Complete response with fluorouracil and irinotecan with a BRAFV600E and EGFR inhibitor in BRAF-mutated metastatic colorectal cancer: a case report

Background: Patients with BRAF (v-Raf murine sarcoma viral oncogene homolog B) V600E-mutated metastatic colorectal cancer (mCRC) have a poor prognosis. The Southwest Oncology Group (SWOG) 1406 study evaluated the efficacy of vemurafenib in combination with irinotecan and cetuximab for simultaneous inhibition of epidermal growth factor receptor (EGFR) and BRAF in patients with BRAF(V600E)-mutated mCRC. Although the combination achieved higher progression-free survival (PFS) and disease control rates (DCRs), there was no complete response (CR) for the drug combination. In this case report, we report the complete recession of metastasis in a patient treated with irinotecan, cetuximab, vemurafenib, and 5-fluorouracil. Case presentation: A 44-year-old male patient with hepatitis B was diagnosed with rightsided colon adenocarcinoma. He was treated with capecitabine plus oxaliplatin as postoperative adjuvant chemotherapy for eight cycles with a disease-free survival (DFS) of 1 year before the emergence of peritoneal and pelvic metastases. BRAF(V600E) mutation was positive and chemotherapy included 12 courses of 5-fluorouracil, vemurafenib, irinotecan, and cetuximab. Complete response with recession of metastases was observed. Conclusion: The combination of fluorouracil and irinotecan with a BRAF(V600E) and EGFR inhibitor may have synergistic action, leading to recession of secondary metastases in patients with BRAF(V600E)-mutated colorectal cancer.