P2.03b-078 MET Gene Amplification and Overexpression in Chinese NSCLC Patients without EGFR Mutations: Topic: Biomarkers

Abstract

The prevalence and clinic pathologic characteristics of MET amplification and overexpression in Chinese patients with non-small cell lung cancer (NSCLC) remain unknown. In this multicenter study, we focus on revealing the frequency and clinic pathological characteristics of MET amplification and explore the predictive value of MET amplification and overexpression status to survival in Chinese NSCLC patients. MET amplification was detected by fluorescence in-situ hybridization (FISH) in 791 patients with EGFR wild-type samples. MET protein expression was detected by immunohistochemistry. In total, 8 patients were identified as harboring MET amplification from 791 NSCLC patients with EGFR wild-type. Among these 8 patients, one was with histology of adeno-squamous carcinoma and 7 of adenocarcinoma. There was no statistically significant difference among age, gender, smoking status and histologic type between patients with and without MET amplification. MET amplification was more frequent in advanced stage and solid predominant subtype of adenocarcinoma. MET protein expression was performed in 395 patients and 138 were positive. Patients with MET protein expression positive had an inferior overall survival compared to those without MET protein expression (45.0 months vs 65.8 months; P=0.001). Multivariate analysis revealed that MET expression was independent prognostic factor for poor overall survival (HR=1.497, P=0.017), while the MET amplification shows weak relevance for overall survival (HR=1.974, P=0.251). MET amplification was rare in Chinese NSCLC without EGFR mutation, with a prevalence of about 1%. MET expression but not amplification could be an independent prognostic factor for shorter OS among those EGFR wild-type NSCLC patients.