Durvalumab With Chemotherapy as First Line Treatment in Patients With Advanced Biliary Tract Cancers (aBTCs)

Inclusion Criteria: * Histologically confirmed, unresectable advanced or metastatic biliary tract carcinoma (BTC) including cholangiocarcinoma (intrahepatic or extrahepatic), gallbladder carcinoma, and ampulla of Vater (AoV) carcinoma * Participants with unresectable or metastatic BTC * A World Health Organisation Eastern Cooperative Oncology Group Performance Status (WHO/ECOG PS) of 0 to 2 * At least one lesion that qualifies as a Response Evaluation Criteria in Solid Tumours version 1.1 (RECIST 1.1) target lesion at baseline * Adequate organ and bone marrow function * Body weight of \> 30 kg * Negative pregnancy test (serum) for women of childbearing potential * Female participants must be one year post-menopausal (amenorrhoeic for 12 months without an alternative medical cause) * Male and female participants and their partners must be surgically sterile or on their chosen method of birth control as per the protocol. Exclusion Criteria: * Any evidence of diseases such as severe or uncontrolled systemic diseases, including uncontrolled hypertension, active bleeding diseases, active infection, active interstitial lung disease/pneumonitis, serious chronic gastrointestinal conditions associated with diarrhoea, psychiatric illness/social situations, history of uncontrolled or symptomatic cardiac disease, and history of allogenic organ transplant * Active or prior documented autoimmune or inflammatory disorders * History of another primary malignancy, except for malignancy treated with curative intent and with no known active disease ≥ 5 years before the first dose of study intervention * History of leptomeningeal carcinomatosis * History of active primary immunodeficiency * Known to have tested positive for human immunodeficiency virus \[HIV\] (positive HIV 1/2 antibodies) or active tuberculosis infection * Participants co-infected with Hepatitis B virus (HBV) and Hepatitis C virus (HCV) or co-infected with HBV and Hepatitis D virus (HDV) * Persistent toxicities (Common Terminology Criteria for Adverse Events \[CTCAE\] Grade \> 1) caused by previous anticancer therapy * Central nervous system metastases requiring treatment or history of spinal cord compression * Known allergy or hypersensitivity to any of the study intervention or any of the study intervention excipients. * Any concurrent chemotherapy, other than the one allowed in the study, investigational medicinal product (IMP), biologic, or hormonal therapy for cancer treatment * Palliative radiotherapy with a limited field of radiation within 2 weeks of the first dose of study intervention, or radiotherapy with a wide field of radiation or radiotherapy affecting more than 30% of the bone marrow within 4 weeks before the first dose of study intervention * Receipt of live attenuated vaccine within 30 days prior to the first dose of study intervention * Major surgical procedure within 28 days prior to the first dose of IMP * Prior exposure to immune-mediated therapy excluding therapeutic anticancer vaccines * Receipt of the last dose of anticancer therapy within 28 days prior to the first dose of IMP