Hope for Cancer Patients Is Planted in the Form of 2 Million Yew Trees : Medicine: Experimental farm may ease shortage of anti-cancer chemical produced by the slow-growing trees.

On 11 1/2 acres of western Oregon soil, at intervals of six inches, hope has been planted.

Hope takes the form of 2 million eight-inch cuttings from yew trees. By mid-decade, these trees are to be marshaled in the fight against cancer.

They contain taxol--the most promising cancer drug discovered in the last 10 years, according to the National Cancer Institute.

“Nobody’s ever grown yew this way to extract taxol. It’s a gigantic experiment,” said Mark E. Triebwasser, manager of the Aurora nursery.

Altogether, Weyerhaeuser Co. has planted 5 million yew trees in Aurora, about 20 miles south of Portland, and at a second nursery near Olympia, Wash. Included in the Olympia nursery are 700,000 trees from a 1991 pilot planting.

Weyerhaeuser expects to plant another 10 million yews next year under a multimillion-dollar contract with Bristol-Myers Squibb Co., the pharmaceutical company that is bringing the drug to market, said Richard F. Piesch, manager of Weyerhaeuser’s taxol program in Centralia, Wash.

Taxol is one of the hot stories of recent medical research because of the deadly nature of the disease it treats.

Ovarian cancer causes more deaths than any other cancer of the female reproductive system--partly because it often develops without any outward symptoms, and by the time it is discovered the disease has spread.

Enter the Pacific yew, one of the slowest-growing trees in the world, measuring only six inches in diameter at 75 to 90 years of age. For years, it was regarded by timber managers as little more than a weed to be burned with slash after a logging operation.

But during the 1980s, researchers discovered that the yew contains taxol, which promotes the formation of straw-like structures, microtubules, that inhibit cell division.

One study found that 20% of ovarian cancer patients showed some shrinkage of tumors with taxol. Studies also found that more than half of breast cancer patients responded to the drug, and it shows promise as a treatment for lung cancer and melanoma.

So far, the drug has been used only in clinical trials. But Rep. Ron Wyden (D-Ore.) said that the federal Food and Drug Administration was expected to approve commercial sales of taxol by the end of the year.

As a result, the demand for yew bark is expected to double.

Only about 3% of the yew has been stripped for taxol in Oregon, Washington, Idaho, Montana and California, according to inventories by government researchers. Last year, about 1.5 million pounds of bark were collected on public and private lands, enough to treat 24,000 cancer patients, Piesch said.

Judges have forbidden clear-cutting on old-growth forests, however, where yew is predominantly found, to protect the rare northern spotted owl.

As the backlog of prior timber sales for clear-cut dries up next year, the Forest Service’s interim guidelines for harvesting will kick in. The guidelines may lead to skyrocketing collection costs because they require selective cutting of less than 50% of each yew stand.

The Weyerhaeuser nurseries could play a crucial role in meeting the demand.

“We anticipate by 1995 they will have the first crop and will continue to get major amounts of taxol, anywhere from 25% to 50% to 100% of demand,” said Dr. Zola Horovitz, Bristol-Myers’ vice president of licensing.

Bristol-Myers has said it would like to be out of the woods by the middle of the decade, preferring the genetically superior, steady and cost-efficient supplies provided by nurseries.

The trees will be harvested two to four years from planting and likely will only be two or three feet tall and half an inch in diameter. It takes three 150-year-old Pacific yew trees, about 10 inches in diameter, to yield enough drug to treat one cancer patient.

To extract enough taxol from the baby trees, a number of technologies are rapidly coming together, including the capacity to synthesize taxol from every part of the tree--the bark, wood and needles--in amounts comparable to that found in Pacific yew bark, Horovitz said.

An Italian company, Indena, can synthesize taxol from needles and twigs, and Bristol-Myers has only to select a site to begin synthetic production by the end of the year, Horovitz said. The operation will give a big boost to Weyerhaeuser, whose fledgling yew trees have sparse bark but many green needles.

Weyerhaeuser is using its decades of expertise in replanting logged forests to cultivate the fastest-growing yew with the most taxol.

Initially, only Pacific yew bark, used in the clinical trials, will be approved by the FDA as a source of taxol. But Horovitz said he does not anticipate any problems with approval of other taxol sources, including different types of yew trees.

That’s important for Weyerhaeuser, whose nursery beds contain 80% to 90% ornamental yew. The company found ornamental varieties high in taxol content and easier to replicate for genetic uniformity, Piesch said.

Once considered a trash tree by loggers clear-cutting Douglas fir, the yew also has become the target of genetics studies. Thirty varieties, transplanted from British Columbia to Northern California, are in study beds in Weyerhaeuser nurseries across the country.

“Bristol-Myers came to the Weyerhaeuser research department and said, ‘What can you tell us about the genetics of the yew?’ ” Triebwasser said. “Their reply was: ‘We really don’t know.’ ”

“It was regarded as a weed tree.”