July 14, 2008
Bapineuzumab, an experimental Alzheimer's drug now undergoing testing, showed promise in mid-stage trials in people with early to moderate Alzheimer's disease. The drug, made by the drug companies Wyeth and Elan, is aimed at beta-amyloid, a protein that can build up in the brains of those with the disease. The drug is a monoclonal antibody (an immune-system molecule) that clears toxic beta-amyloid from the brain.
In Phase II clinical trials in 240 men and women with Alzheimer's disease, bapineuzumab slowed the progression of memory loss and other symptoms. Brain scans also showed that some of those taking the drug had less loss of brain volume than those taking a look-alike placebo pill. In the tests, conducted around the United States, half of patients got the experimental drug, while half got the dummy medicine.
But the drug provided benefits only in those who did not carry the APO-E4 gene. An estimated 40 percent to 70 percent of people with Alzheimer's disease carry that gene, which can be inherited from one or both parents. Carrying the gene increases the odds that you will develop Alzheimer's in old age, but many people who have the gene never develop Alzheimer's.
The results were promising, the drug companies announced. As with all drugs, some people suffered side effects, including the buildup of fluids in the brain, a condition called "vasogenic edema." And the higher the dose, the more pronounced the adverse effects, particularly in those who carry the APO-E4 gene. However, the pharmaceutical sponsors felt the drug was safe enough to continue testing.
More advanced, Phase III trials in more than 4,000 people with Alzheimer's were started late in 2007. However, it will likely be several years before the results of those trials are known. If results prove positive, then the drug can be approved for sale.
Bapineuzumab is one of several promising new drugs now undergoing more advanced testing for Alzheimer's disease. Unlike existing drugs for Alzheimer's, like Aricept, Exelon and Razadyne, which may moderate symptoms but do not stop the relentless downward spiral of disease, the new drugs are aimed at modulating the disease process, in other words, slowing or stopping disease progression.
Experts caution that testing must be completed in large numbers of people before doctors will know whether the drug is truly effective against Alzheimer's. Many drugs have shown promise in Phase II testing in the past, only to prove useless, or even dangerous, in more advanced trials.
Wyeth, Elan drug companies.