Co-occurring EGFR p.E709X Mutation Mediates Primary Resistance to the Third-Generation EGFR-TKIs in EGFR p.G719X-Mutant Patients with Advanced NSCLC.

Co-occurring EGFR p.E709X mutation mediated primary resistance to the third-generation EGFR-TKIs in EGFR p.G719X-mutant patients but remained sensitive to afatinib. A personalized treatment strategy should be undertaken based on the coexisting EGFR p.E709X mutation status.