Purpose: BRAFV600E mutation is associated with a poor outcome in metastatic colorectal cancer (mCRC). This clinical trial investigated the efficacy of triplet chemotherapy (fluorouracil, folinic acid, oxaliplatin, and irinotecan) combined with either cetuximab or bevacizumab in patients with previously untreated BRAFV600E-mutant mCRC.
Patients and methods: In this controlled, randomized, open-label phase II trial, 109 patients were randomly assigned, 107 of whom were included into the full analysis set (FAS). Patients were randomly assigned in a 2:1 ratio to receive either FOLFOXIRI plus cetuximab in the experimental arm (n = 72) or FOLFOXIRI plus bevacizumab in the control arm (n = 35). The primary end point was objective response rate (ORR) according to RECIST 1.1., evaluated in patients treated according to protocol (ATP population). Progression-free survival (PFS), overall survival (OS), toxicity, and feasibility were analyzed as secondary end points.
Results: Eighteen patients discontinued study treatment before the first tumor assessment, thus resulting in the ATP population of 89 patients. In these patients, ORR was 51% (30/59) in the cetuximab-based experimental arm and 67% (20/30) in the bevacizumab-based control arm (odds ratio, 1.93; 80% CI, 1.06 to 3.52; P = .92 [one-sided]). In the full analysis set, median PFS was significantly inferior in the experimental arm (6.7 months v 10.7 months; hazard ratio [HR], 1.89; P = .006). Median OS analyzed at an event rate of 64.5% showed a trend toward shorter survival in cetuximab-treated patients (12.9 months v 17.1 months; HR, 1.4; P = .20).
Conclusion: To our knowledge, FIRE-4.5 is the first prospective and randomized study investigating first-line treatment of BRAFV600E-mutant mCRC. FOLFOXIRI plus cetuximab does not induce a higher ORR when compared with FOLFOXIRI plus bevacizumab in first-line treatment of BRAFV600E-mutant mCRC. Bevacizumab-based chemotherapy remains the preferable first-line treatment of patients with BRAFV600E-mutant mCRC.