Modifications could eliminate unwanted side effects
By
Randolph E. Schmid
ASSOCIATED PRESS
WASHINGTON, Oct. 13 —
Modifications to an experimental vaccine for Alzheimer’s disease that
was discontinued because of side effects might make it safe, a study
suggests. Researchers in Canada and Germany found that a more refined
form of the vaccine worked in mice, which raised the chance that it
might not produce in humans the inflammation that ended clinical trials.
THAT REMAINS only a possibility
and requires more research, said JoAnne McLaurin of the Centre for Research
in Neurodegenerative Diseases at the University of Toronto. She is the first
author of the study being published Tuesday in the online edition of the
journal Nature Medicine.
In January, the Irish drug company Elan Corp. suspended a 360-patient
experiment with the vaccine after 15 patients suffered serious brain
inflammation. Elan announced in March it was abandoning the vaccine,
although the company said it plans to continue exploring ways to slow the
worsening of Alzheimer’s.
Dave Morgan, an Alzheimer’s researcher at the University of South
Florida, said other groups also have worked on ways to refine the vaccine.
The problem, Morgan said, is that it is not clear why the patients in
the now-halted trial developed brain inflammation — whether immune cells
entered the brain to attack the vaccine, or the vaccine provoked a reaction
in the brain itself.
“Before we put any more vaccines in people, we need to know what the
problem was,” said Morgan, who is not part of the Toronto research team.
The vaccine is meant to clear away tangles of amyloid-beta protein,
called plaques, that accumulate in the brains of Alzheimer’s victims.
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In earlier
tests on mice, the vaccine produced antibodies directed against the AB
proteins that cleared the plaques and reversed symptoms of brain
degeneration.
McLaurin, who is not connected to the Elan research, explained that
her experiments in mice were aimed at finding out what the active antibody
is and how it works.
She and her fellow researchers found they could produce antibodies
against AB protein in mice using a vaccine that included only a small
portion of AB rather than the entire molecule.
That raises the possibility that a vaccine using only a portion of AB
would be less likely to cause the inflammation seen in the earlier trial.
McLaurin said it also might lead to development of a small molecule that
mimics the vaccine, which could sidestep potential problems of the tested
vaccine.
The response to the vaccine seems to target a specific group of AB in
the body, known as protofibrillar precursor, according to the study.
While protofibrillar is not abundant, it is a critical component in
the formation of the plaque that causes the brain disorders in Alzheimer’s,
McLaurin’s team reported.
The team included researchers from the University of Toronto and the
University of Konstanz, Germany.
Alzheimer's is a degenerative brain disease that usually begins
gradually, causing a person to forget recent events or familiar
tasks. How rapidly it advances varies from person to person, but the
disease eventually leads to confusion, personality and behavior
changes and impaired judgment. Communication becomes more difficult
as the disease progresses, leaving those affected struggling to find
words, finish thoughts or follow directions. Eventually, most people
with Alzheimer’s disease become unable to care for themselves.
One in 10 people over 65 and nearly half of those over 85 suffer
from Alzheimer’s disease. Today, 4 million Americans have the
condition. That number could jump to 14 million by the year 2050
unless prevention methods are developed.
Scientists still are not certain of the disease's cause. Advancing
age and family history are risk factors. Researchers are exploring
the role of genetics in the disease, but most agree it's caused by a
variety of factors.
There is no single, comprehensive diagnostic test for Alzheimer’s
disease. Instead, doctors rule out other conditions through a
process of elimination. They usually conduct physical, psychological
and neurological exams and take a thorough medical history.
Diagnosis is about 90 percent accurate, but the only way to confirm
it is through autopsy.
There is no medical treatment currently available to cure or stop
the progression of Alzheimer's disease. There are currently four
FDA-approved Alzheimer's drugs -- Cognex, Aricept, Exelon and
Reminyl -- that may temporarily relieve some symptoms of the
disease. Several other drugs are in development.
ALL INFORMATION, DATA, AND
MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION
PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS
OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR
LEGAL ADVICE. THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND
COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH
YOUR HEALTH CARE PROVIDER.
"A foolish faith in authority is the worst enemy of truth."
-- Albert Einstein, letter to a friend, 1901
"I know of no safe depository of the ultimate powers of the society but the people themselves, and if we think them not enlightened enough to exercise control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion by education."
-- Thomas Jefferson, letter to William C. Jarvis, September 28, 1820
"What's the point of vaccination if it doesn't protect you from the unvaccinated?"
-- Sandy Gottstein
"Who gets to decide what the greater good is and how many will be sacrificed to it?"
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