To understand the time course of ITIH5 upregulation in CCA tumor development more comprehensively, additional data on early tumor stages, e.g., in biliary intraepithelial neoplasia (BilIN) [55] and intraductal papillary neoplasm of the bile duct (IPNB) [56], are required. This evidence concerns the gene ITIH5 and cholangiocarcinoma.