Improved Anti-FLT3 Antigen Binding Proteins

Abstract

The present invention provides novel human fins related tyrosine kinase 3 (FLT3) antigen binding proteins, such as antibodies, having improved FLT3 binding affinity, and/or anti-tumor activity. The FLT3 antibodies of the invention were generated by mutation of a parent FLT3 antibody and tested in in vitro in binding assays as well as in vivo in a mouse tumor model and in human patient tumor samples. The antibodies of the invention are provided as monospecific constructs or in a bispecific FLT3×CD3 antibody format and show excellent target affinity and/or tumor cell killing. The present invention also relates methods for producing the antigen binding proteins of the invention as well as nucleic acids encoding them, vectors for and host cells for their expression. The invention further relates to methods of treating or diagnosing a disease such as leukemia using an FLT3 antigen binding protein (ABP) of the invention.

Claims

1. An Antigen Binding Protein (ABP) capable of binding to human fms related tyrosine kinase 3 (FLT3), comprising: (i) one, preferably two, heavy chain variable domain(s) comprising the CDRH1 region set forth in SEQ ID NO: 01 (SYWMH), the CDRH2 region set forth in SEQ ID NO: 02 (EIDPSDSYKDYNQKFKD), and the CDRH3 region set forth in SEQ ID NO: 03 (AITTTPFDF), or wherein in each case independently the CDRH1, CDRH2 and/or CDRH3 comprise a sequence having no more than three or two, preferably no more than one amino acid substitution(s), deletion(s) or insertion(s) compared to SEQ ID NO: 01, SEQ ID NO: 02, or SEQ ID NO: 03, respectively; and (ii) one, preferably two, light chain variable domain(s) comprising the CDRL1 region set forth in SEQ ID NO: 05 (RASQSISNNLH), the CDRL2 region set forth in SEQ ID NO: 06 (YASQSIS), and the CDRL3 region set forth in SEQ ID NO: 07 (QQSNTWPYT) or wherein in each case independently CDRL1, CDRL2 and/or CDRL3 comprise a sequence having no more than three or two, preferably no more than one amino acid substitution(s), deletion(s) or insertion(s) compared to SEQ ID NO: 05, SEQ ID NO: 06, or SEQ ID NO: 07, respectively; characterized in that, said one, preferably two, heavy chain variable domain(s) and said one, preferably two, light chain variable domain(s), each comprise an antibody framework region having at least a portion of a human antibody consensus framework sequence.

2. The ABP according to claim 1, wherein the heavy chain variable domain human antibody consensus framework sequences are derived from IGHV1-46, preferably IGHV1-46*3, and/or wherein the heavy chain variable domain human antibody consensus framework sequences are derived from IGKV3D-15.

3. The ABP according to claim 1 or 2, wherein the heavy chain variable region comprises the amino acid sequence having a sequence identity of at least 95% to an amino acid sequence selected from SEQ ID NOs: 15, 17, 19, 21, 23 or 76, or, in each case independently, optionally with no more than ten, nine, eight, seven, six, five, four, preferably no more than three, two or one, amino acid substitution(s), insertion(s) or deletion(s) compared to these sequences; and/or wherein the light chain variable region comprises the amino acid sequence having a sequence identity of at least 95% to the amino acid sequence selected from SEQ ID NOs: 16, 18, 20, 22, 24 or 77, or, in each case independently, optionally with no more than ten, nine, eight, seven, six, five, four, preferably no more than three, two or one, amino acid substitution(s), insertion(s) or deletion(s) compared to these sequences.

4. The ABP according to claim 3, wherein in the heavy chain variable region the amino acid positions 16, 18, 19, 20, 22, 48, 57, 60, 69, 70, 75, 76, 78, 80, 81, 87, and 108 are as in any one of SEQ ID NOs: 15, 17, 19, 21 or 23; and/or wherein in the light chain variable region the amino acid positions 49, 55, and 87 are as in any one of SEQ ID NOs: 16, 18, 20, 22 or 24; wherein the numbering is according to the Kabat system.

5. The ABP according to any one of claims 1 to 4, wherein the heavy chain variable region comprises an amino acid sequence having a sequence identity of at least 85%, at least 90%, or at least 95% to the amino acid sequence set forth in SEQ ID NO: 21, and the light chain variable region comprises an amino acid sequence having a sequence identity of at least 95% to the amino acid sequence set forth in SEQ ID NO: 22.

6. The ABP according to any one of claims 1 to 4, wherein the heavy chain variable region comprises an amino acid sequence having a sequence identity of at least 85%, at least 90%, or at least 95% to the amino acid sequence set forth in SEQ ID NO: 76, and the light chain variable region comprises an amino acid sequence having a sequence identity of at least 95% to the amino acid sequence set forth in SEQ ID NO: 77.

7. The ABP according to any one of claims 1 to 6, wherein the heavy chain variable region comprises 48I, and wherein the light chain variable region comprises 87F, wherein the numbering is according to the Kabat system.

8. The ABP according to claim 7, wherein the light chain variable region further comprises 49K, wherein the numbering is according to the Kabat system.

9. The ABP according to any one of claims 1 to 8, wherein the ABP is an antibody, or an antigen binding fragment thereof, composed of at least one, preferably two, antibody heavy chain sequence(s), and at least one, preferably two, antibody light chain sequence(s), wherein said antibody heavy chain sequence(s) and the antibody light chain sequence(s) comprise(s) each a variable region sequences in one of the following combinations V0 to V5: TABLE-US-00016 Heavy Chain Light Chain Variable Region Variable Region (SEQ ID NO) (SEQ ID NO) V.sub.0 76 77 V.sub.1 15 16 V.sub.2 17 18 V.sub.3 19 20 V.sub.4 21 22 V.sub.5 23 24

10. The ABP according to any one of claims 1 to 9 which binds to said FLT3 with a kD that is less than 50 μM and more than 50 nM; preferably which binds to said FLT3 with a kD that is less than 1 μM and more than 300 nM.

11. The ABP according to any one of claims 1 to 10 which binds to a human cell expressing FLT3 with an EC50 that is lower than 10 nM and that is higher than 0.5 nM.

12. The ABP according to any one of claims 1 to 11 which binds to a human cell expressing FLT3 with an EC50 that is lower than 5.5 nM and that is higher than 4.5 nM.

13. The ABP according to any one of claims 1 to 12, which comprises an effector group and/or which is labelled.

14. The ABP according to any one of claims 1 to 13, which is isolated and/or substantially pure.

15. The ABP according to any one of claims 1 to 14 which is an antibody, such as a monoclonal antibody; or which is a fragment of an antibody, such as a fragment of a monoclonal antibody.

16. The ABP according to claim 15, wherein said antibody is a chimeric antibody, such as a human-chimeric antibody.

17. The ABP according to claim 15 or 16, wherein said antibody is an IgG, IgE, IgD, IgA, or IgM immunoglobulin; preferably an IgG immunoglobulin.

18. The ABP according to any one of claims 15 to 17, which is an antibody fragment selected from the list consisting of: Fab, Fab′-SH, Fv, scFv and F(ab′)2.

19. The ABP according to any one of claims 1 to 18, wherein said ABP is modified or engineered to increase antibody-dependent cellular cytotoxicity (ADCC), preferably wherein said ABP is afucosylated.

20. The ABP according to any one of claims 1 to 19, which comprises one or more additional antigen binding domain(s) that bind(s) to antigen(s) other than said FLT3; such as antigen(s) present on a mammalian T-cell, and most preferably human CD3.

21. The ABP according to claim 20, which is bispecific, and preferably which comprises two binding sites binding to FLT3 and two binding sites binding to an antigen other than said FLT3, such as antigen(s) present on a mammalian T-cell, and most preferably to human CD3.

22. The ABP according to claim 21, wherein the two binding sites binding to an antigen other than said FLT3 bind to human CD3, and preferably comprise an UCHT1 anti-CD3 scFv construct, such as the scFv shown in SEQ ID NO: 14.

23. The ABP according to claim 22, comprising two antibody heavy chain sequences and two antibody light chain sequences, wherein said antibody heavy chain sequences and the antibody light chain sequences each comprise amino acid sequences in any one of the following combinations V0 to V5: TABLE-US-00017 Heavy Chain Full Light Chain Full length Sequence length Sequence (SEQ ID NO) (SEQ ID NO) V.sub.0 78 79 V.sub.1 28 29 V.sub.2 30 31 V.sub.3 32 33 V.sub.4 34 35 V.sub.5 36 37

24. An antigen binding protein (ABP) or an antigen-binding fragment thereof, capable of binding to human FLT3 and that is able to compete with the binding of an ABP according to any one of claims 1 to 23 to FLT3.

25. A bispecific antigen binding protein (ABP) which comprises a first antigen binding domain capable of binding to the human fms like tyrosine kinase 3 (FLT3) antigen, and a second antigen binding domain capable of binding to the human cluster of differentiation 3 (CD3) antigen, wherein the bispecific ABP: a. binds to FLT3 with an EC50 of lower than 10 nM as determined by analyzing the binding of the bispecific ABP to FLT3 positive cells by flow cytometry using a fluorescent activated cell sorting (FACS) device; and b. binds to CD3 with an EC50 of lower than 200 nM as determined by analyzing the binding of the bispecific ABP to CD3 positive cells by flow cytometry using a fluorescent activated cell sorting (FACS) device.

26. The bispecific ABP according to claim 25, wherein the bispecific ABP binds to FLT3 with an EC50 of higher than 0.5 nM.

27. The bispecific ABP according to claim 25 or 26, wherein the bispecific ABP binds FLT3 with an kD of less than 50 μM as measured by surface plasmon resonance.

28. The bispecific ABP according to any one of claims 25 to 27, wherein the bispecific ABP binds to CD3 with an EC50 of higher than 1 nM.

29. The bispecific ABP according to any one of claims 25 to 28, which inhibits proliferation and/or viability of leukemic blood mononuclear cells of a patient suffering from acute leukemia in an in-vitro assay compared to an unrelated control to equal or less than 50%.

30. The bispecific ABP according to any one of claims 25 to 29, which comprises not more and not less than two first antigen binding domains and two second antigen binding domains.

31. The bispecific ABP according to any one of claims 25 to 30, wherein at least one amino acid residue of the CH2 domain that is able to mediate binding to Fc receptors in said antibody is lacking or mutated.

32. The bispecific ABP according to any one of claims 25 to 31, wherein the first antigen binding domain comprises the ABP, or antigen binding domain thereof, according to any one of claims 1 to 24.

33. The bispecific ABP of any one of claims 25 to 32, having an activity to bind to a T-cell and to an FLT3 expressing tumor cell, preferably wherein the antibody increases the recruitment of T-cells to a FLT3 expressing tumor cell by binding to FLT3 and CD3.

34. The bispecific ABP according to any one of claims 25 to 33, wherein the second antigen binding domain comprises the heavy chain variable region and a light chain variable region of UCHT1.

35. An isolated nucleic acid comprising a sequence encoding for an ABP, or for an antigen binding fragment or a monomer, such as a heavy or light chain, of an ABP, of any one of claims 1 to 24, or encoding for a bispecific ABP according to any one of claims 25 to 34.

36. A nucleic acid construct (NAC) comprising a nucleic acid of claim 35 and one or more additional sequence features permitting the expression of the encoded ABP or bispecific ABP, or a component of said ABP or bispecific ABP (such as an antibody heavy chain or light chain) in a cell.

37. A recombinant host cell comprising a nucleic acid of claim 35 or a NAC according to claim 36.

38. A pharmaceutical composition comprising: (i) an ABP or bispecific ABP of any one of claims 1 to 34, or (ii) a nucleic acid of claim 35 or a NAC according to claim 36, or (iii) a recombinant host cell according to claim 37, and a pharmaceutically acceptable carrier, stabiliser and/or excipient.

39. A component for use in medicine, wherein the component is selected from the list consisting of: an ABP or bispecific ABP of any one of claims 1 to 34, an isolated nucleic acid of claim 35 or a NAC according to claim 36, a recombinant host cell according to claim 37 and a pharmaceutical composition according to claim 38.

40. The component for use of claim 39, wherein the component is for use in enhancing T cell-mediated killing of and/or inhibiting the proliferation of FLT3 positive tumor cells.

41. The component for use according to claim 33 to 34, wherein the component is for use in the diagnosis, prevention and/or treatment of a proliferative disease, wherein the proliferative disorder is associated with the expression FLt3, and is preferably cancer, such as a cancer selected from leukemia, such as acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL), or a solid cancer selected from prostate cancer, colorectal cancer, cancer of the stomach, lung carcinoma, osteosarcoma, mammary cancer, pancreatic cancer, or squamous cell carcinoma; preferably the cancer is leukemia, such as AML or ALL.

42. A method of enhancing a cell-mediated immune response to a human cell that expresses human FLT3, comprising contacting said cell with an ABP of any one of claims 1 to 24, or a bispecific ABP according to any one of claims 25 to 34, or a nucleic acid encoding said ABP or bispecific ABP according to claim 35, in the presence of an immune cell, such as a T-cell or natural killer (NK) cell, thereby enhancing a cell-mediated immune response against said human cell.

43. A method for the prevention and/or treatment of a proliferative disorder in a subject, comprising the administration of a therapeutically effective amount of a component recited in claim 39 to the subject; and wherein the proliferative disorder is characterized by an expression of FLT3 in cells associated with the proliferative disorder.

Description

BRIEF DESCRIPTION OF THE FIGURES AND SEQUENCES

[0198] The figures show:

[0199] FIG. 1 depicts the Fc-attenuated IgGsc-format that was used for construction of the bispecific FLT3×CD3 antibody-variants described in this invention. Variants of the FLT3 antigen binding domain (V1 to V5) were obtained starting from humanization of the V-regions of the FLT3 antibody 4G8 by CDR-grafting using replacement strategies with different stringency. For generation of different CD3-antigen binding domains (V6 to V9), UCHT1 scFv sequences were used.

[0200] FIG. 2 shows the amino acid sequence of the heavy chain and light chain of CC-2. A: heavy chain sequence of the FLT3 (4G8)×CD3 (humanized hUCHT1) bispecific IgGsc format antibody molecule (SEQ ID NO: 68). The heavy chain comprises the mouse heavy chain (HC) variable region of 4G8, an IgG1 CH1 domain, an IgG1 hinge region, a modified IgG1 CH2 domain, an IgG1 CH3 domain, and a humanized CD3 (UCHT1) single chain Fv fragment. B: shows the amino acid sequence of the kappa light chain of the FLT3 (4G8)×CD3 (humanized hUCHT1) (SEQ ID NO: 69). This light chain completes the heavy chain constructs of SEQ ID NO: 68 to form a chimeric 4G8×UCHT1 IgGsc- and Fabsc-molecule, respectively (see FIG. 1).

[0201] FIG. 3 depicts binding of different CC-2 variants to soluble recombinant FLT3 protein. Respective antibody variants were immobilized to a Biacore chip coated with protein A and binding of His tagged, recombinant FLT3 protein (Sino Biologicals) was determined using a Biacore X instrument (GE Healthcare). Shown are the results of various mutated variants of the FLT3 antigen binding domain (V1 to V5).

[0202] FIG. 4 shows the binding of CC-2 variants to Nalm16 cells expressing FLT3. Calculated EC50 values are indicated at the corresponding bars in FIG. 3. Tested were mutated variants of the FLT3 antigen binding domain (V1 to V5).

[0203] FIG. 5 depicts the depletion of leukemic cells from blood samples of AML patients using the various different CC-2 constructs of the invention. Shown is a comparison of mutated variants of the FLT3 antigen binding domain (V1 to V5). Also indicated are the values of Biacore results of FIG. 3 and flow cytometry EC50 of FIG. 4.

[0204] FIG. 6 shows the binding of CC-2 variants to Jurkat cells expressing CD3. Calculated EC50 values are indicated at the corresponding bars in FIG. 5. Tested were mutated variants of the CD3 antigen binding domain (V7 to V9).

[0205] FIG. 7. depicts the depletion of leukemic cells from blood samples of AML patients using the various different CC-2 constructs of the invention. Shown is a comparison of mutated variants of the CD3 antigen binding domain (V7 to V9). Also indicated are the values of the flow cytometry EC50 of FIG. 6.

[0206] FIG. 8. depicts the results of T cell activation and blast reduction by different CC-2 variants in a flow cytometry assay. The used CC2 variants are different in both their FLT3 antigen binding domains and CD3 antigen binding domains (antibodies used are V6-V6 (V6); V6-V9 (V9); V4-V6 (V4)). A: reduction of CD4 positive cells; B: reduction of CD8 positive cells; C: Blast count.

[0207] FIG. 9. depicts depletion of NALM16 leukemia cells by different variants of CC-2 in a flow cytometry assay. The used CC2 variants are different in both their FLT3 antigen binding domains and CD3 antigen binding domains (antibodies used are V6-V6 (V6); V6-V8 (V8); V4-V6 (V4); V6-V7 (V7)).

[0208] FIG. 10 depicts the anti-leukemic activity of CC-2 variant 4 in vivo in immune-deficient NSG mice engrafted with primary AML (A) or ALL (B). As an example CC-2 variants having the FLT3 antigen binding domain V4 (V4-V6) are shown.

[0209] FIG. 11 depicts antibody dependent cellular cytotoxicity (ADCC) of monospecific anti-FLT3 antibody variant. Shown is the specific lysis of FLT3+ leukemic cells (SEM; DSMZ no. ACC 546) by allogeneic polyclonal natural killer cells (pNKC) in the presence of the indicated FLT3 constructs or Fc-control (each 5 μg/ml) was measured by 2h BATDA-Europium cytotoxicity assays.

[0210] The ABP of the invention are all described in the sequence listing and the following table 1:

TABLE-US-00001 SEQ ID Antibody NO: Name Description Sequence 1 V6-V6 V6 FLT.sub.3 SYWMH CDRH.sub.1 2 V6-V6 V6 FLT.sub.3 EIDPSDSYKDYNQKFKD CDRH.sub.2 3 V6-V6 V6 FLT.sub.3 AITTTPFDF CDRH.sub.3 4 V6-V6 V6 FLT.sub.3 HCV QVQLQQPGAELVKPGASLKLSCKSSGYTFTSYWMH WVRQRPGHGLEWIGEIDPSDSYKDYNQKFKDKATL TVDRSSNTAYMHLSSLTSDDSAVYYCARAITTTPFDF WGQGTTLTVSS 5 V6-V6 V6 FLT.sub.3 RASQSISNNLH CDRL.sub.1 6 V6-V6 V6 FLT.sub.3 YASQSIS CDRL.sub.2 7 V6-V6 V6 FLT.sub.3 QQSNTWPYT CDRL.sub.3 8 V6-V6 V6 FLT.sub.3 LCV DIVLTQSPATLSVTPGDSVSLSCRASQSISNNLHWYQ QKSHESPRLLIKYASQSISGIPSRFSGSGSGTDFTLSIN SVETEDFGVYFCQQSNTWPYTFGGGTKLEIK 9 V6-V6 V6 FLT.sub.3 LCC RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREA KVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLT LSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC 10 V6-V6 V6 CH.sub.1 ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVT VSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSS LGTQTYICNVNHKPSNTKVDKKV 11 V6-V6 V6 Hinge EPKSCDKTHTCPPCP 12 V6-V6 V6 CH.sub.2 APPVAGPSVFLFPPKPKDTLMISRTPEVTCVVVGVSH EDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVV SVLTVLHQDWLNGKEYKCKVSNKQLPSPIEKTISKAK 13 V6-V6 V6 CH.sub.3 GQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDI AVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVD KSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGKS G 14 V6-V6 V6 CD.sub.3 scFv DIQMTQSPSSLSASVGDRVTITCRASQDIRNYLNWYQ QKPGKAPKLLIYYTSRLESGVPSRFSGSGSGTDYTLTI SSLQPEDFATYYCQQGNTLPWTFGQGTKVEIKGGGG SGGGGSGGGGSEVQLVESGGGLVQPGGSLRLSCAAS GYSFTGYTMNWVRQAPGKGLEWVALINPYKGVSTY NQKFKDRFTISVDKSKNTAYLQMNSLRAEDTAVYYC ARSGYYGDSDWYFDVWGQGTLVTVSS 15 V.sub.1-V6 V.sub.1 FLT.sub.3 HCV QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSS 16 V.sub.1-V6 V.sub.1 FLT.sub.3 LCV EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIK 17 V.sub.2-V6 V.sub.2 FLT.sub.3 HCV QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSS 18 V.sub.2-V6 V.sub.2 FLT.sub.3 LCV EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIK 19 V.sub.3-V6 V.sub.3 FLT.sub.3 HCV QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSS 20 V.sub.3-V6 V.sub.3 FLT.sub.3 LCV EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIK 21 V.sub.4-V6 V.sub.4 FLT.sub.3 HCV QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSS 22 V.sub.4-V6 V.sub.4 FLT.sub.3 LCV EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIK 23 V.sub.5-V6 V.sub.5 FLT.sub.3 HCV QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSS 24 V.sub.5-V6 V.sub.5 FLT.sub.3 LCV EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIK 25 V6-V.sub.7 V.sub.7 CD.sub.3 scFv DIQMTQSPSSLSASVGDRVTITCRASQDIRNYLNWYQ QKPGKAPKLLIYYTSRLESGVPSRFSGSGSGTDYTLTI SSLQPEDFATYYCQQGNTLPWTFGQGTKVEIKGGGG SGGGGSGGGGSEVQLVESGGGLVQPGGSLRLSCAAS GYSFTGYTMNWVRQAPGKGLEWVALINPYKGVSTY ADSFKGRFTISVDDSKNTAYLQMNSLRAEDTAVYYC ARSGYYGDSDWYFDVWGQGTLVTVSS 26 V6-V8 V8 CD.sub.3 scFv DIQMTQSPSSLSASVGDRVTITCRASQDIRNYLNWYQ QKPGKAPKLLIYYTSRLESGVPSRFSGSGSGTDYTLTI SSLQPEDFATYYCQQGNTLPWTFGQGTKVEIKGGGG SGGGGSGGGGSEVQLVESGGGLVQPGGSLRLSCAAS GYSFTGYTMNWVRQAPGKGLEWVALINPYKGVSTY NQKFKDRFTISVDDSKNTAYLQMNSLRAEDTAVYYC ARSGYYGDSDWYFDVWGQGTLVTVSS 27 V6-V.sub.9 V.sub.9 CD.sub.3 scFv EVQLVESGGGLVQPGGSLRLSCAASGYSFTGYTMNW VRQAPGKGLEWVALINPYKGVSTYNQKFKDRFTISV DKSKNTAYLQMNSLRAEDTAVYYCARSGYYGDSDW YFDVWGQGTLVTVSSGGGGSGGGGSGGGGSDIQMT QSPSSLSASVGDRVTITCRASQDIRNYLNWYQQKPG KAPKLLIYYTSRLESGVPSRFSGSGSGTDYTLTISSLQP EDFATYYCQQGNTLPWTFGQGTKVEIK 28 V.sub.1-V6 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYNQKFKDRFTISVDKSKNTAYLQM NSLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLV TVSS 29 V.sub.1-V6 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 30 V.sub.2-V6 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYNQKFKDRFTISVDKSKNTAYLQM NSLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLV TVSS 31 V.sub.2-V6 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 32 V.sub.3-V6 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYNQKFKDRFTISVDKSKNTA YLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQ GTLVTVSS 33 V.sub.3-V6 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 34 V.sub.4-V6 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYNQKFKDRFTISVDKSKNTA YLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQ GTLVTVSS 35 V.sub.4-V6 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 36 V.sub.5-V6 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYNQKFKDRFTISVDKSKNTAYLQM NSLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLV TVSS 37 V.sub.5-V6 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 38 V.sub.1-V.sub.7 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYADSFKGRFTISVDDSKNTAYLQMN SLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLVT VSS 39 V.sub.1-V.sub.7 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 40 V.sub.2-V.sub.7 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYADSFKGRFTISVDDSKNTAYLQMN SLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLVT VSS 41 V.sub.2-V.sub.7 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 42 V.sub.3-V.sub.7 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYADSFKGRFTISVDDSKNTAY LQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQG TLVTVSS 43 V.sub.3-V.sub.7 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 44 V.sub.4-V.sub.7 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYADSFKGRFTISVDDSKNTAY LQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQG TLVTVSS 45 V.sub.4-V.sub.7 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 46 V.sub.5-V.sub.7 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYADSFKGRFTISVDDSKNTAYLQMN SLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLVT VSS 47 V.sub.5-V.sub.7 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 48 V.sub.1-V8 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYNQKFKDRFTISVDDSKNTAYLQM NSLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLV TVSS 49 V.sub.1-V8 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 50 V.sub.2-V8 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYNQKFKDRFTISVDDSKNTAYLQM NSLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLV TVSS 51 V.sub.2-V8 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 52 V.sub.3-V8 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYNQKFKDRFTISVDDSKNTA YLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQ GTLVTVSS 53 V.sub.3-V8 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 54 V.sub.4-V8 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYNQKFKDRFTISVDDSKNTA YLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQ GTLVTVSS 55 V.sub.4-V8 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 56 V.sub.5-V8 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTITCRA SQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRF SGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFG QGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLV QPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEW VALINPYKGVSTYNQKFKDRFTISVDDSKNTAYLQM NSLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLV TVSS 57 V.sub.5-V8 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 58 V.sub.1-V.sub.9 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGEVQLVESGGGLVQPGGSLRLSCAA SGYSFTGYTMNWVRQAPGKGLEWVALINPYKGVST YNQKFKDRFTISVDKSKNTAYLQMNSLRAEDTAVYY CARSGYYGDSDWYFDVWGQGTLVTVSSGGGGSGGG GSGGGGSDIQMTQSPSSLSASVGDRVTITCRASQDIR NYLNWYQQKPGKAPKLLIYYTSRLESGVPSRFSGSGS GTDYTLTISSLQPEDFATYYCQQGNTLPWTFGQGTK VEIK 59 V.sub.1-V.sub.9 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 60 V.sub.2-V.sub.9 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYTDYAQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGEVQLVESGGGLVQPGGSLRLSCAA SGYSFTGYTMNWVRQAPGKGLEWVALINPYKGVST YNQKFKDRFTISVDKSKNTAYLQMNSLRAEDTAVYY CARSGYYGDSDWYFDVWGQGTLVTVSSGGGGSGGG GSGGGGSDIQMTQSPSSLSASVGDRVTITCRASQDIR NYLNWYQQKPGKAPKLLIYYTSRLESGVPSRFSGSGS GTDYTLTISSLQPEDFATYYCQQGNTLPWTFGQGTK VEIK 61 V.sub.2-V.sub.9 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 62 V.sub.3-V.sub.9 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGEVQLVESGGGLVQPGGSLRL SCAASGYSFTGYTMNWVRQAPGKGLEWVALINPYK GVSTYNQKFKDRFTISVDKSKNTAYLQMNSLRAEDT AVYYCARSGYYGDSDWYFDVWGQGTLVTVSSGGGG SGGGGSGGGGSDIQMTQSPSSLSASVGDRVTITCRAS QDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRFS GSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFGQ GTKVEIK 63 V.sub.3-V.sub.9 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIYYASQSASGIPARFSGSGSGTEFTLTI SSLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 64 V.sub.4-V.sub.9 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTM TRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFDF WGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGEVQLVESGGGLVQPGGSLRL SCAASGYSFTGYTMNWVRQAPGKGLEWVALINPYK GVSTYNQKFKDRFTISVDKSKNTAYLQMNSLRAEDT AVYYCARSGYYGDSDWYFDVWGQGTLVTVSSGGGG SGGGGSGGGGSDIQMTQSPSSLSASVGDRVTITCRAS QDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRFS GSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFGQ GTKVEIK 65 V.sub.4-V.sub.9 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 66 V.sub.5-V.sub.9 Full Length QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMH heavy WVRQAPGQGLEWIGEIDPSDSYKDYNQKFKDRVTIS RDTSKNTLYLQLSSLRAEDTAVYYCARAITTTPFDFW GQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSL SSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISRTP EVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKQ LPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHY TQKSLSLSPGKSGEVQLVESGGGLVQPGGSLRLSCAA SGYSFTGYTMNWVRQAPGKGLEWVALINPYKGVST YNQKFKDRFTISVDKSKNTAYLQMNSLRAEDTAVYY CARSGYYGDSDWYFDVWGQGTLVTVSSGGGGSGGG GSGGGGSDIQMTQSPSSLSASVGDRVTITCRASQDIR NYLNWYQQKPGKAPKLLIYYTSRLESGVPSRFSGSGS GTDYTLTISSLQPEDFATYYCQQGNTLPWTFGQGTK VEIK 67 V.sub.5-V.sub.9 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIKYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 68 V6-V6 Full Length QVQLQQPGAELVKPGASLKLSCKSSGYTFTSYWMH heavy WVRQRPGHGLEWIGEIDPSDSYKDYNQKFKDKATL TVDRSSNTAYMHLSSLTSDDSAVYYCARAITTTPFDF WGQGTTLTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYNQKFKDRFTISVDKSKNTA YLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQ GTLVTVSS 69 V6-V6 Full Length DIVLTQSPATLSVTPGDSVSLSCRASQSISNNLHWYQ light QKSHESPRLLIKYASQSISGIPSRFSGSGSGTDFTLSIN SVETEDFGVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 70 V6-V.sub.7 Full Length QVQLQQPGAELVKPGASLKLSCKSSGYTFTSYWMH heavy WVRQRPGHGLEWIGEIDPSDSYKDYNQKFKDKATL TVDRSSNTAYMHLSSLTSDDSAVYYCARAITTTPFDF WGQGTTLTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYADSFKGRFTISVDDSKNTAY LQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQG TLVTVSS 71 V6-V.sub.7 Full Length DIVLTQSPATLSVTPGDSVSLSCRASQSISNNLHWYQ light QKSHESPRLLIKYASQSISGIPSRFSGSGSGTDFTLSIN SVETEDFGVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 72 V6-V8 Full Length QVQLQQPGAELVKPGASLKLSCKSSGYTFTSYWMH heavy WVRQRPGHGLEWIGEIDPSDSYKDYNQKFKDKATL TVDRSSNTAYMHLSSLTSDDSAVYYCARAITTTPFDF WGQGTTLTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVTI TCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESGV PSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYNQKFKDRFTISVDDSKNTA YLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQ GTLVTVSS 73 V6-V8 Full Length DIVLTQSPATLSVTPGDSVSLSCRASQSISNNLHWYQ light QKSHESPRLLIKYASQSISGIPSRFSGSGSGTDFTLSIN SVETEDFGVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 74 V6-V.sub.9 Full Length QVQLQQPGAELVKPGASLKLSCKSSGYTFTSYWMH heavy WVRQRPGHGLEWIGEIDPSDSYKDYNQKFKDKATL TVDRSSNTAYMHLSSLTSDDSAVYYCARAITTTPFDF WGQGTTLTVSSASTKGPSVFPLAPSSKSTSGGTAALG CLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP KSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMISR TPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN KQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALH NHYTQKSLSLSPGKSGEVQLVESGGGLVQPGGSLRL SCAASGYSFTGYTMNWVRQAPGKGLEWVALINPYK GVSTYNQKFKDRFTISVDKSKNTAYLQMNSLRAEDT AVYYCARSGYYGDSDWYFDVWGQGTLVTVSSGGGG SGGGGSGGGGSDIQMTQSPSSLSASVGDRVTITCRAS QDIRNYLNWYQQKPGKAPKLLIYYTSRLESGVPSRFS GSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFGQ GTKVEIK 75 V6-V.sub.9 Full Length DIVLTQSPATLSVTPGDSVSLSCRASQSISNNLHWYQ light QKSHESPRLLIKYASQSISGIPSRFSGSGSGTDFTLSIN SVETEDFGVYFCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC 76 Vo-V6 Vo FLT.sub.3 HCV QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH WVRQAPGQGLEVVMGEIDPSDSYKDYNQKFKDRVT MTRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFD FWGQGTTVTVSS 77 Vo-V6 Vo FLT.sub.3 LCV EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ QKPGQAPRLLIYYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYYCQQSNTWPYTFGGGTKLEIK 78 Vo-V6 Full Length QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMH heavy WVRQAPGQGLEVVMGEIDPSDSYKDYNQKFKDRVT MTRDTSTSTVYMELSSLRSEDTAVYYCARAITTTPFD FWGQGITVTVSSASTKGPSVFPLAPSSKSTSGGTAAL GCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSG LYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKV EPKSCDKTHTCPPCPAPPVAGPSVFLFPPKPKDTLMI SRTPEVTCVVVGVSHEDPEVKFNWYVDGVEVHNAK TKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVS NKQLPSPIEKTISKAKGQPREPQVYTLPPSRDELTKN QVSLTCLVKGFYPSDIAVEVVESNGQPENNYKTTPPV LDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEAL HNHYTQKSLSLSPGKSGDIQMTQSPSSLSASVGDRVT ITCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLESG VPSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLP WTFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESG GGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGK GLEWVALINPYKGVSTYNQKFKDRFTISVDKSKNTA YLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQ GTLVTVSS 79 V0-V6 Full Length EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQ light QKPGQAPRLLIYYASQSISGIPARFSGSGSGTEFTLTIS SLQSEDFAVYYCQQSNTWPYTFGGGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWK VDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRGEC

EXAMPLES

[0211] Certain aspects and embodiments of the invention will now be illustrated by way of example and with reference to the description, figures and tables set out herein. Such examples of the methods, uses and other aspects of the present invention are representative only, and should not be taken to limit the scope of the present invention to only such representative examples.

[0212] The examples show:

Example 1: Production of Recombinant Bispecific FLT3×CD3 ABPs (CC-2)

[0213] The 4G8 anti-FLT3 antibody was used for construction of recombinant bispecific ABPs in the IgGsc format (FIG. 1), that is, the variable domain of the mouse FLT3 antibody 4G8 was fused to human constant regions and variable regions of the CD3 antibody UCHT1 in the following order. VL-CL for the light chain and VH-CH1-CH2mod-CH3-scFv(UCHT1) for the heavy chain (see FIG. 1). In these ABPs, the FLT3 binding site is present as Fab2 fragment while the CD3 binding site is present as scFv fragment (cf. again FIG. 1). To abrogate FcR-binding, the following modifications were introduced into the hinge region and the CH2 domain (EU-index): E233P; L234V; L235A; AG236; D265G; A327Q; A330S (see in this respect also International patent application WO 2013/092001). The constructs were cloned in an expression vector derived from pcDNA3.1 (InVitrogen, Thermo Fisher) as also described in International patent application WO 2013/092001 and transiently transfected into CHO-cells. ABPs were purified from the supernatants of transfected cells by affinity chromatography with Protein A resins. (purchased from GE Health Care Freiburg, Germany). The resulting mouse FLT3×CD3 bispecific antibody is denoted V6-V6.

Example 2: Generation of Humanized 4G8 Antibodies

[0214] The 4G8 anti-FLT3 antibody was humanized by grafting the CDR regions of the light chain of the antibody 4G8 (that means the CDR loops of SEQ ID NO: 5 to SEQ ID NO: 7) into (the variable domain) of the human κ light sequence IGKV3-15*01 that is deposited in the IMGT/LIGM-database under accession number M23090, see also Ichiyoshi Y., Zhou M., Casali P. A human anti-insulin IgG autoantibody apparently arises through clonal selection from an insulin-specific ‘germ-line’ natural antibody template. Analysis by V gene segment reassortment and site-directed mutagenesis' J. Immunol. 154(1):226-238 (1995). Further the CDR regions of the heavy chain of the antibody 4G8 (that means the CDR loops of SEQ ID NO: 01 to SEQ ID NO: 03) were included into the (variable domains) of the heavy chain sequence IGHV1-46*03 which is deposited in the IMGT/LIGM-database under accession number L06612 (See also Watson C. T., et al. Complete haplotype sequence of the human immunoglobulin heavy-chain variable, diversity, and joining genes and characterization of allelic and copy-number variation. Am. J. Hum. Genet. 92(4):530-546 (2013). The resulting humanized 4G8 was used as a basis for the mutational analysis/variations of the present invention.

Example 3: Generation of Inventive Variants of Bispecific FLT3×CD3 ABPs (CC-2)

[0215] Multiple variants (V1 to V5) of the FLT3 binding domain of humanized 4G8 were generated. Furthermore, multiple published variants of the CD3 binding domain scFv derived from the humanized CD3 antibody UCHT1 (V7 to V9) were used in various combinations with the inventive FLT3 binding domain variants. The following preferred mutated variants having specific technical effects that are desirous for the use of such humanized 4G8 variants were identified (CDRs are underlined, and mutations are indicated vis-à-vis the corresponding heavy and light chains present in the humanized 4G8 FLT3 antigen binding domain detonated as Variant 0 or V0):

[0216] Humanized 4G8 FLT3 variable region Variant 1 (V1)

Heavy chain variable region:

Mutations: K16G, V18L, K19R, V20L, K22A, K57T, N60A, M69I, T70S, T75K, S76N, V78L, M80L, E81Q, S87A, T108L

[0217]

TABLE-US-00002 QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMHWVRQAPGQGLEWI GEIDPSDSYTDYAQKFKDRVTISRDTSKNTLYLQLSSLRAEDTAVYYC ARAITTTPFDFWGQGTLVTVSS.
Light chain variable region:

Mutations: K49Y, I55A

[0218]

TABLE-US-00003 EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQQKPGQAPRLLI YYASQSASGIPARFSGSGSGTEFTLTISSLQSEDFAVYFCQQSNTWPY TFGGGTKLEIK

[0219] Humanized 4G8 FLT3 variable region Variant 2 (V2)

Heavy chain variable region:

Mutations: K16G, V18L, K19R, V20L, K22A, K57T, N60A, M69I, T70S, T75K, S76N, V78L, M80L, E81Q, S87A, T108L

[0220]

TABLE-US-00004 QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMHWVRQAPGQGLEWI GEIDPSDSYTDYAQKFKDRVTISRDTSKNTLYLQLSSLRAEDTAVYYC ARAITTTPFDFWGQGTLVTVSS
Light chain variable region:

TABLE-US-00005 EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQQKPGQAPRLLI KYASQSISGIPARFSGSGSGTEFTLTISSLQSEDFAVYFCQQSNTWPY TFGGGTKLEIK

[0221] Humanized 4G8 FLT3 variable region Variant 3 (V3)

Heavy chain variable region:

Mutations: 48I

[0222]

TABLE-US-00006 QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMHWVRQAPGQGLEWI GEIDPSDSYKDYNQKFKDRVTMTRDTSTSTVYMELSSLRSEDTAVYYC ARAITTTPFDFWGQGTTVTVSS
Light chain variable region:

Mutations: K49Y, I55A

[0223]

TABLE-US-00007 EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQQKPGQAPRLLI YYASQSASGIPARFSGSGSGTEFTLTISSLQSEDFAVYFCQQSNTWPY TFGGGTKLEIK

[0224] Humanized 4G8 FLT3 variable region Variant 4 (V4)

Heavy chain variable region:

Mutations: 48I

[0225]

TABLE-US-00008 QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYWMHWVRQAPGQGLEWI GEIDPSDSYKDYNQKFKDRVTMTRDTSTSTVYMELSSLRSEDTAVYYC ARAITTTPFDFWGQGTTVTVSS
Light chain variable region:

Mutations: 49K, 87F

[0226]

TABLE-US-00009 EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQQKPGQAPRLLI KYASQSISGIPARFSGSGSGTEFTLTISSLQSEDFAVYFCQQSNTWPY TFGGGTKLEIK

[0227] Humanized 4G8 FLT3 variable region Variant r (V5)

Heavy chain variable region:

Mutations: K16G, V18L, K19R, V20L, K22A, M69I, T70S, T75K, S76N, V78L, M80L, E81Q, S87A, T108L

[0228]

TABLE-US-00010 QVQLVQSGAEVKKPGGSLRLSCAASGYTFTSYWMHWVRQAPGQGLEWI GEIDPSDSYKDYNQKFKDRVTISRDTSKNTLYLQLSSLRAEDTAVYYC ARAITTTPFDFWGQGTLVTVSS
Light chain variable region:

TABLE-US-00011 EIVMTQSPATLSVSPGERATLSCRASQSISNNLHWYQQKPGQAPRLLI KYASQSISGIPARFSGSGSGTEFTLTISSLQSEDFAVYFCQQSNTWPY TFGGGTKLEIK

[0229] Humanized UCHT1 CD3 scFv Variant 1 (V7)

Mutations: N60A, Q61D, K62S, D65G, K73D

[0230]

TABLE-US-00012 DIQMTQSPSSLSASVGDRVTITCRASQDIRNYLNWYQQKPGKAPKLLI YYTSRLESGVPSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPW TFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLVQPGGSLRLSC AASGYSFTGYTMNWVRQAPGKGLEWVALINPYKGVSTYADSFKGRFTI SVDDSKNTAYLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLV TVSS

[0231] Humanized UCHT1 CD3 scFv Variant 2 (V8)

Mutations: K73D

[0232]

TABLE-US-00013 DIQMTQSPSSLSASVGDRVTITCRASQDIRNYLNWYQQKPGKAPKLLI YYTSRLESGVPSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPW TFGQGTKVEIKGGGGSGGGGSGGGGSEVQLVESGGGLVQPGGSLRLSC AASGYSFTGYTMNWVRQAPGKGLEWVALINPYKGVSTYNQKFKDRFTI SVDDSKNTAYLQMNSLRAEDTAVYYCARSGYYGDSDWYFDVWGQGTLV TVSS

[0233] Humanized UCHT1 CD3 scFv Variant 3 (Vg)

Mutations: light chain-heavy chain replacement (VL-VH.fwdarw.VH-VL):

TABLE-US-00014 EVQLVESGGGLVQPGGSLRLSCAASGYSFTGYTMNWVRQAPGKGLEWV ALINPYKGVSTYNQKFKDRFTISVDKSKNTAYLQMNSLRAEDTAVYYC ARSGYYGDSDWYFDVWGQGTLVTVSSGGGGSGGGGSGGGGSDIQMTQS PSSLSASVGDRVTITCRASQDIRNYLNWYQQKPGKAPKLLIYYTSRLE SGVPSRFSGSGSGTDYTLTISSLQPEDFATYYCQQGNTLPWTFGQGTK VEIK
The above variants were used to create the bispecific ABP versions as indicated in the above table 1.

Example 4: Binding Affinity of FLT3 Antigen Binding Domain Variants of the Humanized 4G8

[0234] In FIG. 3 the binding of different FLT3 binding domain variants V1 to V5 as indicated above was tested for their dissociation constant using a soluble recombinant FLT3 protein. Respective antibody variants were immobilized to a Biacore chip coated with protein A and binding of His tagged, recombinant FLT3 protein (Sino Biologicals) was determined using a Biacore X instrument (GE Healthcare). Results are indicated in table 2:

TABLE-US-00015 ka [1/Ms] Ka-STD kd [1/s] Kd-STD KD [M] KD-STD Version 1   489    380.4235  0.022   0.00113137.sub.  6.3E−05 4.7023E−05 Version 2   539.5  454.6697  0.03175 0.00289914.sub.  8.8E−05 6.8377E−05 Version 3   276.5   71.41779 0.02335 0.0006364 .sub.  8.7E−05 2.0011E−05 Version 4 18850   3747.666   0.00887 8.4853E−05 4.8E−07 9.1924E−08 Version 5 29650   7848.885   0.00449 0.00041012.sub.  1.6E−07 5.5861E−08

[0235] In addition, antibody binding affinity was also tested using binding of the antibody to its target(s) as expressed on cells. Analyzed is the binding of CC-2 variants to Nalm16 cells expressing FLT3 (FIG. 4) or Jurkat cells expressing CD3 (FIG. 6). Variants V1 to V9 (with V6 being V6-V6) were produced after transient transfection of CHO cells using the insert sequences listed above. The antibodies were purified by protein A affinity- and size exclusion-chromatography. V1 to V5 contain different variants of the FLT3 antibody as indicated above and an identical CD3 binding antibody (a UCHT1 variant that binds to CD3 with an EC50 of ˜10 nM). V6 to V9 contain the parental 4G8 antibody that binds to FLT3 with an EC50 of ˜1 nM and different UCHT1 variants. To measure antibody binding to FLT3 and CD3 NALM16 (FLT3+) and Jurkat (CD3+) cells were incubated with the respective variants for 30 min, washed, stained with a goat anti human Fcγ-specific and PE-conjugated secondary antibody (Jackson Immuno Research), washed again and analyzed by flow cytometry (FACSCalibur, BD Biosciences).

[0236] Conclusions: As shown in FIGS. 3 and 4 variant 5 has the highest binding affinity to FLT3 followed by V4 as measured by surface plasmon resonance (Biacore) and flow cytometry, respectively.

Example 5: Depletion of Leukemic Cells from Blood Samples of AML Patients of Different FLT3-Binding or CD3-Binding Domain Variants

[0237] Peripheral blood mononuclear cells (PBMC) were obtained from patients with acute leukemia by density gradient centrifugation, incubated for 5 days with the indicated CC-2 variants at 1 μg/ml and analyzed by flow cytometry using a FACSCanto-II (BD Biosciences). Leukemic cells were identified using antibodies to CD33, CD34 or CD117. For calibration of cell numbers a defined amount of compensation beads (BD Biosciences) was added to every sample. Data were obtained from three (V4, V5, V6, V9) and two (V3) independent experiments with cells from two different donors. All values were related to data obtained with a control IgGsc antibody with unrelated specificity. Results for FLT3 binding variants are indicated in FIG. 5, for CD3 binding variants in FIG. 7.

[0238] Conclusion: Anti leukemic activity initially follows the affinity values on both sides of the bispecific molecule. Highly active and affine to FLT3 is the variant V5. However, surprisingly, the less affine variant V4 has a significant better cytotoxic potential against leukemic cells as the other variants, indicating that for certain applications a lower affinity range for anti-FLT3 antibodies may be selected. A similar result was seen for the CD3 binding part.

[0239] T cell activity and Blast cell reduction was analyzed for different antibody concentrations in FIGS. 8 and 9. A PBMC preparation of patient MM2 was obtained and incubated with the indicated concentrations of CC-2 variants. After 5 days T cell activation and depletion of leukemic cells was assessed by flow cytometry (FIG. 8). Nalm16 cells were incubated for 3 days with the indicated concentrations of CC-2 variants at an E:T ratio of 2:1 and were then analyzed by flow cytometry (FIG. 9).

Example 6: Anti Leukemic Activity of ABPs of the Invention In Vivo

[0240] In order to test in-vivo application of the CC-2 variants of the invention, preferred variants for FLT3 and CD3 binding were tested for their therapeutic potential in an immune deficient mouse model (FIG. 10). Immunodeficient NSG mice were engrafted with primary AML (left) or ALL (right) cells. On day 7 PBMC together with CC-2 (V4-V6) or control antibody were injected, and bsAb treatment was repeated on day 10. At day 17, leukemic burden (ratio hCD45.sup.+/mCD45.sup.+ cells) in bone marrow was determined by flow cytometry.

[0241] Conclusions: The experiment demonstrates therapeutic potential for even less affine CC2 variants such as V4.

[0242] The invention illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising”, “including,” containing”, etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by exemplary embodiments and optional features, modification and variation of the inventions embodied therein herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention.

Example 7: Humanized 4G8 Variants in Monospecific IgG Format

[0243] In order to test the superiority of the generated antibody variants of the invention the new variable domain sequences were cloned into a monospecific anti-FLT3 human IgG format. For this, the respective variable heavy and light chain sequences were cloned into a monospecific human IgG format. For this, antibody genes were codon optimized for expression in human cells and designed with NheI and Not restriction sites at the 5′ and 3′ ends. Genes were synthesized and then cloned into a mammalian expression vector following standard procedures. Following sequence verification plasmids were prepared in sufficient quantity for transfection using Plasmid Plus purification kits (Qiagen).

[0244] HEK 293 (human embryonic kidney 293) mammalian cells were passaged to the optimum stage for transient transfection. Cells were transiently transfected with expression vector and cultured for a further 6 days.

[0245] Cultures were harvested by centrifugation at 4000 rpm and filtered through a 0.22 mm filter. A first step of purification was performed by Nickel affinity chromatography with elution using PBS containing 400 mM imidazole. A second step of purification was performed by size exclusion chromatography with elution in PBS (phosphate buffered saline) pH7.2. Antibody concentration was determined by UV spectroscopy and the antibodies concentrated as necessary. Antibody purity was determined by SDS-PAGE (sodium dodecyl sulphate polyacrylamide gel electrophoresis) and HPLC (high performance liquid chromatography). HPLC was performed on an Agilent 1100 series instrument using MabPac size exclusion column run in PBS at 0.2 ml/min.

[0246] In order to elucidate superiority of generated 4G8 variants a monospecific IgG with the heavy and light chain variable domain sequences of the V4 variant (variable domain heavy and light chain sequences as shown in SEQ ID NOs: 21 and 22 respectively) was compared with the parent (mouse) IgG V6 (variable domain heavy and light chain sequences as shown in SEQ ID NOs: 4 and 8 respectively) and Fc control in an ADCC assay. For this pNKC were generated by incubation of non-plastic adherent PBMCs with K562-41BBL-IL15 feeder cells obtained from St Jude's Children's Research Hospital as described previously (Schmiedel B J et al. Int J Cancer 2011; 128: 2911-2922; Fujisaki H et al. Cancer Res 2009; 69: 4010-4017). BATDA-Europium kills were performed as described previously (Baessler T et al. Cancer Res 2009: 69: 1037-1045). The results are shown in FIG. 11.

[0247] The data in FIG. 11 show exemplary results for one pNKC donor at the indicated effector:target ratios. Superior lysis rates for V4 compared to V6 FLT3 monospecific IgG antibody variants could be observed in this experimental setting thus demonstrating improved therapeutic potential of the variants of the invention compared to the parent 4G8 antibody.