Omics-driven biomarker discovery for immune checkpoint inhibitor-based therapy in biliary tract cancer: a narrative review

Biliary tract cancer (BTC) is a rare but highly aggressive malignancy associated with poor prognosis. Over the past decade, immune checkpoint inhibitor (ICI)-based therapies have shown considerable therapeutic promise for BTC. The heterogeneity of ICI responses necessitates reliable biomarkers. Omics studies have provided critical insights into the mechanisms underlying ICI response and resistance, enabling the identification of predictors of clinical benefit in BTC. In this review, we comprehensively summarize recent advances in omics-based biomarker discovery for ICI-based therapy in BTC, from bulk omics to single-cell and spatial omics, and highlight their potential clinical applications for advancing personalized precision medicine in BTC patients.