Biodegradable Polymeric Nanoparticles Containing an Immune Checkpoint Inhibitor (aPDL1) to Locally Induce Immune Responses in the Central Nervous System

Abstract Immunotherapy is an efficient approach to clinical oncology. However, the immune privilege of the central nervous system (CNS) limits the application of immunotherapeutic strategies for brain cancers, especially glioblastoma (GBM). Tumor resistance to immune checkpoint inhibitors is a further challenge in immunotherapies. To overcome the immunological tolerance of brain tumors, a novel multifunctional nanoparticle (NP) for highly efficient synergetic immunotherapy is reported. The NP contains an anti‐PDL1 antibody (aPDL1), upconverting NPs, and the photosensitizer 5‐ALA; the surface of the NP is conjugated with the B1R kinin ligand to facilitate transport across the blood‐tumor‐barrier. Upon irradiation with a 980 nm laser, 5‐ALA is transformed into protoporphyrin IX, generating reactive oxygen species. Photodynamic therapy (PDT) further promotes intratumoral infiltration of cytotoxic T lymphocytes and sensitizes tumors to PDL1 blockade therapy. It is demonstrated that combining PDT and aPDL1 can effectively suppress GBM growth in mouse models. The proposed NPs provide a novel and effective strategy for boosting anti‐GBM photoimmunotherapy.