Patterns of Failure Outcomes for Combination of Stereotactic Radiosurgery and Immunotherapy for Melanoma Brain Metastases

BACKGROUND: Previous series have demonstrated central nervous system activity for immune checkpoint inhibitors (ICIs) and shown improved local control between stereotactic radiosurgery (SRS) and ICI for lung cancer brain metastases. OBJECTIVE: To assess whether the addition of ICI to SRS for melanoma brain metastasis improves outcomes when compared with historical control group treated in the era before ICI availability. METHODS: In this single institution retrospective series, outcomes of 24 patients with melanoma receiving concurrent ICI and SRS were compared with 111 historical controls treated before ICI era. Overall survival (OS) was estimated using the Kaplan-Meier method. Cumulative incidence of local and distant failures was estimated using a competing risk model that accounted for baseline differences using propensity score adjustments. RESULTS: The median OS time was improved in patients receiving ICI compared with the historical control group (17.6 vs 6.6 months, hazard ratio [HR] = 0.056, P = .0005). Cumulative incidence at 1 year for local failure in the historical control and ICI groups was approximately 12.5% and 6.5%, respectively (HR = 0.25, P = .19), while cumulative incidence of distant brain failure in the historical control and ICI groups was approximately 48% and 28%, respectively (HR = 0.326, P = .015) CONCLUSION: Distant brain failure and OS were improved in patients receiving concurrent ICI with SRS compared with historical controls. Local failure trended in the same direction; however, owing to small sample size, this did not reach statistical significance. While these data remain to be validated, they suggest that patients with brain metastasis may benefit from concurrent use of ICI with SRS.