A melanin-mediated cancer immunotherapy patch

Transdermal microneedle patch integrated with whole tumor lysate containing melanin facilitates cancer immunotherapy upon near-infrared light irradiation. Lighting up antitumor responses Dendritic cell (DC)–based and whole tumor antigen vaccines have shown promise as cancer therapies but have been constrained by suboptimal antigen presentation and T cell activation. Ye et al. now demonstrate how a transdermal microneedle patch loaded with tumor lysate and melanin can lead to improved antitumor vaccine responses. They treated mice transdermally with a microneedle patch loaded with whole tumor lysate from B16F10 melanoma combined with melanin and exposed the patch to near-infrared light irradiation, which promoted heat generation by melanin and enhanced antigen uptake by DCs. This light-triggered heat response enhanced T cell migration and localized proinflammatory cytokine production and was effective at targeting both primary and distal secondary tumors. Melanin is capable of transforming 99.9% of the absorbed sunlight energy into heat, reducing the risk of skin cancer. We here develop a melanin-mediated cancer immunotherapy strategy through a transdermal microneedle patch. B16F10 whole tumor lysate containing melanin is loaded into polymeric microneedles that allow sustained release of the lysate upon insertion into the skin. In combination with the near-infrared light irradiation, melanin in the patch mediates the generation of heat, which further promotes tumor-antigen uptake by dendritic cells, and leads to enhanced antitumor vaccination. We found that the spatiotemporal photoresponsive immunotherapy increases infiltration of polarized T cells and local cytokine release. These immunological effects increase the survival of mice after tumor challenge and elicited antitumor effects toward established primary tumor and distant tumor. Collectively, melanin generates local heat, boosts T cell activities by transdermal vaccines, and promotes antitumor immune responses.