Immunogenic Cell Death Augmented by Manganese Zinc Sulfide Nanoparticles for Metastatic Melanoma Immunotherapy.

Both T-cell deprivation and insufficient tumor immunogenicity seriously hinder the efficacy of immune-mediated tumor destruction in melanoma. In this work, an amphiphilic polyethylene glycol-poly(2-hexoxy-2-oxo-1,3,2-dioxaphospholane) copolymer with a thermally sensitive flowable core (mPEG- b -PHEP) was chosen to incorporate IR780 dye and manganese zinc sulfide nanoparticles (ZMS) to form polymer micelles (denoted PP IR780-ZMS ), which precisely controlled the release of ZMS after being triggered by near-infrared light (NIR). Mn 2+ -mediated chemodynamic therapy (CDT) by photothermal trigger boosted the generation of reactive oxygen species (ROS), making the PP IR780-ZMS smart bomblets in vivo . It was demonstrated that PP IR780-ZMS could maximize immunogenic cell death (ICD) in cancer, which is characterized by abundant damage-associated molecular pattern (DAMP) exposure. As a result, the cytotoxic T cells (CD8 + ) and helper T cells (CD4 + ) expanded and infiltrated the neoplastic foci, which further reprogrammed the suppressive tumor microenvironment (TME) against the primary tumor and pulmonary metastases with safe systemic cytokine expression. In addition, Mn 2+ -mediated cGAS-STING signaling pathway activation enhanced the antitumor immunity of this nanocomposite, providing a practical strategy for expanding the use of Mn-based nanostructures.