Researchers have found a new tool in the fight against cancer, combining a new immunotherapy drug with a hydrogel.

Scientists from Rice University and the University of Texas Health Science Center at Houston have developed STINGel, a therapy that combines a new class of immunotherapy drugs with an injectable hydrogel that releases it in a more prolonged, steady dose.

The researchers found that slow-release peptide gels could continuously deliver immunotherapy drugs to tumor sites for extended periods of time.

The hydrogel, which is harmless to normal cells, has immunotherapy drugs inside called cyclic dinucleotides (CDNs), which have been shown to attack cancer cells. CDNs are a powerful new class of immunotherapy drugs known as STING (Stimulator of Interferon Genes) agonists, currently in clinical trials.

However, research has found that the CDN drugs are flushed quickly from the body, and current trials require multiple injections.

“The normal approach to CDN delivery is simple injection, but this leads to very rapid diffusion of the drug throughout the body and reduces its concentration at the site of the tumor to very low levels," Rice chemist and bioengineer Jeffrey Hartgerink said in a statement. "Using the same amount of CDN, the STINGel approach allows the concentration of CDN near the tumor to remain much higher for long periods of time."

The researchers tested the new drug in both lab cultures and in vivo. For the in vivo testing, six groups of 10 rodents each were treated with either CDN alone, control collagens alone or with CDN, MDP alone or STINGel (CDN plus MDP).

The researchers found that only one in 10 CDN or collagen plus CDN rodents survived at least 105 days. However, six of 10 animals treated with STINGel survived and also proved resistant to further implantation of cancer cells. This likely means that their immune systems were trained to successfully identify and destroy both existing cancer and future occurrences of cancer.

The study stated: “The highly localized delivery of CDN from this nanostructured biomaterial affects the local histological response in a subcutaneous model, and dramatically improves overall survival in a challenging murine model of head and neck cancer compared to CDN alone or CDN delivered from a collagen hydrogel.”

The team also tested more common hydrogels and were unable to provide the same controlled release. The other hydrogels also did not provide an additional benefit over CDN treatment.

"The MDP hydrogel provides a unique environment for the release of CDN that other gels just can't match," Hartgerink said.

"The CDN we used in this study is currently in clinical trials," he added. "We think that our STINGel approach has the potential to significantly broaden the scope of this powerful immunotherapy drug to a larger range of resistant cancers."

The study was published in Science Direct.