The landscape of MET mutations in Chinese biliary tract cancers.

Abstract

e16652 Background: Biliary tract cancers (BTCs) are malignancies with poor prognosis and limited treatment options. MET is recurrently altered in various cancers that confer susceptibility to targeted MET inhibitors. It has been reported that the MET mutation frequency is 2-7% in intrahepatic cholangiocarcinoma (ICC) and 3.7% in extrahepatic cholangiocarcinoma (ECC) in Western countries. However, the characterization of MET in Chinese BTCs are not clear. Methods: Next-generation sequencing (NGS) targeting 450 cancer genes was performed on formalin-fixed, paraffin-embedded (FFPE) tumor tissues and matching blood samples that collected from a cohort of 926 Chinese BTC patients. Genomic alterations, including single nucleotide variations (SNV), short and long insertions/deletions (Indels), copy number variations, and gene rearrangements/fusions, were analyzed. The testing was carried out by a College of American Pathologists (CAP) accredited and Clinical Laboratory Improvement Amendments (CLIA) certified laboratory. Results: MET mutations were detected in 4.1% of patients with BTCs, including 5.3% in ICC, 3.4% in hilar cholangiocarcinoma (HCCA), 3.0% in ECC, and 2.6% in gallbladder cancer (GBCA). Gene amplification was the most common type of MET mutation in BTC (2.6%) compared with gene rearrangements/fusions (1.1%) and SNV (0.9%). Novel MET fusion partners, including TNS3 and TRIM4, and MET exon 14 skipping mutation, were also detected. There was no difference in tumor mutational burden (TMB) between patients with and without MET mutation (average TMB: 6.5 vs. 5.6 muts/Mb, P= 0.213). Among these BTC patients, an advanced ICC patient (performance status [PS] 3) who harbored MET gene amplification, received crizotinib as the first-line treatment. Four months later, the patient had a complete response without obvious side effects. Conclusions: To our knowledge, this is the largest BTCs cohort and the first report of MET mutation profiling in the Chinese patients. MET mutations were detected in 4.5% BTCs, and MET inhibitors may be potential treatment options for BTC patients. All types of MET mutations, including gene amplification, SNVs, and gene fusions, were detected in BTCs, which demonstrated that NGS might be a powerful tool to detect MET mutations. Altogether, MET is a promising target in BTCs, and detection of MET mutations is important and essential for predicting the sensitivity of targeted therapy. Clinical trial information: NCT03892577 .