WASHINGTON — A federal advisory committee decided Friday night not to recommend approval of the first drug to treat Alzheimer's disease, a controversial therapy that so far has shown mixed results in clinical trials.
The eight-member advisory committee, in a meeting that lasted almost 14 hours, made its decision without a formal vote. The chairman of the panel, Dr. Steven H. Ferris of the New York University Medical Center, said that members had arrived at a consensus opposed to marketing the drug tacrine.
The drug, also known as THA, is not a cure for the progressive and ultimately fatal disease, but it has helped some Alzheimer's patients improve their ability to think and function, according to its manufacturer, Warner-Lambert Co. of Morris Plains, N.J. However, the drug has also been shown to cause liver damage in some patients.
During a hearing before the committee, Warner-Lambert presented results from two separate clinical trials, one conducted in the United States and the other in Britain.
The panel, known formally as the Peripheral and Central Nervous System Drugs Advisory Committee, voted to accept the American study as indicating the drug might be somewhat effective for short periods of time, but it rejected the British study as posing too many uncertainties. The panel also expressed concern about the drug's potential to cause liver damage.
The committee's action is only a recommendation, but the Food and Drug Administration generally follows such decisions by its advisory committees.
Alzheimer's disease causes a gradual deterioration of mental processes, including memory. It is the fourth leading cause of death among adults and afflicts about 4 million Americans, killing 100,000 annually. It strikes more than 10% of the population over age 65 and nearly 50% of those 85 or older.
Eventually, Alzheimer's patients are unable to care for themselves and require constant supervision. The disease's inexorable progression--which often can take years--typically inflicts an enormous emotional and financial toll on the victim's families and friends.
The Alzheimer's Assn., a national voluntary organization, has estimated the total annual cost of caring for the nation's Alzheimer's patients at $80 billion to $90 billion.
During the hearing before the advisory committee, the drug's manufacturer said it was convinced that the clinical trial conducted at 16 university centers in the United States had demonstrated clear improvement in Alzheimer's patients. But Warner-Lambert Vice President Ronald M. Cresswell acknowledged that one of the two measures used to evaluate the drug had shown uncertain results.
Cresswell said that researchers evaluated the drug using two tests, the Alzheimer's Disease Assessment Scale and the Clinical Global Indication of Change.
Cresswell said that the first test, which measures a patient's ability to remember certain words, showed an "overwhelmingly statistically significant" finding in favor of the drug. He said that 41% of the patients tested showed improvement in word recognition scores after taking the drug. The second test did not produce similar statistically significant findings, he said.
Nevertheless, based on scores from the first test, he said, the company believes that the drug "improves the quality of life" for Alzheimer's patients.
THA, which would be marketed by Warner-Lambert under the name Cognex, is the first drug that has been considered for the treatment of Alzheimer's, and it has sparked considerable debate since the first study of its effects was published in 1986. That report, published by Dr. William K. Summers of Arcadia, Calif., in the New England Journal of Medicine, said that the drug had alleviated the symptoms of 17 Alzheimer's patients.
The study prompted demand for the drug, which is available abroad.
"If you reject it, you deny this drug to the large population that has no other treatment, and you deny it for at least another year and a half," Cresswell told the panel.
Ferris replied that the committee believed it had no other choice.
"We simply find that the data are insufficient," he said. "I don't think we should be influenced by an emotional side of the story."