The role of APOBEC in early-stage epidermal growth factor receptor-mutant non-small cell lung cancer

Background: APOBEC plays a crucial role in the mutation process and immune response of non-small cell lung cancer (NSCLC). This study evaluated the role of the APOBEC mutation signature in early-stage epidermal growth factor receptor (EGFR) mutant NSCLC. This study aimed to assess the impact of APOBEC enrichment on recurrence-free survival (RFS), post-recurrence tyrosine kinase inhibitor (TKI) progression-free survival (PFS), and post-recurrence survival (PRS). Methods: We conducted whole-exome sequencing and whole-transcriptome sequencing in 100 patients diagnosed with pathologic stage II-IIIA non-squamous NSCLC. Results: Among the 100 patients, 18 (18 %) exhibited APOBEC (≥2) enrichment, which did not show a significant association with RFS (P = 0.14). Patients with APOBEC enrichment showed a shorter post-recurrence TKI PFS compared to those without APOBEC enrichment (8.13 months vs. 24.57 months, P = 0.017). In multivariate analysis, poor post-recurrence TKI PFS was associated with the type of EGFR mutation (L858R vs. exon 19 deletion, HR = 1.91, P = 0.04), TP53 mutation (HR = 2.07, P = 0.03), and APOBEC enrichment (≥2 vs. < 2, HR = 2.23, P = 0.02). PRS was 61.10 months and 21.77 months for patients with APOBEC enrichment and patients without APOBEC enrichment, respectively (P = 0.029). In multivariate analysis, poor PRS of EGFR-TKI was associated with the type of EGFR mutation (L858R vs. exon 19 deletion, HR = 2.29, P = 0.04) and APOBEC enrichment (≥2 vs. < 2, HR = 2.71, P = 0.02). Conclusions: APOBEC enrichment may present at initial diagnosis of early-stage EGFR mutant NSCLC and is associated with poor post-recurrence TKI PFS and PRS rather than RFS.