Abstract
BACKGROUND: In-depth insight into the genomic features of the uncommon EGFR p.L861Q mutant NSCLC is scarcely performed, and no consensus on the preferred treatment strategy has been established. Moreover, the therapeutic implications of EGFR-TKI stratified by clinical and molecular features remained largely unknown. METHODS: A multi-center NGS database comprising 44,993 NSCLC samples was utilized for the genomic landscape profiling of EGFR p.L861Q mutation. Furthermore, a real-world cohort of 207 patients harboring EGFR p.L861Q mutation with complete treatment history was curated for comprehensive clinical analysis. RESULTS: L861Q is prevalent in approximately 2.1% of EGFR-mutated NSCLC and is typically co-mutated with EGFR p.G719X on the same allele (20%) and exhibits co-occurrent EGFR copy number amplification in approximately 17% of cases. In the first-line setting, afatinib and third-generation EGFR-TKI have been shown to yield notably superior treatment outcomes compared to first-generation EGFR-TKI (1(st) vs.2(nd) vs.3(rd) generations, ORR: 15.8% vs.56.5% vs.46.7%, P=0.01; median PFS: 6.4 vs.13.5 vs.15.1 months, P=0.002). This finding consistently held for patients without CNS metastases (1(st) vs.2(nd) vs.3(rd) generations, median PFS:6.0 vs.18.2 vs.14.1 months, P=0.003). In contrast, third-generation EGFR-TKI demonstrated superior efficacy compared to afatinib or first-generation TKI among the subgroup of brain metastasis (Pooled 1(st)/2(nd)-generation vs.3(rd)-generation TKI, brain ORR:0.00% vs.33.33%; median PFS:7.9 vs.19.3 months, P=0.021). Additional concurrent EGFR mutations or EGFR amplification did not yield a discernible impact on the efficacy of EGFR-TKI. CONCLUSIONS: The present study comprehensively elucidates the molecular features of EGFR p.L861Q mutation and underscores the optimal therapeutic choice of first-line EGFR-TKI based on brain metastatic status.