Experimental Drug Might Help Fight Alzheimer's After
WEDNESDAY, July 20 (HealthDay News)-- An experimental drug for
treating Alzheimer's disease that previously showed troubling side
effects may actually be safe in the long run, researchers
The keys to the safety of the drug, bapineuzumab, may be
lowering the dose and not giving it to patients with ApoE4, a gene
mutation linked to Alzheimer's, according to two studies scheduled
for presentation Wednesday at the Alzheimer's Association
International Conference on Alzheimer's Disease in Paris.
"The data from the open-label trial are encouraging. Patients were able to tolerate bapineuzumab for two to four additional years without the emergence of any new safety concerns," said Dr. Stephen Salloway, author of one of the studies. "This is important because we are conceptualizing this drug as a long-term treatment for Alzheimer's disease."
Encouraging does not translate into certainty, however, another
expert pointed out.
"I think it is too early to tell from the data from this small Phase 2 safety trial," said Ian Murray, an assistant professor of neuroscience and experimental therapeutics at Texas A&M Health Science Center College of Medicine in College Station. "We will have to wait for larger trials to comment on this as a potential therapy."
The studies were funded by Pfizer Inc. and Janssen Alzheimer
Although bapineuzumab has shown promise in certain Alzheimer's
patients, other research found that patients taking a higher dose
of the drug had an increased risk of brain inflammation from water
retention. This resulted in headache, memory loss, hallucinations,
reduced coordination or other symptoms. But no problems were seen
with lower doses.
Bapineuzumab is a humanized monoclonal antibody, which binds to
and might be able to eliminate beta amyloid peptide in the brains
of people with Alzheimer's. Most experts believe that the build up
of beta amyloid proteins, which accumulate as plaque, is
responsible for Alzheimer's.
Salloway's study looked at the drug's safety in 194 Alzheimer's
patients, most of whom had mild- to-moderate Alzheimer's and
participated in a long-term (78 weeks or longer) study. Some of the
participants were followed for four years or more.
Ninety-one percent of participants had side effects, about a
quarter of which were attributable to bapineuzumab. Of these, 85
percent were mild or moderate.
The overall rate of vasogenic edema (water on the brain) was 9.3
percent, a number that decreased over time, said Salloway, a
professor of neurology and psychiatry at Alpert Medical School of
Brown University and director of the Butler Hospital Memory and
Aging Program in Providence, R.I. The edema was symptomless in most
cases, he said.
The other study, which involved looking at more than 2,000 MRI
scans from 262 patients, found 36 cases of amyloid-related imaging
abnormalities (ARIA) may have been linked to the bapineuzumab.
These imaging abnormalities may indicate inflammation of the
brain caused by water retention.
But only 8 of those 36 cases involved symptoms, and they were
more likely to be found in patients with APOE-e4 who were taking
higher doses of the drug. The likelihood of these effects
diminished with additional infusions of lower-dose
"There is a growing sense that VE [vasogenic edema] or ARIA [amyloid-related imaging abnormalities] is a manageable side effect and may actually be a sign that the drug is clearing amyloid from the brain and the blood vessels," said Salloway. "Treatment will require ongoing monitoring with MRI."
The researchers, who said monitoring of bapineuzumab will
continue, are now awaiting the results of a larger Phase III trial
on the drug.
Because this study was presented at a medical meeting, the data
and conclusions should be viewed as preliminary until published in
a peer-reviewed journal.
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