ERBB2 and biliary tract neoplasm: In order to investigate the amplification status of HER2 in patients with biliary tract carcinoma, HER2 copy number alternations (CNAs) in biliary tract cancer populations were analyzed, including a total of 329 patients CNA data using the cBioPortal tools from 3 studies: Gallbladder Cancer (MSK, Cancer 2018), Cholangiocarcinoma (MSK, Clin Cancer Res 2018) and Cholangiocarcinoma (TCGA, Firehose Legacy) (Figure S1A).