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

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.