FDA OKs Taxol for Treating Ovarian Cancer
The Food and Drug Administration on Tuesday approved the use of the drug taxol for the treatment of advanced ovarian cancer, while researchers held out hope that it might eventually be effective in earlier stages of the disease and against other kinds of cancers.
Health officials cautioned, however, that while studies show the drug can prolong life for some ovarian cancer patients, taxol is not considered a cure. Nonetheless, taxol--once in extremely short supply because its only source was the bark of the Pacific yew tree--offers an important new option for women whose ovarian cancer has not responded to other treatments.
Preliminary research also has indicated that the drug may be useful in the treatment of breast, lung, head and neck cancers.
Approval also was granted Tuesday in Canada.
Ovarian cancer accounts for 4% of cancers among women. About 21,000 new cases are diagnosed annually, while an estimated 13,000 previously diagnosed women die each year. About one woman in 70 will develop the disease in her lifetime.
The disease is considered a “silent” cancer because women who contract it rarely display symptoms until the later stages, when it becomes difficult to treat. The most common sign is abdominal enlargement caused by the accumulation of fluid.
The risk of developing ovarian cancer increases with age, with the highest rates occurring after age 60. Women who have never had children are twice as likely as mothers to develop ovarian cancer, as are those who have had breast cancer.
“Ovarian cancer is a very difficult cancer to treat,” said FDA Commissioner David A. Kessler. “Any additional treatment option is very welcome in dealing with a disease as devastating as ovarian cancer, although, in the end, it is not a cure.”
Approval of the drug, which is manufactured by Bristol-Myers Squibb Co., of Wallingford, Conn., came swiftly--only five months after the company filed its application. Kessler said that the speed demonstrated the agency’s commitment to getting new drugs to the market faster than in years past.
“We’ve demonstrated that we can do it with AIDS and this shows we can do it for cancer drugs too,” he said. “We are committed to doing it for all breakthrough drugs.”
Studies have shown that the drug shrinks tumors by more than 50% in up to one-third of women whose cancer has not responded to other treatments. It has also been shown to add an average of nine months to a woman’s life span.
In a small number of women--about 6% of those in the studies with late-stage ovarian cancer--the results were quite dramatic, marked by the complete disappearance of tumors. But researchers cautioned that it is still too early to know whether these women actually have been cured.
Taxol is “not a magical cure, but it’s an advance for certain women,” said Dr. Sam Broder, director of the National Cancer Institute, who has studied the drug for several years. “This drug can alleviate the suffering for certain women with ovarian cancer that is not treatable by other means.”
Until recently, the biggest obstacle associated with taxol was its scarcity. Two years ago, the amount of the drug available could treat only about 500 women annually.
“Supply was an agonizing problem,” Broder said. “There were many thousands of women needing the drug. . . . That women would be begging for their lives was just unthinkable to us.”
Adequate supplies are now expected to be available, in part because additional sources of the drug have been found in the needles and twigs of yew species in Europe and Asia.
In addition, companies have developed better extraction methods and learned to use existing supplies more efficiently, Broder said.
Researchers also are seeking alternative sources and trying to develop a synthetic version of taxol.
For the first time, an environmental impact statement was required before drug approval was granted. The harvesting of the drug must “strike a balance” between obtaining enough of it and “protecting the yew forest ecosystem,” the FDA said.
Kessler said that the arrangements--made between the company, the Department of Agriculture’s Forest Service and the Interior Department’s Bureau of Land Management--forbid harvesting in spotted owl conservation areas and allow only partial harvesting from other forest areas.
When detected early, ovarian cancer can be treated through surgery. In later stages, it typically has been treated with platinum-based drugs, such as cis-platin.
Taxol’s side effects are similar to other cancer therapies and can include hair loss, numbness in the fingers and toes and a decrease in white blood cells, which can increase the chance of infection.
BACKGROUND
Taxol was discovered years ago as part of the search for cancer treatments derived from natural sources. Until recently, the sole source of the drug was the rare Pacific yew tree. Harvesting the tree for its bark could cause its extinction. It takes about 60 pounds of bark--four trees’ worth--to make enough taxol for one patient. Recently there has been progress in making the drug from more plentiful yew species. Researchers also are trying to develop a synthetic version.
