One of the best-known examples is osimertinib, which has demonstrated impressive antitumor activity against NSCLC harboring an EGFR mutation, either an exon 19 deletion (Ex19del), an exon 21 p.L858R, or an exon 20 p.T790M, the latter being acquired under first-generation kinase inhibitors (erlotinib, gefitinib) [2]. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.