Nevertheless, about 60% of the patients with the EGFR T790M mutation who initially respond positively to the EGFR inhibitors such as gefitinib, erlotinib, afatinib, and dacomitinib in NSCLC eventually develop acquired drug resistance (ADR) in 9–15 months (8, 9). The gene discussed is EGFR; the disease is non-small cell lung carcinoma.