<b>Case presentation:</b> A 58-year-old man with stage IV NSCLC received gefitinib because next-generation sequencing (NGS) revealed an <i>EGFR</i> 19del, followed by osimertinib and pemetrexed with the emergence of <i>EGFR</i> T790M. Here, EGFR is linked to non-small cell lung carcinoma.