A new, preliminary
treatment involving triple-gene therapy appears safe and effective in helping
to control motor function in Parkinson's disease patients, according to new
The therapy, called
ProSavin, works by reprogramming brain cells to produce dopamine, the chemical
essential for controlling movement, the researchers said. Lack of dopamine
causes the tremors, limb stiffness and loss of balance that patients with the
neurodegenerative disease suffer.
"We demonstrated that
we are able to safely administer genes into the brain of patients and make
dopamine, the missing agent in Parkinson's patients," said researcher
Kyriacos Mitrophanous, head of research at Oxford BioMedica in England, the
company that developed the therapy and funded the study.
More on the ProSavin treatment
ProSavin also helps to
smooth out the peaks and valleys often produced by the drug levodopa, the
current standard treatment, Mitrophanous said.
The treatment uses a
harmless virus to deliver three dopamine-making genes directly to the area of
the brain that controls movement, he explained. These genes are able to convert
non-dopamine-producing nerve cells into dopamine-producing cells.
Although the study results
are promising, the researchers suggest they should be "interpreted with
caution" because the perceived benefits fall into the range of
"placebo effect" seen with other clinical trials.
Hoping to improve on their
results, the researchers have since re-engineered the therapy. "We have a
new version which makes more dopamine in patients, and this new version is
undergoing safety studies before we initiate trails in patients," he said.
Experts reacted positively
but cautiously to the findings, which were published online in The
Lancet. While the treatment seems safe, its potential as a replacement for
current therapy still must be proved, they noted.
"The ProSavin study
was a positive and important first step for a potential gene therapy for
Parkinson's disease," said Dr. Michael Okun, national medical director at
the National Parkinson Foundation. "The results of this preliminary study
revealed a promising safety profile, and it will be interesting to observe
longer-term benefits and how ProSavin will compare to other therapies such as
deep brain stimulation."
Read: Gene therapy vs. Parkinson’s
More info on new treatment
Mitrophanous thinks this
new treatment will eventually outperform deep brain stimulation or levodopa.
Over time, patients need
larger doses of levodopa. Its benefit starts to wear off five to 10 years after
starting the drug, he said.
Patients can then try deep
brain stimulation, which involves putting wires into the brain that are
attached to a battery pack, Mitrophanous said.
"With our approach,
the brain cells are permanently modified to make their own dopamine, so you
wouldn't have to rely on external stimulation," he said.
Not a cure
The researchers don't say
new this therapy is a cure, because brain cells continue to die. "But the
hope is that we would give patients an additional five years before the disease
progresses further," Mitrophanous said.
"If you imagine you
get five to 10 years of good control of symptoms with levodopa, we hope we
would lengthen that. An extra five years, maybe longer, would be a real benefit
to these patients," Mitrophanous said.
Dr. Andrew Feigin, a
neurologist at the Movement Disorders Centre of the Cushing Neuroscience
Institute in Manhasset, New York, said the study adds to growing evidence that
"gene therapy for Parkinson's disease can be undertaken in a safe and
Read: Caffeine may treat Parkinson's disease
Results of the study
For the study, Mitrophanous
and his colleagues tried three doses of ProSavin in 15 Parkinson's patients who
no longer responded well to other treatments. They rated the patients' response
on a scale that measures speech, tremors, rigidity, finger taps, posture, gait,
and slow movement.
All patients showed
significant improvements in motor scores in the 12 hours after they stopped
taking their other medications and at six months and a year after surgery, the
"It appears that the
highest dose of ProSavin provided the greatest level of dopamine
production," Mitrophanous said. This led to the greatest improvement in
motor scores and consistently less need for levodopa, he said.
Patients injected with
ProSavin had mild to moderate side effects. The most common while on medication
were involuntary movements (dyskinesias) and switching between mobility and
immobility, called on-off phenomena, which occurs as levodopa wears off.
Parkinson's disease affects
some 5 million people worldwide.
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