Evaluation of tumor MET protein expression, MET gene amplification, and HER2 expression in Chinese patients with advanced gastric or gastroesophageal junction (G/GEJ) cancer.

4048 Background: Gastric cancer is a disease with high unmet medical needs in China. MET and its ligand, hepatocyte growth factor, are potential targets in G/GEJ cancer. This study evaluated overall survival (OS) according to tumor MET expression, MET gene amplification, and the association between MET and HER2 status in Chinese patients with advanced G/GEJ cancer. Methods: Baseline tumor biopsy samples (formalin-fixed, paraffin-embedded primary tumor) from patients with stage IV unresectable G/GEJ cancer, archived at Sun Yat-Sen University Cancer Center, were assessed for MET and HER2 protein levels and MET and HER2 gene amplification by IHC and FISH, respectively. MET-positive: membrane protein staining in ≥ 25% or ≥ 50% of tumor cells. HER2-positive: IHC 2+ and a confirmatory HER2 FISH-positive result (HER2:centromere 17 ratio ≥ 2.0), or IHC 3+. MET-amplified: MET:centromere 7 ratio > 2.0. We evaluated associations between Kaplan-Meier OS and MET status (log-rank test), MET expression and METgene ampli...