Therefore, this study aimed to investigate the potential impact of acquired EGFR amplification on the efficacy of third‐generation EGFR‐TKI monotherapy in patients with advanced NSCLC harboring EGFR‐sensitive mutations who developed the T790M mutation following resistance to first‐line EGFR‐TKI therapy. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.