Improved Overall Survival and Locoregional Disease Control With Concurrent PD-1 Pathway Inhibitors and Stereotactic Radiosurgery for Lung Cancer Patients With Brain Metastases

Abstract

Despite the emerging role of programmed cell death-1 (PD-1) pathway inhibitorsfor patients with advanced lung cancer, a paucity of data are available on the activity of these agents among patients with brain metastases. We investigated the outcomes of PD-1 pathway inhibitors and stereotactic radiosurgery (SRS) for the treatment of patients with brain metastases from lung cancer. We retrospectively reviewed the medical records of non-small-celllung cancer patients with brain metastases consecutively treated with PD-1 pathway inhibitors and SRS at our institution from 2012 to 2017. Overall survival (OS), distant brain failure (DBF), and local control (LC) were assessed using Kaplan-Meier estimates and Cox regression models. We identified 37 patients treated with SRS to 85 lesions (90.6% intact and 9.4% resected) and a median total of 7 doses of PD-1 pathway inhibitors (83.8% nivolumab, 10.8% atezolizumab, 5.4% pembrolizumab). Most lesions were treated with 18Gy in a single fraction (n=61; 71.8%). Patients treated with concurrent SRS and PD-1 pathway inhibitors had longer OS and reduced rates of DBF compared with patients treated with SRS before or after PD-1 pathway inhibitor therapy (1-year OS, 87.3% vs 70.0% vs 0%, P=.008; 1-year DBF, 38.5% vs 65.8% vs 100%, P=.042). LC was favorable among lesions treated with SRS concurrent with or after PD-1 pathway inhibitor therapy compared with before PD-1 pathway inhibitor therapy (1-year LC, 100% vs 72.3%, P=.016). Three lesions transiently enlarged after SRS and then had partially or completely resolved on follow-up imaging. Four patients required steroids for SRS-associated toxicity. No patient experienced grade ≥ 4 toxicity. Concurrent treatment with SRS and PD-1 pathway inhibitors was associated with favorable OS and locoregional disease control. This combination of therapy was well tolerated and merits further evaluation in larger cohorts in a prospective setting.