New agent may enhance effectiveness of radiotherapy

There is increasing interest in using the body's own immune system to attack tumor cells -- a strategy that can be very effective without the side effects associated with conventional chemotherapy.

Skin cancers have been successfully treated using a topical cream, imiquimod, which recruits immune cells through a molecule known as toll-like receptor 7 (TLR7), a protein that recognizes foreign and potentially harmful material.

Previously, researchers in Manchester have shown that they can also stimulate the immune system into generating an immune response against non-skin cancers by injecting an agent similar to TLR7 into the blood.

In collaboration with AstraZeneca and Dainippon Sumitomo Pharma, the Manchester group have looked at another molecule that activates TLR7, known as DSR-6434. Using mouse models of two different types of cancer, they investigated DSR-6434 on its own and in combination with radiotherapy and measured the effect on the primary tumor and the number of secondary tumors in the lungs.

Professor Ian Stratford, from Manchester Pharmacy School who, with Professor Tim Illidge, led the research published in the International Journal of Cancer, said: "We have already seen a strong immune system response from other immunotherapy agents in combination with radiation -- this new agent appears to be even more potent."

His team showed that administering DSR-6434 together with radiotherapy led to tumor shrinkage and increased long-term survival. They found that the combination treatment also reduced the occurrence of secondary lung tumors.

"It looks like there's good reason to use radiotherapy alongside immunotherapy agents in the treatment of solid tumors. These results strongly suggest that this sort of combination therapy should be evaluated in clinical trials with cancer patients," added Professor Stratford.