BEIJING, Oct. 15(Xinhuanet) -- A gene therapy that has been tested on lab macaque monkeys in the long term suggests it can treat Parkinson's disease without causing the jerky, involuntary movements associated with current drugs, said French researchers as quoted by media reports Thursday.
Too-low levels of dopamine cause Parkinson's disease. Standard treatment, called dopamine replacement therapy, uses oral drugs that briefly raise dopamine levels -- but levels of the chemical still remain unstable, leading to a movement disorder called dyskinesias.
By contrast, tests on macaque monkeys, started three and a half years ago, found the gene therapy, called ProSav, safely restored concentrations of dopamine in the brain, corrected motor problems and prevented dyskinesias.
Dopamine was restored and sustained at about 50 percent of normal concentrations, resulting in motor improvements without the side effects seen with conventional drugs, the study found.
After inducing Parkinson's-like symptoms, such as tremors and rigidity, in macaque monkeys, French researchers inserted three genes involving dopamine production. The genes had been introduced into animals before, but separately, never with the same viral delivery system, according to the study.
When the therapy might be ready for use in people, however, remains unclear.
"What they've done, and the success they've had is very exciting and very promising, but I wouldn't basically say the next step is doing this in humans," Dr. Fatta Nahab, assistant professor of neurology and director of movement disorder research at the University of Miami Miller School of Medicine, said. "It's a small study. I think we're going to need more, larger trials in non-human primates to assess for safety."
The French researcher said that an early-phase clinical trial in humans is in progress. "So far, six Parkinson's disease patients have been treated -- no serious adverse events, encouraging results so far. But the study is not ended, so still no final results."
(Agencies)
