An old epilepsy treatment may provide to a new approach to treating many types of cancer, US scientists have claimed. The team from the National Cancer Institute in Bethesda, Maryland, have found that the anti-convulsant drug valproic acid has a powerful anti-tumour effect when combined with the experimental drug UCN-01.

Evidence of the combination's ability to kill a variety of tumour cells is reported in the latest edition of the British Journal of Cancer. The principal investigator, Dr Dao Nguyen, said: ”We are very encouraged by these latest results, and strongly believe that drug combinations including valproic acid will, in time, reach the clinic and help cancer patients.”

Dr Nguyen’s team in the surgical branch of the NCI’s Section of Thoracic

Oncology was researching ways to enhance the anticancer effects of a group of molecules called histone deacetylase inhibitors (HDACIs). When they found that valproic acid was a member of this group - and had also shown anti-cancer properties - they realised it would be a good candidate for development because its pharmacology was already well known.

Valproic acid has a weak anti-cancer effect on its own but, in combination with UCN-01, it becomes highly effective against tumour cells. Having shown that valproic acid combinations can kill cancer cells in the lab, the research team still have to show that it can work in people.

In addition, valproic acid can cause serious side effects in many patients, including liver and stomach problems and weight gain. Dr Nguyen added: ”We also need to continue searching for combinations of valproic acid and other agents that achieve potent killing of cancer cells at lower concentrations. This will reduce the side effects associated with high doses of the drug.”

Professor Herbie Newell, Director of Translational Research at Cancer Research UK, added: ”As cancer researchers, we have to be alert to the fact that it is not just ’new‘ drugs that can help us treat cancer. There are a number of drugs being developed that started out life as treatments for other illnesses. Research of this kind, taking well-known drugs and enhancing their existing anti-cancer effects, can save time and money in the search for new and better cancer treatments.”

Earlier this month, Cancer Research UK announced a new initiative with some of the world's biggest pharmaceutical and biotechnology companies that it hopes will exploit untapped anti-cancer medicines that are currently collecting dust on industry shelves.

The Clinical Development Partnerships initiative aims to increase the number of successful new treatments for cancer by taking undeveloped anti-cancer agents from industry and putting them into clinical trials. By Michael Day.