 Up to 7% of NSCLC patients have EML4-ALK translocations or mutations in the ROS1 gene; these patients may benefit from ALK inhibitors which are now approved for this subset of patients.Crizotinib gained FDA approval in August 2011 and is an inhibitor of several kinases, specifically ALK, ROS1 and MET.Crizotinib has been shown in clinical studies to have response rates of ~60% if patients are shown to have ALK positive disease.