Cancer evades host immune surveillance by using immune checkpoints,w hich are inhibitor y pathways cr ucial for maintaining self-tolerance1.Tumor cells express multiple inhibitory ligands,and tumor-infiltrating lymphocytes(TIL)express a variety of inhibitory receptors.Inhibitory receptors cytotoxic T-lymphocyte-associated protein 4(CTLA-4)and programmed death-1 Cancer evades host immune surveillance by using immune checkpoints, w hich are inhibitor y pathways cr ucial for maintaining self-tolerance 1. Tumor cells express multiple inhibitory ligands, and tumor-infiltrating lymphocytes (TIL) express a variety of inhibitory receptors. Inhibitory receptors cytotoxic T -lymphocyte-associated protein 4 (CTLA-4) and programmed death-1