Targeted Co-Delivery of Antigen and Dual-Agonists by Hybrid Nanoparticles for Enhanced Cancer Immunotherapy.

Among approaches of current cancer immunotherapy, dendritic cells (DCs)-targeted vaccine based on nanotechnology could be a promising way to efficiently induce potent immune responses. To enhance DCs targeting and vaccine efficiency, we included Imiquimod (IMQ), a toll-like receptor 7/8 (TLR 7/8) agonist and Monophosphoryl Lipid A (MPLA), a TLR4 agonist to synthesize lipid-polymer hybrid nanoparticles using PCL-PEG-PCL and DOTAP (IMNPs) as well as DSPE-PEG-mannose (MAN-IMNPS). The spatio-temporal delivery of MPLA (within outer lipid layer) to extracellular TLR4 and IMQ (in the hydrophobic core of NPs) to intracellular TLR7/8 can activate DCs synergistically to improve vaccine efficacy. Ovalbumin (OVA) as a model antigen was readily absorbed by positively charged DOTAP and showed a quick release in vitro. Our results demonstrated that this novel nanovaccine enhanced cellular uptake, cytokines production and maturation of DCs. Compared with quick metabolism of free OVA-agonists, depot effect of OVA-IMNPs was observed whereas MAN-OVA-IMNPs promoted trafficking to secondary lymphoid organs. After immunization with subcutaneous injection, nanovaccine, especially MAN-OVA-IMNPs induced more antigen-specific CD8+ T cells, greater lymphocyte activation, stronger cross-presentation, and more generation of memory T cells, antibody, IFN-γ, and Granzyme B. Prophylactic vaccination of MAN-OVA-IMNPs significantly delayed tumor development and prolonged survival in mice. Therapeutic tumor challenge indicated that MAN-OVA-IMNPs prohibited tumor progression more efficiently than other formulations and the combination with immune checkpoint blockade further enhanced antitumor effects. Hence, DCs-targeted vaccine co-delivery with IMQ and MPLA adjuvants by hybrid cationic nanoparticles in a spatio-temporal manner is a promising multifunctional antigen delivery system in cancer immunotherapy.