Durable Remission After Targeted Therapy in BRAF V600E–Mutant Metastatic Colorectal Cancer: Case Report

BRAF mutation leads to constitutive activation of the MAPK pathway and is associated with the immune-activating molecular subtype of colorectal cancer. Targeted therapy for BRAF V600E–mutant metastatic colorectal cancer (CRC) has significantly improved outcomes for these patients when combined with anti–epithelial growth factor receptor (EGFR) therapy. However, most patients ultimately develop disease progression. We report a case of a patient with metastatic-deficient mismatch repair, BRAF V600E– mutated CRC, who achieved a durable complete response to vemurafenib plus cetuximab and chemotherapy despite initial high burden of disease, including peritoneal involvement. Recent clinical trials of combined anti-EGFR/anti–BRAF V600E therapy in BRAF V600E-mutant CRCs have found a few instances of robust response. Further study of combined targeted and chemotherapeutic regimens and the immunogenic properties of BRAF mutation may yield promising results.