitopes is not identical to another. Such trivalent binding molecules comprise three Epitope Binding Domains, two of which are Diabody-Type Binding Domains, which provide Binding Domain A and Binding Domain B, and one of which is a Fab-Type Binding Domain, or an scFv-Type Binding Domain, which provides Binding Domain C (see, e.g., FIGS. 6A-6H, PCT Publication Nos. WO 2015/184207 and WO 2015/184203). Such trivalent binding molecules thus comprise “VL1”/“V111” domains that are capable of binding the First Epitope and “VL2”/“VH2” domains that are capable of binding the Second Epitope and “VL3” and “VH3” domains that are capable of binding the “third” epitope of such trivalent binding molecule. A “Diabody-Type Binding Domain” is the type of Epitope Binding Domain present in a diabody, as described above. Each of a “Fab-Type Binding Domain” and an “scFv-Type Binding Domain” are Epitope Binding Domains that are formed by the interaction of the VL Domain of an immunoglobulin Light Chain and a complementing VH Domain of an immunoglobulin Heavy Chain. Fab-Type Binding Domains differ from Diabody-Type Binding Domains in that the two polypeptide chains that form a Fab-Type Binding Domain comprise only a single Epitope Binding Domain, whereas the two polypeptide chains that form a Diabody-Type Binding Domain comprise at least two Epitope Binding Domains. Similarly, scFv-Type Binding Domains also differ from Diabody-Type Binding Domains in that they comprise only a single Epitope Binding Domain. Thus, as used herein Fab-Type, and scFv-Type Binding Domains are distinct from Diabody-Type Binding Domains.

Typically, the trivalent Binding Molecules of the present invention will comprise four different polypeptide chains (see FIGS. 6A-6B), however, the molecules may comprise fewer or greater numbers of polypeptide chains, for example by fusing such polypeptide chains to one another (e.g., via a peptide bond) or by dividing such polypeptide chains to form additional polypeptide chains, or by associating fewer or additional polypeptide chains via disulfide bonds. FIGS. 6E-6F illustrate this aspect of the present invention by schematically depicting such molecules having three polypeptide chains. As provided in FIGS. 6A-611, the trivalent binding molecules of the present invention may have alternative orientations in which the Diabody-Type Binding Domains are N-terminal (FIGS. 6A, 6B, 6C, 6E and 6F) or C-terminal (FIGS. 6D, 6G and 6H) to an Fc Domain. CH2 and CH3 Domains useful for the generation of trivalent binding molecules are provided above and include knob-bearing and hole-bearing domains.

In certain embodiments, the first polypeptide chain of such trivalent binding molecules of the present invention contains: (i) a VL1-containing Domain, (ii) a VH2-containing Domain, (iii) a Heterodimer-Promoting Domain, and (iv) a Domain containing a CH2-CH3 sequence. The VL1 and VL2 Domains are located N-terminal or C-terminal to the CH2-CH3-containing domain as presented in Table 4 (also see, FIGS. 6A and 6B). The second polypeptide chain of such embodiments contains: (i) a VL2-containing Domain, (ii) a VH1-containing Domain, and (iii) a Heterodimer-Promoting Domain. The third polypeptide chain of such embodiments contains: (i) a VH3-containing Domain, (ii) a CH1-containing Domain and (iii) a Domain containing a CH2-CH3 sequence. The third polypeptide chain may be the Heavy Chain of an antibody that contains a VH3 and a Heavy Chain constant region, or a polypeptide that contains such domains. The fourth polypeptide of such embodiments contains: (i) a VL3-containing Domain and (ii) a CL-containing Domain. The fourth polypeptide chains may be a Light Chain of an antibody that contains a VL3 complementary to the VH3 of the third polypeptide chain, or a polypeptide that contains such domains. The third or fourth polypeptide chains may be isolated from naturally occurring antibodies. Alternatively, they may be constructed recombinantly, synthetically or by other means.

The Light Chain Variable Domain of the first and second polypeptide chains are separated from the Heavy Chain Variable Domains of such polypeptide chains by an intervening spacer peptide having a length that is too short to permit their VL1/VH2 (or their VL2/VH1) domains to associate together to form an Epitope Binding Domain capable of binding either the First or Second Epitope. A preferred intervening spacer peptide (Linker 1) for this purpose has the sequence (SEQ ID NO:16):

As described above, the trivalent binding molecules of the present invention may comprise three polypeptides. Trivalent binding molecules comprising three polypeptide chains may be obtained by linking the domains of the fourth polypeptide N-terminal to the VH3-containing Domain of the third polypeptide (e.g., using an intervening spacer peptide (Linker 4)). Alternatively, a third polypeptide chain of a trivalent binding molecule of the invention containing the following domains is utilized: (i) a VL3-containing Domain, (ii) a VH3-containing Domain, and (iii) a Domain containing a CH2-CH3 sequence, wherein the VL3 and VH3 are spaced apart from one another by an intervening spacer peptide that is sufficiently long (at least 9 or more amino acid residues) so as to allow the association of these domains to form an Epitope Binding Domain. One preferred intervening spacer peptide for this purpose has the sequence:

It will be understood that the VL1/VH1, VL2/VH2, and VL3/VH3 Domains of such trivalent binding molecules may be different so as to permit binding that is mono-specific, bispecific or trispecific. In particular, the VL and VH Domains may be selected such that a trivalent binding molecule comprises two Binding Domains for a First Epitope and one Binding Domains for a Second Epitope, or one Binding Domain for a First Epitope and two Binding Domains for a Second Epitope, or one Binding Domain for a First Epitope, one Binding Domain for a Second Epitope and one Binding Domain for a Third Epitope.

The general structure of the polypeptide chains of representative trivalent binding molecules of invention is provided in FIGS. 6A-6H and in Table 5:

As provided above, such trivalent binding molecules may comprise three, four, five, or more polypeptide chains.

As stated above, the present invention is directed to a CD16 x DA Binding Molecule (e.g., an antibody, a diabody, an scFv, an antibody, a TandAb, etc.) comprising a Binding Domain capable of binding an epitope of CD16 (i.e., a “CD16-Binding Domain”) and a Binding Domain capable of binding an epitope of a Disease Antigen (i.e., a “Disease Antigen-Binding Domain”). The invention thus encompasses binding molecules comprising one or more of the VH and/or VL Domains of an antibody that binds to CD16, or more preferably, the CDR_H1, CDR_H2, and CDR_H3, and the CDR_L1, CDR_L2 and CDR_L3 portions of such Domains. In a preferred embodiment of the invention, such binding molecules will additionally contain Binding Domains sufficient to permit such molecules to bind to epitopes of one, two, three or or more than three Disease Antigens. The present invention is also directed to pharmaceutical compositions that comprise such molecule(s).

By possessing Binding Domains sufficient to immunospecifically bind CD16 and a Disease Antigen, the molecules of the present invention have the ability to co-localize CD16-expressing cells (and especially Natural Killer cells) to the site(s) of cells expressing the Disease Antigen so as to enhance the likelihood of ADCC-mediated killing of the target cell. As discussed above, such molecules may be bispecific, or may be capable of binding more than two epitopes.

In one embodiment, such CD16-binding molecules of the present invention will be mono-specific so as to possess the ability to bind to only a single epitope of CD16 and only a single epitope of a Disease Antigen.

Alternatively, such molecules may be multi-specific, i.e., capable of binding one, two, three or four total epitopes, which may be apportioned in any manner to bind one, two or three epitope(s) of CD16 (which two or three CD16 epitopes may be the same or different) and three, two or one epitope(s) of one or more Disease Antigen(s).

Thus, where such molecules are capable of immunospecifically binding to only a single Disease Antigen, they may be capable of immunospecifically binding to only one CD16 epitope and to one, two or three epitope(s) of the Disease Antigen (which two Disease Antigen epitopes may be the same or different, and which three epitopes may be the same, or may be different, or may be two epitopes that are the same and one epitope that is different), or they may be capable of immunospecifically binding to only two CD16 epitopes (which two epitopes may be the same or different) and one or two epitope(s) of the Disease Antigen (which two Disease Antigen epitopes may be the same or different), or they may be capable of immunospecifically binding to three CD16 epitopes (which three epitopes may be the same, or may be different or may be two epitopes that are the same and one epitope that is different) and 1 epitope of the Disease Antigen.

Similarly, where such molecules are capable of immunospecifically binding to two different Disease Antigens (e.g., a First Disease Antigen and a Second Disease Antigen), they may be capable of immunospecifically binding to only one CD16 epitope and to one or two epitope(s) of the First Disease Antigen (which two First Disease Antigen epitopes may be the same or different) and two or one epitope(s) of the Second Disease Antigen (which two Second Disease Antigen epitopes may be the same or different), or they may be capable of immunospecifically binding to only two CD16 epitopes (which two epitopes may be the same or different) and one epitope of the First Disease Antigen and one epitope of the Second Disease Antigen.

Similarly, such molecules may be capable of immunospecifically binding to three different Disease Antigens (e.g., a First Disease Antigen, a Second Disease Antigen and a Third Disease Antigen) and only one CD16 epitope.

Thus, for example, such molecules may bind:

• • (1) a single epitope of CD16 and a single epitope of a Disease Antigen that is arrayed on the surface of the target cell;
  • (2) a single epitope of CD16 and two epitopes of a Disease Antigen that is arrayed on the surface of the target cell
  • (3) a single epitope of CD16 and three epitopes of a Disease Antigen that is arrayed on the surface of the target cell;
  • (4) a single epitope of CD16, one epitope of a First Disease Antigen that is arrayed on the surface of the target cell, and one epitope of a Second Disease Antigen that is arrayed on the surface of the target cell;
  • (5) a single epitope of CD16, two epitopes of a First Disease Antigen that is arrayed on the surface of the target cell, and one epitope of a Second Disease Antigen that is arrayed on the surface of the target cell;
  • (6) two epitopes of CD16 and a single epitope of a Disease Antigen that is arrayed on the surface of the target cell;
  • (7) two epitopes of CD16 and two epitopes of a Disease Antigen that is arrayed on the surface of the target cell;
  • (8) two epitopes of CD16 and one epitope of a First Disease Antigen that is arrayed on the surface of the target cell and one epitope of a Second Disease Antigen that is arrayed on the surface of the target cell;
  • (9) three epitopes of CD16 and one epitope of a Disease Antigen that is arrayed on the surface of the target cell;
  • in all cases in which binding is to more than one epitope of CD16 or a Disease Antigen, such epitopes may be the same or may be different or may be the same as one such epitope and different from another such epitope.

Table 6 illustrates possible combination binding specificities of exemplary molecules of the invention.

By forming more complex molecules, one may obtain CD16-binding molecules that are capable of binding one or more Disease Antigens and that possess more than four epitope binding domains. Thus, no limitation is placed on the nature of epitopes or additional epitopes that may be bound by the molecules of the present invention other than that such additional binding capability does not prevent the molecule or Binding Domain thereof that is capable of binding to an epitope of CD16 from such binding and does not prevent the molecule or Binding Domain thereof that is capable of binding to an epitope of a Disease Antigen from such binding. Thus, the CD16 Binding molecules of the present invention may possess Epitope Binding Domains alternative or additional Epitope Binding Domains. As an example, the invention contemplates a binding molecule that comprises a First Epitope Binding Domain capable of immunospecifically binding an epitope of CD16 and a Second Epitope Binding Domain that is capable of immunospecifically binding an epitope of a Disease Antigen that is arrayed on the surface of such target cell and a Third Epitope Binding Domain capable of immunospecifically binding a different cell surface molecule, such as a non-CD16 cell surface molecule of a Natural Killer cell.

The present invention is directed molecules (e.g., an antibody, a diabody, an scFv, an antibody, a TandAb, etc.) capable of binding human CD16 by virtue of their possession of a CD16 Binding Domain. The present invention is particularly directed to such CD-16 Binding Molecules that are CD16 x DA Binding Molecules. Listed below are exemplary antibodies that may be used to produce the binding molecules and combination therapy of the present invention.

The present invention provides murine anti-human CD16 monoclonal antibodies: CD16-M1 and CD16-M2, and their humanized derivatives: hCD16-M1 and hCD16-M2, which are novel, high affinity anti-human CD16 monoclonal antibodies that bind well to both the CD16 158F allotype and the CD16 158V allotype, and that bind CD16 at a site that does not block CD16-IgG binding. Such antibodies are particularly preferred for the purposes of the present invention since they can be readily employed in a patient population irrespective of its 158F/158V CD16A polymorphisms.

The amino acid sequence of the VH Domain of murine anti-human CD16 monoclonal antibody CD16-M1 (SEQ ID NO:64) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of murine anti-human CD16 monoclonal antibody CD16-M1 (SEQ ID NO:65) is shown below (CDR_Lresidues are shown underlined):

The CDRs of anti-human CD16 monoclonal antibody CD16-M1 are shown in Table 7.

hCD16-M1 is a humanized derivative of murine anti-human CD16 monoclonal antibody CD16-M1. The amino acid sequence of the VH Domain of hCD16-M1 (SEQ ID NO:72) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of hCD16-M1 (SEQ ID NO:73) is shown below (CDR_Lresidues are shown underlined):

hCD16-M1A is an optimized derivative of the humanized anti-human CD16 monoclonal antibody hCD16-M1. hCD16-M1A comprises the VL Domain of hCD16-M1 (SEQ ID NO:73) and an optimized VH Domain comprising mutations in CDR_H3. The amino acid sequence of the optimized VH Domain of hCD16-M1A (SEQ ID NO:58) is shown below (the mutated CDR_H3 residues are shown underlined):

hCD16-M1B is an optimized derivative of the humanized anti-human CD16 monoclonal antibody hCD16-M1. hCD16-M1B comprises the VH Domain of hCD16-M1 (SEQ ID NO:72) and an optimized VL Domain comprising mutations in CDR_L3. The amino acid sequence of the optimized VL Domain of hCD16-M1B (SEQ ID NO:59) is shown below (the mutated CDR_L3 residues are shown underlined):

hCD16-M1AB is an optimized derivative of the humanized anti-human CD16 monoclonal antibody hCD16-M1. hCD16-M1AB comprises the optimized VH Domain of hCD16-M1A (SEQ ID NO:58) and the optimized VL Domain of hCD16-M1B (SEQ ID NO:59).

The CDRs of humanized anti-human CD16 monoclonal antibody hCD16-M1 and the optimized anti-human CD16 monoclonal antibodies hCD16-M1A, hCD16-M1B, hCD16-M1AB are shown in Table 8.

As will be recognized, CDR_L1 of hCD16-M1, hCD16-M1A, hCD16-M1B, and hCD16-M1AB (RASQNVGTHVA; SEQ ID NO:74) differs from CDR_L1 of CD16-M1 (KASQNVGTHVA; SEQ ID NO:69) in its first residue. Either CDR_L1 may be employed interchangeably, and the present invention encompasses humanized, and optimized CD16 Binding Molecules that comprise a CD16 Epitope Binding Domain having the amino acid sequence of 1, 2 or 3 of the following CDR_Hs, and/or 1, 2 or 3 of the such CDR_Ls.

The amino acid sequence of the VH Domain of murine anti-human CD16 monoclonal antibody CD16-M2 (SEQ ID NO:75) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of murine anti-human CD16 monoclonal antibody CD16-M2 (SEQ ID NO:76) is shown below (CDR_Lresidues are shown underlined):

The CDRs of anti-human CD16 monoclonal antibody CD16-M2 are shown in Table 9:

hCD16-M2 is a humanized derivative of murine anti-human CD16 monoclonal antibody CD16-M2. Humanization resulted in two suitable VH Domains (hCD16-M2 VH1 and hCD16-M2 VH2), either of which may be employed with the obtained humanized VL Domain (hCD16-M2 VL1).

The amino acid sequence of VH Domain hCD16-M2 VH1 (SEQ ID NO:83) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of VH Domain hCD16-M2 VH2 (SEQ ID NO:84) is shown below (CDR_Hresidues are shown underlined):

As will be recognized, the amino acid sequence of hCD16-M2 VH1 (SEQ ID NO:83) differs from that of hCD16-M2 VH2 (SEQ ID NO:84) in possessing a T98R substitution in the residue that immediately precedes CDR_H3 (shown boxed above).

The amino acid sequence of the VL Domain hCD16-M2 VL1 (SEQ ID NO:85) is shown below (CDR_Lresidues are shown underlined):

The CDRs of humanized anti-human CD16 monoclonal antibody hCD16-M2 are shown in Table 10.

The CD16 x DA Binding Molecules of the present invention, and particularly the trispecific CD16 x DA Binding Molecules of the present invention may comprise a binding site for a non-CD16 cell surface molecule of an effector cell. As used herein, the term “effector cell” denotes a cell that directly or indirectly mediates the killing of target cells (e.g., foreign cells, infected cells or cancer cells). Examples of effector cells include helper T Cells, cytotoxic T Cells, Natural Killer (NK) cells, plasma cells (antibody-secreting B cells), macrophages and granulocytes. Preferred cell surface molecules of such cells include CD2, CD3, CD8, CD16, TCR, and the NKG2D receptor. Accordingly, molecules capable of immunospecifically binding an epitope of such molecules, or to other effector cell surface molecules may be used in accordance with the principles of the present invention. Exemplary antibodies, whose VH and VL Domains may be used to construct molecules capable of mediating the redirected killing of a target cell are provided below.

A preferred non-CD16 cell surface molecule of a Natural Killer effector cell is the NKG2D receptor. The NKG2D receptor is expressed on all human (and other mammalian) Natural Killer cells (Bauer, S. et al. (1999) “Activation Of NK Cells And T Cells By NKG2D, A Receptor For Stress-Inducible MICA,” Science 285(5428):727-729; Jamieson, A. M. et al. (2002) “The Role Of The NKG2D Immunoreceptor In Immune Cell Activation And Natural Killing,” Immunity 17(1):19-29) as well as on all CD8⁺ T cells (Groh, V. et al. (2001) “Costimulation Of CD8αβ T Cells By NKG2D Via Engagement By MIC Induced On Virus-Infected Cells,” Nat. Immunol. 2(3):255-260; Jamieson, A. M. et al. (2002) “The Role Of The NKG2D Immunoreceptor In Immune Cell Activation And Natural Killing,” Immunity 17(1):19-29). Such binding ligands, and particularly those which are not expressed on normal cells, include the histocompatibility 60 (H60) molecule, the product of the retinoic acid early inducible gene-1 (RAE-1), and the murine UL16-binding proteinlike transcript 1 (MULTI) (Raulet D. H. (2003) “Roles Of The NKG2D Immunoreceptor And Its Ligands,” Nature Rev. Immunol. 3:781-790; Coudert, J. D. et al. (2005) “Altered NKG2D Function In NK Cells Induced By Chronic Exposure To Altered NKG2D Ligand-Expressing Tumor Cells,” Blood 106:1711-1717). Molecules that specifically bind to the NKG2D Receptor include the anti-NKG2D antibodies “KYK-1.0” and “KYK-2.0” (Kwong, K Y et al. (2008) “Generation, Affinity Maturation, And Characterization Of A Human Anti-Human NKG2D Monoclonal Antibody With Dual Antagonistic And Agonistic Activity,” J. Mol. Biol. 384:1143-1156).

The amino acid sequence of the VH Domain of KYK-1.0 (SEQ ID NO:86) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of KYK-1.0 (SEQ ID NO:87) is shown below (CDR_Lresidues are shown underlined):

The amino acid sequence of a VH Domain of KYK-2.0 (SEQ ID NO:88) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of a VL Domain of KYK-2.0 (SEQ ID NO:89) is shown below (CDR_Lresidues are shown underlined):

Other exemplary antibodies that bind to the cell surface of a Natural Killer cell include antibodies: A1, AC2, EPR3678(2), EPR20461, EPR20627 and IMG17B5F11 (which bind CD39); TB01, HNK-1/Leu-7 and NK1 (which bind CD57); FN50 (which binds CD69); 5B5, B-L2, TS82b and C33 (which bind CD82); 3B3, B199.2 and EP7169 (which bind CD161); 17D9 (which binds CLEC1B); 2F9 (which binds KIR2DL1); EPR8825 (which binds KIR2DL2); mAb 33 (which binds KIR2DL4); 11E3, 17B4, EPR4392(2), EPR20261 and EPR 20627 (which bind Lymphocyte Activation Gene 3); A10, C7, CX5, 1D11 and MM0489-10R27 (which bind NKG2D); BMK13 (which binds PRG2); EPR9916 (which binds SLAMF6); etc. Antibodies capable of binding to each of such exemplary non-CD16 cell surface molecule are commercially available from Abcam plc and other sources, and may be readily adapted to the purposes of the present invention.

In one embodiment, the molecules of the present invention that are capable of mediating the redirected killing of a target cell will bind an effector cell by immunospecifically binding an epitope of CD2 present on the surface of such effector cell. Molecules that specifically bind CD2 include the anti-CD2 antibody “CD2 mAb Lo-CD2a.”

The amino acid sequence of the VH Domain of CD2 mAb Lo-CD2a (ATCC Accession No: 11423); SEQ ID NO:90) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of CD2 mAb Lo-CD2a (ATCC Accession No: 11423; SEQ ID NO:91) is shown below (CDR_Lresidues are shown underlined):

In one embodiment, the molecules of the present invention that are capable of mediating the redirected killing of a target cell will bind an effector cell by immunospecifically binding an epitope of CD8 present on the surface of such effector cell. Antibodies that specifically bind CD8 include the anti-CD8 antibodies “OKT8” and “TRX2.”

The amino acid sequence of the VH Domain of OKT8 (SEQ ID NO:92) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of OKT8 (SEQ ID NO:93) is shown below (CDR_Lresidues are shown underlined):

The amino acid sequence of the VH Domain of TRX2 (SEQ ID NO:94) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of TRX2 (SEQ ID NO:95) is shown below (CDR_Lresidues are shown underlined):

The Disease Antigens of the present invention comprise cell surface antigens that are characteristic of a cancer cell (“Cancer Antigens”) as well as cell surface antigens that are characteristic of a pathogen cell or a cell infected by a pathogen (Pathogen-Associated Antigens”).

As used herein, the term “Cancer Antigen” denotes an antigen that is characteristically expressed on the surface of a cancer cell, and that may thus be treated with an Antibody-Based Molecule or an Immunomodulatory Molecule. Examples of Cancer Antigens include, but are not limited to: 19.9 as found in colon cancer, gastric cancer mucins; 4.2; A33 (a colorectal carcinoma antigen; Almqvist, Y. (2006) “In vitro and in vivo Characterization of 177Lu-huA33: A Radioimmunoconjugate Against Colorectal Cancer,” Nucl. Med. Biol. 33(8):991-998); ADAM-9 (United States Patent Publication No. 2006/0172350; PCT Publication No. WO 06/084075); AH6 as found in gastric cancer; ALCAM (PCT Publication No. WO 03/093443); APO-1 (malignant human lymphocyte antigen) (Trauth, B. C. et al. (1989) “Monoclonal Antibody-Mediated Tumor Regression By Induction Of Apoptosis,” Science 245:301-304); B1 (Egloff, A. M. et al. (2006) “Cyclin B1 And Other Cyclins As Tumor Antigens In Immunosurveillance And Immunotherapy Of Cancer,” Cancer Res. 66(1):6-9); B7-H3 (Collins, M. et al. (2005) “The B7 Family Of Immune-Regulatory Ligands,” Genome Biol. 6:223.1-223.7). Chapoval, A. et al. (2001) “B7-H3: A Costimulatory Molecule For T Cell Activation and IFN-γ Production,” Nature Immunol. 2:269-274; Sun, M. et al. (2002) “Characterization of Mouse and Human B7-H3 Genes,” J. Immunol. 168:6294-6297); BAGE (Bodey, B. (2002) “Cancer-Testis Antigens: Promising Targets For Antigen Directed Antineoplastic Immunotherapy,” Expert Opin. Biol. Ther. 2(6):577-584); beta-catenin (Prange W. et al. (2003) “Beta-Catenin Accumulation In The Progression Of Human Hepatocarcinogenesis Correlates With Loss Of E-Cadherin And Accumulation Of P53, But Not With Expression Of Conventional WNT-1 Target Genes,” J. Pathol. 201(2):250-259); blood group ALe^b/Le^yas found in colonic adenocarcinoma; Burkitt's lymphoma antigen-38.13; C14 as found in colonic adenocarcinoma; CA125 (ovarian carcinoma antigen) (Bast, R. C. Jr. et al. (2005) “New Tumor Markers: CA125 And Beyond,” Int. J. Gynecol. Cancer 15(Suppl 3):274-281; Yu et al. (1991) “Coexpression Of Different Antigenic Markers On Moieties That Bear CA 125 Determinants,” Cancer Res. 51(2):468-475); Carboxypeptidase M (United States Patent Publication No. 2006/0166291); CD5 (Calin, G. A. et al. (2006) “Genomics Of Chronic Lymphocytic Leukemia MicroRNAs As New Players With Clinical Significance,” Semin. Oncol. 33(2):167-173; CD19 (Ghetie et al. (1994) “Anti-CD19 Inhibits The Growth Of Human B-Cell Tumor Lines In Vitro And Of Daudi Cells In SCID Mice By Inducing Cell Cycle Arrest,” Blood 83:1329-1336; Troussard, X. et al. 1998 Hematol Cell Ther. 40(4):139-48); CD20 (Reff et al. (1994) “Depletion Of B Cells In Vivo By A Chimeric Mouse Human Monoclonal Antibody To CD20,” Blood 83:435-445; Thomas, D. A. et al. 2006 Hematol Oncol Clin North Am. 20(5):1125-36); CD22 (Kreitman, R. J. (2006) “Immunotoxins For Targeted Cancer Therapy,” AAPS J. 8(3):E532-51); CD23 (Rosati, S. et al. (2005) “Chronic Lymphocytic Leukaemia: A Review Of The Immuno-Architecture,” Curr. Top. Microbiol. Immunol. 294:91-107); CD25 (Troussard, X. et al. (1998) “Hairy Cell Leukemia. What Is New Forty Years After The First Description?” Hematol. Cell. Ther. 40(4):139-148); CD27 (Bataille, R. (2006) “The Phenotype Of Normal, Reactive And Malignant Plasma Cells. Identification Of “Many And Multiple Myelomas” And Of New Targets For Myeloma Therapy,” Haematologica 91(9):1234-1240); CD28 (Bataille, R. (2006) “The Phenotype Of Normal, Reactive And Malignant Plasma Cells. Identification Of “Many And Multiple Myelomas” And Of New Targets For Myeloma Therapy,” Haematologica 91(9):1234-1240); CD33 (Sgouros et al. (1993) “Modeling And Dosimetry Of Monoclonal Antibody M195 (Anti-CD33) In Acute Myelogenous Leukemia,” J. Nucl. Med. 34:422-430); CD36 (Ge, Y. (2005) “CD36: A Multiligand Molecule,” Lab Hematol. 11(1):31-7); CD40/CD154 (Messmer, D. et al. (2005) “CD154 Gene Therapy For Human B-Cell Malignancies,” Ann. N. Y. Acad. Sci. 1062:51-60); CD45 (Jurcic, J. G. (2005) “Immunotherapy For Acute Myeloid Leukemia,” Curr. Oncol. Rep. 7(5):339-346); CD56 (Bataille, R. (2006) “The Phenotype Of Normal, Reactive And Malignant Plasma Cells. Identification Of “Many And Multiple Myelomas” And Of New Targets For Myeloma Therapy,” Haematologica 91(9):1234-1240); CD46 (U.S. Pat. No. 7,148,038; PCT Publication No. WO 03/032814); CD52 (Eketorp, S. S. et al. (2014) “Alemtuzumab (Anti-CD52 Monoclonal Antibody) As Single-Agent Therapy In Patients With Relapsed/Refractory Chronic Lymphocytic Leukaemia (CLL)-A Single Region Experience On Consecutive Patients,” Ann Hematol. 93(10):1725-1733; Suresh, T. et al. (2014) “New Antibody Approaches To Lymphoma Therapy,” J. Hematol. Oncol. 7:58; Hoelzer, D. (2013) “Targeted Therapy With Monoclonal Antibodies In Acute Lymphoblastic Leukemia,” Curr. Opin. Oncol. 25(6):701-706); CD56 (Bataille, R. (2006) “The Phenotype Of Normal, Reactive And Malignant Plasma Cells. Identification Of “Many And Multiple Myelomas” And Of New Targets For Myeloma Therapy,” Haematologica 91(9):1234-1240); CD79a/CD79b (Troussard, X. et al. (1998) “Hairy Cell Leukemia. What Is New Forty Years After The First Description?” Hematol. Cell. Ther. 40(4): 139-148; Chu, P. G. et al. (2001) “CD79: A Review,” Appl. Immunohistochem. Mol. Morphol. 9(2):97-106); CD103 (Troussard, X. et al. (1998) “Hairy Cell Leukemia. What Is New Forty Years After The First Description?” Hematol. Cell. Ther. 40(4):139-148); CD317 (Kawai, S. et al. (2008) “Interferon-A Enhances CD317 Expression And The Antitumor Activity Of Anti-CD317 Monoclonal Antibody In Renal Cell Carcinoma Xenograft Models,” Cancer Science 99(12):2461-2466; Wang, W. et al. (2009) HM1.24 (CD317) Is A Novel Target Against Lung Cancer For Immunotherapy Using Anti-HM1.24 Antibody,” Cancer Immunology, Immunotherapy 58(6):967-976; Wang, W. et al. (2009) “Chimeric And Humanized Anti-HM1.24 Antibodies Mediate Antibody-Dependent Cellular Cytotoxicity Against Lung Cancer Cells. Lung Cancer,” 63(1):23-31; Sayeed, A. et al. (2013) “Aberrant Regulation Of The BST2 (Tetherin) Promoter Enhances Cell Proliferation And Apoptosis Evasion In High Grade Breast Cancer Cells,” PLoS ONE 8(6)e67191, pp. 1-10); CDK4 (Lee, Y. M. et al. (2006) “Targeting Cyclins And Cyclin-Dependent Kinases In Cancer: Lessons From Mice, Hopes For Therapeutic Applications In Human,” Cell Cycle 5(18):2110-2114); CEA (carcinoembryonic antigen; Foon et al. (1995) “Immune Response To The Carcinoembryonic Antigen In Patients Treated With An Anti-Idiotype Antibody Vaccine,” J. Clin. Invest. 96(1):334-42); Mathelin, C. (2006) “Circulating Proteinic Biomarkers And Breast Cancer,” Gynecol. Obstet. Fertil. 34(7-8):638-646; Tellez-Avila, F. I. et al. (2005) “The Carcinoembryonic Antigen: Apropos Of An Old Friend,” Rev. Invest. Clin. 57(6):814-819); CEACAM5/CEACAM6 (Zheng, C. et al. (2011) “A Novel Anti-CEACAM5 Monoclonal Antibody, CC4, Suppresses Colorectal Tumor Growth and Enhances NK Cells-Mediated Tumor Immunity,” PLoS One 6(6):e21146, pp. 1-11); CO17-1A (Ragnhammar et al. (1993) “Effect Of Monoclonal Antibody 17-1A And GM-CSF In Patients With Advanced Colorectal Carcinoma—Long-Lasting, Complete Remissions Can Be Induced,” Int. J. Cancer 53:751-758); CO-43 (blood group Le^b); CO-514 (blood group Le^a) as found in adenocarcinoma; CTA-1; CTLA-4 (Peggs, K. S. et al. (2006) “Principles And Use Of Anti-CTLA4 Antibody In Human Cancer Immunotherapy,” Curr. Opin. Immunol. 18(2):206-13); Cytokeratin 8 (PCT Publication No. WO 03/024191); D1.1; D₁56-22; DR5 (Abdulghani, J. et al. (2010) “TRAIL Receptor Signaling And Therapeutics,” Expert Opin. Ther. Targets 14(10): 1091-1108; Andera, L. (2009) “Signaling Activated By The Death Receptors Of The TNFR Family,” Biomed. Pap. Med. Fac. Univ. Palacky Olomouc Czech. Repub. 153(3): 173-180; Carlo-Stella, C. et al. (2007) “Targeting TRAIL Agonistic Receptors for Cancer Therapy,” Clin, Cancer 13(8):2313-2317; Chaudhari, B. R. et al. (2006) “Following the TRAIL to Apoptosis,” Immunologic Res. 35(3):249-262); E₁series (blood group B) as found in pancreatic cancer; EGFR (Epidermal Growth Factor Receptor; Adenis, A. et al. (2003) “Inhibitors Of Epidermal Growth Factor Receptor And Colorectal Cancer,” Bull. Cancer. 90 Spec No: 5228-5232); Ephrin receptors (and in particular EphA2 (U.S. Pat. No. 7,569,672; PCT Publication No. WO 06/084226); Erb (ErbB1; ErbB3; ErbB4; Zhou, H. et al. (2002) “Lung Tumorigenesis Associated With Erb-B-2 And Erb-B-3 Overexpression In Human Erb-B-3 Transgenic Mice Is Enhanced By Methylnitrosourea,” Oncogene 21(57):8732-8740; Rimon, E. et al. (2004) “Gonadotropin Induced Gene Regulation In Human Granulosa Cells Obtained From IVF Patients: Modulation Of Genes Coding For Growth Factors And Their Receptors And Genes Involved In Cancer And Other Diseases,” Int. J. Oncol. 24(5):1325-1338); GAGE (GAGE-1; GAGE-2; Akcakanat, A. et al. (2006) “Heterogeneous Expression Of GAGE, NY-ESO-1, MAGE-A and SSX Proteins In Esophageal Cancer: Implications For Immunotherapy,” Int. J. Cancer. 118(1): 123-128); GD2/GD3/GM2 (Livingston, P. O. et al. (2005) “Selection Of GM2, Fucosyl GML Globo H And Polysialic Acid As Targets On Small Cell Lung Cancers For Antibody Mediated Immunotherapy,” Cancer Immunol. Immunother. 54(10):1018-1025); ganglioside GD2 (GD2; Saleh et al. (1993) “Generation Of A Human Anti-Idiotypic Antibody That Mimics The GD2 Antigen,” J. Immunol., 151, 3390-3398); ganglioside GD3 (G_D3; Shitara et al. (1993) “A Mouse/Human Chimeric Anti-(Ganglioside GD3) Antibody With Enhanced Antitumor Activities,” Cancer Immunol. Immunother. 36:373-380); ganglioside GM2 (G_M2; Livingston et al. (1994) “Improved Survival In Stage III Melanoma Patients With GM2 Antibodies: A Randomized Trial Of Adjuvant Vaccination With GM2 Ganglioside,” J. Clin. Oncol. 12:1036-1044); ganglioside GM3 (GM3; Hoon et al. (1993) “Molecular Cloning Of A Human Monoclonal Antibody Reactive To Ganglioside GM3 Antigen On Human Cancers,” Cancer Res. 53:5244-5250); GICA 19-9 (Herlyn et al. (1982) “Monoclonal Antibody Detection Of A Circulating Tumor Associated Antigen. I. Presence Of Antigen In Sera Of Patients With Colorectal, Gastric, And Pancreatic Carcinoma,” J. Clin. Immunol. 2:135-140); gp100 (Lotem, M. et al. (2006) “Presentation Of Tumor Antigens By Dendritic Cells Genetically Modified With Viral And Nonviral Vectors,” J. Immunother. 29(6):616-27); Gp37 (human leukemia T cell antigen; Bhattacharya-Chatterjee et al. (1988) “Idiotype Vaccines Against Human T Cell Leukemia. II. Generation And Characterization Of A Monoclonal Idiotype Cascade (Ab1, Ab2, and Ab3),” J. Immunol. 141:1398-1403); gp75 (melanoma antigen; Vijayasardahl et al. (1990) “The Melanoma Antigen Gp75 Is The Human Homologue Of The Mouse B (Brown) Locus Gene Product,” J. Exp. Med. 171(4):1375-1380); gpA33 (Heath, J. K. et al. (1997) “The Human A33 Antigen Is A Transmembrane Glycoprotein And A Novel Member Of The Immunoglobulin Superfamily,” Proc. Natl. Acad. Sci. (U.S.A.) 94(2):469-474; Ritter, G. et al. (1997) “Characterization Of Posttranslational Modifications Of Human A33 Antigen, A Novel Palmitoylated Surface Glycoprotein Of Human Gastrointestinal Epithelium,” Biochem. Biophys. Res. Commun. 236(3):682-686; Wong, N. A. et al. (2006) “EpCAM and gpA33 Are Markers Of Barrett's Metaplasia,” J. Clin. Pathol. 59(3):260-263); HER2 antigen (HER2/neu, p185^HER2; Pal, S. K. et al. (2006) “Targeting HER2 Epitopes,” Semin. Oncol. 33(4):386-391); HMFG (human milk fat globule antigen; WO1995015171); human papillomavirus-E6/human papillomavirus-E7 (DiMaio, D. et al. (2006) “Human Papillomaviruses And Cervical Cancer,” Adv. Virus Res. 66:125-59; HMW-MAA (high molecular weight melanoma antigen; Natali et al. (1987) “Immunohistochemical Detection Of Antigen In Human Primary And Metastatic Melanomas By The Monoclonal Antibody 140.240 And Its Possible Prognostic Significance,” Cancer 59:55-63; Mittelman et al. (1990) “Active Specific Immunotherapy In Patients With Melanoma. A Clinical Trial With Mouse Antiidiotypic Monoclonal Antibodies Elicited With Syngeneic Anti-High-Molecular-Weight-Melanoma-Associated Antigen Monoclonal Antibodies,” J. Clin. Invest. 86:2136-2144); I antigen (differentiation antigen; Feizi (1985) “Demonstration By Monoclonal Antibodies That Carbohydrate Structures Of Glycoproteins And Glycolipids Are Onco-Developmental Antigens,” Nature 314:53-57); IL13Rα2 (PCT Publication No. WO 2008/146911; Brown, C. E. et al. (2013) “Glioma IL13Rα2 Is Associated With Mesenchymal Signature Gene Expression And Poor Patient Prognosis,” PLoS One. 18; 8(10):e77769; Barderas, R. et al. (2012) “High Expression Of IL-13 Receptor A2 In Colorectal Cancer Is Associated With Invasion, Liver Metastasis, And Poor Prognosis,” Cancer Res. 72(11):2780-2790; Kasaian, M. T. et al. (2011) “IL-13 Antibodies Influence IL-13 Clearance In Humans By Modulating Scavenger Activity Of IL-13Rα2,” J. Immunol. 187(1): 561-569; Bozinov, O. et al. (2010) “Decreasing Expression Of The Interleukin-13 Receptor IL-13Ralpha2 In Treated Recurrent Malignant Gliomas,” Neurol. Med. Chir. (Tokyo) 50(8):617-621; Fujisawa, T. et al. (2009) “A novel role of interleukin-13 receptor alpha2 in pancreatic cancer invasion and metastasis,” Cancer Res. 69(22):8678-8685); Integrin β6 (PCT Publication No. WO 03/087340); JAM-3 (PCT Publication No. WO 06/084078); KID3 (PCT Publication No. WO 05/028498); KID31 (PCT Publication No. WO 06/076584); KS 1/4 pan-carcinoma antigen (Perez et al. (1989) “Isolation And Characterization Of A cDNA Encoding The Ks1/4 Epithelial Carcinoma Marker,” J. Immunol. 142:3662-3667; Möller et al. (1991) “Bispecific-Monoclonal-Antibody-Directed Lysis Of Ovarian Carcinoma Cells By Activated Human T Lymphocytes,” Cancer Immunol. Immunother. 33(4):210-216; Ragupathi, G. 2005 Cancer Treat Res. 123:157-80); L6 and L20 (human lung carcinoma antigens; Hellström et al. (1986) “Monoclonal Mouse Antibodies Raised Against Human Lung Carcinoma,” Cancer Res. 46:3917-3923); LEA; LUCA-2 (United States Patent Publication No. 2006/0172349; PCT Publication No. WO 06/083852); M1:22:25:8; M18; M39; MAGE (MAGE-1; MAGE-3; (Bodey, B. (2002) “Cancer-Testis Antigens: Promising Targets For Antigen Directed Antineoplastic Immunotherapy,” Expert Opin. Biol. Ther. 2(6):577-584); MART (Kounalakis, N. et al. (2005) “Tumor Cell And Circulating Markers In Melanoma: Diagnosis, Prognosis, And Management,” Curr. Oncol. Rep. 7(5):377-382; mesothelin (Chang, K. et al. (1996) “Molecular Cloning Of Mesothelin, A Differentiation Antigen Present On Mesothelium, Mesotheliomas, And Ovarian Cancers,” Proc. Natl. Acad. Sci. (U.S.A.) 93:136-140); MUC-1 (Mathelin, C. (2006) “Circulating Proteinic Biomarkers And Breast Cancer,” Gynecol. Obstet. Fertil. 34(7-8):638-646); MUM-1 (Castelli, C. et al. (2000) “T-Cell Recognition Of Melanoma-Associated Antigens,” J. Cell. Physiol. 182(3):323-331); Myl; N-acetylglucosaminyltransferase (Dennis, J. W. (1999) “Glycoprotein Glycosylation And Cancer Progression,” Biochim. Biophys. Acta. 6; 1473(1):21-34); neoglycoprotein; NS-10 as found in adenocarcinomas; OFA-1; OFA-2; Oncostatin M (Oncostatin Receptor Beta; U.S. Pat. No. 7,572,896; PCT Publication No. WO 06/084092); p15 (Gil, J. et al. (2006) “Regulation Of The INK4b-ARF-INK4a Tumour Suppressor Locus: All For One Or One For All,” Nat. Rev. Mol. Cell Biol. 7(9):667-677); p97 (melanoma-associated antigen; Estin et al. (1989) “Transfected Mouse Melanoma Lines That Express Various Levels Of Human Melanoma-Associated Antigen p97,” J. Natl. Cancer Instit. 81(6):445-454); PEM (polymorphic epithelial mucin; Hilkens et al. (1992) “Cell Membrane-Associated Mucins And Their Adhesion Modulating Property,” Trends in Biochem. Sci. 17:359-363); PEMA (polymorphic epithelial mucin antigen); PIPA (U.S. Pat. No. 7,405,061; PCT Publication No. WO 04/043239); PSA (prostate-specific antigen; Henttu et al. (1989) “cDNA Coding For The Entire Human Prostate Specific Antigen Shows High Homologies To The Human Tissue Kallikrein Genes,” Biochem. Biophys. Res. Comm. 10(2):903-910; Israeli et al. (1993) “Molecular Cloning Of A Complementary DNA Encoding A Prostate-Specific Membrane Antigen,” Cancer Res. 53:227-230; Cracco, C. M. et al. (2005) “Immune Response In Prostate Cancer,” Minerva Urol. Nefrol. 57(4):301-311); PSMA (prostate-specific membrane antigen; Ragupathi, G. (2005) “Antibody Inducing Polyvalent Cancer Vaccines,” Cancer Treat. Res. 123:157-180); prostatic acid phosphate (Tailor et al. (1990) “Nucleotide Sequence Of Human Prostatic Acid Phosphatase Determined From A Full-Length cDNA Clone,” Nucl. Acids Res. 18(16):4928); R24 as found in melanoma; ROR1 (U.S. Pat. No. 5,843,749); sphingolipids; SSEA-1; SSEA-3; SSEA-4; sTn (Holmberg, L. A. (2001) “Theratope Vaccine (STn-KLH),” Expert Opin. Biol. Ther. 1(5):881-91); T cell receptor derived peptide from a cutaneous T cell lymphoma (see Edelson (1998) “Cutaneous T-Cell Lymphoma: A Model For Selective Immunotherapy,” Cancer J. Sci. Am. 4:62-71); T₅A₇found in myeloid cells; TAG-72 (Yokota et al. (1992) “Rapid Tumor Penetration Of A Single-Chain Fv And Comparison With Other Immunoglobulin Forms,” Cancer Res. 52:3402-3408); TL5 (blood group A); TNF-receptor (TNF-α receptor, TNF-β receptor; TNF-γ receptor (van Horssen, R. et al. (2006) “TNF-Alpha In Cancer Treatment: Molecular Insights, Antitumor Effects, And Clinical Utility,” Oncologist 11(4):397-408; Gardnerova, M. et al. (2000) “The Use Of TNF Family Ligands And Receptors And Agents Which Modify Their Interaction As Therapeutic Agents,” Curr. Drug Targets 1(4):327-364); TRA-1-85 (blood group H); Transferrin Receptor (U.S. Pat. No. 7,572,895; PCT Publication No. WO 05/121179); 5T4 (TPBG, trophoblast glycoprotein; Boghaert, E. R. et al. (2008) “The Oncofetal Protein, 5T4, Is A Suitable Target For Antibody-Guided Anti-Cancer Chemotherapy With Calicheamicin,” Int. J. Oncol. 32(1):221-234; Eisen, T. et al. (2014) “Naptumomab Estafenatox: Targeted Immunotherapy with a Novel Immunotoxin,” Curr. Oncol. Rep. 16:370, pp. 1-6); TSTA (tumor-specific transplantation antigen) such as virally-induced tumor antigens including T-antigen DNA tumor viruses and envelope antigens of RNA tumor viruses, oncofetal antigen-alpha-fetoprotein such as CEA of colon, bladder tumor oncofetal antigen (Hellström et al. (1985) “Monoclonal Antibodies To Cell Surface Antigens Shared By Chemically Induced Mouse Bladder Carcinomas,” Cancer. Res. 45:2210-2188); VEGF (Pietrantonio, F. et al. (2015) “Bevacizumab Based Neoadjuvant Chemotherapy For Colorectal Cancer Liver Metastases: Pitfalls And Helpful Tricks In A Review For Clinicians,” Crit. Rev. Oncol. Hematol. 95(3): 272-281; Grabowski, J. P. (2015) “Current Management Of Ovarian Cancer,” Minerva Med. 106(3):151-156; Field, K. M. (2015) “Bevacizumab And Glioblastoma: Scientific Review, Newly Reported Updates, And Ongoing Controversies,” Cancer 121(7):997-1007; Suh, D. H. et al. (2015) “Major Clinical Research Advances In Gynecologic Cancer In 2014,” J. Gynecol. Oncol. 26(2):156-167; Liu, K. J. et al. (2015) “Bevacizumab In Combination With Anticancer Drugs For Previously Treated Advanced Non-Small Cell Lung Cancer,” Tumour Biol. 36(3):1323-1327; Di Bartolomeo, M. et al. (2015) “Bevacizumab Treatment In The Elderly Patient With Metastatic Colorectal Cancer,” Clin. Interv. Aging 10:127-133); VEGF Receptor (O'Dwyer. P. J. (2006) “The Present And Future Of Angiogenesis-Directed Treatments Of Colorectal Cancer,” Oncologist 11(9):992-998); VEP8; VEP9; VIM-D5; and Y hapten, Le^yas found in embryonal carcinoma cells. Additional Cancer Antigens, and molecules (e.g., antibodies) that bind them are disclosed in Table 11. 5T4, B7-H3, CEACAM5/CEACAM6, CD123, DR5, EGFR, an Ephrin receptor, gpA33, HER2/neu, IL13Rα2, ROR1, and VEGF are particularly preferred “Cancer Antigens” of the present invention.

Exemplary antibodies, whose VH and VL Domains may be used to construct the binding molecules of the present invention that are capable of binding a Cancer Antigen arrayed on the surface of a cancer cell and mediating the redirected killing of such cancer cells are listed in Table 11, additional antibodies that may be used to construct molecules capable of binding a Cancer Antigen arrayed on the surface of a cancer cell and mediating the redirected killing of such cancer cells are provided below.

B7-H3 is a Cancer Antigen that is over-expressed on a wide variety of solid tumor types and is a member of the B7 family of molecules that are involved in immune regulation (see, U.S. Pat. No. 8,802,091; US 2014/0328750; US 2013/0149236; Loo, D. et al. (2012) “Development Of An Fc-Enhanced Anti-B7-H3Monoclonal Antibody With Potent Antitumor Activity,” Clin. Cancer Res. 18(14):3834-3845). In particular, several independent studies have shown that human malignant cancer cells (e.g., cancer cells of neuroblastomas and gastric, ovarian and non-small cell lung cancers) exhibit a marked increase in expression of B7-H3 protein and that this increased expression was associated with increased disease severity (Zang, X. et al. (2007) “The B7 Family And Cancer Therapy: Costimulation And Coinhibition,” Clin. Cancer Res. 13:5271-5279), suggesting that B7-H3 is exploited by tumors as an immune evasion pathway (Hofmeyer, K. et al. (2008) “The Contrasting Role Of B7-H3,” Proc. Natl. Acad. Sci. (U.S.A.) 105(30):10277-10278).

B7-H3 has also been found to co-stimulate CD4+ and CD8+ T-cell proliferation. B7-H3 also stimulates IFN-γ production and CD8+ lytic activity (Chapoval, A. et al. (2001) “B7-H3: A Costimulatory Molecule For T Cell Activation and IFN-γ Production,” Nature Immunol. 2:269-274; Sharpe, A. H. et al. (2002) “The B7-CD28 Superfamily,” Nature Rev. Immunol. 2:116-126). However, the protein also possibly acts through NFAT (nuclear factor for activated T cells), NF-κB (nuclear factor kappa B), and AP-1 (Activator Protein-1) factors to inhibit T-cell activation (Yi. K. H. et al. (2009) “Fine Tuning The Immune Response Through B7-H3 And B7-H4,” Immunol. Rev. 229:145-151). B7-H3 is also believed to inhibit Th1, Th2, or Th17 in vivo (Prasad, D. V. et al. (2004) “Murine B7-H3 Is A Negative Regulator Of T Cells,” J. Immunol. 173:2500-2506; Fukushima, A. et al. (2007) “B7-H3 Regulates The Development Of Experimental Allergic Conjunctivitis In Mice,” Immunol. Lett. 113:52-57; Yi. K. H. et al. (2009) “Fine Tuning The Immune Response Through B7-H3 And B7-H4,” Immunol. Rev. 229:145-151).

Preferred B7-H3-binding molecules possess the VL and/or VH Domains, of humanized anti-human B7-H3 monoclonal antibody “B7-H3 mAb-B,” “B7-H3 mAb-C,” “B7-H3 mAb-D,” and more preferably possess 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of such anti-B7-H3 monoclonal antibodies.

Upon humanization, antibody B7-H3 mAb-B yielded two variant VH Domains, B7-H3 mAb-B VIII and B7-H3 mAb-B VH2; and two variant VL Domains B7-113 mAb-B VL1 and B7-H3 mAb-B VL2, which may be used in any combination of VH/VL Domains to yield a functional B7-H3 Binding Domain.

The amino acid sequence of the VH Domain of B7-H3 mAb-B VIII (SEQ ID NO:96) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VH Domain of B7-H3 mAb-B VH2 (SEQ ID NO:97) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of B7-H3 mAb-B VL1 (SEQ ID NO:98) is shown below (CDR_Lresidues are shown underlined).

The amino acid sequence of the VL Domain of B7-H3 mAb-B VL2 (SEQ ID NO:99) is shown below (CDR_Lresidues are shown underlined).

The amino acid sequence of the VH Domain of humanized B7-H3 mAb-C (SEQ ID NO:100) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of humanized B7-H3 mAb-C (SEQ ID NO:101) is shown below (CDR_Lresidues are shown underlined).

The amino acid sequence of the VH Domain of B7-H3 mAb-D (SEQ ID NO:102) is shown below (CDR_Hresidues are shown underlined).

The amino acid sequence of the VL Domain of B7-H3 mAb-D (SEQ ID NO:103) is shown below (CDR_Lresidues are shown underlined).

Particularly preferred, are B7-H3-binding molecules which possess a humanized VH and/or VL Domain including but not limited to “Enoblituzumab” (also known as MGA271; CAS Reg No. 1353485-38-7). Enoblituzumab is an Fc-optimized monoclonal antibody that binds to HER2/neu and mediates enhanced ADCC activity. The amino acid sequences of the complete Heavy and Light Chains of Enoblituzumab are known in the art (see., e.g., WHO Drug Information, 2017, Recommended INN: List 77, 31(1):49).

The amino acid sequence of the VH Domain of Enoblituzumab (SEQ ID NO:104) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of Enoblituzumab (SEQ ID NO:105) is shown below (CDR_Lresidues are shown underlined):

In addition to the above-identified preferred anti-B7-H3 Binding Molecules, the invention contemplates the use of any of the following anti-B7-H3 Binding Molecules: LUCA1; BLA8; PA20; or SKN2 (see, U.S. Pat. Nos. 7,527,969; 8,779,098 and PCT Patent Publication WO 2004/001381); M30; cM30; M30-H1-L1; M30-H1-L2; M30-H1-L3; M30-H1-L4; M30-H1-L5; M30-H1-L6; M30-H1-L7; M30-H4-L1; M30-H4-L2; M30-H4-L3; and M30-H4-L4 (see, US Patent Publication 2013/0078234 and PCT Patent Publication WO 2012/147713); and 8119 (see U.S. Pat. Nos. 7,666,424; 7,737,258; 7,740,845; 8,148,154; 8,414,892; 8,501,471; 9,062,110; US Patent Publication 2010/0143245 and PCT Patent Publication WO 2008/116219).

The present invention specifically includes and encompasses CD16 x B7-H3 Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of any of B7-H3 mAb-B, B7-H3 mAb-B VH1, B7-H3 mAb-B VH2, B7-H3 mAb-B VL1, B7-H3 mAb-B VL2, B7-H3 mAb-C, B7-H3 mAb-D, or Enoblituzumab, or any of the other anti-B7-H3 antibodies provided herein; and more preferably possess 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of such anti-B7-H3 monoclonal antibodies.

Carcinoembryonic Antigen-Related Cell Adhesion Molecules 5 (CEACAM5) and 6 (CEACAM6) have been found to be associated with various types of cancers including medullary thyroid cancer, colorectal cancer, pancreatic cancer, hepatocellular carcinoma, gastric cancer, lung cancer, head and neck cancers, urinary bladder cancer, prostate cancer, uterine cancer, endometrial cancer, breast cancer, hematopoietic cancer, leukemia and ovarian cancer (PCT Pubmication No. WO 2011/034660), and particularly colorectal, gastrointestinal, pancreatic, non-small cell lung cancer (NSCL), breast, thyroid, stomach, ovarian and uterine carcinomas (Zheng, C. et al. (2011) “A Novel Anti-CEACAM5 Monoclonal Antibody, CC4, Suppresses Colorectal Tumor Growth and Enhances NK Cells-Mediated Tumor Immunity,” PLoS One 6(6):e21146, pp. 1-11).

CEACAM5 has been found to be overexpressed in 90% of gastrointestinal, colorectal and pancreatic cancers, 70% of non-small cell lung cancer cells and 50% of breast cancers (Thompson, J. A. et al. (1991) “Carcinoembryonic Antigen Gene Family: Molecular Biology And Clinical Perspectives,” J. Clin. Lab. Anal. 5:344-366). Overexpressed carcinoembryonic antigen-related cellular adhesion molecule 6 (CEACAM6) plays important roles in the invasion and metastasis of a variety of human cancers, including medullary thyroid cancer, colorectal cancer, pancreatic cancer, hepatocellular carcinoma, gastric cancer, lung cancer, head and neck cancers, urinary bladder cancer, prostate cancer, uterine cancer, endometrial cancer, breast cancer, hematopoietic cancer, leukemia and ovarian cancer (PCT Pubmication No. WO 2011/034660; Deng, X. et al. (2014) “Expression Profiling Of CEACAM6 Associated With The Tumorigenesis And Progression In Gastric Adenocarcinoma,” Genet. Mol. Res. 13(3):7686-7697; Cameron, S. et al. (2012) “Focal Overexpression Of CEACAM6 Contributes To Enhanced Tumourigenesis In Head And Neck Cancer Via Suppression Of Apoptosis,” Mol. Cancer 11:74, pp. 1-11; Chapin, C. et al. (2012) “Distribution And Surfactant Association Of Carcinoembryonic Cell Adhesion Molecule 6 In Human Lung,” Amer. J. Physiol. Lung Cell. Mol. Physiol. 302(2):L216-L25; Riley, C. J. et al. (2009) “Design And Activity Of A Murine And Humanized Anti-CEACAM6 Single-Chain Variable Fragment In The Treatment Of Pancreatic Cancer,” Cancer Res. 69(5): 1933-1940; Lewis-Wambi, J. S. et al. (2008) “Overexpression Of CEACAM6 Promotes Migration And Invasion Of Oestrogen-Deprived Breast Cancer Cells,” Eur. J. Cancer 44(12):1770-1779; Blumenthal, R. D. et al. (2007) “Expression Patterns Of CEACAM5 And CEACAM6 In Primary And Metastatic Cancers,” BMC Cancer. 7:2, pp. 1-15). Antibodies that immunospecifically bind CEACAM5 and CEACAM6 are commercially available (Santa Cruz Biotechnology, Inc., Novus Biologicals LLC; Abnova Corporation).

The amino acid sequence of the VH Domain of the humanized anti-CEACAM5/ANTI-CEACAM6 antibody 16C3 (EP 2585476) (SEQ ID NO:106) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of the humanized anti-CEACAM5/ANTI-CEACAM6 antibody 16C3 (EP 2585476) (SEQ ID NO:107) is shown below (CDR_Lresidues are shown underlined):

The amino acid sequence of the VH Domain of the humanized anti-CEACAM5/CEACAM6 antibody hMN15 (WO 2011/034660) (SEQ ID NO:108) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of the humanized anti-CEACAM5/CEACAM6 antibody hMN15 (WO 2011/034660) (SEQ ID NO:109) is shown below (CDR_Lresidues are shown underlined):

The present invention specifically includes and encompasses CD16 x CEACAM5/CEACAM6 Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-CEACAM5/CEACAM6 monoclonal antibodies 16C3 or hMN15.

Epidermal Growth Factor Receptor (EGFR) is a Cancer Antigen of certain metastatic colorectal cancer, metastatic non-small cell lung cancer and head and neck cancer. Exemplary antibodies that bind human EGRF are “Cetuximab” and “Panitumumab.” Cetuximab is a recombinant human-mouse chimeric epidermal growth factor receptor (EGFR) IgG1 monoclonal antibody (Govindan R. (2004) “Cetuximab In Advanced Non-Small Cell Lung Cancer,” Clin. Cancer Res. 10(12 Pt 2):42415-4244s; Bou-Assaly, W. et al. (2010) “Cetuximab (Erbitux),” Am. J. Neuroradiol. 31(4):626-627). Panitumumab (Vectibix®, Amgen) is a fully humanized epidermal growth factor receptor (EGFR) IgG2 monoclonal antibody (Foon, K. A. et al. (2004) “Preclinical And Clinical Evaluations Of ABX-EGF, A Fully Human Anti-Epidermal Growth Factor Receptor Antibody,” Int. J. Radiat. Oncol. Biol. Phys. 58(3):984-990; Yazdi, M. H. et al. (2015) “A Comprehensive Review of Clinical Trials on EGFR Inhibitors Such as Cetuximab and Panitumumab as Monotherapy and in Combination for Treatment of Metastatic Colorectal Cancer,” Avicenna J. Med. Biotechnol. 7(4):134-144).

The amino acid sequence of the VH Domain of the chimeric anti-EGFR antibody Cetuximab (SEQ ID NO:110) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of the chimeric anti-EGFR antibody Cetuximab (SEQ ID NO:111) is shown below (CDR_Lresidues are shown underlined):

The amino acid sequence of the VH Domain of Panitumumab (SEQ ID NO:112) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of Panitumumab (SEQ ID NO:113) is shown below (CDR_Lresidues are shown underlined):

The present invention specifically includes and encompasses CD16 x EGFR Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-EGFR monoclonal antibodies Cetuximab or Panitumumab.

The receptor tyrosine kinase, Ephrin type-A receptor 2 (EphA2) is normally expressed at sites of cell-to-cell contact in adult epithelial tissues, however, recent studies have shown that it is also overexpressed in various types of epithelial carcinomas, with the greatest level of EphA2 expression observed in metastatic lesions. High expression levels of EphA2 have been found in a wide range of cancers and in numerous cancer cell lines, including prostate cancer, breast cancer, non-small cell lung cancer and melanoma (Xu, J. et al. (2014) “High EphA2 Protein Expression In Renal Cell Carcinoma Is Associated With A Poor Disease Outcome,” Oncol. Lett. August 2014; 8(2): 687-692; Miao, B. et al. (2014) “EphA2 is a Mediator of Vemurafenib Resistance and a Novel Therapeutic Target in Melanoma,” Cancer Discov. pii: CD-14-0295). EphA2 does not appear to be merely a marker for cancer, but rather appears to be persistently overexpressed and functionally changed in numerous human cancers (Chen, P. et al. (2014) “EphA2 Enhances The Proliferation And Invasion Ability Of LnCap Prostate Cancer Cells,” Oncol. Lett. 8(1):41-46). Exemplary antibodies that bind human EphA2 are “EphA2 mAb 1,” “EphA2 mAb 2” and “EphA2 mAb 3.”

The amino acid sequence of the VH Domain of EphA2 mAb 1 (SEQ ID NO:114) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of EphA2 mAb 1 (SEQ ID NO:115) is shown below (CDR_Lresidues are shown underlined):

The amino acid sequence of the VH Domain of EphA2 mAb 2 (SEQ ID NO:116) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of EphA2 mAb 2 (SEQ ID NO:117) is shown below (CDR_Lresidues are shown underlined):

The amino acid sequence of the VH Domain of EphA2 mAb 3 (SEQ ID NO:118) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of EphA2 mAb 3 (SEQ ID NO:119) is shown below (CDR_Lresidues are shown underlined):

The present invention specifically includes and encompasses CD16 x EphA2 Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_L5 of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of anti-EphA2 monoclonal antibodies EphA2 mAb 1, EphA2 mAb 2 and EphA2 mAb 3.

The 43 kD transmembrane glycoprotein A33 (gpA33) is expressed in >95% of all colorectal carcinomas (Heath, J. K. et al. (1997) “The Human A33 Antigen Is A Transmembrane Glycoprotein And A Novel Member Of The Immunoglobulin Superfamily,” Proc. Natl. Acad. Sci. (U.S.A.) 94(2):469-474; Ritter, G. et al. (1997) “Characterization Of Posttranslational Modifications Of Human A33 Antigen, A Novel Palmitoylated Surface Glycoprotein Of Human Gastrointestinal Epithelium,” Biochem. Biophys. Res. Commun. 236(3):682-686; Wong, N. A. et al. (2006) “EpCAM and gpA33 Are Markers Of Barrett's Metaplasia,” J. Clin. Pathol. 59(3):260-263). An exemplary antibody that binds to human gpA33 is “gpA33 mAb 1.”

The amino acid sequence of the VH Domain of gpA33 mAb 1 (SEQ ID NO:120) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of gpA33 mAb 1 (SEQ ID NO:121) is shown below (CDR_Lresidues are shown underlined):

The present invention specifically includes and encompasses CD16 x gpA33 Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of anti-gpA33 monoclonal antibodies gpA33 mAb 1, or of any of the anti-gpA33 monoclonal antibodies provided in WO 2015/026894.

HER2/neu is a 185 kDa receptor protein that was originally identified as the product of the transforming gene from neuroblastomas of chemically treated rats. HER2/neu has been extensively investigated because of its role in several human carcinomas and in mammalian development (Hynes et al. (1994) Biochim. Biophys. Acta 1198:165-184; Dougall et al. (1994) Oncogene 9:2109-2123; Lee et al. (1995) Nature 378:394-398). Exemplary antibodies that bind human HER2/neu include “Margetuximab,” “Trastuzumab” and “Pertuzumab.” Margetuximab (also known as MGAH22; CAS Reg No. 1350624-75-7) is an Fc-optimized monoclonal antibody that binds to HER2/neu and mediates enhanced ADCC activity. Trastuzumab (also known as rhuMAB4D5, and marketed as HERCEPTIN®; CAS Reg No 180288-69-1; see, U.S. Pat. No. 5,821,337) is the humanized version of antibody 4D5, having IgG1/kappa constant regions. Pertuzumab (also known as rhuMAB2C4, and marketed as PERJETA™; CAS Reg No 380610-27-5; see for example, WO2001/000245) is a humanized version of antibody 2C4 having IgG1/kappa constant regions.

The present invention specifically includes and encompasses CD16 x HER2/neu Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-HER2/neu monoclonal antibodies Margetuximab, Trastuzumab or Pertuzumab.

The amino acid sequence of the VH Domain of Margetuximab (SEQ ID NO:122 is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of Margetuximab (SEQ ID NO:123) is shown below (CDR_Lresidues are shown underlined):

The amino acid sequences of the complete Heavy and Light Chains of Margetuximab are known in the art (see., e.g., WHO Drug Information, 2014, Recommended INN: List 71, 28(1):93-94).

The amino acid sequence of the VH Domain of Trastuzumab (SEQ ID NO:124) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of Trastuzumab (SEQ ID NO:125) is shown below (CDR_Lresidues are shown underlined):

The amino acid sequence of the VH Domain of Pertuzumab (SEQ ID NO:126) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of Pertuzumab (SEQ ID NO:127) is shown below (CDR_Lresidues are shown underlined):

In addition to the above-identified preferred anti-HER2/neu Binding Molecules, the invention includes and encompasses CD16 x HER2/neu Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of any of the following anti-HER2/neu Binding Molecules: 1.44.1; 1.140; 1.43; 1.14.1; 1.100.1; 1.96; 1.18.1; 1.20; 1.39; 1.24; and 1.71.3 (U.S. Pat. Nos. 8,350,011; 8,858,942; and PCT Patent Publication WO 2008/019290); F5 and C1 (U.S. Pat. Nos. 7,892,554; 8,173,424; 8,974,792; and PCT Patent Publication WO 99/55367); and also the anti-HER2/neu Binding Molecules of US Patent Publication US2013017114 and PCT Patent Publications WO2011/147986 and WO 2012/143524).

The present invention specifically includes and encompasses CD16 x HER2/neu Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of any of Margetuximab, Trastuzumab or Pertuzumab, or any of the other anti-HER2/neu antibodies provided herein; and more preferably possess 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of such anti-HER2/neu monoclonal antibodies.

VEGF-A is a chemical signal that stimulates angiogenesis in a variety of diseases, especially in certain metastatic cancers such as metastatic colon cancer, and in certain lung cancers, renal cancers, ovarian cancers, and glioblastoma multiforme of the brain. An exemplary antibody that binds to human VEGF-A is “Bevacizumab” (Avastin®). Bevacizumab is a recombinant humanized IgG1 monoclonal antibody (Midgley, R. et al. (2005) “Bevacizumab—Current Status And Future Directions,” Ann. Oncol. 16(7):999-1004; Hall, R. D. et al. (2015) “Angiogenesis Inhibition As A Therapeutic Strategy In Non-Small Cell Lung Cancer (NSCLC),” Transl. Lung Cancer Res. 4(5):515-523; Narita, Y. (2015) “Bevacizumab For Glioblastoma,” Ther. Clin. Risk Manag. 11:1759-1765).

The amino acid sequence of the VH Domain of Bevacizumab (SEQ ID NO:128) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of Bevacizumab (SEQ ID NO:129) is shown below (CDR_Lresidues are shown underlined):

The present invention specifically includes and encompasses CD16 x VEGF Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_L5 of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-VEGF monoclonal antibody Bevacizumab.

The oncofetal protein, 5T4, is a tumor-associated protein displayed on the cell membrane of many carcinomas, including kidney, colon, prostate, lung, carcinoma and in acute lymphoblastic leukemia (see, Boghaert, E. R. et al. (2008) “The Oncofetal Protein, 5T4, Is A Suitable Target For Antibody-Guided Anti-Cancer Chemotherapy With Calicheamicin,” Int. J. Oncol. 32(1):221-234; Eisen, T. et al. (2014) “Naptumomab Estafenatox: Targeted Immunotherapy with a Novel Immunotoxin,” Curr. Oncol. Rep. 16:370, pp. 1-6). Exemplary antibodies that bind to human 5T4 include “5T4 mAb 1” and “5T4 mAb 2.”

The amino acid sequence of the VH Domain of 5T4 mAb 1 (SEQ ID NO:130) is shown below (CDR residues are shown underlined):

The amino acid sequence of the VL Domain of an 5T4 mAb 1 (SEQ ID NO:131) is shown below (CDR residues are shown underlined):

The amino acid sequence of the VH Domain of 5T4 mAb 2 (SEQ ID NO:132) is shown below (CDR residues are shown underlined):

The amino acid sequence of the VL Domain of 5T4 mAb 2 (SEQ ID NO:133) is shown below (CDR residues are shown underlined):

The present invention specifically includes and encompasses CD16 x 5T4 Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-5T4 monoclonal antibodies 5T4 mAb 1 or 5T4 mAb 2, or of any of the anti-5T4 antibodies provided in WO 2013/041687 or WO 2015/184203.

The present application additionally specifically includes and encompasses CD16 x 5T4 Trispecific Binding Molecules that are capable of binding to 5T4, to CD16 and to CD8, and particularly such trispecific binding molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-5T4 monoclonal antibodies 5T4 mAb 1 or 5T4 mAb 2 or of any of the anti-5T4 monoclonal antibodies provided in WO 2015/184203, and/or the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of any of the anti-CD8 monoclonal antibodies provided herein.

Interleukin-13 Receptor α2 (IL13Rα2) is overexpressed in a variety of cancers, including glioblastoma, colorectal cancer, cervical cancer, pancreatic cencer, multiple melanoma, osteosarcoma, leukemia, lymphoma, prostate cancer and lung cancer (PCT Pubmication No. WO 2008/146911; Brown, C. E. et al. (2013) “Glioma IL13Rα2 Is Associated With Mesenchymal Signature Gene Expression And Poor Patient Prognosis,” PLoS One. 18; 8(10):e77769; Barderas, R. et al. (2012) “High Expression Of IL-13 Receptor A2 In Colorectal Cancer Is Associated With Invasion, Liver Metastasis, And Poor Prognosis,” Cancer Res. 72(11):2780-2790; Kasaian, M. T. et al. (2011) “IL-13 Antibodies Influence IL-13 Clearance In Humans By Modulating Scavenger Activity Of IL-13Rα2,” J. Immunol. 187(1):561-569; Bozinov, O. et al. (2010) “Decreasing Expression Of The Interleukin-13 Receptor IL-13Ralpha2 In Treated Recurrent Malignant Gliomas,” Neurol. Med. Chir. (Tokyo) 50(8):617-621; Fujisawa, T. et al. (2009) “A Novel Role Of Interleukin-13 Receptor Alpha2 In Pancreatic Cancer Invasion And Metastasis,” Cancer Res. 69(22):8678-8685). Antibodies that immunospecifically bind to IL13Rα2 are commercially available and have been described in the art (Abnova Corporation, Biorbyt, LifeSpan BioSciences, United States Biologicals; see also PCT Publication No. WO 2008/146911). Exemplary antibodies that bind to human IL13Rα2 include “hu08” (see, e.g., PCT Publication No. WO 2014/072888).

The amino acid sequence of the VH Domain of hu08 (SEQ ID NO:134) is shown below (CDR residues are shown underlined):

The amino acid sequence of the VL Domain of hu08 (SEQ ID NO:135) is shown below (CDR residues are shown underlined):

The present invention specifically includes and encompasses CD16 x IL13Rα2 Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-IL13Rα2 monoclonal antibody hu08.

CD123 (interleukin 3 receptor alpha, IL-3Ra) is a 40 kDa molecule and is part of the interleukin 3 receptor complex (Stomski, F. C. et al. (1996) “Human Interleukin-3 (IL-3) Induces Disulfide-Linked IL-3 Receptor Alpha-And Beta-Chain Heterodimerization, Which Is Required For Receptor Activation But Not High-Affinity Binding,” Mol. Cell. Biol. 16(6):3035-3046). Interleukin 3 (IL-3) drives early differentiation of multipotent stem cells into cells of the erythroid, myeloid and lymphoid progenitors. CD123 has been reported to be overexpressed on malignant cells in a wide range of hematologic malignancies including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) (Muñoz, L. et al. (2001) “Interleukin-3 Receptor Alpha Chain (CD123) Is Widely Expressed In Hematologic Malignancies,” Haematologica 86(12):1261-1269). Overexpression of CD123 is associated with poorer prognosis in AML (Tettamanti, M. S. et al. (2013) “Targeting Of Acute Myeloid Leukaemia By Cytokine-Induced Killer Cells Redirected With A Novel CD123-Specific Chimeric Antigen Receptor,” Br. J. Haematol. 161:389-401).

An exemplary antibody that binds to human CD123, and that may be employed in the present invention, is “CD123 mAb 1” (see, e.g., PCT Patent Publication WO 2015/026892).

The amino acid sequence of the VH Domain of CD123 mAb 1 (SEQ ID NO:136) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of CD123 mAb 1 (SEQ ID NO:137) is shown below (CDR_Lresidues are shown underlined):

The present invention specifically includes and encompasses CD16 x CD123 Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-CD123 monoclonal antibody CD123 mAb 1 or any of the anti-CD123 antibodies disclosed in US 2017/081424 and WO 2016/036937.

CD19 (B lymphocyte surface antigen B4, Genbank accession number M28170) is a component of the B cell-receptor (BCR) complex, and is a positive regulator of B cell signaling that modulates the threshold for B cell activation and humoral immunity. CD19 is one of the most ubiquitously expressed antigens in the B cell lineage and is expressed on >95% of B cell malignancies, including acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin's Lymphoma (NHL). Notably, CD19 expression is maintained on B cell lymphomas that become resistant to anti-CD20 therapy (Davis et al. (1999) “Therapy of B-cell Lymphoma With Anti-CD20 Antibodies Can Result In The Loss Of CD20 Antigen Expression.” Clin Cancer Res, 5:611-615, 1999). CD19 has also been suggested as a target to treat autoimmune diseases (Tedder (2009) “CD19: A Promising B Cell Target For Rheumatoid Arthritis,” Nat. Rev. Rheumatol. 5:572-577).

An exemplary antibody that binds to human CD19, and that may be employed in the present invention, is the anti-CD19 antibody disclosed in WO 2016/048938 (referred to herein as “CD19 mAb 1”).

The amino acid sequence of the VH Domain of CD19 mAb 1 (SEQ ID NO:123) is shown below (CDR_Hresidues are shown underlined):

The amino acid sequence of the VL Domain of CD19 mAb 1 (SEQ ID NO:139) is shown below (CDR_Lresidues are shown underlined):

The present invention specifically includes and encompasses CD16 x CD19 Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_L5 of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-CD19 monoclonal antibody CD19 mAb 1, or any of the anti-CD19 antibodies disclosed in U.S. Pat. No. 7,112,324.

As used herein, the term “Pathogen-Associated Antigen” denotes an antigen that is characteristically expressed on the surface of a pathogen-infected cell, and that may thus be treated with an Antibody-Based Molecule or an Immunomodulatory Molecule. Examples of Pathogen-Associated Antigens include, but are not limited to antigens expressed on the surface of a cell infected with: a Herpes Simplex Virus (e.g., infected cell protein (ICP)47, gD, etc.), a varicella-zoster virus, a Kaposi's sarcoma-associated herpesvirus, an Epstein-Barr Virus (e.g., LMP-1, LMP-2A, LMP-2B, etc.), a Cytomegalovirus (e.g., UL11, etc.), Human Immunodeficiency Virus (e.g., env proteins gp160, gp120, gp41, etc.), a Human Papillomavirus (e.g., E6, E7, etc.), a human T-cell leukemia virus (e.g., env proteins gp64, gp46, gp21, etc.), Hepatitis A Virus, Hepatitis B Virus, Hepatitis C Virus, Vesicular Stomatitis Virus (VSV), Bacilli, Citrobacter, Cholera, Diphtheria, Enterobacter, Gonococci, Helicobacter pylori, Klebsiella, Legionella, Meningococci, mycobacteria, Pseudomonas, Pneumonococci, rickettsia bacteria, Salmonella, Serratia, Staphylococci, Streptococci, Tetanus, Aspergillus (fumigatus, niger, etc.), Blastomyces dermatitidis, Candida (albicans, krusei, glabrata, tropicalis, etc.), Cryptococcus neoformans, Genus Mucorales (mucor, absidia, rhizopus), Sporothrix schenkii, Paracoccidioides brasiliensis, Coccidioides immitis, Histoplasma capsulatum, Leptospirosis, Borrelia burgdorferi, helminth parasite (hookworm, tapeworms, flukes, flatworms (e.g. Schistosomia), Giardia Zambia, trichinella, Dientamoeba Fragilis, Trypanosoma brucei, Trypanosoma cruzi, and Leishmania donovani). Such antibodies are available commercially from a wide number of sources, or can be obtained by immunizing mice or other animals (including for the production of monoclonal antibodies) with such antigens.

Exemplary antibodies, whose VH and VL Domains may be used to construct molecules capable of binding a Pathogen-Associated Antigen arrayed on the surface of a pathogen-infected cell are antibodies are provided below, additional antibodies are known in the art.

The env protein of HIV is an exemplary Pathogen-Associated Antigen, and antibodies that bind the env protein of HIV are exemplary of antibodies capable of binding a Pathogen-Associated Antigen.

The initial step in HIV-1 infection occurs with the binding of cell surface CD4 to trimeric HIV-1 envelope glycoproteins (env), a heterodimer of a transmembrane glycoprotein (gp41) and a surface glycoprotein (gp120). The gp120 and gp41 glycoproteins are initially synthesized as a single gp160 polypeptide that is subsequently cleaved to generate the non-covalently associated gp120/gp41 complex. The ectodomain of env is a heterodimer with mass of approximately 140 kDa, composed of the entire gp120 component, and approximately 20 kDa of gp41 (Harris, A. et al. (2011) “Trimeric HIV-1 Glycoprotein Gp140 Immunogens And Native HIV-1 Envelope Glycoproteins Display The Same Closed And Open Quaternary Molecular Architectures,” Proc. Natl. Acad. Sci. (U.S.A.) 108(28):11440-11445). Antibodies that that immunospecifically bind to env proteins are commercially available and have been described in the art (see, e.g., GenBank Accession No. AFQ31503; Buchacher, A. et al. (1994) “Generation Of Human Monoclonal Antibodies Against HIV-1 Proteins; Electrofusion And Epstein-Barr Virus Transformation For Peripheral Blood Lymphocyte Immortalization,” AIDS Res. Hum. Retroviruses 10(4):359-369; Shen, R. (2010) “GP41-Specific Antibody Blocks Cell-Free HIV Type 1 Transcytosis Through Human Rectal Mucosa And Model Colonic Epithelium,” J. Immunol. 184(7):3648-3655; WO 2012/162068; and WO 2016/054101). Exemplary antibodies that bind to HIV env include “7B2” (GenBank Accession No. AFQ31503) and “A32” (PCT Publication No. WO 2014/159940).

Antibody 7B2 (Genbank accession numbers JX188438 and JX188439) is an anti-HIV env human IgG1 antibody that binds HIV gp41 at 598-604 in the immunodominant helix-loop-helix region of the molecule (Sadraeian, M. et al. (2017) “Selective Cytotoxicity Of A Novel Immunotoxin Based On Pulchellin A Chain For Cells Expressing HIV Envelope,” Sci. Rep. 7(1):7579 doi: 10.1038/s41598-017-08037-3). The antibody was isolated from an HIV-1 chronically infected subject using Epstein-Barr (EB) virus B cell transformation and heterohybridoma production (Pincus, S. H. et al. (2003) “In Vivo Efficacy Of Anti-Glycoprotein 41, But Not Anti-Glycoprotein 120, Immunotoxins In A Mouse Model Of HIV Infection,” J. Immunol. 170(4):2236-2241). Antibody 7B2 has been found to be capable of recognizing both virus particles and infected cells (Santra, S. et al. (2015) “Human Non-neutralizing HIV-1 Envelope Monoclonal Antibodies Limit the Number of Founder Viruses during SHIV Mucosal Infection in Rhesus Macaques,” PLoS Pathog. 11(8):e1005042. doi: 10.1371/journal.ppat.1005042; Tay, M. Z. et al. (2016) “Antibody-Mediated Internalization of Infectious HIV-1 Virions Differs among Antibody Isotypes and Subclasses,” PLoS Pathog. 12(8):e1005817. doi: 10.1371/journal.ppat.1005817).

The amino acid sequence of the VH Domain of 7B2 (SEQ ID NO:140) is shown below (CDR residues are shown underlined):

The amino acid sequence of the VL Domain of 7B2 (SEQ ID NO:141) is shown below (CDR residues are shown underlined):

Monoclonal antibody A32 recognizes a conformational epitope in the C1 region of HIV-1 Env gp120 (Wyatt et al. (1995) “Involvement Of The V1/V2 Variable Loop Structure In The Exposure Of Human Immunodeficiency Virus Type 1 gp120 Epitopes Induced By Receptor Binding,” J. Virol. 69:5723-5733) and mediates potent ADCC activity and could block a significant proportion of ADCC-mediating Ab activity detectable in HIV-1 infected individuals (Ferrari, G. et al. (2011) “An HIV-1 gp120 Envelope Human Monoclonal Antibody That Recognizes a C1 Conformational Epitope Mediates Potent Antibody Dependent Cellular Cytotoxicity (ADCC) Activity and Defines a Common ADCC Epitope in Human HIV-1 Serum,” J. Virol. 85(14): 7029-7036).

Multiple VH Domains of Antibody A32 have been reported in the art that possess minor changes in framework regions 1 and/or 4 reported (see, e.g., Protein Data Base Accession number PDB: 4YBL_H, US 2015/0239961 and WO 2006/044410). Any of these variant Antibody A32 VH Domains may be employed in accordance with the present invention. The amino acid sequence of an illustrative VH Domain of A32 (SEQ ID NO:142) is shown below (CDR residues are shown underlined):

The amino acid sequence of the VL Domain of A32 (SEQ ID NO:143) is shown below (CDR residues are shown underlined):

The amino acid sequence of the VL Domain of A32 (SEQ ID NO:143) may be employed with the illustrative VH Domain of A32 (SEQ ID NO:142) or with any of the variant Antibody A32 VH Domains (see, e.g., Protein Data Base Accession number PDB: 4YBL_H, US 2015/0239961 and WO 2006/044410) to form an anti-HIV-1 Env gp120 Epitope Binding Site.

The present invention specifically includes and encompasses CD16 x HIV Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-HIV monoclonal antibodies 7B2 or A32, or of any of the anti-HIV antibodies disclosed in WO 2016196975, WO 2016/149710, WO 2016/149698, WO 2016/149695, WO 2015/048610, WO 2012/030904, WO 2013/163427, WO 2013/192589, WO 2014/063059, WO 20170/11413, WO 2016/054101, WO 2014/159940, or WO 2017/011414.

The present application additionally specifically includes and encompasses CD16 x HIV Binding Molecules that are capable of binding to HIV, to CD16 and to CD8, and particularly such trispecific binding molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-HIV monoclonal antibodies 7B2 or A32 or of any of the anti-HIV monoclonal antibodies provided in WO 2015/184203, WO 2016/054101, WO 2017/011413, WO 2017/011414.

A further illustrative Pathogen-Associated Antigen is RSV glycoprotein F. An exemplary anti-RSV glycoprotein F antibody is Palivizumab (see, e.g., Protein Data Bank (PDB) ID No. 2HWZ). Alternative anti-RSV glycoprotein F antibodies include motavizumab (see, e.g., PDB ID No. 3IXT) and a variant of palivizumab (also referred to herein as “vPalivizumab”) that has been engineered to remove a cysteine residue from palivizumab' s CDR_L1. The amino acid sequence of the VH Domain of the variant of palivizumab (SEQ ID NO:144) is shown below (CDR residues are shown underlined):

The amino acid sequence of the VL Domain of the variant of palivizumab (SEQ ID NO:145) is shown below (CDR residues are shown underlined):

The present invention specifically includes and encompasses CD16 x RSV Binding Molecules that comprise the VL and/or VH Domain, and/or 1, 2 or all 3 of the CDR_Ls of the VL Region and/or 1, 2 or all 3 of the CDR_Hs of the VH Domain of the anti-RSV monoclonal antibody palivizumab or vPalivizumab.

The principles of the present invention are illustrated by a series of exemplary CD16 x DA Binding Molecules incorporating different murine or humanized anti-CD16 binding domains and having a Binding Domain that is immunospecific for a Disease Antigen. The covalent diabody structures and sequences of such illustrative CD16 x DA Binding Molecules are summarized in Table 12, and are described in detail below. As will be recognized, analogous diabodies and other bispecific molecules may likewise be constructed (by employing the VL and VH domains of desired antibodies in lieu of the VL and VH domains used in the illustrative CD16 x DA Binding Molecules.