Solid-in-Oil (S/O) Nanodispersions for Transdermal Cancer Immunotherapy

Transcutaneous immunization is a novel, non-invasive alternative to conventional immunization by injection. Skin immunocompetence comprised of abundant antigen-presenting cells in the epidermal and dermal layers of the skin can provide an effective tool for transcutaneous immunization, whereas the outermost, hydrophobic layer of skin, the stratum corneum, hinders penetration of antigens into the skin. To realize effective transcutaneous delivery of antigens, we have developed a solid-in-oil (S/O) technique that produces an oil dispersion of hydrophilic biomolecules.

In this study, we applied this technique to a cancer antigen and aimed to develop an effective transcutaneous cancer vaccine. We chose the melanoma, a kind of the skin cancer, to evaluate the cancer immunity. Because a melanoma antigen, TRP-2 peptide, has low solubility in water, we added lysine residues to the N-terminus of the peptide and the newly developed peptide antigen, K-TRP-2, was used as a melanoma antigen. In addition, we tried the use of R-848 as hydrophobic adjuvant to induce stronger immunity. The in vivo experiment revealed the effective prevention of tumor and the metastasis was achieved by S/O formulation containing R-848.