RecruitingDrug trialInvestigation of Predictive Biomarkers in Patients With Advanced BTC Treated With Lenvatinib Plus PembrolizumabThe goal of this observational study is to evaluate the clinical efficacy and safety of lenvatinib plus pembrolizumab combination therapy in patients with advanced biliary tract cancer (BTC). This study aims to identify potential biomarkers that may predict treatment response by analyzing genetic data from blood and tissue samples. The study will focus on real-world clinical outcomes and the exploratory discovery of biomarkers associated with the efficacy of this treatment regimen.