Bi-specific monovalent diabodies that are capable of binding CD123 and CD3, and uses thereof

1. A CD123 binding molecule comprising:

a VH Domain of a monoclonal antibody capable of binding to CD123 (VH CD123 ) (SEQ ID NO:26); and

CDR1 (SEQ ID NO:44), CDR2 (SEQ ID NO:45), and CDR3 (SEQ ID NO:46) of a VL Domain of a monoclonal antibody capable of binding to CD123 (VL CD123 ).

2. A CD123 binding molecule comprising:

a VL Domain of a monoclonal antibody capable of binding to CD123 (VL CD123 ) (SEQ ID NO:25); and

CDR1 (SEQ ID NO:47), CDR2 (SEQ ID NO:48), and CDR3 (SEQ ID NO:49) of a VII Domain of a monoclonal antibody capable of binding to CD123 (VH CD123 ).

3. A CD123 binding molecule comprising a VH Domain of a monoclonal antibody capable of binding to CD123 (VH CD123 ) (SEQ ID NO:26) and a VL Domain of a monoclonal antibody capable of binding to CD123 (VL CD123 ) (SEQ ID NO:25).

4. The CD123 binding molecule of claim 3 , wherein said molecule further comprises a VH Domain of a monoclonal antibody capable of binding to CD3 (VH CD3 ), and a VL Domain of a monoclonal antibody capable of binding to CD3 (VL CD3 ).

5. The CD123 binding molecule of claim 4 , wherein said molecule is a diabody capable of specific binding to an epitope of CD123 and to an epitope of CD3, wherein the diabody comprises a first polypeptide chain and a second polypeptide chain, covalently bonded to one another, wherein:

A. the first polypeptide chain comprises, in the N-terminal to C-terminal direction:

i. a Domain 1, comprising

(1) a sub-Domain (1A), which comprises said VL Domain of a monoclonal antibody capable of binding to CD3 (VL CD3 );

(2) a sub-Domain (1B), which comprises said VH Domain of a monoclonal antibody capable of binding to CD123 (VH CD123 ) (SEQ ID NO:26);

ii. a Domain 2, wherein said Domain 2 is an E-coil Domain (SEQ ID NO:34) or a K-coil Domain (SEQ ID NO:35);

B. the second polypeptide chain comprises, in the N-terminal to C-terminal direction:

i. a Domain 1, comprising

(1) a sub-Domain (1A), which comprises said VL Domain of a monoclonal antibody capable of binding to CD123 (VL CD123 ) (SEQ ID NO:25); and

(2) a sub-Domain (1B), which comprises said VH Domain of a monoclonal antibody capable of binding to CD3 (VH CD3 );

ii. a Domain 2, wherein said Domain 2 is a K-coil Domain (SEQ ID NO:35) or an E-coil Domain (SEQ ID NO:34), wherein said Domain 2 of said first and said second polypeptide chains are not both E-coil Domains or both K-coil Domains; and

and wherein:

(a) said VL Domain of said first polypeptide chain and said VH Domain of said second polypeptide chain form an Antigen Binding Domain capable of specifically binding to an epitope of CD3; and

(b) said VL Domain of said second polypeptide chain and said VH Domain of said first polypeptide chain form an Antigen Binding Domain capable of specifically binding to an epitope of CD123.

6. The CD123 binding molecule of claim 5 , wherein said VL CD3 comprises SEQ ID NO: 21 and said VH CD3 comprises SEQ ID NO: 22.

7. The CD123 binding molecule of claim 5 , wherein:

(i) said first polypeptide chain additionally comprises a Domain 3 comprising a CH2 Domain and/or a CH3 Domain; or

(ii) said second polypeptide chain additionally comprises a Domain 3 comprising a CH2 Domain and/or a CH3 Domain.

8. The CD123 binding molecule of claim 7 , which further comprises a third polypeptide chain comprising a CH2 Domain and/or a CH3 Domain.

9. The CD123 binding molecule of claim 8 , wherein:

(i) said Domain 3 of said first polypeptide chain comprises CH2 and CH3 Domains (SEQ ID NO:56), and said third polypeptide chain comprises CH2 and CH3 Domains (SEQ ID NO:11);

(ii) said Domain 3 of said first polypeptide chain comprises a CH2 and CH3 Domain (SEQ ID NO:11), and said third polypeptide chain comprises a CH2 and CH3 Domain (SEQ ID NO:56);

(iii) said Domain 3 of said second polypeptide chain comprises CH2 and CH3 Domains (SEQ ID NO:56), and said third polypeptide chain comprises CH2 and CH3 Domains (SEQ ID NO:11); or

(iv) said Domain 3 of said second polypeptide chain comprises a CH2 and CH3 Domain (SEQ ID NO:11), and said third polypeptide chain comprises a CH2 and CH3 Domain (SEQ ID NO:56).

10. The CD123 binding molecule of claim 9 , further comprising a cysteine-containing peptide (SEQ ID NO:55) N-terminal to SEQ ID NO:11 and SEQ ID NO:56.

11. The CD123 binding molecule of claim 10 , wherein said VL CD3 comprises SEQ ID NO: 21 and said VH CD3 comprises SEQ ID NO: 22.

12. A polynucleotide encoding said first polypeptide chain and/or said second polypeptide chain of the CD123 binding molecule of claim 5 .

13. The polynucleotide of claim 12 , which comprises SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO: 14 or SEQ ID NO:16.

14. A CD123 binding molecule encoded by:

(i) SEQ ID NO:2 and SEQ ID NO:4;

(ii) SEQ ID NO:14, SEQ ID NO:16 and SEQ ID NO:12; or

(iii) SEQ ID NO:18, SEQ ID NO:2 and SEQ ID NO:12.

15. A pharmaceutical composition comprising the CD123 binding molecule of claim 3 and a physiologically acceptable carrier.

16. A pharmaceutical composition comprising the CD123 binding molecule of claim 5 and a physiologically acceptable carrier.

17. A pharmaceutical composition comprising the CD123 binding molecule of claim 8 and a physiologically acceptable carrier.

18. A pharmaceutical composition comprising the CD123 binding molecule of claim 11 and a physiologically acceptable carrier.