Comprehensive profiling of EGFR mutation subtypes reveals genomic-clinical associations in non-small-cell lung cancer patients on first-generation EGFR inhibitors.

Common sensitizing mutations in epidermal growth factor receptor (cEGFR), including exon 19 deletions (19-Del) and exon 21 L858R substitution, are associated with high sensitivity to EGFR-TKIs in NSCLC patients. The treatment for NSCLC patients with uncommon EGFR (uEGFR) mutations remains a subject of debate due to heterogeneity in treatment responses. In this manuscript, the targeted next-generation sequencing (NGS) data of a large cohort of EGFR-mutated NSCLC patients was assessed to elucidate genomic profiles of tumors carrying cEGFR or uEGFR mutations. The results showed that NSCLC patients with uEGFR mutations were more likely to harbor co-occurring genetic alterations in the Hippo pathway and a higher TMB compared with cEGFR-positive patients. Smoking-related mutations were found to significantly enriched in uEGFR-positive patients. Subgroup analyses were performed to identify potential prognostic biomarkers in patients harboring various EGFR subtype mutations. L858R-positive patients with co-existing ARID2 mutations had shorter progression-free survival (PFS) than those who were L858R- or 19-Del-positive but ARID2-negative (median: 2.3 vs. 12.0 vs. 8.0 months, P = 0.038). Furthermore, mutational profiles, such as top frequently mutated genes and mutational signatures of patients with various EGFR subtype mutations were significantly different. Our study analyzed the mutational landscape of NSCLC patients harboring cEGFR and uEGFR mutations, revealing specific genomic characteristics associated with uEGFR mutations that might explain the poor prognosis of first-generation EGFR-TKIs.