Osimertinib, a third-generation EGFR-TKI irreversible, was initially approved for the sequential treatment of patients who present with T790M mutation and have disease progression with first- or second-generation EGFR-TKI [14-16], and more recently it was approved for the first-line treatment of metastatic NSCLC with EGFR exon 19 deletions or exon 21 L858R mutations, with improved overall survival (OS) [17]. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.