UK to begin trials of yew bark cancer drug

A MAJOR series of British trials is being planned into the powerful anti-cancer agent Taxol, which is derived from the bark of the Pacific yew tree, the Cancer Research Campaign said yesterday.

For the first time the drug will be used at the start of treatment rather than when the cancer is well developed. It acts by interfering with the mechanism that makes cells divide, and can reduce the size of tumours.

A spokeswoman for the campaign said it was hoped that trials would start soon.

The announcement was made following the news last week that the US Food and Drug Administration had approved the use of Taxol for women with ovarian cancer for whom other treatments had failed. The licence given to Bristol-Myers Squibb, which has spent more than dollars 150m ( pounds 100m) in developing the drug, is the first for Taxol, which came to the notice of Western researchers 20 years ago. Some economists estimate sales of dollars 50m in the first year, rising to dollars 350m by 1995.

The new British trials have the potential for increasing that market even further. Discussions now taking place between the campaign and the drug company are for tests on lung, head and neck cancers, as well as the ovarian and breast cancers with which Taxol has been mostly associated.

But more significantly the British plan is to use the drug in the early stages of cancer rather than waiting until established treatments have been tried and failed.

Professor Gordon McVie, medical director of the campaign, said: 'Taxol has withstood the hardest test by working where other drugs have failed and we are now confident that, if used earlier, when patients are not so sick, chances of a cure will be significantly higher. It has worked as a tail-gunner, if you like, and now it is time to bring it to the front line of the armoury.'

The use of Taxol has been controversial since it comes from the bark of the Pacific yew tree, Taxus brevifolia, which is rare and slow growing. Taking the bark kills the tree, and two or three thousand trees are needed to produce 2lbs (1.9kg) of Taxol. The race is on between the drug companies to produce a synthetic version or to find a close copy.

In a statement following the FDA approval, Bristol-Myers Squibb thanked the US Forest Survey and Bureau of Land Management for its co-operation in obtaining the yew bark - currently the only approved source for human use.

Leon E Rosenburg, president of the company's research institute, said: 'Part of our commitment to Taxol involves a significant investment in the development of alternative sources. In 1993, sources other than Pacific yew bark will begin to be used for Taxol on a commercial scale. We now expect that by 1995 Pacific bark will no longer be needed.'

Other British research on the cancer-killing properties of yew includes investigation of the leaves of the English yew, Taxus baccata, which produce chemicals similar to Taxol.

Scientists from Leicester University and the University of Manchester Institute of Science and Technology are working on two other English yew compounds, Baccatine III and Taxinine.