ROS1 and neoplasm: Molecular profiling performed on the resected brain metastases showed IHC 3+ positivity for ALK, with no further alterations in EGFR, KRAS, BRAF, or ROS1. Programmed death-ligand 1 (PD-L1) staining (Klon E1L3N) showed expression on tumor cells of <1% (TC0) and expression on immune cells of ≥1% and <5% (IC1).