In both randomized clinical trials (RCTs) and Real-World Evidence (RWE), osimertinib has shown an ORR ranging from 50% to 71% in patients with stage 4 NSCLC who have EGFR with Exon 19 deletion, T790M, or Exon 21 mutation with L858R substitution mutations and have received prior treatment with EGFR TKIs such as erlotinib or gefitinib. Here, EGFR is linked to non-small cell lung carcinoma.