Autologous tumor cell vaccine is an individualized tumor treatment strategy to elicit tumor-specific immune responses. However, it is difficult to exert efficacy in "cold" tumors, which lack tumor-infiltrating T cells and are not sensitive to immunotherapy. Here, a dendritic cells (DCs) activation hydrogel is constructed based on bifunctional fusion membrane nanoparticles (FM-NPs) composed of autologous tumor cell membranes and Mycobacterium phlei membrane extracts. The FM-NPs not only provide tumor antigens but also can activate DCs. Afterward, the FM-NPs are loaded in an injectable alginate hydrogel together with granulocyte-macrophage colony-stimulating factor (GM-CSF). GM-CSF releases rapidly and recruits DCs to hydrogel, while FM-NPs retain in hydrogel to continuously interconnected with DCs, enriching mature DCs loaded with tumor antigens. In the 4T1 mouse breast tumor model, this hydrogel promotes the maturation of DCs in tumordraining lymph nodes and induces sufficient effector memory T cells that migrate to the tumor microenvironment. This successfully converts the "cold" tumors to "hot", thus exerting a significant antitumor effect synergized with the PD-1 antibody. It is also verified the inhibitory effect of FM-NPs using human gastric cancer organoids. Altogether, these findings demonstrate the application potential for the bifunctional fusion membrane-based hydrogel as an autologous tumor vaccine by activating DCs.

In situ vaccination is a promising strategy to convert the immunosuppressive tumor microenvironment into an immunostimulatory one with limited systemic exposure and side effect. However, sustained clinical benefits require long-term and multidimensional immune activation including innate and adaptive immunity. Here, we develop a probiotic food-grade Lactococcus lactis-based in situ vaccination (FOLactis) expressing a fusion protein of Fms-like tyrosine kinase 3 ligand and co-stimulator OX40 ligand. Intratumoural delivery of FOLactis contributes to local retention and sustained release of therapeutics to thoroughly modulate key components of the antitumour immune response, such as activation of natural killer cells, cytotoxic T lymphocytes, and conventional-type-1-dendritic cells in the tumors and tumor-draining lymph nodes. In addition, intratumoural administration of FOLactis induces a more robust tumor antigen-specific immune response and superior systemic antitumour efficacy in multiple poorly immune cell-infiltrated and anti-PD1-resistant tumors. Specific depletion of different immune cells reveals that CD8+ T and natural killer cells are crucial to the in situ vaccine-elicited tumor regression. Our results confirm that FOLactis displays an enhanced antitumour immunity and successfully converts the ‘cold’ tumors to ‘hot’ tumors.

T cell receptor‐engineered T (TCR‐T) cell therapy has demonstrated therapeutic effects in basic research and clinical trials for treating solid tumors. Due to the peptide‐dependent recognition and the human leukocyte antigen (HLA)‐restriction, TCR‐T cell therapy is generally custom designed to target individual antigens. The lack of suitable universal targets for tumor cells significantly limits its clinical applications. Establishing a universal TCR‐T treatment strategy is of great significance. This study designed and evaluated the HLA‐peptide‐addressing universal (HAUL) TCR‐T cell therapy based on HLA‐peptide (pHLA) loaded membrance fusogenic deliver system. The pHLA‐NP‐based tumor cell membrane modification technology can transfer the pHLA onto the surface of tumor cells through membrane fusogenic nanoparticles. Then tumor cells are recognized and killed by TCR‐T cells specifically. The HAUL TCR‐T cell therapy technology is a universal technology that enables tumor cells to be identified and killed by specific TCR‐T cells, regardless of the HLA typing of tumor cells.