NKG2D-IG fusion protein for cancer immunotherapy
Methods and compositions for cancer immunotherapy are provided. The methods involve the use of a chimeric molecule (e.g., fusion protein) comprising a dimeric NKG2D portion and an Fc portion, which binds one or more NKG2D ligands. In some embodiments, the molecule further comprises a drug moiety (e.g., an IL15/Ra moiety). The methods disclosed herein are useful for the treatment of cancer that is associated with abnormal expression of one or more NKG2D ligands.
1. A dimeric NKG2D-Fc chimera including two distinct NKG2D ligand binding sites, each NKG2D ligand binding site attached to an Fc fragment, wherein: each NKG2D ligand binding site comprises NKG2D or a ligand binding portion of NKG2D; and the Fc fragment comprises a fragment crystallizable region (Fc) of an immunoglobulin.
2. The dimeric NKG2D-Fc chimera according to claim 1 , further comprising a drug moiety.
3. The dimeric NKG2D-Fc chimera according to claim 2 , wherein the drug moiety is attached to an amino terminus or a carboxy terminus of the chimera.
4. The dimeric NKG2D-Fc chimera according to claim 2 , further comprising at least one linking molecule, wherein the at least one linking molecule is not a contiguous portion of NKG2D, the Fc fragment, or drug moiety and which covalently joins:
(a) an amino acid of the NKG2D or the ligand binding portion of NKG2 to an amino acid of the Fc fragment, or
(b) an amino acid of the Fc fragment to the drug moiety.
5. The dimeric NKG2D-Fc chimera according to claim 4 , wherein the at least one linking molecule is a peptide linker of about 2 to about 25 amino acids in length.
6. The dimeric NKG2D-Fc chimera according to claim 4 , wherein the at least one linking molecule is a glycine-serine linker.
7. The dimeric NKG2D-Fc chimera according to claim 6 , wherein the glycine-serine linker is represented by:
the formula (GS) n , wherein n is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12; or
the formula (GGGGS) n (SEQ ID NO: 2), wherein n is 1, 2, 3, 4, or 5.
8. The dimeric NKG2D-Fc chimera according to claim 7 , wherein the glycine-serine linker is represented by the formula (GS) 3 or the formula (GGGGS) 4 (SEQ ID NO:3).
9. The dimeric NKG2D-Fc chimera according to claim 1 , wherein the ligand binding portion of NKG2D comprises an extracellular fragment of NKG2D.
10. The dimeric NKG2D-Fc chimera according to claim 1 , wherein the Fc fragment comprises a fragment crystallizable region (Fc) of a human immunoglobulin (IgG).
11. The dimeric NKG2D-Fc chimera according to claim 2 , wherein the drug moiety is selected from the group consisting of: cytokine, chemokine, small molecule, toxin, radionuclide, and an enzyme.
12. The dimeric NKG2D-Fc chimera according to claim 11 , wherein the drug moiety is a cytokine selected from the group consisting of: IL-2, IL-12, IL-15, IL-18, IL-21 and IFN-α.
13. The dimeric NKG2D-Fc chimera according to claim 11 , wherein the drug moiety comprises a heterocomplex of IL-15 and soluble IL-15 receptor alpha chain.
14. A composition comprising: a dimeric NKG2D-Fc chimera including two distinct NKG2D ligand binding sites, each NKG2D ligand binding site attached to an Fc fragment, wherein: each NKG2D ligand binding site comprises NKG2D or a ligand binding portion of NKG2D; and the Fc fragment comprises a fragment crystallizable region (Fc) of an immunoglobulin; and a pharmaceutically acceptable carrier.