Melanoma brain metastasis: the impact of stereotactic radiosurgery, BRAF mutational status, and targeted and/or immune-based therapies on treatment outcome.

OBJECTIVE The goal of this study was to investigate the impact of stereotactic radiosurgery (SRS), BRAF status, and targeted and immune-based therapies on the recurrence patterns and factors associated with overall survival (OS) among patients with melanoma brain metastasis (MBM). METHODS A total of 366 patients were treated for 1336 MBMs; a lesion-based analysis was performed on 793 SRS lesions. The BRAF status was available for 78 patients: 35 had BRAF mut and 43 had BRAF wild-type ( BRAF-WT) lesions. The Kaplan-Meier method evaluated unadjusted OS; cumulative incidence analysis determined the incidences of local failure (LF), distant failure, and radiation necrosis (RN), with death as a competing risk. RESULTS The 12-month OS was 24% (95% CI 20%-29%). On multivariate analysis, younger age, lack of extracranial metastases, better Karnofsky Performance Status score, and fewer MBMs, as well as treatment with BRAF inhibitors (BRAFi), anti-PD-1/CTLA-4 therapy, or cytokine therapy were significantly associated with OS. For patients who underwent SRS, the 12-month LF rate was lower among those with BRAF mut lesions (6%, 95% CI 2%-11%) compared with those with BRAF-WT lesions (22%, 95% CI 13%-32%; p < 0.01). The 12-month LF rates among lesions treated with BRAFi and PD-1/CTLA-4 agents were 1% (95% CI 1%-4%) and 7% (95% CI 1%-13%), respectively. On multivariate analysis, BRAF inhibition within 30 days of SRS was protective against LF (HR 0.08, 95% CI 0.01-0.55; p = 0.01). The 12-month rates of RN were low among lesions treated with BRAFi (0%, 95% CI 0%-0%), PD-1/CTLA-4 inhibitors (2%, 95% CI 1%-5%), and cytokine therapies (6%, 95% CI 1%-13%). CONCLUSIONS Prognostic schema should incorporate BRAFi or immunotherapy status and use of targeted therapies. Treatment with a BRAF inhibitor within 4 weeks of SRS improves local control without an increased risk of RN.