This is a phase 3 study. All subjects are patients with unresectable locally advanced or metastatic biliary tract cancer (BTC), Eastern Cooperative Oncology Group (ECOG) performance status 0-1. The purpose of this study is to evaluate the efficacy and safety of AK112 in combination with chemotherapy versus durvalumab in combination with chemotherapy in patients with unresectable locally advanced or metastatic BTC.

Inclusion Criteria:

• Be able and willing to provide written informed consent.
• Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Has a life expectancy of at least 3 months.
• Has a histologically or cytologically confirmed diagnosis of biliary tract cancer (BTC).
• Has no prior systemic anti-tumor therapy for unresectable locally advanced or metastatic BTC.
• Has measurable disease based on Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.
• Has adequate organ function.

Exclusion Criteria:

• Has other malignancies within 5 years prior to enrollment.
• Is currently participating in a study of an investigational agent or using an investigational device.
• Has known active central nervous system (CNS) metastases.
• Has an active autoimmune disease that has required systemic treatment in the past 2 years.
• Has an active infection requiring systemic therapy.
• Has known active Hepatitis B or Hepatitis C.
• History of myocardial infarction, unstable angina, congestive heart failure within 12 months prior to enrollment.
• Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the study.
• Has received a live virus vaccine within 30 days of the planned first dose of study therapy.
• Has any concurrent medical condition that, in the opinion of the Investigator, would complicate or compromise compliance with the study or the well-being of the subject.