(Adds status of drug, paragraph 3)
By Julie Steenhuysen
CHICAGO Nov 17 An experimental Merck & Co Inc
(MRK.N) drug that raises levels of a natural growth hormone
failed to improve memory skills in people with mild to moderate
Alzheimer's disease, U.S. researchers said on Monday.
The compound, called MK-677, stimulates the release of
insulin-like growth factor 1, or IGF-1, which has been shown in
mice to reduce levels of beta amyloid protein that forms sticky
plaques in the brain.
Merck spokesman Ian McConnell said the company has
discontinued research on the drug in Alzheimer's disease, but
studies in other conditions are still under way.
These plaques are a hallmark of Alzheimer's disease, a
progressive disease marked by memory loss, confusion and
eventually, the inability to care for oneself.
The study, published in the journal Neurology, was designed
to test whether age-related declines in levels of IGF-1 drive
the accumulation of amyloid beta in Alzheimer's patients, and
if restoring IGF-1 might help slow progression of the disease.
"This work suggests that targeting this hormone system may
not be an effective approach to slowing the rate of Alzheimer's
disease progression," said study leader Dr. Jeff Sevigny of
Merck Research Laboratories in North Wales, Pennsylvania, in a
The researchers studied 416 people with mild-to-moderate
Alzheimer's disease who underwent brain scans and other tests.
Half of the group took MK-677 and the other half took a placebo
for one year.
While the drug succeeded in boosting levels of IGF-1 by 73
percent after a year, if failed to keep the disease from
advancing. "This compound showed no clinical benefit in the
population we studied," Sevigny said in a telephone interview.
Sevigny said Merck proceeded with the study in large part
because the drug worked in mice with a form of Alzheimer's
disease, but the mouse model may not be the best at predicting
what will happen in humans with Alzheimer's disease.
"We need to have better animal models to predict the
efficacy of compounds in humans," he said.
There is no cure for Alzheimer's, and current drugs merely
delay symptoms. Sevigny said the findings underscore the
complexity of the disease.
Alzheimer's is the most common form of dementia, affecting
an estimated 5.2 million people in the United States and 26
million globally, according to the Alzheimer's Association.
(Editing by Will Dunham and Eric Walsh)