In a case, it was reported approximately 5% of NSCLC cases upon progression to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) and approximately 10% of patients treated with osimertinib (a mutant-selective EGFR TKI) for EGFR T790M-positive NSCLC. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.