Immunotherapies in clinical development for biliary tract cancer.

Introduction: Cancers of the biliary tract (BTC) are aggressive malignancies with limited treatment options and an overall dismal prognosis. In recent years, two concepts, namely precision oncology and immune oncology (IO) have profoundly influenced and, in some cancers, even revolutionized tumor treatments. While positive data from randomized trials have led to the incorporation of targeted concepts for genetically select BTC patients, IO is not yet implemented in clinical practice.Areas covered: We discuss published results from completed, as well as from ongoing studies on IO in BTC, based on a literature search on Pubmed and information provided by clinicaltrials.gov in October 2020. Apart from monotherapy, we outline IO-based combination approaches and highlight pivotal studies whose results will likely influence the future development of relevant concepts in BTC.Expert opinion: Despite partially positive signals, IO thus far disappointed in unselected BTC populations and should currently not be considered as a preferred systemic treatment in patients with microsatellite stable disease outside of clinical trials. In the coming years, a better understanding of the molecular mechanisms underlying resistance to checkpoint inhibition, and the identification of positive predictive biomarkers will be important for the successful integration of IO into treatment concepts for BTC patients.