Combined Immunotherapy and Stereotactic Radiotherapy Improves Neurologic Outcomes in Patients with Non-Small Cell Lung Cancer Brain Metastases

Abstract Purpose To compare outcomes of patients with non-small cell lung cancer (NSCLC) brain metastases treated with stereotactic radiotherapy (SRT) alone versus SRT and immune checkpoint inhibitors (ICIs). Patients and Methods Patients treated for their first diagnosis of intracranial metastases with SRT or SRT plus ICI were retrospectively identified. Overall survival (OS), local control (LC), distant brain failure (DBF), neurologic death and rates of radiation necrosis were calculated. Univariate (UVA) and multivariable (MVA) analyses with competing risk analysis were performed. Results Seventy-seven patients with 132 lesions were analyzed, including 44 patients with 68 lesions in the SRT group and 33 patients with 64 lesions in the SRT plus ICI group. There were no differences in baseline factors between groups. Use of ICI predicted for decreased DBF (p = 0.01, HR 0.45, CI 0.24-0.84), decreased rates of neurologic death (p = 0.02, HR 0.29, CI 0.10-0.85), and better OS (p = 0.03, HR 0.46, CI 0.23-0.91). Two–year LC was 97% for the SRT+ICI group, and 86% for the SRT alone group (p=0.046). Actuarial 2-year DBF was 39% for the SRT+ICI group and 66% for the SRT alone group (p = 0.016). On MVA, ICI use persisted in predicting lower incidence of neurologic death (p = 0.01, HR 0.25, CI 0.09-0.72) and DBF (p = 0.01, HR 0.47, CI 0.25-0.85) when adjusted for competing risk of death. Conclusion In this cohort of patients with NSCLC brain metastases, ICI use combined with SRT predicted for improved LC and OS and decreased DBF and risk of neurologic death.