ABSTRACT
BACKGROUND: Overexpression of epidermal growth factor receptor (EGFR) is common in pancreatic cancer and associated with the poor prognosis of this malignancy. OBJECTIVE: To develop anti-EGFR antibody-drug conjugates (ADCs) for use in a novel EGFR-targeting approach to treat pancreatic cancer. METHODS: A humanized anti-EGFR monoclonal antibody (RC68) was generated by mouse immunization and complementary-determining region grafting technology. Two RC68-based ADCs, RC68-MC-VC-PAB-MMAE and RC68-PY-VC-PAB-MMAE, were synthesized by conjugating monomethyl auristatin E (MMAE), a small-molecule cytotoxin, to RC68 through two distinct linkers (MC and PY). Internalization of the RC68-based ADCs was examined by flow cytometry. The in vitro and in vivo antitumor activities of RC68-based ADCs were evaluated in human pancreatic cancer cells and in a BXPC-3 xenograft nude mouse model, respectively. RESULTS: The RC68-based ADCs bound to EGFR on the surface of tumor cells and were effectively internalized, resulting in the death of EGFR-positive cancer cell lines. The RC68-based ADCs (at 5 or 10 mg/kg) were more potent than gemcitabine hydrochloride (60 mg/kg) at inhibiting the growth of BXPC-3 xenografts. Moreover, RC68-PY-VC-PAB-MMAE was found to have superior stability in human plasma compared with RC68-MC-VC-PAB-MMAE. CONCLUSION: A novel EGFR-targeting ADC, RC68-PY-VC-PAB-MMAE, shows promise as an effective, selective, and safe therapeutic agent for EGFR-positive pancreatic cancer.