New Source for Cancer Drug

SAN FRANCISCO--Taxol is a potent and popular cancer drug, but it is harvested from the needles of an endangered tree, and the demand for the drug could outpace the trees' productivity. Today, researchers at the American Chemical Society's semiannual meeting announced that they have isolated the compound from hazelnut trees and fungi, a finding that could lead to an abundant new source of the drug and possibly lower its cost.

Generically known as paclitaxel, Taxol is one of the biggest selling cancer drugs worldwide. It is used to treat ovarian and breast cancer, and many breast cancer survivors take the drug to prevent a recurrence of the disease. For now, there's enough paclitaxel to go around, but demand could soon grow: Investigators are testing the drug's power over other cancers, Alzheimer's disease, and multiple sclerosis, among others. If those uses pan out, supplies might become scarce. That's because paclitaxel is made by modifying a precursor compound extracted from the needles of the Pacific yew, an endangered tree that grows along the coast of the Pacific Northwest.

Angela Hoffman, a chemist at the University of Portland, Oregon, had previously looked for ways to boost paclitaxel production in yew trees. To her surprise, she found a new source of the compound while working on a completely different project. She and her colleagues were studying hazelnut trees to see why some were more susceptible than others to Eastern filbert blight, which is devastating hazelnut groves in Oregon's Willamette Valley. The researchers prepared extracts from several types of hazelnut trees, and after purifying and analyzing the samples, Hoffman noticed the familiar chemical signature of paclitaxel.

Hoffman and her colleagues determined that hazelnut trees make paclitaxel in their leaves, twigs, and nuts, although only at about 10% the concentration in yew trees. They also found that fungi living on hazelnut trees produce paclitaxel.

Down the road, it's the fungi that could be the most valuable find, says David Houck, a natural products expert at Phytera, a drug company in Worcester, Massachusetts. Paclitaxel-producing fungi have also been isolated from yew trees, he says. If a fungus could be coaxed into churning out the drug in vats, "it would definitely have value," Houck says.