[0001] This application claims priority under 35 U.S.C. §119(e) and §120 to U.S. Provisional Patent Application No. 62/159,111, filed May 8, 2015, U.S. Provisional Patent Application No. 62/251,005, filed November 4, 2015 and U.S. Provisional Patent Application No.

62/250,971, filed November 4, 2015, U.S.S.N. 14/952,714, filed November 11, 2015 and PCT/US2015/062772, filed November 25, 2015, all of which are expressly incorporated herein by reference in their entirety, with particular reference to the figures, legends and claims therein.

BACKGROUND OF THE INVENTION

[0002] Antibody-based therapeutics have been used successfully to treat a variety of diseases, including cancer and autoimmune/inflammatory disorders. Yet improvements to this class of drugs are still needed, particularly with respect to enhancing their clinical efficacy. One avenue being explored is the engineering of additional and novel antigen binding sites into antibody-based drugs such that a single immunoglobulin molecule co-engages two different antigens. Such non-native or alternate antibody formats that engage two different antigens are often referred to as bispecifics. Because the considerable diversity of the antibody variable region (Fv) makes it possible to produce an Fv that recognizes virtually any molecule, the typical approach to bispecific generation is the introduction of new variable regions into the antibody.

[0003] A number of alternate antibody formats have been explored for bispecific targeting (Chames & Baty, 2009, mAbs l[6]:l-9; Holliger & Hudson, 2005, Nature Biotechnology 23[9]:1126-1136; Kontermann, mAbs 4(2):182 (2012), all of which are expressly incorporated herein by reference). Initially, bispecific antibodies were made by fusing two cell lines that each produced a single monoclonal antibody (Milstein et al., 1983, Nature 305:537-540). Although the resulting hybrid hybridoma or quadroma did produce bispecific antibodies, they were only a minor population, and extensive purification was required to isolate the desired antibody. An engineering solution to this was the use of antibody fragments to make bispecifics. Because such fragments lack the complex quaternary structure of a full length antibody, variable light and heavy chains can be linked in single genetic constructs.

Antibody fragments of many different forms have been generated, including diabodies, single chain diabodies, tandem scFv's, and Fab∑ bispecifics (Chames & Baty, 2009, mAbs l[6]:l-9; Holliger & Hudson, 2005, Nature Biotechnology 23[9]:1126-1136; expressly incorporated herein by reference). While these formats can be expressed at high levels in bacteria and may have favorable penetration benefits due to their small size, they clear rapidly in vivo and can present manufacturing obstacles related to their production and stability. A principal cause of these drawbacks is that antibody fragments typically lack the constant region of the antibody with its associated functional properties, including larger size, high stability, and binding to various Fc receptors and ligands that maintain long half-life in serum (i.e. the neonatal Fc receptor FcRn) or serve as binding sites for purification (i.e. protein A and protein G).

[0004] More recent work has attempted to address the shortcomings of fragment-based bispecifics by engineering dual binding into full length antibody -like formats (Wu et al., 2007, Nature Biotechnology 25[11]:1290-1297; USSNl 2/477,711; Michaelson et al., 2009, mAbs 1[2]:128-141; PCT/US2008/074693; Zuo et al., 2000, Protein Engineering 13[5]:361-367;

USSN09/865,198; Shen et al., 2006, J Biol Chem 281[16]:10706-10714; Lu et al., 2005, J Biol Chem 280[20]:19665-19672; PCT/US2005/025472; expressly incorporated herein by reference). These formats overcome some of the obstacles of the antibody fragment bispecifics, principally because they contain an Fc region. One significant drawback of these formats is that, because they build new antigen binding sites on top of the homodimeric constant chains, binding to the new antigen is always bivalent.

[0005] For many antigens that are attractive as co-targets in a therapeutic bispecific format, the desired binding is monovalent rather than bivalent. For many immune receptors, cellular activation is accomplished by cross-linking of a monovalent binding interaction. The mechanism of cross-linking is typically mediated by antibody/antigen immune complexes, or via effector cell to target cell engagement. For example, the low affinity Fc gamma receptors (FcyRs) such as FcyRIIa, FcyRIIb, and FcyRIIIa bind monovalently to the antibody Fc region. Monovalent binding does not activate cells expressing these FcyRs; however, upon immune complexation or cell-to-cell contact, receptors are cross-linked and clustered

on the cell surface, leading to activation. For receptors responsible for mediating cellular killing, for example FcyRIIIa on natural killer (NK) cells, receptor cross-linking and cellular activation occurs when the effector cell engages the target cell in a highly avid format (Bowles & Weiner, 2005, J Immunol Methods 304:88-99, expressly incorporated by reference).. Similarly, on B cells the inhibitory receptor FcyRIIb downregulates B cell activation only when it engages into an immune complex with the cell surface B-cell receptor (BCR), a mechanism that is mediated by immune complexation of soluble IgG's with the same antigen that is recognized by the BCR (Heyman 2003, Immunol Lett 88[2]:157-161; Smith and Clatworthy, 2010, Nature Reviews Immunology 10:328-343; expressly incorporated by reference). As another example, CD3 activation of T-cells occurs only when its associated T-cell receptor (TCR) engages antigen-loaded MHC on antigen presenting cells in a highly avid cell-to-cell synapse (Kuhns et al., 2006, Immunity 24:133-139). Indeed nonspecific bivalent cross-linking of CD3 using an anti-CD3 antibody elicits a cytokine storm and toxicity (Perruche et al., 2009, J Immunol 183[2]:953-61; Chatenoud & Bluestone, 2007, Nature Reviews Immunology 7:622-632; expressly incorporated by reference). Thus for practical clinical use, the preferred mode of CD3 co-engagement for redirected killing of targets cells is monovalent binding that results in activation only upon engagement with the co-engaged target.

[0006] CD38, also known as cyclic ADP ribose hydrolase, is a type II transmembrane glycoprotein with a long C-terminal extracellular domain and a short N-terminal cytoplasmic domain. Among hematopoietic cells, an assortment of functional effects have been ascribed to CD38 mediated signaling, including lymphocyte proliferation, cytokine release, regulation of B and myeloid cell development and survival, and induction of dendritic cell maturation. CD38 is unregulated in many hematopoeitic malignancies and in cell lines derived from various hematopoietic malignancies including non-Hodgkin's lymphoma (NHL), Burkitt's lymphoma (BL), multiple myeloma (MM), B chronic lymphocytic leukemia (B-CLL), B and T acute lymphocytic leukemia (ALL), T cell lymphoma (TCL), acute myeloid leukemia (AML), hairy cell leukemia (HCL), Hodgkin's Lymphoma (HL), and chronic myeloid leukemia (CML). On the other hand, most primitive pluripotent stem cells of the hematopoietic system are CD38-. In spite of the recent progress in the discovery and development of anti-cancer agents, many forms of cancer involving CD38-expressing tumors still have a poor prognosis. Thus, there is a need for improved methods for treating such forms of cancer.

[0007] B-cell antigen CD19 (CD19, also known as B-cell surface antigen B4, Leu-12) is a human pan-B-cell surface marker that is expressed from early stages of pre-B cell development through terminal differentiation into plasma cells. CD 19 promotes the proliferation and survival of mature B cells. It associates in a complex with CD21 on the cell surface. It also associates with CD81 and Leu-13 and potentiates B cell receptor (BCR) signaling. Together with the BCR, CD19 modulates intrinsic and antigen receptor-induced signaling thresholds critical for clonal expansion of B cells and humoral immunity. In collaboration with CD21 it links the adaptive and the innate immune system. Upon activation, the cytoplasmic tail of CD19 becomes phosphorylated which leads to binding by Src-family kinases and recruitment of PI-3 kinase. It is an attractive immunotherapy target for cancers of lymphoid origin since it is also expressed on the vast majority of NHL cells as well as some leukemias.

[0008] A number of antibodies or antibody conjugates that target CD19 have been evaluated in pre-clinical studies or in clinical trials for the treatment of cancers. These anti-CD19 antibodies or antibody conjugates include but are not limited to MT-103 (a single-chain bispecific CD19/CD3 antibody; Hoffman et al, 2005 Int J Cancer 115:98-104; Schlereth et al, 2006 Cancer Immunol Immunother 55:503-514), a CD19/CD16 diabody (Schlenzka et al, 2004 Anti-cancer Drugs 15:915-919; Kipriyanov et al, 2002 J Immunol 169:137-144), BU12-saporin (Flavell et al, 1995 Br J Cancer 72:1373-1379), and anti-CD19-idarubicin (Rowland et al, 1993 Cancer Immunol Immunother 55:503-514); all expressly incorporated by reference.

[0009] CD123, also known as interleukin-3 receptor alpha (IL-3R ), is expressed on dendritic cells, monocytes, eosinophils and basophils. CD123 is also constitutively expressed by committed hematopoietic stem/progenitor cells, by most of the myeloid lineage (CD13+, CD14+, CD33+, CD151ow), and by some CD19+ cells. It is absent from CD3+ cells.

[0010] Thus while bispecifics generated from antibody fragments suffer biophysical and pharmacokinetic hurdles, a drawback of those built with full length antibody -like formats is that they engage co-target antigens multivalently in the absence of the primary target antigen, leading to nonspecific activation and potentially toxicity. The present invention solves this problem by introducing novel bispecific antibodies directed to CD3 and CD38.

BRIEF SUMMARY OF THE INVENTION

[0011] Accordingly, in one aspect the present invention provides heterodimeric antibodies comprising: a) a first monomer comprising: i) a first heavy chain comprising: 1) a first variable heavy domain; 2) a first constant heavy chain comprising a first Fc domain; 3) a scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the C-terminus of said Fc domain using a domain linker; b) a second monomer comprising a second heavy chain comprising a second variable heavy domain and a second constant heavy chain comprising a second Fc domain; and c) a common light chain comprising a variable light domain and a constant light domain.

[0012] In a further aspect, the invention provides heterodimeric antibodies comprising: a) a first monomer comprising: i) a first heavy chain comprising: 1) a first variable heavy domain; 2) a first constant heavy domain comprising a first Fc domain; and 3) a first variable light domain, wherein said first variable light domain is covalently attached to the C-terminus of said first Fc domain using a domain linker; b) a second monomer comprisingd) a second variable heavy domain; ii) a second constant heavy domain comprising a second Fc domain; and iii) a third variable heavy domain, wherein said second variable heavy domain is covalently attached to the C-terminus of said second Fc domain using a domain linker; c) a common light chain comprising a variable light domain and a constant light domain.

[0013] In an additional aspect, the invention provides heterodimeric antibodies comprising: a) a first monomer comprising: i) a first heavy chain comprising: 1) a first variable heavy domain; 2) a first constant heavy chain comprising a first CHI domain and a first Fc domain; 3) a scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached between the C-terminus of said CHI domain and the N-terminus of said first Fc domain using domain linkers; b) a second monomer comprising a second heavy chain comprising a second variable heavy domain and

a second constant heavy chain comprising a second Fc domain; and c) a common light chain comprising a variable light domain and a constant light domain.

[0014] In a further aspect, the invention provides heterodimeric antibodies comprising: a) a first monomer comprising: i) a first heavy chain comprising: 1) a first variable heavy domain; 2) a first constant heavy domain comprising a first Fc domain; and 3) a first variable light domain, wherein said second variable light domain is covalently attached between the C-terminus of the CHI domain of said first constant heavy domain and the N-terminus of said first Fc domain using domain linkers; b) a second monomer comprising: i) a second variable heavy domain; ii) a second constant heavy domain comprising a second Fc domain; and iii) a third variable heavy domain, wherein said second variable heavy domain is covalently attached to the C-terminus of said second Fc domain using a domain linker; c) a common light chain comprising a variable light domain and a constant light domain.

[0015] In an additional aspect, the invention provides heterodimeric antibodies comprising: a) a first monomer comprising: i) a first heavy chain comprising: 1) a first variable heavy domain; 2) a first constant heavy chain comprising a first CHI domain and a first Fc domain; 3) a scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached between the C-terminus of said CHI domain and the N-terminus of said first Fc domain using domain linkers; b) a second monomer comprising a second Fc domain; and c) a light chain comprising a variable light domain and a constant light domain.

[0016] In some aspects, the first and second Fc domains have a set of amino acid substitutions selected from the group consisting of S364K E357Q : L368D/K370S;

L368D/ 370S : S364K; L368E/ 370S : S364K; T411T/E360E/Q362E : D401K; L368D/K370S : S364K E357L and K370S : S364K/E357Q. Furthermore, the variable heavy domain(s) and the variable light domain(s) bind a first target tumor antigen (TTA), the scFv binds a second TTA or human CD3. In some embodiments, the TTA is selected from the group consisting of CD19, CD20 and CD123.

[0017] In a further aspect, the invention provides anti-CD3 antigen binding domains having CDRs and/or the variable domains and/or the scFv sequences depicted in the Figures for

H1.32_L1.47, H1.89_L1.47, H1.90_L1.47, H1.33_L.1.47 and H1.31_L1.47. The invention further provides nucleic acid compositions, expression vector compositions and host cells.

[0018] In an additional aspect, the invention provides heterodimeric antibodies comprising a) a first monomer comprising: i) a first Fc domain; ii) an anti-CD3 scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the N-terminus of said Fc domain using a domain linker; b) a second monomer comprising a heavy chain comprising: i) a heavy variable domain; and ii) a heavy chain constant domain comprising a second Fc domain; and c) a light chain comprising a variable light domain and a variable light constant domain; wherein the anti-CD3 scFv is selected from the group consisting of anti-CD3 H1.32_L1.47, anti-CD3 H1.89_L1.47, anti-CD3 H1.90_L1.47 and anti-CD3 H1.33_L1.47 (SEQ ID NO:XX). The heavy variable domain and the light variable domain bind a TTA (including, but not limited to CD19, Cd20, CD38 and CD123).

[0019] In an additional aspect, the invention provides anti-CD20 antibody binding domains comprising : a) a variable light domain comprising a vlCDRl having the sequence

RASWSVSYIH (SEQ ID NO:XX), a vlCDR2 having the sequence ATSNLAS (SEQ ID

NO:XX), and a vlCDR3 having the sequence QQWTHNPPT (SEQ ID NO:XX); and b) a variable heavy domain comprises a vhCDRl having the sequence SYNMH (SEQ ID NO:XX), a vhCDR2 having the sequence AIYPGNGATSYSQKFQG (SEQ ID NO:XX) and a vhCDR3 having the sequence SYYMGGDWYFDV (SEQ ID NO:XX). In some embodiments, the anti-CD20 antibody binding domains have the C2B8 H1.202_L1.113 sequences.

[0020] In an additional aspect, the invention provides anti-CD20 antibody binding domains comprising: a) a variable light domain comprising a vlCDRl having the sequence

RASSSVSYIH (SEQ ID NO:XX), a vlCDR2 having the sequence ATSNLAS (SEQ ID NO:XX), and a vlCDR3 having the sequence QQWTSNPPT (SEQ ID NO:XX); and b) a variable heavy domain comprises a vhCDRl having the sequence SYNMH (SEQ ID NO:XX), a vhCDR2 having the sequence AIYPGNGDTSYNQKFQG (SEQ ID NO:XX) and a vhCDR3 having the sequence STYYGGDWYFNV (SEQ ID NO:XX).

[0021] In some embodiments, the anti-CD20 antibody binding domains have the

C2B8_H1L1 sequences.

[0022] In an additional aspect, the invention provides heterodimeric antibodies comprising a) a first monomer comprising: i) a first Fc domain; ii) an anti-CD3 scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the N-terminus of said Fc domain using a domain linker; b) a second monomer comprising a heavy chain comprising: i) a heavy variable domain; and ii) a heavy chain constant domain comprising a second Fc domain; and c) a light chain comprising a variable light domain and a variable light constant domain; wherein the variable heavy and light chains form a C2B8 H1.202_L1.113 or C2B8_H1L1 binding domain.

[0023] In an additional aspect, the invention provides heterodimeric antibodies comprising a) a first monomer comprising: i) a first Fc domain; ii) an anti-CD3 scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the N-terminus of said Fc domain using a domain linker; b) a second monomer comprising a heavy chain comprising: i) a heavy variable domain; and ii) a heavy chain constant domain comprising a second Fc domain; and c) a light chain comprising a variable light domain and a variable light constant domain. In this embodiment, the variable domains bind CD123 and can have the sequences of 7G3_H1.109_L1.47.

[0024] In additional aspects, the present invention provides heterodimeric antibodies selected from the group consisting of XENP15049, XENP15051; XENP15050, XENP13676, XENP14696, XENP15629, XENP15053, XENP15630, XENP15631, XENP15632, XENP15633, XENP15634, XENP15635, XENP15636, XENP15638, XENP15639, XENP13677, XENP14388, XENP14389, XENP14390, XENP14391,XENP14392, XENP14393, XENP16366, XENP16367, XENP16368, XENP16369, XENP16370, XENP16371, XENP16372, XENP16373, XENP16375, XENP16376, XENP16377, XENP14045 and XENP13928. Nucleic acids, expression vectors and host cells are all provided as well, in addition to methods of making these proteins and treating patients with them.

[0025] In additional aspects, the present invention provides heterodimeric antibodies comprising a set of 6 CDRs (vhCDRl, vhCDR2, vhCDR3, vlCDRl, vlCDR2 and vlCDR3)

from the variable regions of one of the antigen binding domains from a heterodimeric antibody selected from the group consisting of XENP15049, XENP15051; XENP15050, XENP13676, XENP14696, XENP15629, XENP15053, XENP15630, XENP15631, XENP15632, XENP15633, XENP15634, XENP15635, XENP15636, XENP15638, XENP15639, XENP13677, XENP14388, XENP14389, XENP14390, XENP14391,XENP14392, XENP14393, XENP16366, XENP16367, XENP16368, XENP16369, XENP16370, XENP16371, XENP16372, XENP16373, XENP16375, XENP16376, XENP16377, XENP14045 and XENP13928. Nucleic acids, expression vectors and host cells are all provided as well, in addition to methods of making these proteins and treating patients with them.

[0026] In additional aspects, the present invention provides heterodimeric antibodies comprising two sets of CDRs, a first set of each of 6 CDRs (vhCDRl, vhCDR2, vhCDR3, vlCDRl, vlCDR2 and vlCDR3) from the variable regions of one of the antigen binding domains and the second set from the variable regions of the other, second antigen binding domains of a heterodimeric antibody selected from the group consisting of XENP15049, XENP15051; XENP15050, XENP13676, XENP14696, XENP15629, XENP15053, XENP15630, XENP15631, XENP15632, XENP15633, XENP15634, XENP15635, XENP15636, XENP15638, XENP15639, XENP13677, XENP14388, XENP14389, XENP14390, XENP14391,XENP14392, XENP14393, XENP16366, XENP16367, XENP16368, XENP16369, XENP16370, XENP16371, XENP16372, XENP16373, XENP16375, XENP16376, XENP16377, XENP14045 and

XENP13928. Nucleic acids, expression vectors and host cells are all provided as well, in addition to methods of making these proteins and treating patients with them.

[0027] In additional aspects, the present invention provides heterodimeric antibodies comprising two sets of vh and vl domains, a first set from the variable regions of one of the antigen binding domains and the second set from the variable regions of the other, second antigen binding domains of a heterodimeric antibody selected from the group consisting of XENP15049, XENP15051; XENP15050, XENP13676, XENP14696, XENP15629, XENP15053, XENP15630, XENP15631, XENP15632, XENP15633, XENP15634, XENP15635, XENP15636, XENP15638, XENP15639, XENP13677, XENP14388, XENP14389, XENP14390,

XENP14391,XENP14392, XENP14393, XENP16366, XENP16367, XENP16368, XENP16369, XENP16370, XENP16371, XENP16372, XENP16373, XENP16375, XENP16376, XENP16377,

XENP14045 and XENP13928. Nucleic acids, expression vectors and host cells are all provided as well, in addition to methods of making these proteins and treating patients with them.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figures 1A, IB and 1C depict several formats of the present invention. Two forms of the "bottle opener" format are depicted, one with the anti-CD3 antigen binding domain comprising a scFv and the anti-TTA antigen binding domain comprising a Fab, and one with these reversed. The mAb-Fv, mAb-scFv, Central-scFv and Central-Fv formats are all shown. While they are depicted as having the anti-CD3 as the scFv, as discussed herein, any Fv sequences can be switched out and combined; that, the anti-CD3 and the anti-TTA domains of the mAb-Fv, mAb-scFv, central-scFv and central-Fv can be switched. In addition, "one-armed" formats, where one monomer just comprises an Fc domain, are shown, both a one arm Central-scFv and a one arm Central-Fv. A dual scFv format is also shown.

[0029] Figure 2 depicts the sequences of the "High CD3" anti-CD3_H1.30_L1.47 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined). As is true of all the sequences depicted in the Figures, this charged linker may be replaced by an uncharged linker or a different charged linker, as needed.

[0030] Figure 3 depicts the sequences of the "High-Int #l"Anti-CD3_H1.32_L1.47 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined). As is true of all the sequences depicted in the Figures, this charged linker may be replaced by an uncharged linker or a different charged linker, as needed.

[0031] Figure 4 depicts the sequences of the "High-Int #2" Anti-CD3_H1.89_L1.47 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined). As is true of all the sequences depicted in the Figures, this charged linker may be replaced by an uncharged linker or a different charged linker, as needed.

[0032] Figure 5 depicts the sequences of the "High-Int #3" Anti-CD3_H1.90_L1.47 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined). As is true of all the sequences depicted in the Figures, this charged linker may be replaced by an uncharged linker or a different charged linker, as needed.

[0033] Figure 6 depicts the sequences of the "Int" Anti-CD3_H1.90_L1.47 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined). As is true of all the sequences depicted in the Figures, this charged linker may be replaced by an uncharged linker or a different charged linker, as needed.

[0034] Figure 7 depicts the sequences of the "Low" Anti-CD3_H1.31_L1.47 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined). As is true of all the sequences depicted in the Figures, this charged linker may be replaced by an uncharged linker or a different charged linker, as needed.

[0035] Figure 8 depicts the sequences of the High CD38: OKT10_H1.77_L1.24 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined).

[0036] Figure 9 depicts the sequences of the intermediate CD38: OKT10_H1L1.24 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined).

[0037] Figure 10 depicts the sequences of the Low CD38: OKT10_H1L1 construct, including the variable heavy and light domains (CDRs underlined), as well as the individual vl and vhCDRs, as well as an scFv construct with a charged linker (double underlined).

[0038] Figure 11 depicts the sequences of XENP15331.

[0039] Figure 12 depicts the sequences of XENP13243.

[0040] Figure 13 depicts the sequences of XENP14702.

[0041] Figure 14 depicts the sequences of XENP15426.

[0042] Figure 15 depicts the sequences of XENP14701.

[0043] Figure 16 depicts the sequence of XENP14703.

[0044] Figure 17 depicts the sequence of XENP13243.

[0045] Figure 18 depicts the sequences of XENP18967.

[0046] Figure 19 depicts the sequences of XENP18971.

[0047] Figure 20 depicts the sequences of XENP18969.

[0048] Figure 21 depicts the sequences of XENP18970.

[0049] Figure 22 depicts the sequences of XENP18972.

[0050] Figure 23 depicts the sequences of XENP18973.

[0051] Figure 24 depicts the sequences of XENP15055.

[0052] Figure 25 depicts the sequences of XENP13544.

[0053] Figure 26 depicts the sequences of XENP13694.

[0054] Figure 27 depicts the sequence of human CD3 ε.

[0055] Figure 28 depicts the full length (SEQ ID NO:130) and extracellular domain (ECD;

SEQ ID NO:131) of the human CD38 protein.

[0056] Figure 29A -29E depict useful pairs of heterodimerization variant sets (including skew and pi variants). On Figure 29E, there are variants for which there are no corresponding "monomer 2" variants; these are pi variants which can be used alone on either monomer, or included on the Fab side of a bottle opener, for example, and an appropriate charged scFv linker can be used on the second monomer that utilizes a scFv as the second antigen binding domain. Suitable charged linkers are shown in Figure 33.

[0057] Figure 30 depict a list of isosteric variant antibody constant regions and their respective substituions. pl_(-) indicates lower pi variants, while pl_(+) indicates higher pi variants. These can be optionally and independently combined with other

heterodimerization variants of the invention (and other variant types as well, as outlined herein).

[0058] Figure 31 depict useful ablation variants that ablate FcyR binding (sometimes referred to as "knock outs" or "KO" variants).

[0059] Figure 32 show two particularly useful embodiments of the invention.

[0060] Figure 33 depicts a number of charged scFv linkers that find use in increasing or decreasing the pi of heterodimeric antibodies that utilize one or more scFv as a component. The (+H) positive linker finds particular use herein, particularly with anti-CD3 vl and vh sequences shown herein. A single prior art scFv linker with a single charge is referenced as "Whitlow", from Whitlow et al., Protein Engineering 6(8):989-995 (1993). It should be noted that this linker was used for reducing aggregation and enhancing proteolytic stability in scFvs.

[0061] Figure 34 depicts a list of engineered heterodimer-skewing Fc variants with heterodimer yields (determined by HPLC-CIEX) and thermal stabilities (determined by DSC). Not determined thermal stability is denoted by "n.d.".

[0062] Figure 35 Expression yields of bispecifics after protein A affinity purification.

[0063] Figure 36 Cationic exchange purification chromatograms.

[0064] Figure 37 Redirected T cell cytotoxicity assay, 24 h incubation, 10k RPMI8226 cells, 400k T cells. Test articles are anti-CD38 x anti-CD3 bispecifics. Detection was by LDH

[0065] Figure 38 Redirected T cell cytotoxicity assay, 24 h incubation, 10k RPMI8226 cells, 500k human PBMCs. Test articles are anti-CD38 x anti-CD3 bispecifics. Detection was by LDH.

[0066] Figure 39 depicts the sequences of XENP14419,

[0067] Figure 40 depicts the sequences of XENP14420.

[0068] Figure 41 depicts the sequences of XENP14421.

[0069] Figure 42 depicts the sequences of XENP14422.

[0070] Figure 43 depicts the sequences of XENP14423.

[0071] Figure 44 Redirected T cell cytotoxicity assay, 96 h incubation, 40k RPMI8226 cells, 400k human PBMC. Test articles are anti-CD38 x anti-CD3 Fab-scFv-Fcs. Detection was by flow cytometry, specifically the disappearance of CD38+ cells.

[0072] Figure 45 Further analysis of redirected T cell cytotoxicity assay described in Figure 1. The first row shows the Mean Fluorescence Intensity (MFl) of activation marker CD69 on CD4+ and CD8+ T cells as detected by flow cytometry. The second row shows the percentage of CD4+ and CD8+ T cells that are Ki-67+, a measure of cell proliferation. The third row shows the intracellular Mean Fluorescence Intensity (MFl) of granzyme B inhibitor PI-9 on CD4+ and CD8+ T cells as detected by flow cytometry.

[0073] Figure 46 Design of mouse study to examine anti-tumor activity of anti-CD38 x anti-CD3 Fab-scFv-Fc bispecifics.

[0074] Figure 47 Tumor size measured by IVIS® as a function of time and treatment

[0075] Figure 48 IVIS® bioluminescent images (Day 10)

[0076] Figure 49 Depletion of CD38+ cells in cynomolgus monkeys following single doses of the indicated test articles

[0077] Figure 50 T cell activation measured by CD69 Mean Fluorescence Intensity (MFl) in cynomolgus monkeys, color coding as in Figure 49.

[0078] Figure 51 Serum levels of IL-6, following single doses of the indicated test articles.

[0079] Figure 52 depicts the sequences of XENP15427.

[0080] Figure 53 depicts the sequences of XENP15428.

[0081] Figure 54 depicts the sequences of XENP15429.

[0082] Figure 55 depicts the sequences of XENP15430.

[0083] Figure 56 depicts the sequences of XENP15431.

[0084] Figure 57 depicts the sequences of XENP 15432.

[0085] Figure 58 depicts the sequences of XENP15433.

[0086] Figure 59 depicts the sequences of XENP15434.

[0087] Figure 60 depicts the sequences of XENP15435.

[0088] Figure 61 depicts the sequences of XENP15436.

[0089] Figure 62 depicts the sequences of XENP15437.

[0090] Figure 63 depicts the sequences of XENP15438.

[0091] Figure 64 shows binding affinities in a Biacore assay.

[0092] Figure 65 shows the Heteroditner purity during stable pool generation using varied Light chain, Fab-Fc, and scFv-Fc ratios.

[0093] Figure 66 Human IgM and IgG2 depletion by anti-CD38 x anti-CD3 bispecifics in a huPBMC mouse model.

[0094] Figure 67 depicts stability-optimized, humanized anti-CD3 variant scFvs.

Substitutions are given relative to the H1_L1.4 scFv sequence. Amino acid numbering is Kabat numbering.

[0095] Figure 68. Amino acid sequences of stability-optimized, humanized anti-CD3 variant scFvs. CDRs are underlined. For each heavy chain light chain combination, four sequences are listed: (i) scFv with C-terminal 6xHis tag, (ii) scFv alone, (iii) VH alone, (iv) VL alone.

[0096] Figure 69 Redirected T cell cytotoxicity assay, 24 h incubation, 10k RPMI8226 cells, 500k PBMC. Test articles are anti-CD38 (OKT10_H1L1, OKT10_H1.77_L1.24) x anti-CD3 Fab-scFv-Fcs. Detection was by LDH.

[0097] Figure 70 huPBL-SCID Ig-depletion study. Test articles were dosed 8 d after PBMC engraftment at 0.03, 0.3, or 3 mg kg. Route of administration was intraperitoneal. Blood samples were taken 14 d after PBMC engraftment, processed to serum, and assayed for human IgM and IgG2.

[0098] Figure 71 depicts the sequences of XENP15049.

[0099] Figure 72 depicts the sequences of XENP15051.

[00100] Figure 73 depicts the sequences of XENP15050.

[00101] Figure 74 depicts the sequences of XENP13676.

[00102] Figure 75 depicts the sequences of XENP14696.

[00103] Figure 76 depicts the sequences of XENP15629.

[00104] Figure 77 depicts the sequences of XENP15053.

[00105] Figure 78 depicts the sequences of XENP15630.

[00106] Figure 79 depicts the sequences of XENP15631.

[00107] Figure 80 depicts the sequences of XENP15632.

[00108] Figure 81 depicts the sequences of XENP15633.

[00109] Figure 82 depicts the sequences of XENP15634.

[00110] Figure 83 depicts the sequences of XENP15635.

[00111] Figure 84 depicts the sequences of XENP15636.

[00112] Figure 85 depicts the sequences of XENP15638.

[00113] Figure 86 depicts the sequences of XENP15639.

[00114] Figure 87 depicts the sequences of XENP13677.

[00115] Figure 88 depicts the sequences of XENP14388.

[00116] Figure 89 depicts the sequences of XENP14389.

[00117] Figure 90 depicts the sequences of XENP14390.

[00118] Figure 91 depicts the sequences of XENP14391.

[00119] Figure 92 depicts the sequences of XENP14392.

[00120] Figure 93 depicts the sequences of XENP14393.

[00121] Figure 94 depicts the sequences of XENP16366.

[00122] Figure 95 depicts the sequences of XENP16367

[00123] Figure 96 depicts the sequences of XENP16368.

[00124] Figure 97 depicts the sequences of XENP16369.

[00125] Figure 98 depicts the sequences of XENP16370.

[00126] Figure 99 depicts the sequences of XENP16371. [00127] Figure 100 depicts the sequences of XENP16372.

[00128] Figure 101 depicts the sequences of XENP16373.

[00129] Figure 102 depicts the sequences of XENP16374.

[00130] Figure 103 depicts the sequences of XENP16375.

[00131] Figure 104 depicts the sequences of XENP16376. The CDRs, vh and vl sequences of the anti-CD20 Fab arm are shown in Figure 121.

[00132] Figure 105 depicts the sequences of XENP16377.

[00133] Figure 106 depicts the sequences of the CD20 and CD123 antigens.

[00134] Figure 107 Surface plasmon resonance determination of CD3 affinity. Test articles are anti-CD20 (C2B8_H1.202_L1.113) x anti-CD3 Fab-scFv-Fcs. Human CD368-Fc (Sino Biological) was covalently bound to the chip surface. Test articles were passed over at 3.125, 12.5, 50, and 200 nM.

[00135] Figure 108 Surface plasmon resonance determination of CD3 affinity. Test articles are anti-CD20 (C2B8_H1.202_L1.113) x anti-CD3 Fab-scFv-Fcs. Cynomolgus monkey CD368-Fc (Sino Biological) was covalently bound to the chip surface. Test articles were passed over at 3.125, 12.5, 50, and 200 nM.

[00136] Figure 109 Surface plasmon resonance determination of CD3 affinity. Test articles are anti-CD20 (C2B8_H1.202_L1.113) x anti-CD3 Fab-scFv-Fcs. Human CD368-Fc (Sino Biological) was covalently bound to the chip surface. Test articles were passed over at 31.25, 125, 500, and 2000 nM.

[00137] Figure 110 Surface plasmon resonance determination of CD3 affinity. Test articles are anti-CD20 (C2B8_H1.202_L1.113) x anti-CD3 Fab-scFv-Fcs. Cynomolgus monkey CD368-Fc (Sino Biological) was covalently bound to the chip surface. Test articles were passed over at 31.25, 125, 500, and 2000 nM.

[00138] Figure 111 Surface plasmon resonance determination of CD3 affinity. Test articles are anti-CD20 (C2B8_H1.202_L1.113) x anti-CD3 Fab-scFv-Fcs. Cynomolgus monkey CD368-Fc (Sino Biological) was covalently bound to the chip surface. Test articles were passed over at 31.25, 125, 500, and 2000 nM.

[00139] Figure 112 Redirected T cell cytotoxicity assay, 24 h incubation, 10k Ramos cells, 250k PBMC. Test articles are anti-CD20 (C2B8_H1.202_L1.113) x anti-CD3 Fab-scFv-Fcs. Detection was by LDH.

[00140] Figure 113 Redirected T cell cytotoxicity assay, 24 h incubation, 20k Jeko cells, 200k PBMC (CD19-depleted). Test articles are anti-CD20 (C2B8_H1.202_L1.113) x anti-CD3 Fab-scFv-Fcs. Detection was by flow cytometry, specifically the disappearance of CD19+ cells.

[00141] Figure 114 IL-6 production after 24 h for the experiment described in Figure

113.

[00142] Figure 115 Redirected T cell cytotoxicity assay, 5 h incubation, 20k Jeko cells,

500k PBMC (CD19-depleted). Test articles are anti-CD20 (C2B8_H1L1) x anti-CD3 Fab-scFv-Fcs. Detection was by flow cytometry, specifically the disappearance of CD19+ cells.

[00143] Figure 116 Redirected T cell cytotoxicity assay, 24 h incubation, 20k Jeko cells,

500k PBMC (CD19-depleted). Test articles are anti-CD20 (C2B8_H1.202_L1.113) x anti-CD3 Fab-scFv-Fcs. Detection was by flow cytometry, specifically the disappearance of CD19+ cells.

[00144] Figure 117 IL-6 production after 24 h for the experiment described in Figure

113.

[00145] Figure 118 Redirected T cell cytotoxicity assay, 24 h incubation, 10k

RPMI8226 cells, 500k PBMC. Test articles are anti-CD38 (OKT10_H1L1,

OKT10_H1.77_L1.24) x anti-CD3 Fab-scFv-Fcs. Detection was by LDH.

[00146] Figure 119 huPBL-SCID Ig-depletion study. Test articles were dosed 1 and 8 d after PBMC engraftment at 5 mg/kg. Route of administration was intraperitoneal. Blood samples were taken 14 d after PBMC engraftment, processed to serum, and assayed for human IgM and IgG2.

[00147] Figure 120 huPBL-SCID Ig-depletion study. Test articles were dosed 8 d after

PBMC engraftment at 0.03, 0.3, or 3 mg kg. Route of administration was intraperitoneal.

Blood samples were taken 14 d after PBMC engraftment, processed to serum, and assayed for human IgM and IgG2.

[00148] Figure 121 depicts the sequences of High CD20 C2B8_H1.202_L1.113. The charged linker depicted is (+H), although other charged or uncharged linkers can be used, such as those depicted in Figure 33.

[00149] Figure 122 depicts the sequences of Low CD20 C2B8_H1L1. The charged linker depicted is (+H), although other charged or uncharged linkers can be used, such as those depicted in Figure 33.

[00150] Figure 123 depicts the sequences of CD123 7G3_H1.109_L1.57. The charged linker depicted is (+H), although other charged or uncharged linkers can be used, such as those depicted in Figure 33.

[00151] Figure 124 shows a matrix of possible combinations for the invention. An

"A" means that the CDRs of the referenced CD3 sequences can be combined with the CDRs of the TTA on the right hand side. That is, the vhCDRs from the variable heavy chain CD3 HI.30 sequence and the vlCDRs from the variable light chain of CD3 LI.57 sequence can be combined with the vhCDRs from the CD38 OKT10 HI.77 sequence and the vlCDRs from the OKT10L1.24 sequence. A "B" means that the CDRs from the CD3 constructs can be combined with the variable heavy and light domains from the TTA. That is, the vhCDRs from the variable heavy chain CD3 HI.30 sequence and the vlCDRs from the variable light chain of CD3 LI.57 sequence can be combined with the variable heavy domain CD38 OKT10 HI.77 sequence and the OKT10L1.24 sequence. A "C" is reversed, such that the variable heavy domain and variable light domain from the CD3 sequences are used with the CDRs of the TTAs. A "D" is where both the variable heavy and variable light chains from each are combined. An "E" is where the scFv of the CD3 is used with the CDRs of the TTA, and an "F" is where the scFv of the CD3 is used with the variable heavy and variable light domains of the TTA antigen binding domain. All of these combinations can be done in bottle opener formats, for example with any of the backbone formats shown in Figure 162, or in alternative formats, such as mAb-Fv, mAb-scFv, Central-scFv, Central-Fv or dual scFv formats of Figure 1, including the format backbones shown in Figures 131 and 132). In general, however,

formats that would include bivalent binding of CD3 are disfavored. That is, "A"s (CD3 CDRs X TTA CDRs) can be added to bottle opener sequences (including those of Figure 162 or inclusive of different heterodimerization variants) or into a mAb-scFv backbone of Figure 132, a central-scFv, a mAb-Fv format or a central-Fv format.

[00152] Figure 125. Schematic of anti-CD123 x anti-CD3 Fab-scFv-Fc bispecific.

[00153] Figure 126. Table showing variants engineered to increase affinity and stability of 7G3_H1L1.

[00154] Figure 127. Table showing the properties of final affinity and stability optimized humanized variants of 7G3.

[00155] Figure 128. Binding of XENP14045 (anti-CD123 x anti-CD3) bispecific binding to the CD123 positive AML cell line KG-la.

[00156] Figure 129. Redirected T cell cytotoxicity (RTCC) of XENP14045 killing KG-la cells.

[00157] Figure 130. RTCC of XENP14045 with KG-la cells using different ratios of effector to target (E:T) cells, demonstrating the "serial killing" by T cells generated by XENP14045.

[00158] Figure 131. Drug serum levels of 2 mg/kg XENP14045 given IV to C57BL/6 mice. The half-life of bispecific was 6.2 days.

[00159] Figure 132. Killing of CD123+ blood basophils and plasmacytoid dendritic cells (PDCs) in cynomolgus monkeys given a single IV dose of 0.01, 0.1, or 1 mg kg

XENP14045.

[00160] Figure 133. Killing of CD123+ basophils and plasmacytoid dendritic cells

(PDCs) in the bone marrow of cynomolgus monkeys given a single IV dose of 0.01, 0.1, or 1 mg/kg XENP14045.

[00161] Figure 134. Redistribution of T cells following a single IV dose of XENP14045 in cynomolgus monkeys.

[00162] Figure 135. CD69 induction of T cells following a single IV dose of

XENP14045 in cynomolgus monkeys.

[00163] Figure 136A-136C. Sequences of the invention. CDR regions are underlined.

[00164] Figure 137. Heterodimer purity during stable pool generation using varied

Light chain, Fab-Fc, and scFv-Fc ratios (top). Heterodimer purity of various conditions of pool F2 (bottom).

[00165] Figure 138. SEC showing high purity of XENP14045 cell line material after two-step purification.

[00166] Figure 139 depicts the T cell killing of CD123+ cells.

[00167] Figure 140 depicts the bispecific mechanism to recruit cytotoxic T cells to kill

AML stem cells and blasts.

[00168] Figure 141 depicts the efficient production of the XENP14045 bispecific.

[00169] Figure 142 shows that the XENP14045 bispecific antibody binds to human

AML, with a KD of 8.1 nM to human CD3.

[00170] Figure 143 shows that the XENP14045 bispecific antibody is cross reactive with primate cells, and has a KD of 5.7 nM to cyno CD3.

[00171] Figure 144 shows that the anti-CD123 X anti-CD3 kills human AML cell lines.

[00172] Figure 145 shows that the anti-CD123 X anti-CD3 kills human AML cell lines.

[00173] Figure 146 shows the long half life of the bispecific in mice.

[00174] Figure 147 shows the single dose in monkeys.

[00175] Figure 148 shoes the depletion of CD123+ cells in monkeys in blood basophiles. Basophil gate, flow cytometry is CD20- CD16+ CD14- CD4- CD8- FceRl+.

[00176] Figure 149 shows the depletion in bone marrow basophils, using the same gating.

[00177] Figure 150 shows the repeat dosing that depletes CD123+ cells in monkeys.

[00178] Figure 151 shows the depletion of CD123+ cells in monkeys. Basophil gate, flow cytometry is CD20- CD16+ CD14- CD4- CD8- FceRl+. Plasmoacytoid dendritic cell gate, flow cytometiry: CD20- CD16- CD14- Cd4- CD8- CD303+.

[00179] Figure 152 shows depletion in bone marrow in monkeys. Gating as in Figure

151.

[00180] Figure 153 shows the CD123+ cell depletion correlates with T cell

redistibution and activation; Figure 153 is T cell redistribtion.

[00181] Figure 154 shows the CD123+ cell depletion correlates with T cell

redistibution and activation; Figure 154 is T cell activation.

[00182] Figure 155 shows the CD123+ cell depletion correlates with T cell

redistibution and activation; Figure 155 is cytokine release.

[00183] Figures 156A-156D depicts materials associated with the difficulty of humanizing anti-CD123 murine sequences as described in Example 3. Figure 125A-C shows the loss of affinity due to the humanization (mainly through vH), as 13760 is the Fab of the H0L0 starting murine antibody, with 13763 being the first humanized vH candidate and 13761 having both humanized heavy and light Fab chains. Figure 125D shows the -10 fold loss in RTCC potency as a result of the humanization.

[00184] Figure 157 depicts the results of a first round of humanization ("library 1"), generating 108 variants, including LDA, targeted and reversion substitutions that were affinity screened in a Fab format on a Biacore CD123 chip, with the stability of neutral and higher affinity variants screened on DSF.

[00185] Figure 158A and 158B shows the increases in Tm as discussed in Example 3.

[00186] Figures 159A and 159B shows the results of turning the Fabs into a bottle opener format, using a scFv to CD3 and the Fab as developed. Figure 159A shows the binding assay and Figure 159B shows the RTCC assay.

[00187] Figures 160A-160E show the results from "round 2" of the humanization as outlined in Example 3. It should be noted that XENP13967 is the equivalent to XENP14045 on the CD123 side; 13967 has a different CD3 scFv as shown in the sequences.

[00188] Figure 161 shows the results of the round 2 Tm assay of Example 3.

[00189] Figure 162A-162D shows the sequences of several useful bottle opener format backbones, without the Fv sequences (e.g. the scFv and the vh and vl for the Fab side). As will be appreciated by those in the art and outlined below, these sequences can be used with any vh and vl pairs outlined herein, with one monomer including a scFv (optionally including a charged scFv linker) and the other monomer including the Fab sequences (e.g. a vh attached to the "Fab side heavy chain" and a vl attached to the "constant light chain"). The scFv can be anti-CD3 or anti-TTA, with the Fab being the other. That is, any Fv sequences outlined herein for CD3, CD123, CD38, CD19 or CD20 can be incorporated into these Figure 162 backbones in any combination.

[00190] It should be noted that these bottle opener backbones find use in the Central-scFv format of Figure IB, where an additional, second Fab (vh-CHl and vl-constant light) with the same antigen binding as the first Fab is added to the N-terminus of the scFv on the "bottle opener side".

[00191] Figure 163 shows the sequence of a mAb-scFv backbone of use in the invention, to which the Fv sequences of the invention are added. As will be appreciated by those in the art and outlined below, these sequences can be used with any vh and vl pairs outlined herein, with one monomer including both a Fab and an scFv (optionally including a charged scFv linker) and the other monomer including the Fab sequence (e.g. a vh attached to the "Fab side heavy chain" and a vl attached to the "constant light chain"). The monomer 1 side is the Fab-scFv pi negative side, and includes the heterodimerization variants L368D/ 370S, the isosteric pi variants N208D/Q295E/N384D/Q418E/N421D, the ablation variants E233P/L234V/L235A/G236del/S267K, (all relative to IgGl). The monomer 2 side is the scFv pi positive side, and includes the heterodimerization variants 364K E357Q.

However, other skew variant pairs can be substituted, particularly [S364K/E357Q :

L368D / 370S]; [L368D / K370S: S364K]; [L368E / K370S: S364K]; [T411T / E360E / Q362E:

D401K]; [L368D/ 370S : S364K/E357L] and [K370S : S364K/E357Q].

DETAILED DESCRIPTION OF THE INVENTION

I. Definitions

[00192] In order that the application may be more completely understood, several definitions are set forth below. Such definitions are meant to encompass grammatical equivalents.

[00193] By "ablation" herein is meant a decrease or removal of activity. Thus for example, "ablating FcyR binding" means the Fc region amino acid variant has less than 50% starting binding as compared to an Fc region not containing the specific variant, with less than 70-80-90-95-98% loss of activity being preferred, and in general, with the activity being below the level of detectable binding in a Biacore assay. Of particular use in the ablation of FcyR binding are those shown in Figure 16.

[00194] By "ADCC" or "antibody dependent cell-mediated cytotoxicity" as used herein is meant the cell-mediated reaction wherein nonspecific cytotoxic cells that express FcyRs recognize bound antibody on a target cell and subsequently cause lysis of the target cell. ADCC is correlated with binding to FcyRIIIa; increased binding to FcyRIIIa leads to an increase in ADCC activity.

[00195] By "ADCP" or antibody dependent cell-mediated phagocytosis as used herein is meant the cell-mediated reaction wherein nonspecific cytotoxic cells that express FcyRs recognize bound antibody on a target cell and subsequently cause phagocytosis of the target cell.

[00196] By "modification" herein is meant an amino acid substitution, insertion, and/or deletion in a polypeptide sequence or an alteration to a moiety chemically linked to a protein. For example, a modification may be an altered carbohydrate or PEG structure attached to a protein. By "amino acid modification" herein is meant an amino acid substitution, insertion, and/or deletion in a polypeptide sequence. For clarity, unless otherwise noted, the amino acid modification is always to an amino acid coded for by DNA, e.g. the 20 amino acids that have codons in DNA and RNA.

[00197] By "amino acid substitution" or "substitution" herein is meant the replacement of an amino acid at a particular position in a parent polypeptide sequence with a different amino acid. In particular, in some embodiments, the substitution is to an amino acid that is not naturally occurring at the particular position, either not naturally occurring within the organism or in any organism. For example, the substitution E272Y refers to a variant polypeptide, in this case an Fc variant, in which the glutamic acid at position 272 is replaced with tyrosine. For clarity, a protein which has been engineered to change the nucleic acid coding sequence but not change the starting amino acid (for example exchanging CGG (encoding arginine) to CGA (still encoding arginine) to increase host organism expression levels) is not an ''amino acid substitution"; that is, despite the creation of a new gene encoding the same protein, if the protein has the same amino acid at the particular position that it started with, it is not an amino acid substitution.

[00198] By "amino acid insertion" or "insertion" as used herein is meant the addition of an amino acid sequence at a particular position in a parent polypeptide sequence. For example, -233E or 233E designates an insertion of glutamic acid after position 233 and before position 234. Additionally, -233 ADE or A233ADE designates an insertion of AlaAspGlu after position 233 and before position 234.

[00199] By "amino acid deletion" or "deletion" as used herein is meant the removal of an amino acid sequence at a particular position in a parent polypeptide sequence. For example, E233- or E233# or E233()designates a deletion of glutamic acid at position 233. Additionally, EDA233- or EDA233# designates a deletion of the sequence GluAspAla that begins at position 233.

[00200] By "variant protein" or "protein variant", or "variant" as used herein is meant a protein that differs from that of a parent protein by virtue of at least one amino acid modification. Protein variant may refer to the protein itself, a composition comprising the protein, or the amino sequence that encodes it. Preferably, the protein variant has at least one amino acid modification compared to the parent protein, e.g. from about one to about seventy amino acid modifications, and preferably from about one to about five amino acid modifications compared to the parent. As described below, in some embodiments the parent polypeptide, for example an Fc parent polypeptide, is a human wild type sequence, such as the Fc region from IgGl, IgG2, IgG3 or IgG4, although human sequences with variants can also serve as "parent polypeptides", for example the IgGl/2 hybrid of Figure 19. The protein variant sequence herein will preferably possess at least about 80% identity with a parent protein sequence, and most preferably at least about 90% identity, more preferably at least about 95-98-99% identity . Variant protein can refer to the variant protein itself,

compositions comprising the protein variant, or the DNA sequence that encodes it.

Accordingly, by "antibody variant" or "variant antibody" as used herein is meant an

antibody that differs from a parent antibody by virtue of at least one amino acid

modification, "IgG variant" or "variant IgG" as used herein is meant an antibody that differs from a parent IgG (again, in many cases, from a human IgG sequence) by virtue of at least one amino acid modification, and "immunoglobulin variant" or "variant immunoglobulin" as used herein is meant an immunoglobulin sequence that differs from that of a parent immunoglobulin sequence by virtue of at least one amino acid modification. "Fc variant" or "variant Fc" as used herein is meant a protein comprising an amino acid modification in an Fc domain. The Fc variants of the present invention are defined according to the amino acid modifications that compose them. Thus, for example, N434S or 434S is an Fc variant with the substitution serine at position 434 relative to the parent Fc polypeptide, wherein the numbering is according to the EU index. Likewise, M428L/N434S defines an Fc variant with the substitutions M428L and N434S relative to the parent Fc polypeptide. The identity of the WT amino acid may be unspecified, in which case the aforementioned variant is referred to as 428L/434S. It is noted that the order in which substitutions are provided is arbitrary, that is to say that, for example, 428L/434S is the same Fc variant as M428L/ 434S, and so on. For all positions discussed in the present invention that relate to antibodies, unless otherwise noted, amino acid position numbering is according to the EU index. The EU index or EU index as in Kabat or EU numbering scheme refers to the numbering of the EU antibody (Edelman et al., 1969, Proc Natl Acad Sci USA 63:78-85, hereby entirely incorporated by reference.) The modification can be an addition, deletion, or substitution. Substitutions can include naturally occurring amino acids and, in some cases, synthetic amino acids. Examples include U.S. Pat. No. 6,586,207; WO 98/48032; WO 03/073238; US2004-0214988A1; WO 05/35727A2; WO 05/74524A2; J. W. Chin et al., (2002), Journal of the American Chemical Society 124:9026-9027; J. W. Chin, & P. G. Schultz, (2002), ChemBioChem 11:1135-1137; J. W. Chin, et al., (2002), PICAS United States of America 99:11020-11024; and, L. Wang, & P. G. Schultz, (2002), Chem. 1-10, all entirely incorporated by reference.

[00201] As used herein, "protein" herein is meant at least two covalently attached amino acids, which includes proteins, polypeptides, oligopeptides and peptides. The peptidyl group may comprise naturally occurring amino acids and peptide bonds, or synthetic peptidomimetic structures, i.e. "analogs", such as peptoids (see Simon et al., PNAS USA 89(20):9367 (1992), entirely incorporated by reference). The amino acids may either be naturally occurring or synthetic (e.g. not an amino acid that is coded for by DNA); as will be appreciated by those in the art. For example, homo-phenylalanine, dtrulline, ornithine and noreleucine are considered synthetic amino acids for the purposes of the invention, and both D- and L-(R or S) configured amino acids may be utilized. The variants of the present invention may comprise modifications that include the use of synthetic amino acids incorporated using, for example, the technologies developed by Schultz and colleagues, including but not limited to methods described by Cropp & Shultz, 2004, Trends Genet. 20(12) :625-30, Anderson et al., 2004, Proc Natl Acad Sci USA 101 (2):7566-71, Zhang et al., 2003, 303(5656):371-3, and Chin et al., 2003, Science 301(5635):964-7, all entirely incorporated by reference. In addition, polypeptides may include synthetic derivatization of one or more side chains or termini, glycosylation, PEGylation, circular permutation, cyclization, linkers to other molecules, fusion to proteins or protein domains, and addition of peptide tags or labels.

[00202] By "residue" as used herein is meant a position in a protein and its associated amino acid identity. For example, Asparagine 297 (also referred to as Asn297 or N297) is a residue at position 297 in the human antibody IgGl.

[00203] By "Fab" or "Fab region" as used herein is meant the polypeptide that comprises the VH, CHI, VL, and CL immunoglobulin domains. Fab may refer to this region in isolation, or this region in the context of a full length antibody, antibody fragment or Fab fusion protein. By "Fv" or "Fv fragment" or "Fv region" as used herein is meant a polypeptide that comprises the VL and VH domains of a single antibody. As will be appreciated by those in the art, these generally are made up of two chains.

[00204] By "IgG subclass modification" or "isotype modification" as used herein is meant an amino acid modification that converts one amino acid of one IgG isotype to the corresponding amino acid in a different, aligned IgG isotype. For example, because IgGl comprises a tyrosine and IgG2 a phenylalanine at EU position 296, a F296Y substitution in IgG2 is considered an IgG subclass modification.

[00205] By "non-naturally occurring modification" as used herein is meant an amino acid modification that is not isotypic. For example, because none of the IgGs comprise a serine at position 434, the substitution 434S in IgGl, IgG2, IgG3, or IgG4 (or hybrids thereof) is considered a non-naturally occurring modification.

[00206] By "amino acid" and "amino acid identity" as used herein is meant one of the

20 naturally occurring amino acids that are coded for by DNA and RNA.

[00207] By "effector function" as used herein is meant a biochemical event that results from the interaction of an antibody Fc region with an Fc receptor or ligand. Effector functions include but are not limited to ADCC, ADCP, and CDC.

[00208] By "IgG Fc ligand" as used herein is meant a molecule, preferably a polypeptide, from any organism that binds to the Fc region of an IgG antibody to form an Fc/Fc ligand complex. Fc ligands include but are not limited to FcyRIs, FcyRIIs, FcyRIIIs, FcRn, Clq, C3, mannan binding lectin, mannose receptor, staphylococcal protein A, streptococcal protein G, and viral FcyR. Fc ligands also include Fc receptor homologs (FcRH), which are a family of Fc receptors that are homologous to the FcyRs (Davis et al., 2002, Immunological Reviews 190:123-136, entirely incorporated by reference). Fc ligands may include undiscovered molecules that bind Fc. Particular IgG Fc ligands are FcRn and Fc gamma receptors. By "Fc ligand" as used herein is meant a molecule, preferably a polypeptide, from any organism that binds to the Fc region of an antibody to form an Fc/Fc ligand complex.

[00209] By "Fc gamma receptor", "FcyR" or "FcqammaR" as used herein is meant any member of the family of proteins that bind the IgG antibody Fc region and is encoded by an FcyR gene. In humans this family includes but is not limited to FcyRI (CD64), including isoforms FcyRIa, FcyRIb, and FcyRIc; FcyRII (CD32), including isoforms FcyRIIa (including allotypes H131 and R131), FcyRIIb (including FcyRIIb-l and FcyRIIb-2), and FcyRIIc; and FcyRIII (CD16), including isoforms FcyRIIIa (including allotypes V158 and F158) and FcyRIIIb (including allotypes FcyRIIb-NAl and FcyRIIb-NA2) (Jefferis et al., 2002, Immunol Lett 82:57-65, entirely incorporated by reference), as well as any undiscovered human FcyRs or FcyR isoforms or allotypes. An FcyR may be from any organism, including but not

limited to humans, mice, rats, rabbits, and monkeys. Mouse FcyRs include but are not limited to FcyRI (CD64), FcyRII (CD32), FcyRIII (CD16), and FcyRIII-2 (CD16-2), as well as any undiscovered mouse FcyRs or FcyR isoforms or allotypes.

[00210] By "FcRn" or "neonatal Fc Receptor" as used herein is meant a protein that binds the IgG antibody Fc region and is encoded at least in part by an FcRn gene. The FcRn may be from any organism, including but not limited to humans, mice, rats, rabbits, and monkeys. As is known in the art, the functional FcRn protein comprises two polypeptides, often referred to as the heavy chain and light chain. The light chain is beta-2-microglobulin and the heavy chain is encoded by the FcRn gene. Unless otherwise noted herein, FcRn or an FcRn protein refers to the complex of FcRn heavy chain with beta-2-microglobulin. A variety of FcRn variants used to increase binding to the FcRn receptor, and in some cases, to increase serum half-life, are shown in the Figure Legend of Figure 83.

[00211] By "parent polypeptide" as used herein is meant a starting polypeptide that is subsequently modified to generate a variant. The parent polypeptide may be a naturally occurring polypeptide, or a variant or engineered version of a naturally occurring polypeptide. Parent polypeptide may refer to the polypeptide itself, compositions that comprise the parent polypeptide, or the amino acid sequence that encodes it. Accordingly, by "parent immunoglobulin" as used herein is meant an unmodified immunoglobulin polypeptide that is modified to generate a variant, and by "parent antibody" as used herein is meant an unmodified antibody that is modified to generate a variant antibody. It should be noted that "parent antibody" includes known commercial, recombinantly produced antibodies as outlined below.

[00212] By "Fc" or "Fc region" or "Fc domain" as used herein is meant the polypeptide comprising the constant region of an antibody excluding the first constant region immunoglobulin domain and in some cases, part of the hinge. Thus Fc refers to the last two constant region immunoglobulin domains of IgA, IgD, and IgG, the last three constant region immunoglobulin domains of IgE and IgM, and the flexible hinge N-terminal to these domains. For IgA and IgM, Fc may include the J chain. For IgG, the Fc domain comprises immunoglobulin domains Cy2 and Cy3 (Cy2 and Cy3) and the lower hinge region between Cyl (Cyl) and Cy2 (Cy2). Although the boundaries of the Fc region may

vary, the human IgG heavy chain Fc region is usually defined to include residues C226 or P230 to its carboxyl-terminus, wherein the numbering is according to the EU index as in Kabat. In some embodiments, as is more fully described below, amino acid modifications are made to the Fc region, for example to alter binding to one or more FcyR receptors or to the FcRn receptor.

[00213] By "heavy constant region" herein is meant the CHl-hinge-CH2-CH3 portion of an antibody.

[00214] By "Fc fusion protein" or "immunoadhesin" herein is meant a protein comprising an Fc region, generally linked (optionally through a linker moiety, as described herein) to a different protein, such as a binding moiety to a target protein, as described herein. In some cases, one monomer of the heterodimeric antibody comprises an antibody heavy chain (either including an scFv or further including a light chain) and the other monomer is a Fc fusion, comprising a variant Fc domain and a ligand. In some

embodiments, these "half antibody-half fusion proteins" are referred to as "Fusionbodies".

[00215] By "position" as used herein is meant a location in the sequence of a protein.

Positions may be numbered sequentially, or according to an established format, for example the EU index for antibody numbering.

[00216] By "target antigen" as used herein is meant the molecule that is bound specifically by the variable region of a given antibody. A target antigen may be a protein, carbohydrate, lipid, or other chemical compound. A wide number of suitable target antigens are described below.

[00217] By "strandedness" in the context of the monomers of the heterodimeric antibodies of the invention herein is meant that, similar to the two strands of DNA that "match", heterodimerization variants are incorporated into each monomer so as to preserve the ability to "match" to form heterodimers. For example, if some pi variants are engineered into monomer A (e.g. making the pi higher) then steric variants that are "charge pairs" that can be utilized as well do not interfere with the pi variants, e.g. the charge variants that make a pi higher are put on the same "strand" or "monomer" to preserve both

functionalities. Similarly, for "skew" variants that come in pairs of a set as more fully outlined below, the skilled artisan will consider pi in deciding into which strand or monomer that incorporates one set of the pair will go, such that pi separation is maximized using the pi of the skews as well.

[00218] By "target cell" as used herein is meant a cell that expresses a target antigen.

WHAT IS CLAIMED IS:

1. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first heavy chain comprising:

1) a first variable heavy domain;

2) a first constant heavy chain comprising a first Fc domain;

3) a scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the C-terminus of said Fc domain using a domain linker;

b) a second monomer comprising a second heavy chain comprising a second variable heavy domain and a second constant heavy chain comprising a second Fc domain; and

c) a common light chain comprising a variable light domain and a constant light domain;

wherein said first and said second Fc domains have a set of amino acid substitutions selected from the group consisting of S364K/E357Q : L368D/ 370S; L368D/K370S : S364K; L368E/ 370S : S364K; T411T E360E/Q362E : D401K; L368D/K370S : S364K/E357L and K370S : S364K E357Q, and wherein said first variable heavy domain and said variable light domain bind a first target tumor antigen (TTA), said second variable heavy domain and said variable light domain bind said first TTA, and said scFv binds human CD3 (SEQ ID NO:XX).

2. A heterodimeric antibody according to claim 1 wherein said scFv has a polypeptide sequence selected from the group consisting of SEQ ID NO:XX (scFv 13551), SEQ ID NO:XX(scFv 15426), SEQ ID NO:XX(scFv 13423) and SEQ ID NO:XX(scFv 14702).

3. A heterodimeric antibody according to claim 1 or 2 wherein said first variable heavy domain and said variable light domain bind a TTA selected from the group consisting of CD19, CD20 and CD123.

4. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first heavy chain comprising:

1) a first variable heavy domain;

2) a first constant heavy domain comprising a first Fc domain; and

3) a first variable light domain, wherein said first variable light domain is covalently attached to the C-terminus of said first Fc domain using a domain linker;

b) a second monomer comprising:

i) a second variable heavy domain;

ii) a second constant heavy domain comprising a second Fc domain; and iii) a third variable heavy domain, wherein said second variable heavy domain is covalently attached to the C-terminus of said second Fc domain using a domain linker;

c) a common light chain comprising a variable light domain and a constant light domain;

wherein said first and said second Fc domain have a set of amino acid substitutions selected from the group consisting of S364K/E357Q : L368D/ 370S; L368D/K370S : S364K;

L368E/ 370S : S364K; T411T E360E/Q362E : D401K; L368D/K370S : S364K E357L and K370S : S364K/E357Q, wherein said first variable heavy domain and said variable light domain bind a first TTA, said second variable heavy domain and said variable light domain bind said TTA, and said second variable light domain and said third variable heavy domain bind CD3.

5. A heterodimeric antibody according to claim 4 wherein said scFv has a polypeptide sequence selected from the group consisting of SEQ ID NO:XX(scFv 13551), SEQ ID NO:XX(scFv 15426), SEQ ID NO:XX(scFv 13423) and SEQ ID NO:XX(scFv 14702).

6. A heterodimeric antibody according to claim 4 or 5 wherein said first variable heavy domain and said variable light domain bind a TTA selected from the group consisting of CD19, CD20 and CD123.

7. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first heavy chain comprising:

1) a first variable heavy domain;

2) a first constant heavy chain comprising a first CHI domain and a first Fc domain;

3) a scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached between the C-terminus of said CHI domain and the N-terminus of said first Fc domain using domain linkers;

b) a second monomer comprising a second heavy chain comprising a second variable heavy domain and a second constant heavy chain comprising a second Fc domain; and

c) a common light chain comprising a variable light domain and a constant light domain;

wherein said first and said second Fc domain have a set of amino acid substitutions selected from the group consisting of S364K/E357Q : L368D/ 370S; L368D/K370S : S364K;

L368E/ 370S : S364K; T411T E360E/Q362E : D401K; L368D/K370S : S364K E357L and K370S : S364K E357Q, wherein said first variable heavy domain and said variable light domain bind a first TTA, said second variable heavy domain and said variable light domain bind said TTA, and said scFv binds human CD3.

8. A heterodimeric antibody according to claim 7 wherein said scFv has a polypeptide sequence selected from the group consisting of SEQ ID NO:XX(scFv 13551), SEQ ID NO:XX(scFv 15426), SEQ ID NO:XX(scFv 13423) and SEQ ID NO:XX(scFv 14702).

9. A heterodimeric antibody according to claim 7 or 8 wherein said first variable heavy domain and said variable light domain bind a TTA selected from the group consisting of CD19, CD20 and CD123.

10. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first heavy chain comprising:

1) a first variable heavy domain;

2) a first constant heavy domain comprising a first Fc domain; and

3) a first variable light domain, wherein said second variable light domain is covalently attached between the C-terminus of the CHI domain of said first constant heavy domain and the N-terminus of said first Fc domain using domain linkers; b) a second monomer comprising:

i) a second variable heavy domain;

ii) a second constant heavy domain comprising a second Fc domain; and iii) a third variable heavy domain, wherein said second variable heavy domain is covalently attached to the C-terminus of said second Fc domain using a domain linker;

c) a common light chain comprising a variable light domain and a constant light domain;

wherein said first and said second Fc domains have a set of amino acid substitutions selected from the group consisting of S364K/E357Q : L368D/ 370S; L368D/K370S : S364K; L368E/ 370S : S364K; T411T E360E/Q362E : D401K; L368D/K370S : S364K E357L and K370S : S364K E357Q, wherein said first variable heavy domain and said variable light domain bind a first TTA, said second variable heavy domain and said variable light domain bind said TTA, and said second variable light domain and said third variable heavy domain binds human CD3.

11. A heterodimeric antibody according to claim 10 wherein said scFv has a polypeptide sequence selected from the group consisting of SEQ ID NO:XX(scFv 13551), SEQ ID NO:XX(scFv 15426), SEQ ID NO:XX(scFv 13423) and SEQ ID NO:XX(scFv 14702).

12. A heterodimeric antibody according to claim 10 or 11 wherein said first variable heavy domain and said variable light domain bind a TTA selected from the group consisting of CD19, CD20 and CD123.

13. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first heavy chain comprising:

1) a first variable heavy domain;

2) a first constant heavy chain comprising a first CHI domain and a first Fc domain;

3) a scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached between the C-terminus of said CHI domain and the N-terminus of said first Fc domain using domain linkers;

b) a second monomer comprising a second Fc domain; and

c) a light chain comprising a variable light domain and a constant light domain; wherein said first and said second Fc domain have a set of amino acid substitutions selected from the group consisting of S364K/E357Q : L368D/ 370S; L368D/K370S : S364K;

L368E/ 370S : S364K; T411T E360E/Q362E : D401K; L368D/K370S : S364K E357L and K370S : S364K E357Q, wherein said first variable heavy domain and said variable light domain bind a first antigen, said scFv binds a second antigen.

14. A heterodimeric antibody according to claim 13 wherein said scFv has a polypeptide sequence selected from the group consisting of SEQ ID NO:XX(scFv 13551), SEQ ID NO:XX(scFv 15426), SEQ ID NO:XX(scFv 13423) and SEQ ID NO:XX(scFv 14702).

15. A heterodimeric antibody according to claim 13or 14 wherein said first variable

heavy domain and said variable light domain bind a TTA selected from the group consisting of CD19, CD20 and CD123.

16. An anti-CD3 antibody binding domain comprising:

a) a variable light domain comprising a vlCDRl having the sequence

GSSTGAVTTSNYAN (SEQ ID NO:XX), a vlCDR2 having the sequence GTNKRAP (SEQ ID NO:XX), and a vlCDR3 having the sequence ALWYSNHWV (SEQ ID NO:XX); and

b) a variable heavy domain comprises a vhCDRl having the sequence TYAMN (SEQ ID NO:XX), a vhCDR2 having the sequence RIRSKANNYATYYADSVKG (SEQ ID NO:XX) and a vhCDR3 having the sequence HGNFGDSYVSWFAY (SEQ ID NO:XX).

17. An anti-CD3 antibody binding domain according to claim 16 wherein said binding domain is a scFv.

18. An anti-CD3 antibody binding domain according to claim 16 or 17 wherein said variable light domain has the sequence LI.47 (SEQ ID NO:XX) and said variable heavy domain has the sequence H1.32 (SEQ ID NO:XX).

19. An anti-CD3 antibody binding domain according to claim 18 wherein said scFv has the sequence H1.32_L1.47 (SEQ ID NO:XX).

20. A nucleic acid composition encoding the scFv of claim 19.

21. An expression vector comprising the nucleic acid composition of claim 20.

22. A host cell comprising the expression vector of claim 21.

23. An anti-CD3 antibody binding domain comprising:

a) a variable light domain comprising a vlCDRl having the sequence GSSTGAVTTSNYAN (SEQ ID NO:XX), a vlCDR2 having the sequence GTNKRAP (SEQ ID NO:XX), and a vlCDR3 having the sequence ALWYSNHWV (SEQ ID NO:XX); and

b) a variable heavy domain comprises a vhCDRl having the sequence TYAMN (SEQ ID NO:XX), a vhCDR2 having the sequence

RIRSKYNNYATYYADSVKG (SEQ ID NO:XX) and a vhCDR3 having the sequence HGNFGDEYVSWFAY (SEQ ID NO:XX).

24. An anti-CD3 antibody binding domain according to claim 23 wherein said binding domain is a scFv.

25. An anti-CD3 antibody binding domain according to claim 23 or 24 wherein said variable light domain has the sequence LI.47 (SEQ ID NO:XX) and said variable heavy domain has the sequence H1.89 (SEQ ID NO:XX).

26. An anti-CD3 antibody binding domain according to claim 23 wherein said scFv has the sequence H1.89_L1.47 (SEQ ID NO:XX).

27. A nucleic acid composition encoding the scFv of claim 26.

28. An expression vector comprising the nucleic acid composition of claim 27.

29. A host cell comprising the expression vector of claim 28.

30. An anti-CD3 antibody binding domain comprising:

a) a variable light domain comprising a vlCDRl having the sequence GSSTGAVTTSNYAN (SEQ ID NO:XX), a vlCDR2 having the sequence GTNKRAP (SEQ ID NO:XX), and a vlCDR3 having the sequence ALWYSNHWV (SEQ ID NO:XX); and

b) a variable heavy domain comprises a vhCDRl having the sequence TYAMN (SEQ ID NO:XX), a vhCDR2 having the sequence RIRSKYNNYATYYADSVKG (SEQ ID NO:XX) and a vhCDR3 having the sequence HGNFGDPYVSWFAY (SEQ ID NO:XX).

31. An anti-CD3 antibody binding domain according to claim 30 wherein said binding domain is a scFv.

32. An anti-CD3 antibody binding domain according to claim 30 or 31 wherein said

variable light domain has the sequence LI.47 (SEQ ID NO:XX) and said variable heavy domain has the sequence H1.90 (SEQ ID NO:XX).

33. An anti-CD3 antibody binding domain according to claim 30 wherein said scFv has the sequence H1.90_L1.47 (SEQ ID NO:XX).

34. A nucleic acid composition encoding the scFv of claim 33.

35. An expression vector comprising the nucleic acid composition of claim 34.

36. A host cell comprising the expression vector of claim 35.

37. An anti-CD3 antibody binding domain comprising:

a) a variable light domain comprising a vlCDRl having the sequence

GSSTGAVTTSNYAN (SEQ ID NO:XX), a vlCDR2 having the sequence GTNKRAP (SEQ ID NO:XX), and a vlCDR3 having the sequence ALWYSNHWV (SEQ ID NO:XX); and

b) a variable heavy domain comprises a vhCDRl having the sequence TYAMN (SEQ ID NO:XX), a vhCDR2 having the sequence RIRSKYNNYATYYADSVKG (SEQ ID NO:XX) and a vhCDR3 having the sequence HGNFGDSYVSWFDY (SEQ ID NO:XX).

38. An anti-CD3 antibody binding domain according to claim 37 wherein said binding domain is a scFv.

39. An anti-CD3 antibody binding domain according to claim 37 or 38 wherein said

variable light domain has the sequence LI.47 (SEQ ID NO:XX) and said variable heavy domain has the sequence H1.33 (SEQ ID NO:XX).

40. An anti-CD3 antibody binding domain according to claim 38 wherein said scFv has the sequence H1.33_L1.47 (SEQ ID NO:XX).

41. A nucleic acid composition encoding the scFv of claim 38.

42. An expression vector comprising the nucleic acid composition of claim 41.

43. A host cell comprising the expression vector of claim 42.

44. An anti-CD3 antibody binding domain comprising:

a) a variable light domain comprising a vlCDRl having the sequence

GSSTGAVTTSNYAN (SEQ ID NO:XX), a vlCDR2 having the sequence GTNKRAP (SEQ ID NO:XX), and a vlCDR3 having the sequence ALWYSNHWV (SEQ ID NO:XX); and

b) a variable heavy domain comprises a vhCDRl having the sequence TYAMS (SEQ ID NO:XX), a vhCDR2 having the sequence RIRSKYNNYATYYADSVKG (SEQ ID NO:XX) and a vhCDR3 having the sequence HGNFGDSYVSWFAY. (SEQ ID NO:XX).

45. An anti-CD3 antibody binding domain according to claim 44 wherein said binding domain is a scFv.

46. An anti-CD3 antibody binding domain according to claim 44 or 45 wherein said variable light domain has the sequence LI.47 (SEQ ID NO:XX) and said variable heavy domain has the sequence H1.31 (SEQ ID NO:XX).

47. An anti-CD3 antibody binding domain according to claim 46 wherein said scFv has the sequence H1.31_L1.47 (SEQ ID NO:XX).

48. A nucleic acid composition encoding the scFv of claim 47.

49. An expression vector comprising the nucleic acid composition of claim 48.

50. A host cell comprising the expression vector of claim 49.

51. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first Fc domain;

ii) an anti-CD3 scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the N-terminus of said Fc domain using a domain linker;

b) a second monomer comprising a heavy chain comprising:

i) a heavy variable domain; and

ii) a heavy chain constant domain comprising a second Fc domain; and c) a light chain comprising a variable light domain and a variable light constant domain;

wherein said anti-CD3 scFv is selected from the group consisting of anti-CD3 H1.32_L1.47 (SEQ ID NO:XX), anti-CD3 H1.89_L1.47 (SEQ ID NO:XX), anti-CD3 H1.90_L1.47 (SEQ ID NO:XX) and anti-CD3 H1.33_L1.47 (SEQ ID NO:XX), and said heavy variable domain and said light variable domain bind a TTA.

52. A heterodimeric antibody according to claim 51 wherein said TTA is selected from the group consisting of CD19, CD20 and CD123.

53. An anti-CD20 antibody binding domain comprising:

a) a variable light domain comprising a vlCDRl having the sequence RASWSVSYIH (SEQ ID NO:XX), a vlCDR2 having the sequence ATSNLAS (SEQ ID NO:XX), and a vlCDR3 having the sequence QQWTHNPPT (SEQ ID NO:XX); and

b) a variable heavy domain comprises a vhCDRl having the sequence SYNMH (SEQ ID NO:XX), a vhCDR2 having the sequence AIYPGNGATSYSQKFQG (SEQ ID NO:XX) and a vhCDR3 having the sequence SYYMGGDWYFDV (SEQ ID NO:XX).

54. An anti-CD20 antibody binding domain according to claim 53 said variable light domain has the sequence C2B8 LI.113 (SEQ ID NO:XX) and said variable heavy domain has the sequence C2B8 HI.202 (SEQ ID NO:XX).

55. A nucleic acid composition encoding the binding domain of claim 53.

56. An expression vector comprising the nucleic acid composition of claim 55.

57. A host cell comprising the expression vector of claim 56.

58. An anti-CD20 antibody binding domain comprising:

a) a variable light domain comprising a vlCDRl having the sequence RASSSVSYIH (SEQ ID NO:XX), a vlCDR2 having the sequence ATSNLAS (SEQ ID NO:XX), and a vlCDR3 having the sequence QQWTSNPPT (SEQ ID NO:XX); and

b) a variable heavy domain comprises a vhCDRl having the sequence SYNMH (SEQ ID NO:XX), a vhCDR2 having the sequence AIYPGNGDTSYNQKFQG (SEQ ID NO:XX) and a vhCDR3 having the sequence STYYGGDWYFNV (SEQ ID NO:XX).

59. An anti-CD20 antibody binding domain according to claim 58 said variable light domain has the sequence C2B8 LI (SEQ ID NO:XX) and said variable heavy domain has the sequence C2B8 HI (SEQ ID NO:XX).

60. A nucleic acid composition encoding the binding domain of claim 58.

61. An expression vector comprising the nucleic acid composition of claim 60.

62. A host cell comprising the expression vector of claim 61.

63. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first Fc domain;

ii) an anti-CD3 scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the N-terminus of said Fc domain using a domain linker;

b) a second monomer comprising a heavy chain comprising:

i) a heavy variable domain; and

ii) a heavy chain constant domain comprising a second Fc domain; and c) a light chain comprising a variable light domain and a variable light constant domain; wherein said variable light domain comprises a vlCDRl having the sequence RASSSVSYIH (SEQ ID NO:XX), a vlCDR2 having the sequence ATSNLAS (SEQ ID NO:XX), and a vlCDR3 having the sequence QQWTSNPPT (SEQ ID NO:XX) and said variable heavy domain comprises a vhCDRl having the sequence SYNMH (SEQ ID NO:XX), a vhCDR2 having the sequence AIYPGNGDTSYNQKFQG (SEQ ID NO:XX) and a vhCDR3 having the sequence STYYGGDWYFNV (SEQ ID NO:XX).

64. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first Fc domain;

ii) an anti-CD3 scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the N-terminus of said Fc domain using a domain linker;

b) a second monomer comprising a heavy chain comprising:

i) a heavy variable domain; and

ii) a heavy chain constant domain comprising a second Fc domain; and c) a light chain comprising a variable light domain and a variable light constant domain;

wherein said variable light domain comprises a vlCDRl having the sequence RASSSVSYIH (SEQ ID NO:XX), a vlCDR2 having the sequence ATSNLAS (SEQ ID NO:XX), and a vlCDR3 having the sequence QQWTSNPPT (SEQ ID NO:XX) and said variable heavy domain comprises a vhCDRl having the sequence SYNMH (SEQ ID NO:XX), a vhCDR2 having the sequence AIYPGNGDTSYNQKFQG (SEQ ID NO:XX) and a vhCDR3 having the sequence STYYGGDWYFNV (SEQ ID NO:XX).

65. A heterodimeric antibody comprising:

a) a first monomer comprising:

i) a first Fc domain;

ii) an anti-CD3 scFv comprising a scFv variable light domain, an scFv linker and a scFv variable heavy domain; wherein said scFv is covalently attached to the N-terminus of said Fc domain using a domain linker;

b) a second monomer comprising a heavy chain comprising:

i) a heavy variable domain; and

ii) a heavy chain constant domain comprising a second Fc domain; and c) a light chain comprising a variable light domain and a variable light constant domain; wherein said variable light domain comprises a vlCDRl having the sequence KSSQSLLNTGNQKNYLT (SEQ ID NO:XX), a vlCDR2 having the sequence WASTRES (SEQ ID NO:XX), and a vlCDR3 having the sequence QNDYSYPYT (SEQ ID NO:XX) and said variable heavy domain comprises a vhCDRl having the sequence DYYMK (SEQ ID NO:XX), a vhCDR2 having the sequence DllPSNGATFYNQKFKG (SEQ ID NO:XX) and a vhCDR3 having the sequence SHLLRASWFAY (SEQ ID NO:XX).

66. A heterodimeric antibody selected from the group consisting of XENP15049,

XENP15051; XENP15050, XENP13676, XENP14696, XENP15629, XENP15053, XENP15630, XENP15631, XENP15632, XENP15633, XENP15634, XENP15635, XENP15636, XENP15638, XENP15639, XENP13677, XENP14388, XENP14389, XENP14390, XENP14391,XENP14392, XENP14393, XENP16366, XENP16367, XENP16368, XENP16369, XENP16370, XENP16371, XENP16372, XENP16373, XENP16375, XENP16376 and XENP16377.

67. A nucleic acid composition comprising three nucleic acids encoding a heterodimeric antibody selected from the group consisting of XENP15049, XENP15051; XENP15050, XENP13676, XENP14696, XENP15629, XENP15053, XENP15630, XENP15631, XENP15632, XENP15633, XENP15634, XENP15635, XENP15636, XENP15638, XENP15639, XENP13677, XENP14388, XENP14389, XENP14390,

XENP14391,XENP14392, XENP14393, XENP16366, XENP16367, XENP16368, XENP16369, XENP16370, XENP16371, XENP16372, XENP16373, XENP16375, XENP16376 and XENP16377.

68. An expression vector composition comprising three expression vectors each containing a nucleic acid such that the three expression vectors encode a heterodimeric antibody selected from the group consisting of XENP15049, XENP15051; XENP15050, XENP13676, XENP14696, XENP15629, XENP15053, XENP15630, XENP15631, XENP15632, XENP15633, XENP15634, XENP15635, XENP15636, XENP15638, XENP15639, XENP13677, XENP14388, XENP14389, XENP14390, XENP14391,XENP14392, XENP14393, XENP16366, XENP16367, XENP16368, XENP16369, XENP16370, XENP16371, XENP16372, XENP16373, XENP16375, XENP16376 and XENP16377.

69. A host cell comprising the nucleic acid composition of claim 67.

70. A host cell comprising the expression vector composition of claim 68.

71. A method of making a heterodimeric antibody according to claim 66 comprising culturing the host cell of claim 69 or 70 under conditions wherein said antibody is expressed, and recovering said antibody.

72. A method of treating cancer comprising administering a heterodimeric antibody according to claim 66 to a patient in need thereof.