CD123 binding proteins and related compositions and methods
The present disclosure relates to protein molecules that specifically bind to CD123, which may have at least one humanized or human CD123-binding domain. Such molecules are useful for the treatment of cancer. The protein molecule binding to CD123 may have a second binding domain that binds to another target. In one embodiment, multi-specific polypeptide molecules bind both CD123-expressing cells and the T-cell receptor complex on T-cells to induce target-dependent T-cell cytotoxicity, activation, and proliferation. The disclosure also provides pharmaceutical compositions comprising the CD123-binding polypeptide molecules, nucleic acid molecules encoding these polypeptides and methods of making these molecules.
1. A recombinant polypeptide comprising a CD123-binding domain,
wherein the CD123-binding domain comprises (i) an immunoglobulin light chain variable region comprising LCDR1, LCDR2, and LCDR3, and (ii) an immunoglobulin heavy chain variable region comprising HCDR1, HCDR2, and HCDR3, and
wherein the LCDR1 comprises the amino acid sequence set forth in SEQ ID NO:6; the LCDR2 comprises the amino acid sequence set forth in SEQ ID NO:8; the LCDR3 comprises the amino acid sequence set forth in SEQ ID NO:10, the HCDR1 comprises the amino acid sequence set forth in SEQ ID NO:12; the HCDR2 comprises the amino acid sequence set forth in SEQ ID NO:14; and the HCDR3 comprises the amino acid sequence set forth in SEQ ID NO:16.
2. The polypeptide of claim 1 , wherein the CD123-binding domain comprises:
(i) the immunoglobulin light chain variable region comprising the amino acid sequence of SEQ ID NO:2; and
(ii) the immunoglobulin heavy chain variable region comprising the amino acid sequence of SEQ ID NO:4.
3. The polypeptide of claim 1 , wherein the polypeptide binds to human CD123 with specificity.
4. The polypeptide of claim 1 , wherein the CD123-binding domain comprises a human immunoglobulin light chain variable region and a human immunoglobulin heavy chain region.
5. The polypeptide of claim 1 , wherein the CD123-binding domain is a single chain variable fragment (scFv).
6. The polypeptide of claim 5 , wherein the heavy chain variable region of said scFv is amino-terminal to the light chain variable region of said scFv.
7. The polypeptide of claim 5 , wherein the light chain variable region of said scFv is amino-terminal to the heavy chain variable region of said scFv.
8. The polypeptide of claim 1 , wherein said binding domain is conjugated to a drug or a toxin.
9. The polypeptide of claim 1 , further comprising an immunoglobulin constant region.
10. The polypeptide of claim 1 , further comprising a second binding domain.
11. A recombinant polypeptide comprising, in order from amino terminus to carboxyl terminus, (i) a CD123-binding domain, (ii) a hinge region, (iii) an immunoglobulin constant region, (iv) a carboxyl-terminus linker, and (v) a CD3-binding domain,
wherein the CD123-binding domain comprises an immunoglobulin light chain variable region comprising the amino acid sequence of SEQ ID NO:2; and an immunoglobulin heavy chain variable region comprising the amino acid sequence of SEQ ID NO:4; and
wherein the CD3-binding domain comprises an immunoglobulin light chain variable region comprising the amino acid sequence of SEQ ID NO:158; and an immunoglobulin heavy chain variable region comprising the amino acid sequence of SEQ ID NO:159.
12. The polypeptide of claim 11 , wherein the CD123-binding domain is an scFv and the CD3-binding domain is an scFv.
13. The polypeptide of claim 11 , wherein the carboxyl-terminus linker comprises SEQ ID NO:288.
14. The polypeptide of claim 11 , wherein the immunoglobulin constant region comprises immunoglobulin CH2 and CH3 domains of IgG1, IgG2, IgG3, IgG4, IgA1, IgA2 or IgD.
15. The polypeptide of claim 11 , wherein the immunoglobulin constant region comprises a human IgG1 CH2 domain comprising the substitutions L234A, L235A, G237A, and K322A, according to the EU numbering system.
16. The polypeptide of claim 11 , wherein
(i) the polypeptide comprises the amino acid sequence of SEQ ID NO:130; or
(ii) the polypeptide comprises the amino acid sequence of SEQ ID NO:132.
17. The polypeptide of claim 12 , wherein the CD123-binding domain is an scFv comprising an immunoglobulin light chain variable region and an immunoglobulin heavy chain variable region; and wherein said light chain variable region and said heavy chain variable region are joined by an amino acid sequence comprising (Gly4Ser) n , wherein n=1-5 (SEQ ID NO:214).
18. The polypeptide of claim 12 , wherein the CD3-binding domain is an scFv comprising an immunoglobulin light chain variable region and an immunoglobulin heavy chain variable region; and wherein said light chain variable region and said heavy chain variable region are joined by an amino acid sequence comprising (Gly4Ser) n , wherein n=1-5 (SEQ ID NO:214).
19. The polypeptide of claim 11 , wherein the carboxyl-terminus linker comprises an amino acid sequence comprising (Gly4Ser) n , wherein n=1-7 (SEQ ID NO:314).
20. The polypeptide of claim 19 , wherein n=3-5.
21. A dimer comprising two identical polypeptides of claim 11 .
22. A pharmaceutical composition comprising the polypeptide claim 11 and a pharmaceutically acceptable carrier, diluent, or excipient.
23. An isolated nucleic acid molecule encoding the recombinant polypeptide of claim 11 .
24. The isolated nucleic acid molecule of claim 23 , wherein the nucleic acid molecule comprises a nucleotide sequence set forth in SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:129, or SEQ ID NO:131.
25. An expression vector comprising a nucleic acid segment encoding the polypeptide of claim 11 , wherein the nucleic acid segment is operatively linked to regulatory sequences suitable for expression of the nucleic acid segment in a host cell.
26. The expression vector of claim 25 , wherein the nucleic acid segment comprises a nucleotide sequence set forth in SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:129, or SEQ ID NO:131.
27. A recombinant host cell comprising the expression vector of claim 26 .
28. A method for producing a CD123-binding polypeptide, the method comprising culturing a recombinant host cell comprising the expression vector of claim 25 under conditions whereby the nucleic acid segment is expressed, thereby producing the CD123-binding polypeptide.
29. A method for inducing redirected T-cell cytotoxicity (RTCC) against a cancerous cell overexpressing CD123, the method comprising: contacting said CD123-overexpressing cell with the polypeptide of claim 11 , wherein said contacting is under conditions whereby RTCC against the CD123-overexpressing cell is induced.
30. A method for inducing T-cell dependent lysis of a cancerous cell overexpressing CD123, the method comprising: contacting said CD123-overexpressing cell with the polypeptide of claim 11 , wherein said contacting is under conditions whereby T-cell dependent lysis of the CD123-overexpressing cell is induced.
31. A method for treating a cancer in a subject, wherein said cancer is characterized by overexpression of CD123, the method comprising administering to the subject a therapeutically effective amount of the dimer of claim 21 , wherein the cancer is acute myeloid leukemia (AML), B-lymphoid leukemia, blastic plasmocytoid dendritic neoplasm (BPDCN), hairy cell leukemia, acute lymphoblastic leukemia, refractory anemia with excess blasts, myelodysplastic syndrome, chronic myeloid leukemia or Hodgkin's lymphoma.
32. The polypeptide of claim 1 , wherein said polypeptide binds to non-human primate CD123 with specificity.
33. The polypeptide of claim 12 , wherein the CD3-binding domain comprises the amino acid sequence of SEQ ID NO:312.