Generation of a Biliary Tract Cancer Cell Line Atlas Identifies Molecular Subtypes and Therapeutic Targets.

Biliary tract cancers (BTC) are aggressive malignancies encompassing intrahepatic and extrahepatic cholangiocarcinoma, gallbladder carcinoma, and ampullary carcinoma. Here, we report integrative analysis of 63 BTC cell lines via multi-omics and genome-scale CRISPR screens. We identify widespread EGFR dependency in BTC, alongside dependencies selective to anatomic subtypes. Additionally, we delineate strategies to overcome therapeutic resistance, with combined EGFR inhibition potentiating targeting of KRAS-mutant and FGFR2 fusion-driven models and SHP2 inhibition effective in the latter context. Clustering RNA/protein expression and dependencies data revealed functional relationships transcending single-gene alterations, with biliary, squamous, or dual biliary/hepatocyte lineage signatures stratifying BTC models. These subtypes exhibit distinct dependency profiles-including cell fate transcription factors GRHL2, TP63, and HNF1B, respectively-and demonstrate prognostic significance in patient samples. Potential subtype-specific targetable vulnerabilities include integrinα3 and the detoxification enzyme UXS1. This cell line atlas reveals therapeutic targets in molecularly defined BTCs, unveils disease subtypes, and provides a resource for therapeutic development. SIGNIFICANCE: This integrative analysis of BTC cell lines defines the landscape of vulnerabilities across BTCs, stratifying distinct subtypes, and provides a key resource for studying disease heterogeneity. The findings highlight strategies for targeting BTCs with specific genomic alterations, as well as broader approaches based on shared molecular programs and essential pathways.