ABC-12: exploring the microbiome in patients with advanced biliary tract cancer in a first-line study of durvalumab (MEDI4736) in combination with cisplatin/gemcitabine.

Until recently, cisplatin/gemcitabine was standard of care for the first-line treatment of patients with advanced biliary tract cancer (BTC). The addition of durvalumab, an immune checkpoint inhibitor, to the combination of cisplatin/gemcitabine has demonstrated an overall survival (OS) benefit and is now a standard of care first-line treatment option. BTCs exhibit immunogenic features may develop through an accumulation of genetic and epigenetic alterations, and can be influenced by microbial exposure. Microbiota can influence inflammation and immunity, and its disruption may impair tumor response to immunotherapy and chemotherapy. Here, the rationale and design of the multi-center, single-arm ABC-12 trial (ISRCTN11210442) is described, which investigates the role of the microbiome in patients with advanced BTC in a first-line study of durvalumab (MEDI4736) in combination with cisplatin/gemcitabine. The primary objective is to determine the difference in baseline alpha diversity between "responders" (partial or complete response) and "non-responders" at 18 weeks (RECIST 1.1) in patients treated with cisplatin/gemcitabine/durvalumab. Secondary objectives include investigating the association between microbiome parameters and objective response rate, tumor control (partial, complete response, and stable disease), progression-free and OS, and investigating the interaction between treatment effect and microbiome parameters on clinical outcomes.