Metal-Organic Framework-Based Nanovaccine for Relieving Immunosuppressive Tumors via Hindering Efferocytosis of Macrophages and Promoting Pyroptosis and Cuproptosis of Cancer Cells.

Current cancer vaccines face challenges due to an immunosuppressive tumor microenvironment and their limited ability to produce an effective immune response. To address the above limitations, we develop a 3-(2-spiroadamantyl)-4-methoxy-4-(3-phosphoryloxy)-phenyl-1,2-dioxetane (alkaline phosphatase substrate) and XMD8-92 (extracellular signal-regulated kinase 5 inhibitor)-codelivered copper-tetrahydroxybenzoquinone (Cu-THBQ/AX) nanosized metal-organic framework to in situ-generate therapeutic vaccination. Once inside the early endosome, the alkaline phosphatase overexpressed in the tumor cells' membrane activates the in situ type I photodynamic effect of Cu-THBQ/AX for generating •O2-, and the Cu-THBQ/AX catalyzes O2 and H2O2 to •O2- and •OH via semiquinone radical catalysis and Fenton-like reactions. This surge of ROS in early endosomes triggers caspase-3-mediated proinflammatory pyroptosis via activating phospholipase C. Meanwhile, Cu-THBQ/AX can also induce the oligomerization of dihydrolipoamide S-acetyltransferase to trigger tumor cell cuproptosis. The production of •OH could also trigger the release of XMD8-92 for effectively inhibiting the efferocytosis of macrophages to convert immunosuppressive apoptosis of cancer cells into proinflammatory secondary necrosis. The simultaneous induction of pyroptosis, cuproptosis, and secondary necrosis effectively converts the tumor microenvironment from "cold" to "hot" conditions, making it an effective antigen pool. This transformation successfully activates the antitumor immune response, inhibiting tumor growth and metastasis.