Background: Pmab, a fully human monoclonal antibody targeting EGFR, has demonstrated activity in combination with FOLFIRI for second-line treatment of mCRC (study 181). Here, we describe the results of a prespecified subgroup analysis of study 181 to evaluate the efficacy of pmab plus FOLFIRI vs FOLFIRI alone in pts who received prior bev. Methods: Prior bev use for mCRC (yes vs no) was a predefined baseline covariate and stratification factor in study 181. A subgroup analysis was conducted to evaluate the treatment effect of pmab plus chemotherapy on progression-free survival (PFS), overall survival (OS), and tumor response rate in pts with wild-type (WT) KRAS tumors who received prior bev for mCRC. Results: 115 pts (from 20 countries) with WT KRAS tumors who had received prior bev were identified. Worst grade of 3 or 4 adverse events (AE) occurred in 73% of pts in the pmab+FOLFIRI arm vs 57% in FOLFIRI arm. Worst grade 3-4 AEs of interest included: skin toxicity (tox [35 vs 5%]); eye tox (7 vs 0%); nail tox (5 vs 0%); diarrhea (9 vs 8%); stomatitis/oral mucositis (7 vs 2%); pulmonary tox (0 vs 3% [and one grade 5 in the FOLFIRI arm]); vascular tox (2 vs 15%); hypomagnesemia (4 vs 0%); cardiac tox (0 vs 3%); and hypocalcemia (2 vs 0%). Grade 5 AEs occurred in 2% and 3% of pts, respectively. Median PFS and OS were numerically longer, and there was a significantly higher overall response rate (ORR) in the pmab+FOLFIRI arm vs FOLFIRI (Table). Conclusions: Pts with mCRC and WT KRAS tumors who progress after therapy with bev may benefit from second-line therapy with pmab+FOLFIRI.

* Pts who had measureable lesion per central radiology review were included in the analysis of ORR. Abbreviations: CI, confidence interval; HR, hazard ratio; OR, odds ratio.