ROS1 and adenocarcinoma: ROS1 fusions occur in 1%-2% of patients with NSCLC, accounting for approximately 18 500-37 000 newly diagnosed patients globally each year.8-10 In NSCLC, ROS1 fusions are associated with adenocarcinoma histology, younger age at diagnosis, and a history of never or light smoking.8,11 Of note, ROS1 fusions rarely overlap with other oncogenic driver alterations in de novo disease.12 Most patients (85%) with ROS1+ NSCLC present with stage IV cancer and 20%-40% have brain metastases at initial diagnosis.13,14