Therapeutic efficacy of an Fc-enhanced TCR-like antibody to the intracellular WT1 oncoprotein.
OBJECTIVE
RMFPNAPYL (RMF), a Wilms' tumor gene 1 (WT1)-derived CD8 T-cell epitope presented by HLA-A*02:01, is a validated target for T-cell-based immunotherapy. We previously reported ESK1, a high avidity (Kd < 0.2 nmol/L), fully-human monoclonal antibody (mAb) specific for the WT1 RMF peptide/HLA-A*02:01 complex, which selectively bound and killed WT1(+) and HLA-A*02:01(+) leukemia and solid tumor cell lines.


METHODS
We engineered a second-generation mAb, ESKM, to have enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) function due to altered Fc glycosylation. ESKM was compared with native ESK1 in binding assays, in vitro ADCC assays, and mesothelioma and leukemia therapeutic models and pharmacokinetic studies in mice. ESKM toxicity was assessed in HLA-A*02:01(+) transgenic mice.


RESULTS
ESK antibodies mediated ADCC against hematopoietic and solid tumor cells at concentrations below 1 μg/mL, but ESKM was about 5- to 10-fold more potent in vitro against multiple cancer cell lines. ESKM was more potent in vivo against JMN mesothelioma, and effective against SET2 AML and fresh ALL xenografts. ESKM had a shortened half-life (4.9 days vs. 6.5 days), but an identical biodistribution pattern in C57BL/6J mice. At therapeutic doses of ESKM, there was no difference in half-life or biodistribution in HLA-A*02:01(+) transgenic mice compared with the parent strain. Importantly, therapeutic doses of ESKM in these mice caused no depletion of total WBCs or hematopoetic stem cells, or pathologic tissue damage.


CONCLUSIONS
The data provide proof of concept that an Fc-enhanced mAb can improve efficacy against a low-density, tumor-specific, peptide/MHC target, and support further development of this mAb against an important intracellular oncogenic protein.
Sloan Kettering Institute; Weill Cornell Medical College, New York, New York;
Nicholas
N
Veomett
Sloan Kettering Institute;
Tao
T
Dao
Eureka Therapeutics Inc., Emeryville, California; and.
Hong
H
Liu
Eureka Therapeutics Inc., Emeryville, California; and.
Jingyi
J
Xiang
Sloan Kettering Institute;
Dmitry
D
Pankov
Sloan Kettering Institute;
Leonid
L
Dubrovsky
Temple University, Philadelphia, Pennsylvania.
Joseph A
JA
Whitten
Sloan Kettering Institute;
Sun-Mi
SM
Park
Sloan Kettering Institute;
Tatyana
T
Korontsvit
Sloan Kettering Institute;
Victoria
V
Zakhaleva
Sloan Kettering Institute;
Emily
E
Casey
Sloan Kettering Institute;
Michael
M
Curcio
Sloan Kettering Institute;
Michael G
MG
Kharas
Sloan Kettering Institute;
Richard J
RJ
O'Reilly
Eureka Therapeutics Inc., Emeryville, California; and.
Cheng
C
Liu
Sloan Kettering Institute; Weill Cornell Medical College, New York, New York; d-scheinberg@ski.mskcc.org.
David A
DA
Scheinberg
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use*; D000920:Antibody-Dependent Cell Cytotoxicity; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005434:Flow Cytometry; D015789:HLA-A2 Antigen / Q000276:immunology*; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000276:immunology*; D007167:Immunotherapy; D007942:Leukemia, Experimental / Q000276:immunology / Q000628:therapy*; D008297:Male; D008654:Mesothelioma / Q000276:immunology / Q000628:therapy*; D051379:Mice; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008822:Mice, Transgenic; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014407:Tumor Cells, Cultured; D025721:WT1 Proteins / Q000276:immunology*
D000911:Antibodies, Monoclonal; D018984:Epitopes, T-Lymphocyte; D015789:HLA-A2 Antigen; D007141:Immunoglobulin Fc Fragments; D011948:Receptors, Antigen, T-Cell; D025721:WT1 Proteins