Scientists Discover Smarter Way to Activate Immune System Against Cancer

Cambridge, 17th September 2025 – Scientists at the University of Cambridge have made an important discovery that could make cancer treatments safer and more precise. The team has designed a new method to activate the immune system only where it is needed, avoiding harm to healthy organs.

The research focuses on a pathway inside cells called STING, which acts like an alarm system. When STING is activated, it sends signals to the body’s immune system to attack cancer cells. While drugs that switch on STING have shown promise in cancer treatment, they often cause serious side effects if they affect healthy tissues.

To solve this problem, the Cambridge team created a two-part “prodrug” system. Each part is harmless on its own, but when they meet inside a tumour, they combine to form a powerful STING activator. One part of the drug is “caged” and stays inactive until it meets an enzyme called β-glucuronidase, which is usually only found in tumours. When this enzyme unlocks the caged component, it reacts with the second part to trigger the immune system.

Professor Gonçalo Bernardes, who led the research, explained, “This is like sending two safe packages into the body that only unlock and combine when they meet the tumour’s unique chemistry. The result is a strong immune-activating drug that appears only where it is needed.”

Laboratory tests showed that the drug parts have almost no effect on their own. But when they met in tumour conditions, the active compound formed and successfully switched on STING even at very low concentrations. Tests in zebrafish and mouse models showed that the drug acted almost exclusively in tumours, protecting important organs such as the liver, kidneys, and heart.

The results, published in Nature Chemistry, represent a major step forward for STING-based therapies, which have struggled in the past to distinguish between healthy and cancerous tissue. This new method uses a simple chemical design to achieve targeted activation, without relying on complex or artificial reactions.

Beyond cancer, the researchers believe this discovery could lead to a new class of precision medicines, offering treatments that are safer and more effective for a variety of diseases. This work shows how careful chemical design can help the immune system fight disease while protecting the rest of the body.

This breakthrough provides hope for patients and represents an exciting direction in cancer therapy and medical research.