Panitumumab or cetuximab combined with irinotecan in patients with KRAS wild-type metastatic colorectal cancer previously treated with fluoropyrimidine-, oxaliplatin-, and irinotecan-based regimens.

642 Background: Panitumumab and cetuximab are known to be effective in KRAS wild-type metastatic colorectal cancer (mCRC). However, it is not clear whether panitumumab and irinotecan confers benefit that are comparable to those of cetuximab and irinotecan in patients with KRAS wild-type mCRC previously treated with fluoropyrimidine-, oxaliplatin-, and irinotecan-based regimes. Methods: We analyzed 139 patients who had received panitumumab or cetuximabu combined with irinotecan for KRAS wild-type mCRC previously treated with fluor opyrimidine-, oxaliplatin-, and irinotecan-based regimes.We evaluated and compared efficacy and safety of panitumumab plus irinotecan and cetuximab plus irinotecan. Results: Baseline characteristics were similar for the two groups receving cetuximab pulus irinotecan (n = 97) and panitumumab plus irinotecan (n = 42),respectively.In patients with measurable lesions,the response rate (unconfirmed complete or partial response) were 20% (18/92) in the group receving cetuximab plus irintecan and 34% (14/41) in that receving panitumumab plus irinotecan. Median progression-free survival was 5.7 months in the cetuximab plus irinotecan group versus 4.3 months in the panitumumab plus irinotecan group. Median overall survival was 11.2 months in the cetuximab plus irinotecan group versus 13.6 months in the panitumumab plus irinotecan group. The most common adverse events in the cetuximab plus irinotecan versus panitumumab plus irinotecan groups were all-grade rash acneiform (82% versus 90%), paronychia (61% versus 52%), and grade 3-4 neutropenia (26% versus 19%). Conclusions: Panitumumab or cetuximab plus irinotecan were well tolerated and produced similar response rate and survivals compared to those previous clinical traials.These combinations are cosidered as standard treatment in patients with KRAS wild-type mCRC previously treated with fluoropyrimidine-, oxaliplatin-, and irinotecan-based regimes.