Panitumumab Provides Better Survival Outcomes Compared to Cetuximab for Metastatic Colorectal Cancer Patients Treated with Prior Bevacizumab within 6 Months

Abstract

Objective: Anti-epithelial growth factor receptor (EGFR) antibodies cetuximab (Cmab) and panitumumab (Pmab) have shown survival benefit for metastatic colorectal cancer (mCRC) patients. This study aimed to compare Pmab and Cmab according to the interval between bevacizumab discontinuation and anti-EGFR antibody initiation (bevacizumab-free interval; BFI).

Methods: We retrospectively evaluated mCRC patients who received Cmab or Pmab in combination with irinotecan at two institutions. Inclusion criteria were histologically confirmed mCRC, with KRAS exon 2 wild-type tumor, refractory or intolerant to fluoropyrimidines, oxali platin, and irinotecan.

Results: One-hundred-seventy-eight patients fulfilled the eligibility criteria. Among them, there was no significant difference in overall survival (OS) and progression-free survival (PFS) between the Pmab (n = 44) and Cmab groups (n = 134). Of 132 patients with BFI < 6 months, the median OS was 13.3 and 11.5 months in the Pmab (n = 39) and Cmab (n = 93) groups, respectively (p = 0.043). The median PFS was 5.8 and 4.9 months in the Pmab and Cmab groups, respectively (p = 0.055). Multivariate analysis for OS confirmed the superiority of Pmab.

Conclusion: Pmab showed more favorable outcomes in patients treated with bevacizumab within the last 6 months. The interval between prior bevacizumab and subsequent anti-EGFR therapy may be useful for determining the optimal anti-EGFR therapy.

Keywords: Bevacizumab; Cetuximab; Epithelial growth factor receptor; Interval; Irinotecan; Metastatic colorectal cancer; Panitumumab; Vascular endothelial growth factor.