RecruitingPhase 2Drug trialA Study of SHR-A1904 in Previous Systemic Treatment Failed Biliary Tract CancerThis is a multicenter, Phase 2 clinical trial to evaluate the efficacy and safety, PK and immunogenicity of SHR-A1904 in patients with advanced or metastatic biliary tract cancer (BTC). Patients will treat with SHR-A1904 until unacceptable toxicity or disease progression.