Photosensitizer-Free Phototherapy with Peptide Micelle Nanoadjuvants for Cancer Vaccine against Metastasis of Melanoma

Abstract

Here, an external photosensitizer-free vaccination strategy accompanied by delivery of nanoadjuvants is reported as a treatment for melanoma. Melanin-enriched B16F10 melanoma cells showed a strong and specific photothermal effect under irradiation of near-infrared (NIR) wavelength light, and a corresponding killing effect of cancer cells is observed. The irradiated melanoma cells exhibited surface exposure of the eat-me signal, calreticulin, which induced immunogenic cell death. The nanoadjuvant, which comprised imiquimod encapsulated in amphiphilic peptide-based micelles, induced dendritic cell maturation. In B16F10 melanoma tumor-bearing mice, irradiation of NIR light alone increased the temperature of the tumor site to 60 degrees C regardless of nanoadjuvant treatment. To mimic metastasis to sites near the primary tumor site, primary tumor-cured mice are rechallenged with B16F10 cells. In a lung metastasis model induced by intravenous injection of B16F10 cells, only nanoadjuvant-treated group showed significant prevention of B16F10 tumor nodule formation in the lung. The immunotherapeutic effects of this nanoadjuvant are supported by an observed increase of tumor-infiltrating CD8 + T cell populations. The results suggest that the combination of photosensitizer-free phototherapy with a peptide micelle nanoadjuvant has strong potential for clinical translation as a melanoma vaccine.