Patients with non-small cell lung cancer with ROS1 gene rearrangements may benefit from crizotinib treatment, according to a study by Alice Shaw (Massachusetts General Hospital Cancer Center, Boston, USA) and colleagues. ROS1 rearrangements occur in about 1 percent of non-small-cell lung cancers and are more common in nonsmoking patients than in smokers. Crizotinib, an ALK inhibitor, can also inhibit ROS1 signaling through. In a phase 1 extension cohort study, 50 patients with advanced non-small cell lung cancer (who tested positive for ROS1 rearrangement) were enrolled, and these patients received a standard oral dose of 250 mg twice daily of crizotinib. Thirty-six patients experienced objective remission (72%, 95% CI 58 to 84); three patients (6%) experienced complete remission, while 33 patients (66%) experienced partial remission. The median response time for these 36 patients in objective remission was 17.6 months. Twenty-five patients (50%) still had disease progression during follow-up, with a median progression-free survival of 19.2 months. The proportion of patients with overall survival at 12 months was 85%; the median has not been reached. The safety profile of crizotinib was similar to that reported in previous studies; the most common adverse events were visual impairment, diarrhea, nausea, and peripheral edema. TianhongLi (University of California, USA) commented, “Given that routine screening for ROS1 rearrangements is not routinely available in patients with non-small cell lung cancer, most patients with identified ROS1-rearranged non-small cell lung cancer have so far only had molecular diagnostic tests available at academic institutions.” He also implied that the results of this study are expected to increase the number of oncologists outside the academic setting conducting screening for ROS1-rearranged non-small cell lung cancer. ScottLaurie (Ottawa Hospital Cancer Center, Canada) noted, “I think these data are compelling enough to run a [controlled] trial in ROS1-rearranged patients. In an ideal world, a clinical trial comparing crizotinib with standard cisplatin and pemetrexed chemotherapy would confirm these findings, but I’m not so convinced of the practicality or timeliness of the data in such a small subgroup; after all, ROS1 rearrangement accounts for 1% of the non-small cell lung cancer patient population.”