Efficacy and Safety of Zanidatamab With Standard-of-care Therapy Against Standard-of-care Therapy for Advanced HER2-positive Biliary Tract Cancer

Inclusion Criteria

• Histologically- or cytologically-confirmed Biliary Tract Cancer (BTC), including Gallbladder Cancer (GBC), Intrahepatic Cholangiocarcinoma (ICC), or Extrahepatic Cholangiocarcinoma (ECC).
• Locally advanced unresectable or metastatic BTC and not eligible for curative resection, transplantation, or ablative therapies.
• Received no more than 2 cycles of systemic therapy which is limited to Cisplatin and Gemcitabine (CisGem) with or without a PD-1/L1 inhibitor (physician's choice of durvalumab or pembrolizumab, where approved under local regulations) for advanced unresectable or metastatic disease.
• HER2-positive disease (defined as IHC 3+; or IHC 2+/ ISH+) by IHC and in situ Hybridization (ISH) assay (in participants with IHC 2+ tumors) at a central laboratory on new biopsy tissue or archival tissue from the most recent biopsy.
• Assessable (measurable or non-measurable) disease as defined by Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1), per investigator assessment.
• Male or female ≥ 18 years or age (or the legal age of adulthood per country-specific regulations).
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Adequate organ function
• Females of childbearing potential must have a negative pregnancy test result.
• Females of childbearing potential and males with a partner of childbearing potential must be willing to use 2 methods of birth control.

Exclusion Criteria

• Prior treatment with a HER2-targeted agent
• Prior treatment with checkpoint inhibitors, other than durvalumab or pembrolizumab
• The following BTC histologic subtypes are excluded: small cell cancer, neuroendocrine tumors, lymphoma, sarcoma, mixed tumor histology, and mucinous cystic neoplasms detected in the biliary tract region.
• Use of systemic corticosteroids.
• Brain metastases
• Severe chronic or active infections
• History of allogeneic organ transplantation.
• Active or prior autoimmune inflammatory conditions
• History of interstitial lung disease or non-infectious pneumonitis.
• Participation in another clinical trial with an investigational medicinal product within the last 3 months.
• Females who are breastfeeding
• Any other medical, social, or psychosocial factors that, in the opinion of the investigator, could impact safety or compliance with study procedures.
• Use of phenytoin