RecruitingPhase 2Drug trialPerioperative Gemcitabine, Cisplatin, and Pembrolizumab in Potentially Resectable Biliary Tract CancersThe purpose of this study is to determine the safety of peri-operative gemcitabine, cisplatin, and pembrolizumab in patients with BTC, as well as whether the combination of gemcitabine, cisplatin, and pembrolizumab (gem/cis/pembro) is feasible and lead to pathologic responses.