Gene Therapy May Hold Promise for Advanced Parkinson's Disease
Study says new dopamine-producing brain cells help control motor function
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.
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 Center of the Cushing Neuroscience Institute in Manhasset, N.Y., said the study adds to growing evidence that "gene therapy for Parkinson's disease can be undertaken in a safe and well-tolerated manner."
But the findings can't be considered conclusive because the trial did not include a placebo or sham procedure, he said.
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 researchers found.
"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.