Tumor-targeting and activatable biomimetic nanococktails synergistically regulate immune responses for spatiotemporal immunotherapy of low immunogenic solid tumors

Cancer immunotherapy is generally limited by the low immunogenicity of tumor microenvironments (TME). Thus, regulating immune responses in low immunogenic solid tumors is critical for improving immunotherapeutic outcomes. Here, the tumor-targeting and activatable biomimetic nanococktails have been engineered to synergistically and systemically activate a cascade of immune responses and downregulate immunosuppressive T cells for spatiotemporal immunotherapy of low immunogenic solid tumors. The nanococktails had core-shell structures, where the photosensitizers, STING agonists and indoleamine 2,3-dioxygen-ase 1 (IDO1) inhibitors were encapsulated within the core, which can disassociate when responding to the low pH in tumors to disrupt the particle shells and cellular membranes for precision drug delivery and release. The ligands anchored on the shell of nanococktails could efficiently target the receptors that were identified to be highly expressed in the breast cancer cells, facilitating efficient intracellular drug delivery and synergistically inducing anticancer immunity and mitochondrial damage. By intravenous (i.v.) injection, the nanococktails demonstrated high accumulation in triple-negative breast cancer (TNBC), endowing precision diagnosis and effective elimination of primary TNBC tumors. The synergistic effects of STING activation and metalloimmunotherapy induced by nanococktails can amplify systemic immune responses and downregulate immunosuppressive regulatory T cells (Tregs) in primary tumors, lymph nodes and distant tumors, which spatiotemporally inhibited distant tumors and lung metastasis of TNBC with promoted survival rates. This study presents a promising strategy for leveraging nanococktails to regulate immune responses for effective immunotherapy.