ROS1 and neoplasm: In a phase I study involving 50 NSCLC patients with ROS1 rearrangement treated with crizotinib, the ORR was 72% and median PFS was 19.2 months.8 Second-generation ALK TKI, such as ceritinib, has also shown tumor responses in ROS1-rearranged patients.27 Lorlatinib yielded an ORR of 62% in ALK TKI-naive patients with ROS1 rearrangement and 35% in patients who received crizotinib as the only TKI.16 Despite this, crizotinib and entrectinib are the only two ROS1 TKIs approved by FDA for ROS1-rearranged NSCLC to date.