Abstract
BACKGROUND: Although EGFR-TKI resistance mechanisms in non-small cell lung cancer (NSCLC) have been extensively studied, certain patient subgroups remain with unclear mechanisms. This retrospective study analysed mutation data of NSCLC patients with EGFR-sensitive mutations and high programmed death-ligand 1 (PD-L1) expression or high TMB to identify primary resistance mechanisms. METHODS: Hybrid capture-based next-generation sequencing (NGS) was used to analyse mutations in 639 genes in tumor tissues and blood samples from 339 NSCLC patients. PD-L1 immunohistochemical staining was also performed on the same cell blocks. Molecular and pathway profiles were compared among patient subgroups. RESULTS: TMB was significantly higher in lung cancer patients with EGFR-sensitive mutations and high PD-L1 expression. Compared with the high-expression PD-L1 or high TMB and low-expression or TMB groups, the top 10 genes exhibited differences in both gene types and mutation rates. Pathway analysis revealed a significant mutations of the PI3K signaling pathway in the EGFR-sensitive mutation group with high PD-L1 expression (38% versus 12%, p < 0.001) and high TMB group (31% versus 13%, p < 0.05). Notably, PIK3CA and PTEN mutations emerged as the most important differentially mutated genes within the PI3K signaling pathway. CONCLUSIONS: Our findings reveal that the presence of PI3K signaling pathway mutations may be responsible for inducing primary resistance to EGFR-TKIs in NSCLC patients with EGFR-sensitive mutations along with high PD-L1 expression or high TMB. This finding is of great significance in guiding subsequent precision treatments in NSCLC.