To overcome the limitations current cancer vaccines and improve their efficacy, we have developed a versatile antigen delivery platform targeting cross-presenting dendritic cells (DCs) in vivo. By preparing of a solid-in-oil-in-water double emulsion through sequential reagent addition, we developed a tailored nanoemulsion (TNE), which was functionalized to target Clec9A (Clec9A-TNE), a DC-specific endocytic receptor expressed by cross-presenting CD103+ and CD8+ DCs and plasmacytoid (p)DCs in mice and BDCA3+/CD141+ DCs in humans. Clec9A-targeting TNEs are stable in physiological environments and after i.v. injection in mice, they are selectively taken up by CD8+ DCs and pDCs in spleen and tumor bed. TNEs traffic to both early endosomes and lysosomes, essential prerequisite for an efficient antigen processing and presentation through MHC class I and II pathways. Clec9A-targeting TNE encapsulating a reference antigen (ovalbumin, OVA) without adjuvant targeted and activated cross-presenting DCs and promoted antigen-specific CD4+ and CD8+ T-cell proliferation, cytotoxic T-cell activity and antibody responses in vivo. To exploit the tumour “mutanome” with our TNE platform, we have developed a functional assay to rank immunogenicity of individual neo-epitopes using the murine B16-F10 melanoma as a model. Four weekly i.v. injections of Clec9A-targeting TNEs loaded with a functionally selected pool of neo-epitopes strongly inhibited the in vivo growth of the highly aggressive and poorly immunogenic B16F10 melanoma cells and induced strong epitope-specific IFN-g T-cell immunity. Similar findings were also observed in a mouse model of HPV-driven carcinoma in which Clec9A-targeting TNEs loaded with recombinant E6/E7 viral oncoproteins showed a markedly superior efficacy as compared to a standard vaccination protocol.
Versatile, personalized, antigen-specific cancer vaccines are a long-sought therapeutic strategy in cancer immunotherapy. Clec9A-targeting nanoemulsions represent such a platform to deliver recombinant tumour protein or neo-epitope antigens specifically to cross-presenting DCs in vivo. This platform can fully exploit the neo-epitope target repertoire of individual tumours thereby improving the feasibility and efficacy of personalized cancer immunotherapy.