Study Suggests Alzheimer's Vaccine Safe

W A S H I N G T O N, July 11, 2000 -- Preliminary results from the first human study of a possible Alzheimer’s vaccine suggest the experimental compound is safe, San Francisco’s Elan Pharmaceuticals announced at the first World Alzheimer’s Congress today.

The experimental vaccine, known as AN-1792, garnered attention last year when the company, a subsidiary of Ireland’s Elan Corporation, discovered that the compound could ward off and even reduce Alzheimer’s signature brain-clogging amyloid plaques in mice.

“In the brains of Alzheimer’s victims we find a protein that’s widely assumed to play a major role in the cause of this disease,” ABCNEWS ’medical correspondent Dr. Timothy Johnson explained on today’s Good Morning America.

“So scientists have been able to produce a strain of mice in which they can simulate Alzheimer’s…then take some of this protein and inject it into the mice like a vaccine, stimulating the immune system.”

Mice Are Not Human “Of course, mice aren’t humans,” cautioned Elan’s lead scientist Dale Schenk.

The company has begun small studies in people to see if the vaccine is safe. In the first safety results from those Phase 1 trials, none of the 24 Americans with early Alzheimer’s who received a vaccine injection suffered side effects, Schenk said.

“There’s no questionthe vaccine was well-tolerated,” he told the international meetingof 2,800 Alzheimer’s researchers.

Holding Our Breath

“Everybody is now holding their breath about the next stage which would be to test it for effectiveness in humans,” Johnson said.

The company hopes to launch those effectiveness studies by the end of 2001. Elan is enrolling 80 British patients with early Alzheimer’s into another Phase 1 study and giving them three shots of the vaccine over several months. Their immune systems will be checked for early signs that the vaccine is strong enough to activate immune cells necessary to fight disease.

Although no one knows if the vaccine ultimately will help, theexperiments are hopeful because they are grounded in years of basicresearch into just what role the brain-clogging deposits, made of asticky substance called amyloid, actually play, said Alzheimer’sAssociation Vice President Bill Theis.

A Year to Know

Johnson predicts that within a year there will be a good indication of whether or not the vaccine will be effective in humans, adding, “If it is, it will be on the market very quickly, I would think.”

Alzheimer’s disease afflicts some 4 million Americans and costs $100 billion to treat. It starts with simple forgetfulness, progressing to dementia and then death. The three available drug treatments currently available provide only partial relief for a short time.

Alzheimer’s patients’ brains are full of sticky amyloid plaques. It is notclear if the plaques cause Alzheimer’s disease or are a result ofit. Regardless, studies show they lead to death of brain cells.

The plaques’ main ingredient is beta amyloid, a fragment of anormal body protein that somehow goes awry in Alzheimer’s. Somepatients produce too much beta amyloid and others simply do notclear it out of the brain properly.

Amyloid: Immune Stimulus

Elan theorized that a vaccine made from beta amyloid wouldstimulate the immune system to recognize and attack the protein.

Indeed, vaccinated mice developed immune system antibodies thattraveled to the brain and “tagged” amyloid plaques. That taggingseems to alert microglial cells, which Dr. Ivan Lieberburg, Elan’s chief medical officer, calls the brain’s “garbage-men,” to head for the plaques and try to eradicate them. Upon dissection, the brains of vaccinated mice contained no or verysmall plaques while their unvaccinated littermates had extensiveplaques.

Another study unveiled at the Alzheimer’s meeting supportsElan’s work. University of Toronto scientists taught mice bred todevelop an Alzheimer’s-like disease to swim through a water maze.Over several months, vaccinated mice remembered how to get throughthe maze far better than unvaccinated mice, promising evidence thatthe vaccine may affect symptoms, not just plaque.

“Imagine what it would mean if you could actually modify the behavior of someone with Alzheimer’s,” an Elan spokesperson said. “It would be tremendous.”

The Associated Press contributed to this story.