Fig. 1.
Tumor microenvironment of biliary tract cancer and potential cellular targets in combination with immunotherapy. There are different cell types that compose the immunosuppressive tumor microenvironment. It is a potential strategy to improve the efficacy of immune checkpoint inhibitors in combination with the agents targeting on other immune cells. MDSC myeloid derived suppressive cell, CAF cancer-associated fibroblast, ECM extracellular matrix