RET and lung cancer: The direct inhibition of disease-specific fusion oncogenes or their signals is a possible method for overcoming CSS; however, owing to the unknown oncogenic mechanism and the multitargetable potential of fusion oncogenes, such methods have only been established in cases where the fusion component is associated with specific targetable genes such as in BCR-ABL (34), ALK-/ROS-/RET-rearrangement lung cancer (35–37), and NTRK-rearrangement solid tumors (38).