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.