ALK and lung cancer: Small molecule inhibitors are available for treating ALK, ROS1, RET and NTRK1-rearranged receptor tyrosine kinases (RTKs) in lung cancers, but variable or incomplete responses are often observed and acquired resistance is unavoidable (Bivona and Doebele, 2016; Doebele et al., 2015; Drilon et al., 2018; McCoach et al., 2017; Shaw et al., 2013).