Light activated cancer drug hope

Monoclonal antibodies are seen as a key weapon in the fight against cancer, but can attack healthy tissue as well.

Writing in ChemMedChem, Newcastle University researchers say they have found ways to make antibodies only respond when light is shone.

UV light is shone at the site of the tumour to activate the antibodies.

The body does not on its own generate the antibodies needed to fight cancer, as it does so often with other diseases, so there have been high hopes for these therapeutic antibodies.

These often work by stimulating the body's own T-cells, which regulate the production of its own antibodies.

The power and the danger of these treatments was highlighted in 2006, when six men were taken seriously ill after drug trials at an independent research unit sited at London's Northwick Park hospital. Their immune systems had been sent into overdrive.

"It's very difficult to get the antibodies to specifically target the tumour - they get taken to places you don't want them"
Professor Colin Self
University of Newcastle

Some have been safely harnessed into drugs for cancer: Herceptin is one example, Avastin another.

However, there are many others which have been developed but sit unused because a safe way of delivering them to the site of the tumour has yet to be developed.

"It's very difficult to get the antibodies to specifically target the tumour," says Professor Colin Self, who led the Newcastle team. "They get taken to places you don't want them."

Shine a light

To address this problem of delivery, Professor Self and his team have devised a way of "cloaking" the antibodies with a light-sensitive organic oil which stops them from working until they come into contact with light.

UV light is then shone at the site of the tumour, and the antibodies kick into action.

Tests were carried out on six mice who had been given ovarian cancer. The treatment killed the tumours in five of the six rodents.

"Developing treatments that attack cancer cells but leave healthy tissue unharmed is the holy grail of cancer research"
Josephine Querido
Cancer Research UK

Professor Self said his "vision of the future" was one in which someone could be treated as an outpatient, arriving for an injection of cloaked antibodies and then waiting no more than an hour for a few minutes of light therapy.

Clinical trials on humans are to begin next year, should funding be secured, although these will be on secondary skin cancers and not internal tumours.

Even if these and the next stage of clinical trials are successful, those familiar with the process said it could be more than a decade before the treatment is available.

But while the research may be in its infancy, the findings have been welcomed.

"Developing treatments that attack cancer cells but leave healthy tissue unharmed is the holy grail of cancer research," said Josephine Querido, Cancer Research UK senior science information officer.

"Although at a very early stage, this new approach has potential, and we await the outcome of further research with interest."

RELATED INTERNET LINKS
Cancer Research UK
ChemMedChem
The BBC is not responsible for the content of external internet sites