Efficacy of trametinib in a metastatic urothelial carcinoma patient with a BRAF mutation.

Introduction: BRAF mutations in bladder cancer are rare. MEK inhibitors have excellent clinical benefits in the treatment of melanoma.

Case Presentation: A 60-year-old male was diagnosed with muscle-invasive bladder cancer and underwent total cystectomy and ileal conduit diversion. Despite 4 cycles of gemcitabine and cisplatin chemotherapy and 3 courses of pembrolizumab, the left obturator lymph node enlarged. Cancer multi-gene panel testing confirmed the BRAF G469A mutation and trametinib was recommended. Three months after the initiation of trametinib (2 mg, qd), the left obturator lymph node shrank by more than 50%. The disease has remained stable for more than 18 months.

Conclusion: The present case indicates the potential of trametinib to treat mBUC patients with the BRAF G469A mutation in this setting.