BI-SPECIFIC CD3 AND CD19 ANTIGEN-BINDING CONSTRUCTS

1 . An antigen-binding construct comprising

a first antigen-binding polypeptide construct comprising a first scFv comprising a first VL, a first scFv linker, and a first VH, the first scFv monovalently and specifically binding a CD19 antigen, the first scFv selected from the group consisting of an anti-CD19 antibody HD37 scFv, a modified HD37 scFv, an HD37 blocking antibody scFv, and a modified HD37 blocking antibody scFv, wherein the HD37 blocking antibody blocks by 50% or greater the binding of HD37 to the CD19 antigen;

a second antigen-binding polypeptide construct comprising a second scFv comprising a second VL, a second scFv linker, and a second VH, the second scFv monovalently and specifically binding an epsilon subunit of a CD3 antigen, the second scFv selected from the group consisting of the OKT3 scFv, a modified OKT3 scFv, an OKT3 blocking antibody scFv, and a modified OKT3 blocking antibody scFv, wherein the OKT3 blocking antibody blocks by 50% or greater the binding of OKT3 to the epsilon subunit of the CD3 antigen;

a heterodimeric Fc comprising first and second Fc polypeptides each comprising a modified CH3 sequence capable of forming a dimerized CH3 domain, wherein each modified CH3 sequence comprises asymmetric amino acid modifications that promote formation of a heterodimeric Fc and the dimerized CH3 domains have a melting temperature (Tm) of about 68° C. or higher, and wherein the first Fc polypeptide is linked to the first antigen-binding polypeptide construct with a first hinge linker, and the second Fc polypeptide is linked to the second antigen-binding polypeptide construct with a second hinge linker.

2 . The antigen-binding construct of claim 1 , consisting of v12043, v10149, or v1661.

3 . The antigen-binding construct of claim 1 , wherein the first scFv comprises CDR sequences 100% identical to a set of CDR sequences at selected from

a) L1:

(SEQ ID NO:)

QSVDYDGDSYL,

L2:

(SEQ ID NO:)

DAS,

L3:

(SEQ ID NO:)

QQSTEDPWT,

H1:

(SEQ ID NO:)

GYAFSSYW,

H2:

(SEQ ID NO:)

IWPGDGDT,

H3:

(SEQ ID NO:)

RETTTVGRYYYAMDY;

b) L1:

(SEQ ID NO:)

QSVDYEGDSYL,

L2:

(SEQ ID NO:)

DAS,

L3:

(SEQ ID NO:)

QQSTEDPWT,

H1:

(SEQ ID NO:)

GYAFSSYW,

H2:

(SEQ ID NO:)

IWPGDGDT,

H3:

(SEQ ID NO:)

RETTTVGRYYYAMDY;

c) L1:

(SEQ ID NO:)

QSVDYSGDSYL,

L2:

(SEQ ID NO:)

DAS,

L3:

(SEQ ID NO:)

QQSTEDPWT,

H1:

(SEQ ID NO:)

GYAFSSYW,

H2:

(SEQ ID NO:)

IWPGDGDT,

H3:

(SEQ ID NO:)

RETTTVGRYYYAMDY

d) L1:

(SEQ ID NO:)

KASQSVDYDGDSYL,

L2:

(SEQ ID NO:)

DASNLVS,

L3:

(SEQ ID NO:)

QQSTEDPWT,

H1:

(SEQ ID NO:)

GYAFSSYWMN,

H2:

(SEQ ID NO:)

QIWPGDGDTN,

H3:

(SEQ ID NO:)

RETTTVGRYYYAMDY

e) L1:

(SEQ ID NO:)

RASQSVDYEGDSYL,

L2:

(SEQ ID NO:)

DASNLVS,

L3:

(SEQ ID NO:)

QQSTEDPWT,

H1:

(SEQ ID NO:)

GYAFSSYWMN,

H2:

(SEQ ID NO:)

QIWPGDGDTN,

H3:

(SEQ ID NO:)

RETTTVGRYYYAMDY

and

f) L1:

(SEQ ID NO:)

RASQSVDYSGDSYL,

L2:

(SEQ ID NO:)

DASNLVS,

L3:

(SEQ ID NO:)

QQSTEDPWT,

H1:

(SEQ ID NO:)

GYAFSSYWMN,

H2:

(SEQ ID NO:)

QIWPGDGDTN,

H3:

(SEQ ID NO:)

RETTTVGRYYYAMDY.

4 . The antigen-binding construct of claim 3 , wherein the first scFv comprises CDR sequences 95% identical to the set of CDRs according to claim 3 .

5 . The antigen-binding construct of claim 1 , wherein the first VH polypeptide sequence is selected from a wild-type HD37 VH polypeptide sequence, an hVH2 polypeptide sequence, and an hVH3 polypeptide sequence, and the first VL polypeptide sequence is selected from a wild-type HD37 VL polypeptide sequence and an hVL2 polypeptide sequence.

6 . The antigen-binding construct of claim 1 , wherein the first VH polypeptide sequence is 95% identical to a wild-type HD37 VH polypeptide sequence, an hVH2 polypeptide sequence, or an hVH3 polypeptide sequence, and the first VL polypeptide sequences are 95% identical to wild-type HD37 VL polypeptide sequence or an hVL2 polypeptide sequence.

7 . The antigen-binding construct of claim 1 , the HD37 blocking antibody selected from 4G7, B4, B3, HD237, and Mor-208.

8 . The antigen-binding construct of claim 1 , wherein the second scFv comprises a set of CDRs selected from:

a) L1:

(SEQ ID NO:)

SSVSY,

L2:

(SEQ ID NO:)

DTS,

L3:

(SEQ ID NO:)

QQWSSNP,

H1:

(SEQ ID NO:)

GYTFTRYT,

H2:

(SEQ ID NO:)

INPSRGYT,

H3:

(SEQ ID NO:)

ARYYDDHYCLDY

and

b) L1:

(SEQ ID NO:)

SSVSY,

L2:

(SEQ ID NO:)

DTS,

L3:

(SEQ ID NO:)

QQWSSNP,

H1:

(SEQ ID NO:)

GYTFTRYT,

H2:

(SEQ ID NO:)

INPSRGYT,

H3:

(SEQ ID NO:)

ARYYDDHYSLDY

9 . The antigen-binding construct of claim 1 , wherein the second scFv comprises a set of CDRs at least 95% identical to the set of CDRs according to claim 8 .

10 . The antigen-binding construct of claim 1 , wherein the second VH polypeptide sequence is a wild-type OKT3 VH polypeptide sequence, or a polypeptide sequence 95% identical to a wild-type OKT3 VH polypeptide sequence, and the second VL polypeptide sequence is a wild-type OKT3 VL polypeptide sequence, or a polypeptide sequence 95% identical to a wild-type OKT3 VL polypeptide sequence.

11 . The antigen-binding construct of claim 1 , the OKT3 blocking antibody selected from Teplizumab™, UCHT1, and visilizumab.

12 . The antigen-binding construct of claim 1 , the second scFv binding to the OKT3 CD3 epitope.

13 . The antigen-binding construct of any one of claims 1 to 12 , wherein the first VL, first scFv linker polypeptide sequence and first VH polypeptide sequences are arranged from N-terminus to C-terminus as VL-linker-VH.

14 . The antigen-binding construct of any one of claims 1 to 12 , wherein the first VL, first scFv linker polypeptide sequence and first VH polypeptide sequences are arranged from N-terminus to C-terminus as VH-linker-VL.

15 . The antigen-binding construct of any one of claims 1 to 14 , wherein the second VL, second scFv linker polypeptide sequence and second VH polypeptide sequences are arranged from N-terminus to C-terminus as VL-linker-VH.

16 . The antigen-binding construct of any one of claims 1 to 14 , wherein the second VL, second scFv linker polypeptide sequence and second VH polypeptide sequences are arranged from N-terminus to C-terminus as VH-linker-VL.

17 . The antigen-binding construct of any of claims 1 to 16 , wherein one or both scFv comprise a disulphide bond between VL and VH polypeptide sequences.

18 . The antigen-binding construct of any of claims 1 and 3 to 17 , wherein the first or second scFv linker is selected from Table B.

19 . The antigen-binding construct of any of claims 1 and 3 to 18 , wherein the first or second hinge polypeptide linker is selected from Table E.

20 . The antigen-binding construct of claim 1 , wherein the first VL, scFv linker and VH polypeptide sequences are arranged from N-terminus to C-terminus as VL-linker-VH comprising a disulphide bond between the first VL and VH polypeptide sequences, and the second VL, scFv linker and VH polypeptide sequences are arranged from N-terminus to C-terminus as VH-linker-VL comprising a disulphide bond between the second VL and VH polypeptide sequences.

21 . The antigen-binding construct of claim 1 , wherein the first VL, scFv linker and VH polypeptide sequences are arranged from N-terminus to C-terminus as VL-linker-VH comprising a disulphide bond between the VL and VH polypeptide sequences, and the second VL, scFv linker and VH polypeptide sequences are arranged from N-terminus to C-terminus as VL-linker-VH, and a disulphide bond between the VL and VH polypeptide sequences.

22 . The antigen-binding construct of claim 20 or 21 , the heterodimeric Fc comprising at least one CH2 domain comprising one or more amino acid substitutions that reduce the ability of the heterodimeric Fc to bind to FcγRs or complement.

23 . The antigen-binding construct of any one of claims 1 to 22 , wherein the binding affinity of the first scFv for CD19 is between about 0.1 nM to about 5 nM, and the binding affinity of the second scFv for the epsilon subunit of CD3 is between about 1 nM to about 100 nM.

24 . The antigen-binding construct of any one of claims 1 to 23 , wherein the heterodimeric Fc

a. is a human Fc; and/or

b. is a human IgG1 Fc; and/or

c. comprises one or more modifications in at least one of the CH3 domains as described in Table A; and/or

d. further comprises at least one CH2 domain; and/or

e. further comprises at least one CH2 domain comprising one or more modifications; and/or

f. further comprises at least one CH2 domain comprising one or more modifications in at least one of the CH2 domains as described in Table B; and/or

g. further comprises at least one CH2 domain comprising one or more amino acid substitutions that reduce the ability of the heterodimeric Fc to bind to FcγRs or complement as described in Table C; and/or

h. further comprises at least one CH2 domain comprising amino acid substitutions N297A or L234A_L235A, or L234A_L235A_D265S.

25 . The antigen-binding construct of any one of claims 1 to 24 ; wherein the dimerized CH3 domains have a melting temperature (Tm) of 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 77.5, 78, 79, 80, 81, 82, 83, 84, or 85° C. or higher.

26 . The antigen-binding construct of any one of claims 1 to 25 , wherein the antigen-binding construct

a) is capable of synapse formation and bridging between CD19+ Raji B-cells and Jurkat T-cells as assayed by FACS and/or microscopy; and/or

b) mediates T-cell directed killing of CD19-expressing B cells in human whole blood or PBMCs; and/or

c) displays improved biophysical properties compared to v875 or v1661; and/or

d) displays improved protein expression and yield compared to v875 or v1661, e.g., expressed at >4-10 mg/L after SEC (size exclusion chromatography) when expressed and purified under similar conditions; and/or

e) displays heterodimer purity, e.g., >95%.

27 . The antigen-binding construct of any of claims 1 through 26 , wherein the antigen-binding construct is conjugated to a drug.

28 . A pharmaceutical composition the antigen-binding construct of any of claims 1 through 27 and a pharmaceutical carrier.

29 . The pharmaceutical composition of claim 28 , the carrier comprising a buffer, an antioxidant, a low molecular weight molecule, a drug, a protein, an amino acid, a carbohydrate, a lipid, a chelating agent, a stabilizer, or an excipient.

30 . A pharmaceutical composition for use in medicine comprising the antigen-binding construct of any of claims 1 through 27 .

31 . A pharmaceutical composition for use in treatment of cancer comprising the antigen-binding construct of any of claims 1 through 27 .

32 . A method of treating a cancer in a subject, the method comprising administering an effective amount of the antigen-binding construct of any of claims 1 through 27 to the subject.

33 . The method of claim 32 , wherein the subject is a human.

34 . The method of claim 32 , wherein the cancer is a lymphoma or leukemia or a B cell malignancy, or a cancer that expresses CD19, or non-Hodgkin's lymphoma (NHL) or mantle cell lymphoma (MCL) or acute lymphoblastic leukemia (ALL) or chronic lymphocytic leukemia (CLL) or rituximab- or CHOP (Cytoxan™/Adriamycin™vincristine/prednisone therapy)-resistant B cell cancers.

35 . A method of producing the antigen-binding construct of any of claims 1 through 27 , comprising culturing a host cell under conditions suitable for expressing the antigen-binding construct wherein the host cell comprises a polynucleotide encoding the antigen-binding construct of any of claims 1 through 27 , and purifying the antigen-binding construct.

36 . An isolated polynucleotide or set of isolated polynucleotides comprising at least one nucleic acid sequence that encodes at least one polypeptide of the antigen-binding construct any of claims 1 through 27 .

37 . The isolated polynucleotide of claim 36 , wherein the polynucleotide or set of polynucleotides is cDNA.

38 . A vector or set of vectors comprising one or more of the polynucleotides or sets of polynucleotides according to claim 36 , optionally selected from the group consisting of a plasmid, a viral vector, a non-episomal mammalian vector, an expression vector, and a recombinant expression vector.

39 . An isolated cell comprising a polynucleotide or set of polynucleotides according to claim 36 , or a vector or set of vectors of claim 38 , optionally selected from a hybridoma, a Chinese Hamster Ovary (CHO) cell, or a HEK293 cell.

40 . A kit comprising the antigen-binding construct any of claims 1 through 27 and instructions for use.