Siglec-9 ECD fusion molecules
The present disclosure is generally directed to Siglec-9 ECDs and Siglec-9 ECD fusion molecules, and methods of treatment using Siglec-9 ECDs and Siglec-9 ECD fusion molecules.
1. An isolated fusion polypeptide comprising a Siglec-9 extracellular domain (ECD) comprising the amino acid sequence of SEQ ID NO: 78 and lacking the amino acid sequence of SEQ ID NO: 147, wherein the Siglec-9 ECD is joined at its C-terminus to an Fc domain.
2. The isolated polypeptide of claim 1 , wherein the Fc domain has a human IgG1 or IgG4 isotype.
3. The isolated polypeptide of claim 2 , wherein the Fc domain has a human IgG1 isotype that has:
a. reduced binding to FcγRIII;
b. reduced antibody-dependent cellular cytotoxicity (ADCC) and/or reduced complement binding activity;
c. increased binding to FcγRIIa; or
d. any combination of a), b), and/or c),
relative to the IgG1 polypeptide of SEQ ID No: 142.
4. An isolated fusion polypeptide comprising a Siglec-9 extracellular domain (ECD) comprising the amino acid sequence of SEQ ID NO: 78 and lacking a membrane proximal region (MPR) comprising the amino acid sequence of SEQ ID NO: 147, wherein the Siglec-9 ECD is joined at its C-terminus to an Fc domain, wherein the Fc domain has a human IgG1 isotype and comprises an amino acid sequence selected from any one of SEQ ID NOs: 142-144 and 234-239.
5. The isolated polypeptide of claim 2 , wherein the Fc domain comprises the amino acid sequence of SEQ ID NO: 142.
6. The isolated polypeptide of claim 2 , wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:10.
7. The isolated polypeptide of claim 2 , wherein the Fc domain comprises the amino acid sequence of SEQ ID NO: 143.
8. The isolated polypeptide of claim 2 , wherein the polypeptide comprises the amino acid sequence of SEQ ID NO: 227.
9. The isolated polypeptide of claim 2 , wherein the Fc domain has a human IgG4 isotype and comprises the amino acid sequence of SEQ ID NO: 145 or 146.
10. The isolated polypeptide of claim 1 , wherein the polypeptide comprises an amino acid sequence selected from any one of SEQ ID NOs: 45-48 and 228-233, optionally lacking its associated signal peptide.
11. The isolated polypeptide of claim 10 , wherein the polypeptide comprises the amino acid sequence of SEQ ID NO: 45, optionally lacking its associated signal peptide.
12. The isolated polypeptide of claim 10 , wherein the polypeptide comprises the amino acid sequence of SEQ ID NO: 48, lacking its associated signal peptide.
13. The isolated polypeptide of claim 1 , wherein the polypeptide binds sialic acid on the surface of cells.
14. The isolated polypeptide of claim 13 , wherein (a) the cells are tumor cells; (b) the cells express FcR; (c) the cells are myeloid cells; or (d) the cells are myeloid cells selected from monocytes, macrophages, dendritic cells, microglia, and myeloid-derived suppressor cells (MDSCs).
15. The isolated polypeptide of claim 1 , wherein the polypeptide
a. blocks cell binding of any one or more Siglec family members selected from Siglec-3, Siglec-5, Siglec-7, Siglec-9, Siglec-10, and Siglec-15;
b. relieves MDSC-mediated suppression of T-cells, optionally as determined by measuring an increase in IFNγ expression or an increase in T-cell proliferation;
c. repolarizes MDSCs to a pro-inflammatory phenotype;
d. increases expression of CD86 on MDSCs, increases expression of CD11b on MDSCs, and/or decreases expression of CD163 on MDSCs;
e. repolarizes tumor macrophages away from an M2 phenotype;
f. reduces CD163+ and/or CD206+macrophages;
g. induces expression of one or more chemokines selected from CCL3, CCL4, CCL5, CCL17, CXCL1, CXCL9, and IL-8 in MDSCs;
h. reduces myeloid cell recruitment into the tumor microenvironment; or
i. binds to MDSCs with an affinity of less than 100 nM, less than 50 nM, less than 25 nM, less than 20 nM, less than 10 nM, less than 5 nM, less than 2 nM, 1-50 nM, 1-25 nM, 1-20 nM, 1-10 nM, 1-5 nM, or 1-2 nM;
j. any one or more of (a) through (i),
optionally wherein the MDSCs are human MDSCs and/or the macrophages are human macrophages.
16. An isolated nucleic acid comprising a nucleic acid sequence that encodes the isolated polypeptide of claim 1 .
17. An expression vector comprising the isolated nucleic acid of claim 16 .
18. A host cell comprising the expression vector of claim 17 .
19. A method of producing a polypeptide comprising culturing the host cell of claim 18 , and optionally further comprising isolating the polypeptide.
20. A pharmaceutical composition comprising the polypeptide of claim 1 and a pharmaceutically acceptable carrier.