Previous studies have evaluated stereotactic body radiotherapy (SBRT) in oligometastatic patients with NSCLC, including multimodality treatment with anti–programmed cell death protein-1 monotherapy. Questions remain regarding the timing of SBRT and immunotherapy, safety with dual checkpoint blockade, and the utility in widely metastatic patients. This randomized phase 1 trial combined nivolumab and ipilimumab with sequential or concurrent multisite SBRT in patients with stage IV NSCLC to evaluate safety and obtain preliminary activity data.

Treatment-naive patients with metastatic NSCLC were randomized to concurrent (SBRT with immunotherapy) or sequential (SBRT followed by immunotherapy) treatment. A maximum of four treatment fields received SBRT. Nivolumab and ipilimumab were continued until clinical progression, development of toxicity, or after 2 years. Dose-limiting toxicity was defined as greater than or equal to grade 3 toxicity to the relevant organ system attributed to SBRT and immunotherapy occuring within 3 months.

A total of 37 patients were assessable. No dose-limiting toxicity occurred in the concurrent cohort (n = 18). The sequential cohort required a dose reduction in the central lung group owing to two grade 4 pneumonitis events (2 of 19). Overall best response was as follows: 5.4% (2 of 37) complete response, 40.5% (15 of 37) partial response, 16.2% (6 of 37) stable disease, and 37.8% (14 of 37) progressive disease. Median progression-free survival was 5.8 months (95% confidence interval: 3.6–11.4 mo), with median follow-up of 17.0 months. Median overall survival was not reached.

Concurrent nivolumab, ipilimumab, and SBRT were not more toxic than sequential therapy, and multisite SBRT was well tolerated in widely metastatic patients. Multimodality therapy resulted in durable metastasis control and encouraging early overall survival.