MET amplification identified by next-generation sequencing and its clinical relevance for MET inhibitors

Abstract

BACKGROUND: MET amplification plays an important role in the development of non-small-cell lung cancer (NSCLC) either de novo or in resistance to epidermal growth factor receptor tyrosine-kinase inhibitor (EGFR-TKI) settings. Fluorescence in situ hybridization (FISH) is the standard method for MET amplification. With more and more discoveries of oncogenic driver genes, next-generation sequencing (NGS) plays a significant role in precision oncology. Meanwhile, the role of NGS in MET amplification remains uncertain. METHODS: Forty patients diagnosed with advanced NSCLC were included. FISH and NGS were conducted prior to MET inhibitors treatment. MET amplification by FISH was defined as a MET/CEP7 ratio of > 2.0 and/or copy number (CN) > 5. MET amplification by NGS was defined as gene copy number (GCN) ≥ 5. RESULTS: The concordance rate among FISH and NGS was 62.5% (25/40). MET amplification identified by FISH showed the optimal predictive value. The partial response (PR) rate was 68.0% (17/25 with MET amplification) vs. 6.7% (1/15 without MET amplification); the median progression-free survival (PFS) was 5.4 months versus 1.0 months (P < 0.001). MET amplification identified by NGS failed to distinguish significant clinical outcomes. The PR rate was 60.0% (6/10, with MET GCN ≥ 5) vs. 40.0% (12/30, with MET GCN < 5); the median PFS was 4.8 months vs. 2.2 months (P = 0.357). The PR rate was 68.8% (11/16) and the median PFS was 4.8 months in patients with focal amplification by NGS. CONCLUSIONS: MET amplification identified by FISH remains the optimal biomarker to identify suitable candidates for MET-TKI therapy. In comparison, amplification identified by NGS seems not as robust to be effective predictive biomarker. Further exploration is needed regarding the focal amplification by NGS in predicting the efficacy.