Reduction of immunosuppressive tumor microenvironment in cholangiocarcinoma by ex-vivo targeting immune checkpoint molecules.

•NK cells and cytotoxic T cells infiltrate poorly into cholangiocarcinoma.•Regulatory T cells accumulate in cholangiocarcinoma.•PD1, CTLA4 and GITR are over-expressed on tumor-infiltrating T cells in cholangiocarcinoma.•Blocking PD1 or CTLA4 or stimulating GITR enhances effector functions of tumor-infiltrating T cells in cholangiocarcinoma.