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.