EGFR and non-small cell lung carcinoma: Several third-generation EGFR-mutant selective TKIs such as AZD9291 (osimertinib) have been approved for EGFR T790M–positive NSCLC treatment.12 As Oxnard32 summarized, the well-known EGFR T790M erlotinib-resistance mutation occurs both as the result of subclonal presence of T790M followed by outgrowth and as a de novo consequence of mutation in persister cells.