Market forces block tailored medicines, says expert

· 'No incentive' for genetic trials on common drugs
· NHS urged to fund tests shunned by companies

The development of personalised medicines tailored to an individual's genetic makeup is being severely hampered because drug companies do not have the incentive to develop the required genetic tests, claims an expert.

The promise of bespoke medicines was sold as one of the major benefits of decoding the entire human genome. By developing genetic tests, drug companies hoped they could identify which patients would benefit most from a drug, and who was at greatest risk of suffering potentially dangerous side-effects.

But according to a study, while drug companies have begun to develop genetic tests for experimental drugs, many of which have yet to go into clinical trials , common pharmaceuticals already widely prescribed by GPs and hospital doctors are largely being neglected.

"Drug companies are putting all their efforts into creating tests for new drugs that won't be on the market for years. Basically, there's no commercial incentive for the big companies selling existing drugs to go to the expense and effort of developing a test that will ultimately narrow down the number of people who take their drug," said Paul Martin, deputy director of the Institute for the study of Genetics, Biorisks and Society at Nottingham University.

Pharmacogenomics, as the science of personalised medicine is known, works by identifying the genetic differences that determine whether a drug cures a patient, has no effect or, at worst, causes a severe adverse reaction.

In Britain alone, an estimated 10,000 people die each year from the side effects of drugs, with tens of thousands more becoming seriously ill. Dr Martin, who is due to present his findings at a Wellcome Trust conference in Hinxton, Cambridge, tomorrow, said: "This is an issue of market failure. Things could get a lot better, with safer, more cost-effective medicines, but the benefits of this technology might not be realised thanks to this."

The lack of pharmacogenomic tests for drugs already on the market has caused problems for the pharmaceutical industry as well as those taking their medications. Last month, the American drug company Merck was ordered to pay $253m (£141m) to the wife of a triathlete who died after taking the firm's painkiller Vioxx. And earlier this year, the European Medicines Agency told doctors not to give the anti-depressant drug Prozac to children amid fears it can make some feel suicidal and aggressive.

Because the patents have expired on most of the drugs in use today, any drug company can legally produce them, meaning there is even less incentive for one company to produce a pharmacogenomic test. Without a commercial incentive, Dr Martin believes the NHS should fund more studies to cover those drugs the industry is ignoring.

"There are significant public health benefits that could be gained from implementing pharmacogenetics," he said. "If a drug is going to have no effect or a dangerous effect in many people, it is a waste of money and that isn't helping anybody.

"The bottom line is it's fantasy that people will walk into a doctor's office, have a test and then they'll be given the right prescription. Let's be realistic. This talk of a revolution in personalised medicine is nonsense. It's a long, long way off."


Genetic tests

A mouth swab or blood sample is taken to provide DNA. By matching genetic differences to patients who have adverse reactions, companies can work out who will most benefit from their drugs.

Human genome

An international team of scientists announced in 2003 they had unravelled every letter of the human genetic code: 25,000 genes build a human.

Clinical trials

Drugs must go through three levels of trials before they can be approved, testing for safety, whether they work, and on at least several hundred people to identify doses and side-effects