ROS1 and non-small cell lung carcinoma: ROS1 gene fusion was first identified in a NSCLC cell line model, and was observed in a NSCLC patient's specimen by Rikova et al in 2007.7 In a preclinical study, ROS1 gene fusions were shown to be associated with sensitivity to crizotinib therapy, and NSCLC patients harboring ROS1 gene fusions have achieved partial responses to this agent.