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| A long-awaited drug treatment which can halt Alzheimer's disease may be on the horizon after promising results from an early stage clinical trial |
A LONG-awaited drug
treatment which can halt Alzheimer's disease may be on the horizon after
promising results from an early stage clinical trial.
Experts are taking care not to build up false hopes about the
antibody drug, aducanumab, which clears away sticky protein fragments in
the brain linked to Alzheimer's.
But according to one leading charity, the first disease-modifying
therapy for the devastating brain condition may now be within sight.
Dr David Reynolds, chief scientific officer at Alzheimer's Research
UK, said: "These results provide tantalising evidence that a new class
of drug to treat the disease may be on the horizon"
"The findings suggest that aducanumab may slow memory and thinking
decline in people with early Alzheimer's and, although the analysis is
only exploratory in this early trial, it paints a positive picture for
ongoing trials with the drug."
The last Alzheimer's drug licensed in the UK became available more
than a decade ago. Current treatments can reduce symptoms to some extent
but doctors have nothing that can halt or slow progression of the
disease.
An estimated 850,000 people in the UK suffer from some form of
dementia, most having Alzheimer's. By 2025 their numbers are expected to
swell to more than a million.
Alzheimer's is linked to the build up of sticky clumps of
beta-amyloid peptide – pieces of protein – in the brain. Extensive
deposits of the material can be seen in the brains of dead victims.
Beta-amyloid toxicity is thought to be a primary cause of the neural dysfunction and degeneration which underlies the disease.
Scientists have long known that removing beta-amyloid could lead to a
glittering prize – halting or at least slowing Alzheimer's progression.
But until now all attempts to target the peptide with a drug have met
with failure.
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| A total of 165 patients received monthly infusions of either aducanumab or a placebo "dummy drug" for one year. |
Aducanumab is a monoclonal antibody – an immune system agent copied
and produced in a laboratory which selectively targets beta-amyloid.
Tests on mice genetically engineered to develop a disease similar to
Alzheimer's showed that the drug could enter the brain and reduce levels
of beta-amyloid in a dose-dependent fashion.
Scientists also conducted an early Phase I trial to evaluate the
safety and tolerability of monthly aducanumab injections in patients
displaying early symptoms of Alzheimer's disease.
A total of 165 patients received monthly infusions of either aducanumab or a placebo "dummy drug" for one year.
After 54 weeks of treatment, scans showed that levels of beta-amyloid
had been significantly reduced in the brains of patients given the
antibody. Higher doses were associated with greater reduction, the
researchers reported in the journal Nature.
At the higher doses, removal of beta-amyloid was also associated with
slower mental decline. However, the preliminary study was not designed
to assess aducanumab's clinical effectiveness, which will now have to be
tested in larger trials.
Recruiting of patients for bigger trials, including participants from the UK, has already started.
The US-Swiss team led by Dr Alfred Sandrock, from the
Massachusetts-based biotech company Biogen, wrote in the Nature paper:
"These results justify further development of aducanumab for the
treatment of AD (Alzheimer's disease)". Should the slowing of clinical
decline be confirmed in ongoing Phase III clinical trials, it would
provide compelling support for the amyloid hypothesis.
"Together, the clinical and preclinical data support continued
development of aducanumab as a disease-modifying treatment for AD."
In an accompanying article, Dr Eric Reiman, executive director of
Banner Alzheimer's Institute in Phoenix, Arizona, said confirmation that
the treatment worked would be a "game-changer for how we understand,
treat and prevent Alzheimer's disease".
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| "game-changer for how we understand, treat and prevent Alzheimer's disease". |
Dr Reynolds said some side effects seen in the Phase I study were
"concerning" and would have to be addressed. These included headaches
and mostly related to abnormalities revealed by the scans.
The Alzheimer's Society said the "most compelling" evidence from the
trial was the fact that more beta-amyloid was cleared when patients took
higher doses of the drug.
Dr James Pickett, head of research at the charity, said: "No existing
treatments for Alzheimer's directly interfere with the disease process,
and so a drug that actually slows the progress of the disease by
clearing amyloid would be a significant step".
"While there were hints that it might have an effect on the symptoms
of the disease, we need to see the results from further, larger research
trials to understand whether this is the case. These larger trials are
now under way, including in the UK, and due to finish in 2020."
Dr Tara Spires-Jones, from the University of Edinburgh's Centre for
Cognitive and Neural Systems, said: "I am cautiously optimistic about
this treatment, but trying not to get too excited because many drugs
make it through this early stage of testing then go on to fail in larger
trials."
Neuroscientist Professor John Hardy, from University College London,
warned: "These new data are tantalising, but they are not yet
definitive."
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