Usually, if something "grows on trees," it's considered plentiful. Oddly, Taxol, a potent chemotherapeutic agent for treating breast, ovarian, and other cancers, does grow on trees. But it's scarce—and getting scarcer all the time.
That may change now, thanks to a new process, developed by Agricultural Research Service scientists and their collaborators, that promises to dramatically boost manufactured supplies of Taxol.
ARS plant physiologist Donna M. Gibson, in Ithaca, New York, says paclitaxel, the generic term for Taxol, originally came from the bark of the rare Pacific yew tree, Taxus brevifolia Nutt. "However, supplies of yew bark are scarce, and current extraction procedures are inadequate for providing enough of the chemical to meet increasing demand," says Gibson.
Synthetic methods of producing paclitaxel have been tried. But the chemical's molecular structure is so complex that commercial production is unfeasible.
"So production of adequate supplies of paclitaxel and precursors used in semi-synthetic processes may ultimately rely on biological processes like cell culture," Gibson says.
She was one of the first scientists to demonstrate that cell cultures from the yew tree can be used to produce the anticancer compound. Now, along with coinventors at Washington State University at Pullman and Cornell Research Foundation, Inc., at Ithaca, Gibson has filed for a new patent (09/126,229) on a process for enhancing production of paclitaxel.
"The technology screens yew cell lines to determine their potential for producing the chemical," she says. "Using it, producers will be better able to identify and select yew tree cell lines that are 5 to 10 times more productive than those currently being used."
The technique enables Gibson to screen multiple cell lines of all five known Taxus species for their ability to produce paclitaxel in vitro. She has also developed a method that uses an elicitor compound, methyl jasmonate, which, when added to the appropriate culture line, greatly increases the amounts of paclitaxel obtained from the selected cell lines.
Gibson's invention could significantly expand commercial production of taxanes to levels higher than any previously reported—welcome news for cancer patients whose doctors are prescribing this promising drug.—By Hank Becker, Agricultural Research Service Information Staff.
"New Technique Could Boost Taxol Production" was published in the April 1999 issue of Agricultural Research magazine.