Gold Nanocage-Based Photothermal Ablation Facilitates In Situ Vaccination for Melanoma Therapy

Cancer immunotherapy represents a medical break-through, but there are still many patients unable to benefit from it because of the low response rate. The immunosuppressive tumor microenvironment (TME) is the main barrier to immunotherapy. Alleviating intratumoral immunosuppression is critical for improv-ing the immune therapeutic efficacy. This work developed an in situ vaccination strategy by using gold nanocage (AuNC)-based photothermal effect in combination with an adjuvant and PD-L1 suppressor. In specific, this therapeutic strategy included three components: AuNCs as an inducer for tumor antigen production via photothermal ablation, CpG oligodeoxynucleotides as an adjuvant to amplify immune responses, and JQ1 as a PD-L1 suppressor to inhibit an immune checkpoint. The results showed that the in situ vaccination efficiently activated dendritic cells and primed T cells and exhibited a high therapeutic efficacy in the melanoma-bearing mice. This therapeutic strategy can increase the infiltration of cytotoxic T lymphocytes, suppress the PD-L1 expression in the tumor, and repolarize tumor-associated macrophages from pro-tumor M2 to the anti-tumor M1 phenotype, thereby remodeling the TME via regulating the innate immune and adaptive immune responses.