Impact of BRAF mutation and BRAF inhibition on melanoma brain metastases

Abstract

The impact of BRAF mutations in metastatic melanoma on the incidence of brain metastases and melanoma prognosis and the effect of BRAF inhibitors on the incidence of brain metastases has not been defined. Therefore, a retrospective analysis of patients with metastatic melanoma treated at three institutions was carried out to examine the impact of BRAF mutations and a BRAF inhibitor, vemurafenib, on the incidence of brain metastases. A retrospective review of 436 records revealed no difference in the incidence of brain metastases between patients with BRAF-mutated tumors versus those without (incidence rate ratio=1.11, 95% confidence interval: 0.80-1.53; P=0.53). A lower incidence of brain metastases was observed in patients with BRAF-mutated tumors who took vemurafenib before the development of brain metastases versus those who did not (incidence rate ratio=0.51, 95% confidence interval: 0.30-0.86; P=0.009). Although treatment with vemurafenib led to improvement in extracranial disease control, it did not significantly affect progression of existing intracranial disease and survival in these patients (P=0.7). Although our previous preclinical data have indicated that penetration of vemurafenib into the brain is limited, our retrospective analysis showed that there was a lower incidence of brain metastases in patients with BRAF-mutated tumors who took vemurafenib before the diagnosis of brain metastases.