TREATMENT OF CD47+ DISEASE CELLS WITH SIRP ALPHA-FC FUSIONS
CD47+ disease cells, such as CD47+ cancer cells, are treated with an agent that blocks signalling via the SIRPα/CD47 axis. The agent is a human SIRPα fusion protein that displays negligible CD47 agonism and negligible red blood cell binding. The fusion protein comprises an IgV domain from variant 2 of human SIRPα, and an Fc having effector function. The IgV domain binds human CD47 with an affinity that is at least five fold greater than the affinity of the entire extracellular region of human SIRPα. The fusion protein is at least 5 fold more potent than a counterpart lacking effector function.
1 - 23 . (canceled)
24 . A method of inhibiting growth or proliferation of CD47+ disease cells comprising administering to a subject with CD47+ disease cells a combination of an anti-cancer agent and a fusion protein, said fusion protein (SIRPαFc) having a human SIRPα IgV domain fused to an immunoglobulin constant region polypeptide (Fc), wherein the human SIRPα IgV domain and the SIRPαFc fusion protein bind CD47.
25 . The method of claim 24 , wherein the CD47+ disease cells are CD47+ cancer cells.
26 . The method according to claim 25 , wherein the disease cells are CD47+ hematological cancer cells.
27 . The method according to claim 26 , wherein the CD47+ hematological cancer is a leukemia, a lymphoma, a multiple myeloma, or a myelodysplastic syndrome.
28 . The method according to claim 27 , wherein the CD47+ hematological cancer cell is an acute myeloid leukemia or a T cell lymphoma.
29 . The method according to claim 25 , wherein the cancer is a solid tumour comprising CD47+ cancer cells.
30 . The method according to claim 25 , wherein the CD47+ cancer cells are melanoma cells.
31 . The method according to claim 24 , wherein the human SIRPα IgV domain comprises the SIRPα V2 IgV amino acid sequence of SEQ ID NO: 1.
32 . The method according to claim 31 , wherein the Fc component comprises an IgG1 Fc isotype or an IgG4 isotype.
33 . The method according to claim 32 , wherein the Fc component has up to five amino acid substitutions.
34 . The method according to claim 33 , wherein the Fc component comprises a substitution at position 228.
35 . The method according to claim 34 , wherein the Fc component comprises a S228P substitution at position 228.
36 . The method according to claim 33 , having conservative substitutions at one or more sites selected from 228, 234, 235, 236, 252, 256, and 297.
37 . The method according to claim 32 , wherein the Fc component comprises an IgG1 Fc isotype.
38 . The method according to claim 37 , wherein the human SIRPαFc protein comprises the amino acid sequence of SEQ ID NO: 25.
39 . The method according to claim 32 , wherein the human SIRPαFc protein comprises the amino acid sequence of SEQ ID NO: 26.
40 . The method according to claim 24 that comprises administering a dimeric fusion protein having a first human SIRPα IgV domain fused to an immunoglobulin constant region polypeptide (Fc) and a second fusion protein having a human SIRPα IgV domain fused to an immunoglobulin constant region polypeptide (Fc), wherein the first and second fusions are liked through the Fc regions.
41 . The method according to claim 24 , wherein the anti-cancer agent comprises radiation or a radiotoxin or a cytotoxin.
42 . The method according to claim 41 , wherein the anti-cancer agent comprises the cytotoxin and the cytotoxin comprises taxol, ethidium bromide, emetine, mitomycin, etoposide, vincristine, vinblastine, colchicine, doxorubicin, daunorubicin, mitoxantrone, migramycin, or actinomycin D.
43 . The method according to claim 41 , wherein the anti-cancer agent is conjugated to the SIRPαFc fusion protein.
44 . The method according to claim 24 , wherein the anti-cancer agent comprises an antimetabolite, an alkylating agent, an anthracycline, an antibiotic or an anti-mitotic agent.
45 . The method according to claim 44 , wherein the anti-cancer agent comprises methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, cyclophosphamide, busulfan, mitomycin C, cisplatin, dactinomycin, bleomycin, mithramycin, or anthramycin.
46 . The method according to claim 24 , wherein the anti-cancer agent comprises an anti-cancer antibody.
47 . A combination, in unit dosage form, containing an anti-cancer agent and a fusion protein, said fusion protein (SIRPαFc) having a human SIRPα IgV domain fused to an immunoglobulin constant region polypeptide (Fc), wherein the human SIRPα IgV domain and the SIRPαFc fusion protein bind CD47.
48 . The combination according to claim 47 , wherein the anti-cancer agent comprises radiation or a radiotoxin or a cytotoxin.
49 . The combination according to claim 47 , wherein the anti-cancer agent comprises an anti-cancer antibody.
50 . A method of treating cancer comprising administering to a subject with cancer the combination of claim 47 .
51 . A composition containing an anti-cancer agent and a fusion protein, said fusion protein (SIRPαFc) having a human SIRPα IgV domain fused to an immunoglobulin constant region polypeptide (Fc), wherein the human SIRPα IgV domain and the SIRPαFc fusion protein bind CD47.
52 . The composition according to claim 51 , wherein the anti-cancer agent comprises an anti-cancer antibody.
53 . The composition according to claim 51 , wherein the anti-cancer agent is conjugated to the SIRPαFc fusion protein.
54 . The composition according to claim 53 , wherein the anti-cancer agent is a radiotoxin or a cytotoxin.
55 . A method of treating cancer comprising administering to a subject with cancer the composition of claim 51 .