We retrospectively analyzed patients with advanced NSCLC who received osimertinib....In patients who developed resistance to osimertinib, possible genomic resistance mutations were identified in 27 of 49 patients in the molecular analysis set...Other EGFR-dependent molecular modifications included C796S mutation (1/49, 2.0%), G796S mutation (1/49, 2.0%), V802I mutation (1/49, 2.0%), V834L mutation (1/49, 2.0%), E758D mutation (1/49, 2.0%), G724S mutation (1/49, 2.0%) and EGFR amplification (2/49, 4.1%)...A summary of resistance mechanisms to osimertinib are shown in Fig. 2.