First-Line Osimertinib in Patients With EGFR-Mutated Non-Small Cell Lung Cancer: Effectiveness, Resistance Mechanisms, and Prognosis of Different Subsequent Treatments.

MET amplification and C797S mutation are main resistance mechanisms, which could be targeted by crizotinib and gefitinib, respectively. More than 50% patients could receive subsequent anticancer targetable therapies after first-line osimertinib resistance. Immunotherapy may also be an acceptable choice after osimertinib resistance.