Abstract
BACKGROUND/OBJECTIVES: MET overexpression is common in non-small cell lung cancer (NSCLC). The correlation between MET overexpression and immune checkpoint inhibitor (ICI) efficacy in NSCLC is underexplored. METHODS: In this retrospective observational cohort study, we curated a dataset of 279 stage IV NSCLC patients who received ICI treatment and had MET expression assessed by CLIA-certified immunohistochemistry (IHC) assay. MET expression was graded on a scale from 0 to 3+, with overexpression defined as 2+ or 3+. Clinicopathological features associated with MET expression were assessed using logistic regression. Overall survival (OS) and progression-free survival (PFS) were evaluated via Kaplan-Meier analysis and the multivariate Cox proportional hazards model. To derive the most parsimonious and statistically robust models, stepwise refinement based on the Akaike Information Criterion (AIC) was applied. RESULTS: MET overexpression was observed in 220 of 279 patients (78.9%). Adenocarcinoma histology (p = 0.003) and PD-L1 expression (p < 0.001) were independently associated with MET overexpression. Kaplan-Meier analysis showed patients with MET overexpression had significantly superior OS (p = 0.012) and PFS (p = 0.033). Full Cox regression analysis revealed that MET overexpression was associated with longer OS (p = 0.040), independent of PD-L1 levels. Patients with MET overexpression had numerically longer PFS (p = 0.145). Following adjustment for metastatic burden, the AIC-selected OS and PFS models both demonstrated that MET overexpression remained a significant prognostic factor (OS: p = 0.010; PFS: p = 0.026). CONCLUSIONS: This real-world study suggests that MET overexpression, as assessed by IHC, is associated with better survival in advanced NSCLC patients treated with ICIs, independent of PD-L1 level. These results suggest the potential of MET expression as a predictive marker for ICI efficacy in advanced NSCLC patients and support the combination of MET-targeted agents with anti-PD1/PD-L1 ICIs as a promising strategy for NSCLC patients with MET overexpression.