These concerns were initially based on biological evidence indicating that the incretin system and the GLP-1-receptor might play a role in the development of cholangiocarcinoma [5–7], and further highlighted by an observational study using data from the UK Clinical Practice Research Datalink [8] showing that use of DPP4 inhibitors, compared with other second- or third-line glucose-lowering drugs, was associated with an increased risk of cholangiocarcinoma (HR 1.77 [95% CI 1.04, 3.01]). This evidence concerns the gene GLP1R and cholangiocarcinoma.