Biliary tract cancers: moving from the present standards of care towards the use of immune checkpoint inhibitors.

Biliary tract cancers (BTCs) are aggressive and chemoresistant tumors associated with poor prognosis. Thus, more active and effective treatments are urgently needed, among which immunotherapy holds promise for the near future. Preclinical data show that BTCs are mainly immunosuppressed cancers, thus suggesting that their immunogenic potential may be unleashed with the appropriate strategy. Immune checkpoint inhibitors (ICIs) could theoretically be effective in BTCs by blocking those inhibitory checkpoints that limit the activation and the expansion of the effector cells of the immune response. Many currently ongoing trials aim to demonstrate the efficacy of ICIs and to incorporate immunotherapy into the routine management of BTCs. Presently available results are controversial and there is no consensus on the role of ICIs in monotherapy, while combinations of immunotherapy with chemotherapy look more promising. Nevertheless, despite the many proposed over time, there are no predictive biomarkers presently available, thus, the early identification of those patients showing a good response is of great significance.