A global study to assess the efficacy and tolerability of rilvegostomig compared to placebo in combination with investigator's choice of chemotherapy in participants with BTC after surgical resection with curative intent.

This is a Phase III, randomized, double-blind, placebo-controlled, multicenter, global study to assess the efficacy and tolerability of rilvegostomig compared to placebo in combination with investigator's choice of chemotherapy (capecitabine, S-1(tegafur/ gimeracil/ oteracil) or gemcitabine/cisplatin) as adjuvant treatment in participants with BTC after resection with curative intent. This study will be conducted in patients with BTC who are at risk of recurrence after resection with curative intent.

Inclusion Criteria:

• Histologically confirmed adenocarcinoma of the biliary tract (intrahepatic or extrahepatic cholangiocarcinoma (CCA) or muscle invasive gallbladder cancer (GBC)) after macroscopically complete resection (R0 or R1)
• Provision of a tumor sample collected at surgical resection.
• Randomization within 12 weeks after resection with adequate healing and removal of drains.
• Confirmed to be disease-free by imaging within 28 days prior to randomization.
• Eastern Cooperative Oncology Group performance status of 0 or 1

Exclusion Criteria:

• Participants with locally-advanced, unresectable, or metastatic disease at initial diagnosis.
• Ampullary cancer, neuroendocrine, mixed neuroendocrine and non-neuroendocrine neoplasms and nonepithelial tumors.
• Any anti-cancer therapy for BTC prior to surgery
• Active or prior documented autoimmune or inflammatory disorders or any severe or uncontrolled systemic disease
• Current or prior use of immunosuppressive medication within 14 days before the first dose
• Thromboembolic event within 3 months
• Active HBV or HCV infection unless treated.

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All request will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure

When a request has been approved AstraZeneca will provide access to the de-identified individual patient-level data in an approved sponsored tool . Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information. Additionally, all users will need to accept the terms and conditions of the SAS MSE to gain access. For additional details, please review the Disclosure Statements at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure

Double-blind masking