Alzheimer's Scientists Announce Initial Results of Alzheimer Vaccine

Alzheimer's Association
Tuesday, 11 July 2000

Initial results of a phase I clinical trial of a potential vaccine for Alzheimer's disease have shown that the vaccine is well tolerated in humans, according to scientists at Elan Pharmaceuticals, a division of Elan Corporation, plc. In their animal research, scientists identified how the vaccine works to clear plaques out of the brain.

The scientists reported their study results today at World Alzheimer Congress 2000.

In the year since Elan scientists published their findings on the vaccine in transgenic mice —mice genetically altered to develop Alzheimer's disease — they have conducted extensive safety trials on the compound AN-1792 in other animals, and are now completing multi-dose phase I clinical trials in humans in coordination with their partner, American Home Products.

"We are extremely pleased with the progress of our phase I trials which have shown that AN-1792 is well tolerated by the patients," says Dale Schenk, Ph.D., Vice President of Discovery Research at Elan Pharmaceuticals. "During the course of our research, we also developed a greater understanding of how the vaccine works to clear amyloid plaques out of the brain and prevent additional plaques from forming."

Basic Science Findings

AN-1792 is a synthetic form of the naturally occurring beta amyloid protein, which has long been identified as the primary component of amyloid plaques. Scientists have hypothesized that amyloid plaques impede nerve cell function and cause nerve cell death in the brains of people with Alzheimer's disease. Although amyloid plaques are found in the brains of most individuals with Alzheimer's, it is not yet known whether plaques are a cause or a result of the disease process.

While conducting additional animal studies of AN-1792, scientists confirmed that the compound leads to an immune response that increases the clearance of beta amyloid plaques from the brain. During the immune response, anti-beta amyloid antibodies are formed that bind to the amyloid plaques. Simultaneously, certain cells that are a part of the immune system in the brain, microglial cells, are activated and begin engulfing the amyloid plaques.

"Amyloid plaques act as a brain invader," added Schenk. "We are optimistic that we can attack this invader at its source and eventually help the millions of people and families worldwide who are living with this devastating disease."

Clinical Findings

In total, about 100 patients in the United States and the United Kingdom will be involved in the phase I clinical trials of AN-1792. Patients in the U.S. received a single dose of the vaccine through injection and, according to the researchers, no obvious safety concerns have been identified. Phase I multiple dose trials currently are underway in the United Kingdom.

"Just a few years ago, talk of a potential vaccine for Alzheimer's disease would have been viewed with much skepticism and disbelief," says Bill Thies, Ph.D., Alzheimer's Association vice president of medical and scientific affairs. "Announcements like this that are grounded in solid scientific research give us tremendous hope. We now are testing the amyloid hypothesis with this vaccine and traditional drug therapy, and we are moving closer to identifying an intervention that will be able to alter the course of the disease."

Background

Today, there is no cure for Alzheimer's disease and researchers still do not know its cause. There are a few theories about what causes Alzheimer's, one being the amyloid hypothesis. Since the first observations by Dr. Alois Alzheimer in 1906, scientists have long noted the presence of many beta amyloid plaques in the brain tissue of people who had died from Alzheimer's disease.

Many Alzheimer experts hypothesize that it is the presence of these plaques that leads to the brain damage which causes the devastation of a person's memory and thinking ability (cognitive functions). Until these theories can be tested, the true cause of Alzheimer's disease will remain a mystery.

For more information, or to contact Alzheimer's Association, see their website at: www.alz.org