Gene Therapy for Parkinson's Nears
First FDA-Approved Trial to Begin
Oct. 10, 2002 -- Researchers may soon find out if the hope lives up to the hype in using gene therapy to treat Parkinson's patients. Based on the findings of successful animal studies, the FDA has granted approval for the first tests of the experimental therapy in humans.
The small, phase I clinical trial is set to begin in New York later this year. It will be the first gene therapy to be used in people with Parkinson's disease.
Animal tests show the gene therapy stops the progression of the disease as well as reduces its symptoms. The findings appear in the Oct. 11 issue of the journal Science.
People with Parkinson's disease experience a loss a substance called dopamine, which is used to transmit information within the brain. This drop in dopamine creates a disturbance in the part of the brain that controls movement. The region, known as the subthalamic nucleus (STN), becomes extremely overactive and creates the trembling and loss of muscular control found in Parkinson's patients.
But studies have shown that when this area is silenced, patients experience a dramatic reduction in symptoms. The gene therapy uses a virus to deliver a specific gene to the STN, which "re-sets" the overactive cells and helps return brain function to normal.
"Current surgical therapies for such patients attempt to interrupt this network abnormality by destroying overactive brain areas or placing DBS (deep brain stimulation) electrodes to quiet those areas," says researcher Michael G. Kaplitt, MD, director of stereotactic and functional neurosurgery at Weill Cornell Medical College, in a news release.
"Both of these treatments, however, have certain limitations and side effects," says Kaplitt. "Our approach is based on a similar rationale, but we use gene therapy to adjust the chemical signaling of these brain areas to a more normal setting. This exploits the best parts of current therapy but makes it more powerful, less invasive, and potentially safer."
In five tests on laboratory rats with simulated Parkinson's disease, researchers found that the gene therapy worked as anticipated to stop the progression of the disease. Rats that received the therapy retained more of their normal function and did not develop further signs of Parkinson's. The gene therapy has also successfully been tested in primates.
Researchers say the virus used to deliver the gene has already been used in a variety of clinical gene therapy trials and has not been associated with any human disease.