Decorating Bacteria with Triple Immune Nanoactivators Generates Tumor‐Resident Living Immunotherapeutics

Abstract An approach of decorating bacteria with triple immune nanoactivators is reported to develop tumor‐resident living immunotherapeutics. Under cytocompatible conditions, tumor‐specific antigens and checkpoint blocking antibodies are simultaneously conjugated onto bacterial surface and then polydopamine nanoparticles are formed via in situ dopamine polymerization. In addition to serving as a linker, polydopamine with its photothermal effect can repolarize tumor‐associated macrophages to a pro‐inflammatory phenotype. The linked antigens promote the maturation of dendritic cells and generate tumor‐specific immune responses, while the anchored antibodies block immune checkpoints and activate cytotoxic T lymphocytes. Decorated bacteria show spatiotemporal tumor retention and proliferation‐dependent drug release, achieving potent antitumor effects in two antigen‐overexpressing tumor models. This work provides a versatile platform to prepare multimodal and long‐acting therapeutics for cancer immunotherapy.