ANTI-KIT ANTIBODIES AND USES THEREOF
Provided herein, in one aspect, are antibodies that immunospecifically bind to a human KIT antigen comprising the fourth and/or fifth extracellular Ig-like domains (that is, D4 and/or D5 domains), polynucleotides comprising nucleotide sequences encoding such antibodies, and expression vectors and host cells for producing such antibodies. The antibodies can inhibit KIT activity, such as ligand-induced receptor phosphorylation. Also provided herein are kits and pharmaceutical compositions comprising antibodies that specifically bind to a KIT antigen, as well as methods of treating or managing a KIT-mediated disorder or disease and methods of diagnosing a KIT-mediated disorder or disease using the antibodies described herein.
1 . An antibody, which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), comprising:
(i) a variable light (“VL”) chain region comprising a VL CDR1, VL CDR2, and VL CDR3 having the amino acid sequences of SEQ ID NO: 20, SEQ ID NO: 21, and SEQ ID NO: 22, respectively; and
(ii) a variable heavy (“VH”) chain region comprising a VH CDR1, VH CDR2, and VH CDR3 having the amino acid sequences of SEQ ID NO: 23, SEQ ID NO: 24, and SEQ ID NO: 25, respectively.
2 . The antibody of claim 1 , which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), comprising:
(A) a VL chain region comprising the amino acid sequence of SEQ ID NO: 2, and a VH chain region comprising the amino acid sequence of SEQ ID NO: 3; or
(B) a VL chain region comprising the amino acid sequence of SEQ ID NO: 2 and a VH chain region comprising the amino acid sequence of SEQ ID NO: 5.
3 . The antibody of claim 1 , which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), comprising:
a VL chain region comprising a VL CDR1, VL CDR2, and VL CDR3 having the amino acid sequences of SEQ ID NO: 20, SEQ ID NO: 21, and SEQ ID NO: 22, respectively; and a VH chain region comprising the amino acid sequence of SEQ ID NO: 3 or 5.
4 . The antibody of claim 1 , which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), comprising:
a VL chain region comprising the amino acid sequence of SEQ ID NO: 2; and a VH chain region comprising a VH CDR1, VH CDR2, and VH CDR3 having the amino acid sequences of SEQ ID NO: 23, SEQ ID NO: 24, and SEQ ID NO: 25, respectively.
5 . The antibody of claim 1 , which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), wherein said antibody competes for binding to the D4/D5 region of human KIT with an antibody comprising:
a VL chain region comprising the amino acid sequence of SEQ ID NO: 2, and a VH chain region comprising the amino acid sequence of SEQ ID NO: 3 or 5.
6 . An antibody, which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), wherein said antibody binds to the same epitope as the epitope of an antibody comprising:
a VL chain region comprising the amino acid sequence of SEQ ID NO: 2, and a VH chain region comprising the amino acid sequence of SEQ ID NO: 3 or 5.
7 . An antibody, which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), wherein said antibody competes for binding to the D4/D5 region of human KIT with an antibody comprising:
(i) a VL chain region comprising a VL CDR1, VL CDR2, and VL CDR3 having the amino acid sequences of SEQ ID NO: 20, SEQ ID NO: 21, and SEQ ID NO: 22, respectively; and
(ii) a VH chain region comprising a VH CDR1, VH CDR2, and VH CDR3 having the amino acid sequences of SEQ ID NO: 23, SEQ ID NO: 24, and SEQ ID NO: 25, respectively.
8 . An antibody, which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), wherein said antibody binds to the same epitope as the epitope of an antibody comprising:
(i) a VL chain region comprising a VL CDR1, VL CDR2, and VL CDR3 having the amino acid sequences of SEQ ID NO: 20, SEQ ID NO: 21, and SEQ ID NO: 22, respectively; and
(ii) a VH chain region comprising a VH CDR1, VH CDR2, and VH CDR3 having the amino acid sequences of SEQ ID NO: 23, SEQ ID NO: 24, and SEQ ID NO: 25, respectively.
9 . The antibody of any one of claims 1 to 8 , wherein said antibody further comprises a human light chain constant region comprising the amino acid sequence of SEQ ID NO: 12 and a human heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 13.
10 . The antibody of any one of claims 1 to 8 , wherein the antibody further comprises a human light chain constant region and a human heavy chain constant region.
11 . The antibody of claim 10 , wherein the human light chain constant region is a human kappa light chain constant region.
12 . The antibody of claim 10 , wherein the human heavy chain constant region is a human gamma heavy chain constant region.
13 . The antibody of any one of claims 1 to 12 , wherein the antibody is a humanized monoclonal antibody.
14 . The antibody of any one of claims 1 to 13 , wherein the antibody is a monoclonal antibody or an isolated antibody.
15 . The antibody of any one of claims 1 to 13 , wherein the antibody is a human IgG1 or IgG4 antibody.
16 . The antibody of claim 15 , wherein the antibody is an IgG1 isotype f antibody.
17 . The antibody of any one of claims 1 to 16 , wherein the antibody is an inhibitor of KIT activity.
18 . The antibody of claim 17 , wherein the antibody inhibits KIT tyrosine phosphorylation by at least 25% as determined by a solid phase ELISA assay.
19 . The antibody of claim 18 , wherein the antibody inhibits KIT tyrosine phosphorylation by 25% to 80% as determined by a solid phase ELISA assay.
20 . The antibody of claim 17 , wherein the antibody inhibits KIT receptor phosphorylation by at least 50% as determined by a solid phase ELISA assay.
21 . The antibody of claim 17 , wherein the antibody does not block KIT ligand binding to KIT.
22 . The antibody of claim 17 , wherein the antibody does not inhibit KIT receptor dimerization.
23 . The antibody of claim 17 , wherein the antibody does not inhibit KIT receptor dimerization.
24 . The antibody of claim 17 , wherein the antibody enhances KIT receptor internalization or KIT receptor degradation.
25 . The antibody of claim 17 , wherein the antibody induces apoptosis when a cell expressing KIT is contacted with an effective amount of the antibody.
26 . The antibody of any one of claims 1 to 16 , wherein said antibody is internalized by a cell.
27 . A conjugate comprising the antibody of any one of claims 1 to 26 , or a KIT-binding fragment thereof, linked to a therapeutic agent.
28 . The conjugate of claim 27 , wherein the therapeutic agent is a toxin.
29 . The conjugate of claim 28 , wherein the toxin is abrin, ricin A, pseudomonas exotoxin, cholera toxin, or diphtheria toxin.
30 . The conjugate of any one of claims 27 to 29 , wherein the conjugate is internalized by a cell.
31 . A pharmaceutical composition comprising the conjugate of any one of claims 27 to 30 and a pharmaceutically acceptable carrier.
32 . An polynucleotide comprising nucleotide sequences encoding a VH chain region, a VL chain region, or both a VL chain region and a VH chain region, of an antibody of any one of claims 1 to 16 .
33 . The polynucleotide of claim 32 , wherein the polynucleotide comprises a nucleotide sequence encoding a VH chain region, a VL chain region, or both a VL chain region and a VH chain region, of an antibody comprising:
(i) a VL chain region comprising a VL CDR1, VL CDR2, and VL CDR3 having the amino acid sequences of SEQ ID NO: 20, SEQ ID NO: 21, and SEQ ID NO: 22, respectively; and
(ii) a VH chain region comprising a VH CDR1, VH CDR2, and VH CDR3 having the amino acid sequences of SEQ ID NO: 23, SEQ ID NO: 24, and SEQ ID NO: 25, respectively.
34 . The polynucleotide of claim 32 , wherein the polynucleotide comprises a nucleotide sequence encoding a VH chain region, a VL chain region, or both a VL chain region and a VH chain region, of an antibody comprising:
(i) a VL chain region comprising the amino acid sequence of SEQ ID NO: 2; and
(ii) a VH chain region comprising the amino acid sequence of SEQ ID NO: 3 or 5.
35 . The polynucleotide of claim 32 , wherein the polynucleotide comprises a nucleotide sequence encoding a VH chain region, a VL chain region, or both a VL chain region and a VH chain region, of an antibody which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), wherein said polynucleotide comprises the nucleotide sequence of SEQ ID NO:
8 or 9, or SEQ ID NOs: 8 and 9.
36 . The polynucleotide of claim 32 , wherein the polynucleotide comprises a nucleotide sequence encoding a heavy chain, a light chain, or both a light chain and a heavy chain, of an antibody which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15), wherein said polynucleotide comprises the nucleotide sequence of SEQ ID NO: 10 or 11, or SEQ ID NOs: 10 and 11.
37 . An expression vector comprising the polynucleotide of any one of claims 32 to 36 .
38 . The expression vector of claim 37 , which is a mammalian expression vector.
39 . A host cell comprising the expression vector of claim 37 or 38 or one or more polynucleotides of any one of claims 32 - 36 .
40 . A hybridoma cell producing an antibody of any one of claims 1 to 16 .
41 . A pharmaceutical composition comprising the antibody of any one of claims 1 to 26 and a pharmaceutically acceptable carrier.
42 . A kit comprising the antibody of any one of claims 1 to 26 .
43 . A kit comprising the conjugate of any one of claims 27 to 30 .
44 . A method for treating or managing a KIT-mediated disorder, comprising administering to a subject in need thereof a therapeutically effective amount of the antibody of any one of claims 1 to 26 .
45 . A method for treating or managing a KIT-mediated disorder, comprising administering to a subject in need thereof a therapeutically effective amount of the conjugate of any one of claims 27 to 30 .
46 . The method of claim 44 or 45 , wherein the KIT-mediated disorder is cancer, an inflammatory condition, or fibrosis.
47 . The method of claim 46 , wherein the cancer is leukemia, chronic myelogenous leukemia, lung cancer, small cell lung cancer, or gastrointestinal stromal tumors.
48 . The method of claim 46 , wherein the cancer is refractory to treatment by a tyrosine kinase inhibitor.
49 . The method of claim 48 , wherein the tyrosine kinase inhibitor is imatinib mesylate or SU11248.
50 . The method of any one of claims 44 to 49 , wherein the method further comprises administering a second therapeutic agent.
51 . The method of claim 50 , wherein the second therapeutic agent is a chemotherapeutic agent, tyrosine kinase inhibitor, an antibody, or a cytokine.
52 . The method of claim 51 , wherein the tyrosine kinase inhibitor is imatinib mesylate or SU11248.
53 . A method for diagnosing a subject with a KIT-mediated disorder comprising contacting cells or a sample obtained from the subject with the antibody of any one of claims 1 to 16 and detecting the expression level of KIT in the cells or the sample.
54 . The method of claim 53 , wherein the antibody is conjugated to a detectable molecule.
55 . The method of claim 54 , wherein the detectable molecule is an enzyme, a fluorescent molecule, a luminescent molecule, or a radioactive molecule.
56 . A method for inhibiting KIT activity in a cell expressing KIT comprising contacting the cell with an effective amount of the antibody of any one of claims 1 to 16 .
57 . A method for inducing or enhancing apoptosis in a cell expressing KIT comprising contacting the cell with an effective amount of the antibody of any one of claims 1 to 16 .
58 . A method for inducing cell differentiation comprising contacting a cell expressing KIT with an effective amount of the antibody of any one of claims 1 to 16 .
59 . The method of claim 58 , wherein the cell is a stem cell.
60 . An antibody, which specifically binds to an epitope within a D4/D5 region of human KIT (SEQ ID NO: 15), comprising a light chain and a heavy chain, wherein the light chain comprises the amino acid sequence of SEQ ID NO: 6 or the amino acid sequence of SEQ ID NO: 6 starting at position 20, lacking the signal peptide.
61 . An antibody, which specifically binds to an epitope within a D4/D5 region of human KIT (SEQ ID NO: 15), comprising a light chain and a heavy chain, wherein the heavy chain comprises the amino acid sequence SEQ ID NO: 7 or the amino acid sequence of SEQ ID NO: 6 starting at position 20, lacking the signal peptide.
62 . A method of making an antibody which immunospecifically binds to a D4/D5 region of human KIT (SEQ ID NO: 15) comprising culturing the cell of claim 39 or 40 .
63 . The method claim 62 further comprising purifying the antibody obtained from said cell.
64 . The method of claim 50 , wherein the second therapeutic agent is a histone deacetylase inhibitor.