Comparison of Panitumumab Plus Irinotecan and Cetuximab Plus Irinotecan for KRAS Wild-type Metastatic Colorectal Cancer

Abstract

Background/aim: Panitumumab and cetuximab are known to be effective treatments for KRAS wild-type metastatic colorectal cancer (mCRC). However, it remains unclear which of these two biologic agents confers the greatest benefit when combined with irinotecan in patients with KRAS wild-type mCRC previously treated with fluoropyrimidine, oxaliplatin and irinotecan.

Patients and methods: Data, from 139 patients who received panitumumab or cetuximab, in combination with irinotecan, for KRAS wild-type mCRC previously treated with fluoropyrimidine, oxaliplatin and irinotecan were analyzed. The efficacy and safety of panitumumab plus irinotecan was compared to that of cetuximab plus irinotecan.

Results: Baseline characteristics of the panitumumab plus irinotecan (n=42) and cetuximab plus irinotecan (n=97) groups were similar. Among patients with measurable lesions, the response rate was 34% in the panitumumab plus irinotecan group and 20% in the cetuximab plus irinotecan group. Median progression-free survival (PFS) was 4.3 and 5.7 months in the panitumumab and cetuximab groups, respectively. Median overall survival was 13.6 months with panitumumab and 11.2 months with cetuximab.

Conclusion: Panitumumab plus irinotecan was well-tolerated and displayed a similar level of efficacy to that of cetuximab plus irinotecan.

Keywords: Colorectal cancer; KRAS; cetuximab; panitumumab.