CTLA4 and neoplasm: Last, to block immunosuppressive effect of checkpoints, PDT can be combined with ICB-based immunotherapy, in which ICIs, including anti-PD-1/PD-L1 antibodies, siRNA, anti-CTLA4 antibodies and IDO inhibitors, are usually embedded in NPs to effectively avoid the immune escape of tumor cells, ultimately inducing the death of tumor cells by immune-activated CTLs.