1152 Personalized biomimetic hybrid nanovaccines for enhancing T-cell response and efficacy in cancer immunotherapy

<h3>Background</h3> The considerable heterogeneity in the efficacy of immunotherapy among individuals presents a significant obstacle in cancer treatment. Hence, it is critical to develop personalized immunotherapy strategies that specifically modulate T cell activity based on the unique characteristics of each patient‘s tumor. This study aims to develop biomimetic hybrid nanovaccines which ingeniously integrate nanovesicles with autonomous antigen presentation, liposomes responsive to T cell microenvironment, and chemotherapeutic drugs with distinctive immunomodulatory mechanisms to synergistically activate T cells and realize personalized cancer immunotherapy (figure 1). <h3>Methods</h3> The reductive-responsive, docetaxel-loaded liposomes (DTX-Lip) were prepared by thin-film method, the dendritic cells-derived extracellular vesicles (DCEVs) were prepared by extrusion method and the ultimate hybrid nanovaccines (HNVs) were prepared by freeze-thaw method. The occurrence of lipid bilayer membranes fusion was validated by Fluorescence resonance energy transfer (FRET) technology. The antigen presentation and T cell activation ability of the nanovaccines was analyzed by RT-qPCR and western blot. The preliminary anti-cancer efficacy of nanovaccines were evaluated by co-incubating T cells and cancer cells. <h3>Results</h3> The DTX-Lip were spherical and uniform in size, with an average diameter of 94.70 ± 1.87 nm and a drug loading efficiency of 6.54%. DCEVs displayed a consistent vesicular structure with an average size of about 114.6±3.8 nm, showing elevated expression levels of various costimulatory molecules (<i>e.g.</i>, CD80, CD86, CD40) and chemokines (<i>e.g.</i>, CCR7, CCL4, CCL5). Subsequently, the hybrid HNVs were prepared through a freeze-thaw approach and a notable decrease in FRET efficiency was observed, confirming the successful fusion between DCEVs and DTX-Lip. The HNVs demonstrated a uniform spherical configuration with an average size of 134.5 ± 1.3 nm in deionized water, but lost their original morphology upon exposure to 10 mM GSH, showing excellent reductive responsiveness. Confocal microscopy images illustrated the interaction and internalization of HNVs by T cells, leading to the activation of T cells marked by the upregulation of CD25 and CD69. Ultimately, the activated cytotoxic T cells exhibited enhanced levels of IFN-γ, GranzymB, and perforin, enabling them to impede the proliferation of cancer cells effectively. <h3>Conclusions</h3> We have successfully prepared personalized reduction-responsive HNVs by fusing DCs-derived EVs with DTX-loaded liposomes. Notably, the predominant functional membrane proteins present on the HNVs surface closely mirrored those of the original DCs, facilitating the efficient activation of T cells and subsequent potent inhibition of cancer cells. These pivotal outcomes have the potential to accelerate the translation of personalized vaccines aimed at bolstering T cell activity into clinical practice. <h3>Acknowledgements</h3> This work was supported by Frontier Medical Center, Tianfu Jincheng Laboratory Foundation (TFJC2023010003), and International Cooperation Project of Chengdu Science and Technology Bureau (2022-GH02-00023-HZ).