Photothermal therapy improves the efficacy of topical immunotherapy against melanoma

: Melanoma is an aggressive cancer with poor response to traditional therapies. A combination of photothermal therapy and topical immunotherapy is expected to eliminate melanoma effectively. : C57BL/6 mice with early stage and metastatic melanoma were treated with laser immunotherapy (LIT), combining near-infrared laser-based photothermal therapy (PTT) and topical imiquimod (IMQ)-based immunotherapy. The volume of primary and abscopal melanoma, animal survival, tissue temperature, transcriptome, and immune cell response were investigated to evaluate the effect of LIT. : LIT could eliminate primary tumors, inhibited abscopal tumors, and prolonged animal survival. The tumor tissues were selectively destroyed under a photothermal gradient between 38.2 ± 3.7°C and 73.0 ± 2.3°C. Gene expression analysis showed a significant increase in the expression of damage associated molecular patterns. Additionally, the expression of mature dendritic cells, CD4+ T cells, and CD8+ T cells were increased, while myeloid-derived suppressor cells were downregulated after LIT. : The study showed that LIT inhibited the growth of both primary and abscopal melanoma by activating systemic antitumor immune responses and reversing the immunosuppressive tumor microenvironment, making LIT a potential method for advanced melanoma treatment.