Anti-CD3 x anti-epidermal growth factor receptor (EGFR) bispecific antibody redirects T-cell cytolytic activity to EGFR-positive cancers in vitro and in an animal model.
OBJECTIVE
Targeting epidermal growth factor receptor (EGFR) overexpressed by many epithelial-derived cancer cells with anti-EGFR monoclonal antibodies (mAb) inhibits their growth. A limited number of clinical responses in patients treated with the anti-EGFR mAb, (cetuximab), may reflect variability in EGFR type or signaling in neoplastic cells. This study combines EGFR-targeting with the non-MHC-restricted cytotoxicity of anti-CD3 activated T cells (ATC) to enhance receptor-directed cytotoxicity.


METHODS
ATC from normal and patient donors were expanded ex vivo. Specific cytolytic activity of ATC armed with anti-CD3 x anti-EGFR (EGFRBi) against EGFR-expressing cancer cells derived from lung, pancreas, colon, prostate, brain, skin, or EGFR-negative breast cancer cells was evaluated in (51)Cr release assays. In vivo studies comparing tumor growth delay induced by EGFRBi-armed ATCs or cetuximab were done in severe combined immunodeficient/Beige mice (SCID-Beige) bearing COLO 356/FG pancreatic and LS174T colorectal tumors.


RESULTS
At effector/target ratios from 3.125 to 50, both EGFRBi-armed normal and patient ATC were significantly more cytotoxic, by 23% to 79%, against EGFR-positive cells over ATC, cetuximab, anti-CD3 alone, or ATC armed with irrelevant BiAb directed at CD20. EGFRBi-armed ATC also secreted significantly higher levels of some T(H1)/T(H2) cytokines compared with ATC alone. In mice, i.v. infusions of EGFRBi-armed ATC (0.001 mg equivalent/infusion) were equally effective as cetuximab (1 mg/infusion) alone for significantly delaying growth of established COLO 356/FG but not LS174T tumors compared with mice that received ATC alone or vehicle (P < 0.001).


CONCLUSIONS
Combining EGFR antibody targeting with T cell-mediated cytotoxicity may overcome some limitations associated with EGFR-targeting when using cetuximab alone.
Reusch
Ursula
U
Cancer Immunotherapy Program, Adele R. Decof Cancer Center, Providence, Rhode Island, USA.
Sundaram
Magesh
M
Davol
Pamela A
PA
Olson
Sarah D
SD
Davis
James B
JB
Demel
Kurt
K
Nissim
Julie
J
Rathore
Ritesh
R
Liu
Paul Y
PY
Lum
Lawrence G
LG
D000818:Animals; D018033:Antibodies, Bispecific / Q000627:therapeutic use*; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017252:CD3 Complex / Q000276:immunology; D045744:Cell Line, Tumor; D000068818:Cetuximab; D003602:Cytotoxicity, Immunologic; D066246:ErbB Receptors / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy* / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*
D018033:Antibodies, Bispecific; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D017252:CD3 Complex; D066246:ErbB Receptors; D000068818:Cetuximab