A Study of Rilvegostomig or Durvalumab Plus Chemotherapy for First-Line Treatment of Biliary Tract Cancer (ARTEMIDE-Biliary02)

Key inclusion Criteria: * Histologically confirmed adenocarcinoma of the biliary tract, including intra-hepatic or extra-hepatic cholangiocarcinoma (CCA) and gallbladder carcinoma (GBC). * Unresectable locally advanced or metastatic BTC, previously untreated in the advanced disease setting * Known PD-L1 status assessed at a central laboratory using an acceptable tumor sample. * Measurable disease by RECIST 1.1 criteria using CT or MRI and is suitable for accurate repeated measurements. * ECOG Performance Status of 0 or 1 with no deterioration (ie, ECOG PS \> 1) over the previous 2 weeks prior to baseline at screening and prior to randomization. * Adequate bone marrow and organ function. Key exclusion Criteria: * Ampullary carcinoma * Any prior systemic therapy received for unresectable, locally advanced or metastatic BTC. * Any prior exposure to any other therapy targeting immune-regulatory receptors or mechanisms. * Any concurrent chemotherapy, radiotherapy, immunotherapy, investigational, biologic, or hormonal therapy for cancer treatment other than those under investigation in this study. * Active or prior documented autoimmune or inflammatory disorders requiring chronic treatment with steroids or other immunosuppressive treatment. * Active or ongoing interstitial lung disease/pneumonitis (of any grade), serious chronic gastrointestinal conditions associated with diarrhea, or active non-infectious skin disease (including any grade rash, urticaria, dermatitis, ulceration, or psoriasis) requiring systemic treatment.