Encorafenib, cetuximab and chemotherapy in BRAF-mutant colorectal cancer: a randomized phase 3 trial

Abstract

Encorafenib + cetuximab (EC) is approved for previously treated BRAF V600E-mutant metastatic colorectal cancer (mCRC) based on the BEACON phase 3 study. Historically, first-line treatment of BRAF V600E-mutant mCRC with chemotherapy regimens has had limited efficacy. The phase 3 BREAKWATER study investigated EC+mFOLFOX6 versus standard of care (SOC) in patients with previously untreated BRAF V600E mCRC. The dual primary endpoint of progression-free survival is event driven; data were not mature at data cutoff. BREAKWATER met the other dual primary endpoint of objective response rate, demonstrating significant and clinically relevant improvement in objective response rate (EC+mFOLFOX6: 60.9%; SOC: 40.0%; odds ratio, 2.443; 95% confidence interval (CI): 1.403–4.253; 99.8% CI: 1.019–5.855; one-sided P = 0.0008). Median duration of response was 13.9 versus 11.1 months. At this first interim analysis of overall survival, the hazard ratio was 0.47 (95% CI: 0.318–0.691; repeated CI: 0.166–1.322). Serious adverse event rates were 37.7% versus 34.6%. The safety profiles were consistent with those known for each agent. BREAKWATER demonstrated a significantly improved response rate that was durable for first-line EC+mFOLFOX6 versus SOC in patients with BRAF V600E mCRC. ClinicalTrials.gov identifier: NCT04607421 . As presented at the 2025 ASCO GI Cancers Symposium: in the phase 3 BREAKWATER trial, patients with previously untreated BRAF V600E metastatic colorectal cancer received the BRAF inhibitor encorafenib, the anti-EGFR monoclonal antibody cetuximab and chemotherapy mFOLFOX6 versus investigator’s choice of chemotherapy with or without bevacizumab, leading to an improved objective response rate, with the dual primary endpoint of progression free survival still maturing.