High affinity B7-H6 antibodies and antibody fragments

1. An antibody or antigen-binding antibody fragment that binds specifically to B7 homolog 6 (B7-H6) which comprises either of the following:

I. (a) a heavy chain variable region comprising,

(i) a CDR1 of SEQ ID NO: 4,

(ii) a CDR2 of SEQ ID NO: 5, and

(iii) a CDR3 of SEQ ID NO: 6; and

 (b) a light chain variable region comprising,

(i) a CDR1 of SEQ ID NO: 7,

(ii) a CDR2 of SEQ ID NO: 8, and

(iii) a CDR3 of SEQ ID NO: 9;

or

II. (a) a heavy chain variable region comprising,

(i) a CDR1 of SEQ ID NO: 13,

(ii) a CDR2 of SEQ ID NO: 14, and

(iii) a CDR3 of SEQ ID NO: 15; and

 (b) a light chain variable region comprising,

(i) a CDR1 of SEQ ID NO: 16,

(ii) a CDR2 of SEQ ID NO: 17, and

(iii) a CDR3 of SEQ ID NO: 18.

2. The antibody, or antigen-binding antibody fragment, of claim 1 , wherein the antibody is a full-length antibody, optionally wherein the full-length antibody is an IgG molecule.

3. The antibody, or antigen-binding antibody fragment, of claim 1 , wherein the antigen-binding fragment of the antibody is a scFv fragment.

4. The antibody, or antigen-binding antibody fragment, of claim 1 , wherein the antibody, or antigen-binding antibody fragment, is conjugated to a synthetic molecule.

5. The antibody, or antigen-binding antibody fragment, of claim 4 , wherein the antibody, or antigen-binding antibody fragment, is a chimeric antigen receptor and the synthetic molecule comprises a transmembrane domain and an intracellular signaling domain.

6. The antibody, or antigen-binding antibody fragment, of claim 5 , wherein the intracellular signaling domain is a T cell receptor intracellular signaling domain.

7. The antibody, or antigen-binding antibody fragment, of claim 6 , wherein the transmembrane domain and the intracellular T cell receptor signaling domain are obtained from CD3 zeta.

8. The antibody, or antigen-binding antibody fragment, of claim 5 , wherein the intracellular signaling domain is a Fc-gamma intracellular signaling domain.

9. The antibody, or antigen-binding antibody fragment, of claim 5 , further comprising the intracellular domain of a costimulatory protein receptor, optionally wherein the costimulatory protein receptor is CD27, CD28, 4-1BB, ICOS, DAP-10 or OX40 and/or the chimeric antigen receptor further comprises a hinge domain optionally a CD28 or CD8 hinge domain.

10. The antibody, or antigen-binding antibody fragment of claim 4 , wherein the antibody, or antigen-binding antibody fragment, is a bi-specific T-cell engager and the synthetic molecule comprises an antigen binding domain which binds to a T-cell antigen, optionally wherein the antigen binding domain comprises an antibody fragment that specifically binds CD3.

11. The antibody, or antigen-binding antibody fragment of claim 4 , wherein the synthetic molecule is a label, optionally a cytotoxic agent or a therapeutic radioisotope.

12. A recombinant T cell comprising the antibody, or antigen-binding antibody fragment of claim 4 .

13. A pharmaceutical composition or kit comprising the antibody, or antigen-binding antibody fragment of claim 4 and a pharmaceutically acceptable carrier.

14. A chimeric antigen receptor comprising

(a) an antigen-binding antibody fragment of claim 1 ,

(b) a transmembrane domain, and

(c) an intracellular signaling domain.

15. The chimeric antigen receptor of claim 14 , wherein the intracellular signaling domain is a T cell receptor intracellular signaling domain, optionally wherein the transmembrane domain and intracellular T-cell receptor signaling domain are from CD8 zeta and/or the intracellular signaling domain is a FcR-gamma intracellular signaling domain.

16. The chimeric antigen receptor of claim 14 , further comprising a transmembrane domain or an intracellular signaling domain of a costimulatory protein receptor, optionally wherein the costimulatory protein receptor is, CD27, CD28, 4-IBB, 1COS, DAP-10 or OX40 and/or the chimeric receptor further comprises a hinge domain, optionally a CD28 or CD8 hinge region.

17. A recombinant T cell comprising the chimeric antigen receptor claim 14 .

18. A bi-specific T-cell engager comprising

(a) an antigen-binding antibody fragment of claim 1 , and

(b) an antigen binding domain that binds to a T-cell antigen; wherein optionally the antigen binding domain comprises an antibody fragment that specifically binds CD3.

19. A method, comprising administering an effective amount of the antibody, or antigen-binding antibody fragment of claim 1 to a subject in need thereof, wherein said subject has a disease characterized by B7-H6-expressing cells.

20. The method of claim 19 , wherein

(i) the effective amount is an amount effective to kill or reduce, in a subject, growth of cells expressing B7 homolog 6, optionally cancer cells;

(ii) the effective amount is an amount effective to kill or reduce, in a subject, growth of cancer cells expressing B7 homolog 6;

(iii) the subject has myeloid leukemia, acute nonlymphocytic leukemia, acute lymphoblastic leukemia, B-cell lymphoma, breast cancer, cervical cancer, clear cell renal cell carcinoma, dermatofibrosarcoma protuberans, gastric sarcoma, gastrointestinal stromal tumor, glioblastoma, leiomyosarcoma, invasive ductal breast carcinoma, malignant fibrous histiocytoma, melanoma, ovarian serous surface papillary carcinoma, pancreatic cancer, prostate cancer, T-cell acute lymphoblastic leukemia or T-cell lymphoma;

(iv) the effective amount is an amount effective to induce an immune response, in the subject, against cells expressing B7 homolog 6;

(v) the subject has an autoimmune disorder;

(iv) the subject has Sjogren's syndrome; and/or

(vi) the method includes co-administering a second therapeutic agent.