Non-small-cell lung cancer (NSCLC) patients harboring ALK or ROS1 rearrangements invariably acquire resistance to the first- and second-generation tyrosine kinase inhibitors (TKIs), most notably ALK G1202R and ROS1 G2032R.
Development of the acquired ROS1 G2032R mutation has been reported as a resistant mechanism to ROS1 inhibitors in ROS1-rearranged (ROS1<sup>+</sup>) NSCLC patients.
In an ongoing phase I trial, the ALK tyrosine kinase inhibitor (TKI) crizotinib shows remarkable initial responses in patients with non-small cell lung cancer (NSCLC) harboring ROS1 fusions; however, cancers eventually develop crizotinib resistance due to acquired mutations such as G2032R in ROS1.