Bile duct cancer (cholangiocarcinoma) is an aggressive malignancy for which early diagnosis remains challenging. Reliable biomarkers accurately predicting tumour progression or therapy responsiveness are unavailable. Therefore, better diagnostic methods are urgently needed. We hypothesize that tumour cells shed into bile, can be isolated allowing early diagnosis and drug-sensitivity testing in vitro. We will assess if these shed tumour cells can be detected in patient bile samples and confirm tumorigenicity by passing these cells (expanded in organoids) through a bile duct-on-a-chip, mimicking the natural bile duct environment. This provides detailed monitoring of tumour invasion in vitro and allows effective drug-response measurements.