Prior studies have examined stereotactic body radiotherapy (SBRT) in oligometastatic NSCLC patients, including multimodality treatment with anti-PD1 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 (mSBRT) in stage IV NSCLC patients to evaluate safety and obtain preliminary activity data.