RESIST-CCA · Unravelling Malignant Cholangiocyte Subpopulations that Drive Chemoresistance in Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a highly heterogeneous and aggressive group of malignant tumours arising along the biliary tree. Its incidence (~5:100,000) is rising worldwide, and it already represents the second most common primary liver cancer (10–15%). Alarmingly, CCA-related mortality has increased by 37% in Europe over the past two decades, establishing CCA as a major health, social, and economic burden. The delayed diagnosis of CCA, combined with its pronounced chemoresistance, results in an extremely poor prognosis, with 5-year survival rates below 10%.The RESIST-CCA project aims to unravel the molecular and cellular footprint of specific cholangiocyte subpopulations that drive chemoresistance in CCA. Using cutting-edge single-cell and spatial transcriptomics within a patient-specific CCA-on-a-chip model, the project will identify resistant subclones, characterize their molecular signatures, and define their interactions with the tumour microenvironment that enable therapeutic escape. This work will uncover key pathways associated with chemoresistance. Identified mechanisms will be functionally validated through gene editing (CRISPR/Cas9 or RNAi) and pharmacological inhibition, using both the personalized CCA-on-chip microfluidic platform and in vivo patient-derived xenografts (PDX).Overall, RESIST-CCA will generate a high-resolution atlas of chemoresistance in CCA, with a particular focus on the functional impact of intratumoural cholangiocyte heterogeneity. These insights will guide the development of tailored, resistance-guided therapeutic strategies aimed at re-sensitizing specific cholangiocyte subsets. By addressing the underexplored role of cholangiocyte heterogeneity, RESIST-CCA will provide a transformative framework for understanding and overcoming chemoresistance in CCA, with broad implications for other heterogeneous and treatment-refractory cancers.