ALK and lung cancer: Targeted therapy for NSCLC is largely based on the use of TKI, with a significant number of lung cancer drugs being lately approved by the FDA targeting gene mutations, including EGFR, anaplastic lymphoma kinase (ALK), ROS proto-oncogene 1 Receptor Tyrosine Kinase (ROS1), B-Raf proto-oncogene Serine/Threonine Kinase (BRAF), KRAS Proto-Oncogene, GTPase (KRAS), Neurotrophic Tyrosine Receptor Kinase (NTRK), MET Proto-Oncogene, Receptor Tyrosine Kinase (MET), and Ret Proto-Oncogene (RET) [159].