This study compares two treatment combinations for advanced biliary tract cancer (BTC). BTC affects the bile ducts and gallbladder. The study uses drugs called rilvegostomig and durvalumab along with chemotherapy drugs gemcitabine and cisplatin. The goal is to see which combination works better and is safer for patients.

Eligibility: Participants must have a confirmed bile duct or gallbladder cancer that cannot be removed by surgery and has not been treated before. They should have good organ function and a performance status of 0 or 1, meaning they can carry on with daily activities.

Exclusion: Those with ampullary carcinoma or who have had prior treatments for advanced BTC are not eligible. Additionally, patients with certain immune system disorders or lung diseases cannot participate.

• The study will involve regular visits to the clinic for treatment and monitoring.
• Participants may receive compensation for their time and travel.
• Potential risks include side effects from the treatments being studied.