As Osimertinib is an irreversible EGFR-TKI with higher activity against the T790M mutation-positive tumors than other NSCLC mutations, a subgroup analysis was conducted based on the EGFR mutation status (T790M vs Ex19del and/or L858R); the findings for Osimertinib therapy were compared with those for EGFR-TKIs/chemotherapy and showed that T790M mutation-positive patients treated with Osimertinib had a longer PFS, a higher ORR, a higher DCR, and a lower incidence of grade 3 or greater AEs than patients with the Ex19del and/or L858R mutation. Here, EGFR is linked to non-small cell lung carcinoma.