Treatment of brain metastases with stereotactic radiosurgery and immune checkpoint inhibitors: An international meta-analysis of individual patient data

•Immunotherapy and radiosurgery are utilized for brain metastases but data are limited.•In this metaanalysis, concurrent therapy improved 1-year survival and brain control.•The overall rate of radionecrosis was 5.3%.•Prospective trials are needed to more accurately inform on this clinical scenario. While the combination of stereotactic radiosurgery (SRS) and immune checkpoint inhibitors (ICI) is becoming more widely used in the treatment of brain metastases (BM), there is a paucity of prospective data to validate both the safety and efficacy, as well as the optimal timing of these two therapies relative to one another. A PICOS/PRISMA/MOOSE selection protocol was used to identify 17 studies across 15 institutions in 3 countries. Inclusion criteria were patients: diagnosed with BM; treated with SRS/ICI, either concurrently or non-concurrently; with at least one of the primary or secondary outcome measures reported. Weighted random effects meta-analyses using the DerSimonian and Laird method were performed. The primary outcome was 1-year overall survival (OS). Secondary outcomes were 1-year local control (LC), 1-year regional brain control (RBC), and radionecrosis incidence. A total of 534 patients with 1,570 BM were included. The 1-year OS was 64.6% and 51.6% for concurrent and non-concurrent therapy, respectively (p