Prolonged Response to First‐generation Tyrosine Kinase Inhibitor in a Metastatic Non‐small Cell Lung Cancer Harbouring Complex G719X and S768I Mutations: A Case Report from Vietnam and Literature Review

A complex of G719X and S768I mutations is infrequently observed, constituting less than 0.3% of all EGFR-positive non-small cell lung cancer (NSCLC), and the response to first-line TKIs is inconsistent in the literature. In this study, we report a patient with metastatic non-small cell lung cancer carrying rare EGFR compound mutations of G719X and S768I who benefited from first-line treatment with gefitinib in Vietnam. This patient had a prolonged response lasting over 44 months with first-generation TKI. He continued to take gefitinib without experiencing serious adverse events. NSCLC with a rare complex of G719X and S768I mutation revealed a good response to gefitinib.