The FDA and EMA approved Libtayo monotherapy (if PD-L1 expression is ≥ 50% of tumor cells) or in combination with chemotherapy (PD-L1 1-49%) as first-line therapy for adult NSCLC patients who express PD-L1 (in ≥50% tumor cells), with no EGFR, ALK or ROS1 aberrations, and who have locally advanced or metastatic NSCLC and are not candidates for definitive chemoradiation therapy. The gene discussed is ROS1; the disease is non-small cell lung carcinoma.