HUMANIZED FC GAMMA RIIB-SPECIFIC ANTIBODIES AND METHODS OF USE THEREOF
The present invention relates to humanized FcγRIIB antibodies, fragments, and variants thereof that bind human FcγRIIB with a greater affinity than said antibody binds FcγRIIA. The invention encompasses the use of the humanized antibodies of the invention for the treatment of any disease related to loss of balance of Fc receptor mediated signaling, such as cancer, autoimmune and inflammatory disease. The invention provides methods of enhancing the therapeutic effect of therapeutic antibodies by administering the humanized antibodies of the invention to enhance the effector function of the therapeutic antibodies. The invention also provides methods of enhancing the efficacy of a vaccine composition by administering the humanized antibodies of the invention. The invention encompasses methods for treating an autoimmune disease and methods for elimination of cancer cells that express FcγRIIB.
1 . A method of treating cancer in a patient having a cancer characterized by a cancer antigen, said method comprising administering to said patient a therapeutically effective amount of:
(A) a first antibody that comprises an antigen-binding domain that specifically binds the extracellular domain of human FcγRIIB via said antigen-binding domain, wherein said first antibody comprises a heavy chain variable domain comprising the amino acid sequence of SEQ ID NO:37 and a light chain variable domain comprising the amino acid sequence of SEQ ID NO:46, or a fragment of said first antibody that comprises said antigen-binding domain and specifically binds said extracellular domain of human FcγRIIB via said antigen-binding domain; and
(B) a second antibody that specifically binds said cancer antigen and is cytotoxic.
2 . The method of claim 1 , wherein said first antibody is a humanized antibody that comprises a human Fc domain, and wherein said human Fc domain of said humanized antibody comprises at least one amino acid modification.
3 . The humanized antibody of claim 2 , wherein said at least one amino acid modification comprises a substitution at position 243, a substitution at position 292, a substitution at position 300, a substitution at position 305, and a substitution at position 396 and wherein said positions are according to Kabat.
4 . The humanized antibody of claim 3 , wherein the substitution at position 243 is a substitution with leucine, the substitution at position 292 is a substitution with proline, the substitution at position 300 is a substitution with leucine, the substitution at position 305 is a substitution with isoleucine, and the substitution at position 396 is a substitution with leucine and wherein said positions are according to Kabat.
5 . The method of claim 2 , wherein said at least one amino acid modification comprises a substitution at position 265 or 297, wherein said positions are according to Kabat.
6 . The method of claim 5 , wherein said position 265 is substituted with alanine, or said position 297 is substituted with glutamine.
7 . The method of claim 1 , wherein said fragment of said first antibody is selected from the group consisting of an F(ab) fragment, an F(ab′) fragment, an F(ab′) 2 fragment, an Fv fragment, an scFv fragment, and an sdFv fragment.
8 . The method of claim 2 , wherein said first antibody is a single chain antibody.
9 . The method of claim 1 , wherein said second antibody is operably linked to a heterologous polypeptide.
10 . The method of claim 1 , wherein said second antibody is conjugated to a therapeutic agent.
11 . The method of claim 10 , wherein said therapeutic agent is a cytotoxin.
12 . The method of claim 1 , wherein said cancer antigen is a melanoma cancer antigen, a G-Antigen (GAGE), N-acetylglucosaminyltransferase, beta-catenin, MUM-1, CDK4, HER-2/neu, human papillomavirus-E6, human papillomavirus-E7, or MUC-1.
13 . The method of claim 1 , wherein said cancer antigen is a breast, ovarian, stomach, uterine, prostate, cervical, or pancreatic carcinoma antigen.
14 . The method of claim 1 , further comprising the administration of an additional cancer therapy.
15 . The method of claim 14 , wherein said additional cancer therapy is selected from the group consisting of chemotherapy, immunotherapy, radiation therapy, hormonal therapy, or surgery.
16 . The method of claim 1 , wherein said patient is a human.
17 . The method of claim 2 , wherein said human Fc domain of said humanized antibody exhibits increased affinity to an Fc activation receptor, relative to the affinity of a wild-type Fc domain.
18 . The method of claim 17 , wherein said Fc activation receptor is FcγRIIIA.