Alzheimer's vaccine appears safe in human testing

Results presented at first World Congress on Alzheimer's

July 11, 2000
Web posted at: 10:01 a.m. EDT (1401 GMT)

From Rhonda Rowland
CNN Medical Correspondent

WASHINGTON (CNN) -- An experimental vaccine designed to fight Alzheimer's disease appears to be safe in humans.

Scientists with Elan Pharmaceuticals released their results Tuesday at the World Alzheimer's Congress. They show phase one trials, designed to assess safety, are encouraging.

"It's gone remarkably smoothly. In the U.S. we've done single dose studies and they're nearly complete and so far things have gone remarkably well. We've not encountered any problems at all in Alzheimer's patients themselves," Dr. Dale Schenk, vice president of discovery research at Elan Pharmaceuticals told CNN Medical News.

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"By the end of the year we hope to make significant conclusions from those phase one studies, so that sometime in 2001 we can actually begin the key pivotal studies to see just how the vaccine's working."

The current safety trials are taking place in the United States and United Kingdom. When they're completed, the studies will expand to include several hundred patients at a number of medical institutions.

"Assuming everything works out, this vaccine not only will treat Alzheimer's Disease, but will also prevent Alzheimer's. It will completely change the face of Alzheimer's therapeutics now and forever if it works," said Dr. Ivan Lieberburg, executive vice president and chief science and medical officer for the Elan Corporation.

One year ago Elan researchers reported remarkable results of the vaccine in mice. Mice immunized at a young age were protected from Alzheimer's. In animals who already had the disease, the disease was halted and in some cases reversed.

"The amount of reduction of brain pathology was truly remarkable. It was as much as 99 percent reduced in animals that were treated with this vaccine," said Schenk.

Two other research teams have verified Elan's promising results in mice at the meeting. They've taken the work a step further, showing the vaccine produced improvements in behavior.

In addition, researchers and Brigham and Women's Hospital report encouraging results with a similar, nasal vaccine. "There is a 50-60 percent decrease in the amount of amyloid plaques and indeed the amount of a-beta proteins in the brains of mice who have gotten chronic nasal treatment," their report said.

Although it will take time to see if humans have the same results, other researchers say the safety trial results are encouraging.

"I think the vaccine immunization hypothesis is very exciting," said Dr. Ronald Peterson of the Mayo Clinic. "There is a lot of work that needs to be done with regards to its safety, its effectiveness, whether it will work in humans as it has in mice. But nevertheless, the major hypothesis is still very interesting for the possibility of prevention of the disease."

The vaccines are designed to attack the characteristic brain plaques of Alzheimer's. There is still some debate over whether the amyloid plaques are the cause of Alzheimer's dementia. The final outcome of the vaccine studies in humans should either prove or disprove the amyloid plaque theory as the cause of the disease.

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