The use of biomarkers to identify population subgroups with impressive responses to targeted therapies, as observed in ALK-rearranged and ROS1-rearranged NSCLC, for which crizotinib was associated with remarkably prolonged survival [2], and in NSCLC carrying EGFR activating mutations, which are known to increase sensitivity to EGFR tyrosine-kinase inhibitors (TKI) [3,4]. The gene discussed is ROS1; the disease is non-small cell lung carcinoma.