CD8A and central nervous system cancer: Sustained release of PNPPTX from the gel led to a targeting of the residual infiltration of glioma cells and the production of tumor antigens, whereas MNPCpG targeted and activated antigen-presenting cells, which promoted tumor antigen presentation ability and activated CD8+ T and NK cells to counteract the immunosuppression of the glioma microenvironment [198] Of note, this delivery system is in its early stages, and only a few studies, mainly related to chemotherapy, have reported on it.