Dual-responsive nanovaccine for cytosolic delivery of antigens to boost cellular immune responses and cancer immunotherapy

Abstract

Cancer vaccine contributing to the success of the treatment and prevention of tumors has attracted a huge attention as a strategy for tumor immunotherapy in recent years. A major challenge of cancer vaccine is to target cytosols of dendritic cells (DCs) in the lymph nodes (LNs) to enhance efficiency of antigen cross-presentation, which elicits high levels of cytotoxic T-lymphocytes to destruct tumor cells. Here, we address this issue by conjugating ovalbumin (OVA) to PEG-PCL using disulfide bond (-ss-), and the degradable pH-responsive polymer-PEI-PCL as delivery carrier. In addition, the mol ratio of PEG-PCL to PEI-PCL in the mixed micelles was tailored to deliver the OVA to LNs. Subsequently, CpG ODN1826, a TLR-9 agonist, was further introduced into a mixed micelle of 30 nm or less as a unique tumor vaccine. Importantly, the results demonstrated the mixed micelles with 1:1 mol of PCL-PEG and PCL-PEI can effectively migrate to distal LNs where antigen were efficiently captured by DCs, meanwhile, OVA was modified to the surface of mixed micelles via disulfide bonds (-ss-) for promotion efficiency of antigen cross-presentation. More surprisingly, combination of tumor vaccine with anti-PD-1, the therapy of ectopic melanoma (B16-OVA) and lung metastasis melanoma (B16-OVA) is excellent therapeutic effect. Taken together, our works offers a novel strategy for the cytosol delivery of antigens to achieve potent cancer immunotherapy.