July 20, 2006
Scientists meeting at the 10th International Conference on Alzheimer's Disease and Related Disorders in Madrid, Spain, discussed several new therapies that may one day help ease the burden of Alzheimer's disease. They include a drug for prostate cancer, a drug that targets a toxic brain protein, a skin patch, and an experimental vaccine. All require further testing to determine which, if any, are truly safe and effective for the mind-ravaging illness.
In one study involving 227 patients, the drug leuprolide acetate (brand name Lupron Depot), a medication prescribed for men with advanced prostate cancer, showed some benefit in slowing mental decline in men and women with Alzheimer's disease. Those who took the medication showed less decline on mental state tests designed to measure memory loss and other symptoms, although the benefits were slight.
The medication came to the attention of researchers about 10 years ago, after an observant wife noticed that her husband's Alzheimer's symptoms began to improve when he started taking the drug for prostate cancer. Since that time, the drug has undergone various small trials to test for effectiveness and safety in people with Alzheimer's disease. Next up will be a larger study to test for effectiveness in combating the symptoms of Alzheimer's disease.
The drug acts as a hormone, and is delivered through an implant under the skin. Side effects include hot flashes. Scientists are not sure why and how leuprolide may benefit the brain and slow the progression of Alzheimer's symptoms, though it seems to act differently than Alzheimer's drugs currently on the market, such as Aricept and Exelon. Likely years more research may be needed before this medication can be fully tested.
Another small study of an investigational drug called Flurizan showed that people with mild Alzheimer's given high doses (800 mg twice a day) declined more slowly on tests of memory and thinking. Those who stayed on the medication for two years saw greater benefits than those who were on the drug for only a year. Additionally, those on the drug had fewer psychiatric incidents (even during the first year) than those taking a placebo.
The drug is designed to lower a toxic protein called beta-amyloid that builds up in the brains of those with Alzheimer's disease. Beta-amyloid build-up can harm or kill healthy brain cells, including those essential for memory and cognition. A larger trial involving 1,600 patients is currently under way, with results expected to be announced late next year. The company that makes the drug, Myriad Genetics, has also begun to enroll patients in a second large trial of the medication at various medical centers throughout the U.S. and world.
A new skin patch that contains the Alzheimer's drug Exelon (rivastigmine) may be just as effective as pills, say researchers from the Karolinska Institute in Stockholm, Sweden. The skin patch, however, may be gentler. It appears to produce fewer side affects, such as nausea and vomiting, the causes some patients on the pills to stop taking them.
Among 1,195 people with Alzheimer's who were given either standard Exelon capsules or a skin patch that delivers the drug through the skin (much like the nicotine patch to stop smoking), both groups did similar on memory tests. Like all currently approved Alzheimer's drugs, however, Exelon may produce some benefits or delay symptoms but does not stop the underlying disease and relentless downward progression. The patch may be available next year if further testing proves it a safe and effective alternative.
An additional treatment that has shown some initial promise is a mixture of immune system proteins, called antibodies, which may help to "mop up" the excess beta-amyloid proteins that may lead to plaque build-up and brain cell death. The treatment consists of intravenous immunoglobulins (another name for antibodies) that seem to target and remove beta-amyloid.
In a study of 19 people with Alzheimer's who were given injections of the antibodies, beta-amyloid levels increased in the blood. This finding suggests that the vaccine may be removing the toxic protein from the brain, and shifting it to the blood. However, patients in the current study did not show any cognitive improvement but did not deteriorate either. Earlier research has suggested that ongoing treatments with this vaccine treatment may help to slow the mental decline of Alzheimer's disease.
Vaccines and other immune-system treatments are very tricky, however, and some can be dangerous. Several years ago, testing of another promising Alzheimer's vaccine led to severe brain inflammation and death in one patient given the treatment. Many more years of testing is likely required before this or other vaccines are recommended for people with Alzheimer's disease.
The Fisher Center
Many new therapies are currently under development for Alzheimer's disease. They require years of testing to see if they are safe and effective. The Fisher Center for Alzheimer's Research Foundation continues to fund basic research into the underlying causes of Alzheimer's disease and the search for a cure. For more information, visit www.ALZinfo.org.
10th International Conference on Alzheimer's Disease and Related Disorders, Madrid, Spain, July 2006.