ROS1 and non-small cell lung carcinoma: In these patients, clinicians may be tempted to use single agent pembrolizumab as the first-line treatment of ROS1+ NSCLC given the overall survival benefit of Keynote-024 results for PD-L1 expression (> = 50%) and the FDA expanded approval of pembrolizumab approval of pembrolizumab for PD-L1 >  = 1% based on the Keynote-042 results as only EGFR + and ALK + NSCLC were excluded and ROS1+ NSCLC were not excluded from these studies [29, 30].