CD274 and neoplasm: The in vivo study further demonstrated that highly accumulated PD-NPs in the tumor tissues via EPR effect not only turn the immunosuppressive tumor microenvironment to the immune-responsive tumors by recruiting a large amount of immune cells through DOX-mediated ICD, but also enhance the pre-existing antitumor immune responses of T lymphocytes by anti-PD-L1 peptide-mediated blockade of PD-1/PD-L1 interactions.