Robust anti-tumor immunity through the integration of targeted lipid nanoparticle-based mRNA nanovaccines with PD-1/PD-L1 blockade

Tumor mRNA vaccines present a personalized approach in cancer immunotherapy, encoding distinct tumor antigens to evoke robust immune responses and offering the potential against emerging tumor variants. Despite this, the clinical advancement of tumor mRNA vaccines has been hampered by their limited delivery capacity and inefficient activation of antigen-presenting cells (APCs). Herein, we employed microfluidics technology to engineer mannose-modified lipid-based nanovaccines for specifically targeting APCs. The encapsulation process efficiently entrapped the cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) agonist along with mRNA encoding antigens. The targeted nanovaccines (TNVs) exhibited a narrow particle size distribution, ensuring consistent and efficient delivery. These TNVs significantly enhanced gene expression of mRNA, facilitating antigen presentation and immune activation. When compared to non-targeted nanovaccines, TNVs outperformed in terms of antigen presentation and immune activation. Furthermore, the combination of anti-PD-L1 antibodies with TNVs elicited a synergistic anti-tumor effect. This was attributed to the anti-PD-L1 antibodies' ability to overcome the immune suppression of tumor cells. Our findings suggest that the combination treatment elicited the most robust anti-tumor immune activation and immune memory effect. These results indicate that integrating tumor mRNA vaccines with immune checkpoint inhibitors or other immunostimulatory agents may be crucial for enhancing the immune response.