Cadonilimab With Chemotherapy in Treating Advanced Biliary Cancer

The goal of this single-arm, Phase II interventional clinical trial is to test the safety and effectiveness of a combination treatment using the Cadonilimab with Gemcitabine and Cisplatin in patients with unresectable, locally advanced or metastatic biliary tract malignancies. The main questions it aims to answer are: * Is this combined treatment protocol safe for these patients? * Is this combined treatment protocol effective in treating these patients? Participants will be given a combination treatment of Cadonilimab, Gemcitabine, and Cisplatin. Researchers will monitor their health conditions to assess the safety and effectiveness of this treatment protocol.