Disclosed herein are methods of treating cancers characterized by aberrant ROS1 activity by administering an effective amount of foretinib (N1′-[3-fluoro-4-[[6-methoxy-7-(3-morpholinopropoxy)-4-quinolyl]oxy]phenyl]-N1-(4-fluorophenyl)cyclopropane-1,1-dicarboxamide), including methods of identifying mutations in the kinase domain of ROS1 that indicate resistance to crizotinib, but sensitivity to foretinib.
