Immunobiology of biliary tract cancer and recent clinical findings in approved and upcoming immune checkpoint inhibitors

Introduction: Recently, immunotherapy has offered new hope for treating biliary tract cancer (BTC). However, several issues are to be considered, including the lack of validated predictive biomarkers that could help to identify patient groups which are most likely to benefit from such therapeutic approaches. Areas covered: In the current article, we will provide an overview of recent results and ongoing and future research directions of immunotherapy in BTC, with a special focus on recently published, practice-changing data, and ongoing active and recruiting clinical trials. Expert opinion: At this moment, dozens of clinical trials in phases I to III are evaluating the role of cancer immunotherapy in this setting, with the hope of adding more therapeutic options for BTC patients. Future research must focus on the development of novel agents and combinations, but the validation of biomarkers remains an urgent need. As more research results emerge, novel combinatorial strategies are destined to further transform the treatment paradigm for this heterogeneous and aggressive tumor type.