A first case report of recurrent gastric cancer harboring a BRAFV600E mutation responding to dabrafenib plus trametinib

Abstract

Comprehensive genomic profiling (CGP) has been increasingly implemented in clinical practice; however, only a limited proportion of patients ultimately receive genomically matched therapies. The BRAF V600E mutation is extremely rare in gastric cancer, and effective targeted treatment strategies remain undefined. A 63-year-old woman developed a tumor in the right ureter 3 years after gastrectomy for gastric cancer and was diagnosed with recurrent disease. She was initially treated with S-1 plus oxaliplatin and nivolumab; however, the disease progressed. CGP revealed a BRAF V600E mutation, and she subsequently received combination therapy with dabrafenib and trametinib under the Japanese health insurance system. The treatment resulted in a partial response, with a progression-free survival of approximately 6 months and manageable toxicity. To our knowledge, this is the first reported case of BRAF V600E–mutated gastric cancer treated with combined BRAF and MEK inhibition. This case highlights the potential clinical efficacy of dabrafenib plus trametinib, as well as the value of CGP in identifying actionable alterations in gastric cancer.