Abstract
PURPOSE: We evaluated the local control of melanoma brain metastases (MBM) following stereotactic radiosurgery (SRS) in the setting of treatment with or without sequential/concurrent immunotherapy. METHODS: A single-institution IRB-approved retrospective review was conducted on 69 MBM patients with 230 total metastases treated with SRS between November 2008 to February 2017. We compared local control of metastases in the setting of no immunotherapy versus sequential/concurrent immunotherapy (ipilimumab, nivolumab, and pembrolizumab). Local failure was defined as an increase of at least 20% in the sum of longest diameter of a metastasis and its perpendicular diameter. Statistical analysis was performed using Kaplan-Meier estimates with log-rank testing using SPSS. RESULTS: The 6-month LC rate for all lesions was 76.8%. Fifty of the 69 patients (73.9%) received either ipilimumab, nivolumab, or pembrolizumab treatments (133 of 230 metastases). The 6-month LC rate for these metastases was 80.5%. In comparison, the 6-month LC rate for metastases in the cohort not treated with immunotherapy was 58.9% (p = 0.02). Patient pre-treatment characteristics including GPA score, number of brain metastases treated, and treatment volume were not significantly different between the immunotherapy and non-immunotherapy treatment groups. The 6-month LC rates for metastases receiving: (1) immunotherapy both before and after any SRS treatment (n = 55 metastases), (2) before SRS (n = 37 metastases), and (3) after SRS (n = 66 metastases) were (1) 86.5%, (2) 69.2%, and (3) 77.9%, respectively (p = 0.44). CONCLUSIONS: Addition of immunotherapy in melanoma brain metastases treated with stereotactic radiosurgery may improve local intracranial tumor control. Our study suggests that local control is not significantly impacted by whether immunotherapy is administered concurrently or sequentially to radiosurgery. Additional studies on volumetric response and radiation necrosis rates following combined radiosurgery/immunotherapy are underway.