Targeted Codelivery of an Antigen and Dual Agonists by Hybrid Nanoparticles for Enhanced Cancer Immunotherapy

TLDR

Nanotechnology‑based dendritic‑cell vaccines are a promising strategy to elicit potent antitumor immune responses. The study aimed to improve DC targeting and vaccine efficacy by co‑delivering the TLR7/8 agonist imiquimod and the TLR4 agonist monophosphoryl lipid A within lipid‑polymer hybrid nanoparticles. The nanoparticles were engineered with MPLA in the outer lipid layer and IMQ in the hydrophobic core to provide spatiotemporal activation of extracellular TLR4 and intracellular TLR7/8, synergistically stimulating dendritic cells. The resulting MAN‑OVA‑IMNPs vaccine markedly increased antigen uptake, DC maturation, cytokine production, antigen‑specific CD8⁺ T‑cell, antibody, IFN‑γ, and granzyme B responses, delayed tumor onset, prolonged survival, and, when combined with checkpoint blockade, further enhanced antitumor efficacy.

Abstract

Among approaches of current cancer immunotherapy, a dendritic cell (DC)-targeted vaccine based on nanotechnology could be a promising way to efficiently induce potent immune responses. To enhance DC 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 spatiotemporal delivery of MPLA (within the 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, cytokine production, and maturation of DCs. Compared with the quick metabolism of free OVA-agonists, the depot effect of OVA-IMNPs was observed, whereas MAN-OVA-IMNPs promoted trafficking to secondary lymphoid organs. After immunization with a subcutaneous injection, the 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 the survival in mice. The therapeutic tumor challenge indicated that MAN-OVA-IMNPs prohibited tumor progression more efficiently than other formulations, and the combination with an immune checkpoint blockade further enhanced antitumor effects. Hence, the DC-targeted vaccine codelivery with IMQ and MPLA adjuvants by hybrid cationic nanoparticles in a spatiotemporal manner is a promising multifunctional antigen delivery system in cancer immunotherapy.