Leveraging Naturally Assembled Tumor Extracellular Vesicles as Self-Adjuvanting Nanovaccines to Potentiate Cancer...

Area of Science:

• Immunology and Cancer Therapy
• Nanotechnology and Drug Delivery
• Extracellular Vesicle Biology

Background:

• The cyclic guanosine monophosphate-adenosine monophosphate (cGAS)/stimulator of interferon genes (STING) pathway is a promising target for cancer immunotherapy.
• Clinical application of STING agonists is limited by poor drug properties, inefficient tumor antigen delivery, and adverse effects.
• Extracellular vesicles (EVs) released by tumor cells contain antigens and proteins, offering potential for therapeutic applications.

Purpose of the Study:

• To develop a novel EV-based cancer vaccine that activates the cGAS/STING pathway.
• To overcome the limitations associated with current STING agonist therapies.
• To leverage tumor-derived EVs as a platform for enhanced antigen presentation and T-cell activation.

Main Methods:

• Metformin-loaded, positively charged poly(d,l-lactide-co-glycolide) nanoparticles (Met-PC-NPs) were used to treat tumor cells, increasing intracellular reactive oxygen species (ROS).
• Extracellular vesicles (EVs) were harvested from treated tumor cells, resulting in Met-PC-EVs containing double-stranded DNA (dsDNA) and tumor antigens.
• Met-PC-EVs were injected subcutaneously to assess their migration to lymph nodes, activation of antigen-presenting cells, and subsequent T-cell responses.

Main Results:

• Met-PC-EVs effectively delivered dsDNA and tumor antigens to lymph nodes, activating antigen-presenting cells and promoting CD8+ T-cell cross-presentation.
• Subcutaneous injection of Met-PC-EVs demonstrated robust tumor eradication in both prophylactic and therapeutic cancer models.
• The treatment established long-term immune memory and showed synergistic effects when combined with immune checkpoint inhibitors.

Conclusions:

• This study presents a novel strategy for creating effective cancer vaccines by utilizing engineered extracellular vesicles (EVs) to activate the cGAS/STING pathway.
• The developed Met-PC-EVs overcome limitations of current STING agonists by enhancing antigen presentation and T-cell activation.
• This approach offers a clinically translatable method for developing EV-based cancer vaccines with significant therapeutic potential.