Proof-of-concept study of Sym004, an anti-EGFR monoclonal antibody (mAb) mixture, in patients (pts) with anti-EGFR mab-refractory KRAS wild-type (wt) metastatic colorectal cancer (mCRC).

3551 Background: KRAS wt mCRC pts progressing on chemotherapy and anti-EGFR mAbs have limited treatment options. Sym004 is a first-in-class drug mixture of two mAbs targeting non-overlapping epitopes on the EGFR, causing its internalization and degradation. With this unique mechanism of action, Sym004 overcomes acquired resistance to anti-EGFR mAbs in preclinical studies. Methods: Open-label, multicenter trial assessing safety (primary endpoint) and efficacy of 2 dose levels of Sym004 in KRAS wt mCRC pts with prior clinical benefit to anti-EGFR mAbs and subsequent progression during or within 6 months after treatment cessation. Sym004 was administered until disease progression or unaccepta…