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A new approach to cancer treatment: Tiny vesicles help the immune system fight tumors

Scientists at the Nano Life Science Institute (WPI-NanoLSI), Kanazawa University and colleagues have developed a promising new approach to cancer treatment. By using tiny, naturally occurring particles called extracellular vesicles (EVs), they have created a way to boost the body's immune system to fight tumors more effectively. This breakthrough could lead to more targeted cancer therapies with fewer side effects.

The study, in the Journal of Extracellular Vesicles, was led by Rikinari Hanayama. The research team developed a special type of engineered EVs, called antigen-presenting extracellular vesicles (AP-EVs), that activate immune cells inside tumors.

These AP-EVs carry key immune-boosting signals, helping T cells—the body's natural cancer fighters—recognize and attack tumors more effectively. This new approach enhances immune responses while reducing harmful side effects often seen in traditional cancer treatments.

Many modern cancer treatments, such as immune checkpoint inhibitors and cytokine therapies, help the immune system fight cancer. However, these treatments can sometimes harm healthy tissues and cause severe side effects. Extracellular vesicles (EVs) are tiny, bubble-like structures naturally produced by cells to communicate with each other.

Scientists have recently explored their potential as a targeted drug delivery system. In this study, researchers successfully modified EVs to directly deliver immune-activating molecules to tumor-fighting T cells, improving treatment effectiveness while reducing risks.

The researchers tested their engineered vesicles using cell culture experiments and mouse models, analyzing their effects with imaging, flow cytometry, and molecular assays to track immune responses and tumor growth.

By observing how immune cells reacted to AP-EVs, they confirmed that these vesicles could selectively stimulate T cells and enhance their tumor-fighting ability. Advanced imaging techniques also showed that AP-EVs accumulated in tumors, making them a promising tool for targeted cancer therapy.

Key findings:

• Stronger immune response: AP-EVs helped immune cells grow and attack tumors more effectively.
• Changing the tumor environment: The treatment made tumors more visible to the immune system, turning "cold" tumors into "hot" ones that are easier to attack.
• Better treatment when combined: AP-EVs worked even better when combined with an existing immune checkpoint inhibitor (anti-PD-1 therapy).
• Potential for human use: Researchers successfully tested human-compatible versions of AP-EVs, showing promise for future cancer therapies.

Unlike traditional immunotherapy, which can cause broad immune activation and unwanted side effects, AP-EVs provide precise targeting of tumor-fighting T cells, leading to tumor eradication without harming healthy tissue or causing other unwanted side effects. AP-EVs also have the potential to improve the effectiveness of immune checkpoint inhibitors, and other T-cell therapies.

"This discovery is an important step toward using natural biological tools to improve cancer treatment," says Hanayama, lead author of the study. "By using extracellular vesicles, we can enhance immune responses with fewer side effects, potentially leading to better outcomes for patients."

The research team is now working on optimizing AP-EVs for clinical trials and exploring their use for other types of cancer and personalized medicine.