There's evidence that the treatment works -- including the testimonial of Nathan Klein, the first patient to receive the gene therapy. But these findings come only from an early test of the treatment in 12 patients. It will take larger clinical trials to prove the treatment really helps patients.
That having been said, the early results -- appearing in the June 23 issue of The Lancet -- are very promising, says Michael Kaplitt, MD, PhD, associate professor of neurological surgery and director of movement disorders surgery at New York Presbyterian Hospital/Weill Cornell Medical Center.
"There was no toxicity whatever, no matter how you look at it," Kaplitt tells WebMD. "When we started this, there were those who suggested we might do great harm to patients. Yet at the highest dose we were injecting 35 billion of these particles into the brain, and not a single patient had even a fever."
Moreover, there's preliminary evidence the treatment works, says Kaplitt, who is a co-developer of the treatment with colleague Matthew J. During, MD, DSc. During is now with Ohio State University. They founded a company, Neurologix, to develop the treatment.
Gene Therapy for Parkinson's
The gene therapy calls for injection of a genetically engineered virus deep into the brain -- into a region called the subthalamic nucleus or STN. During Parkinson's disease, the STN becomes wildly overactive. The virus gets into brain cells and causes them to make a chemical signal that calms the STN.
Parkinson's disease affects both sides of the brain. But for safety's sake, regulators insisted that Kaplitt and colleagues test the gene therapy on only one side.
The result: Improvements were seen on the side of the body controlled by the treated part of the brain. Improvement began three months after treatment and lasted for a year in most patients.
"Some patients did dramatically better, some did less well. After one year, 10 of the 12 patients were better than they were at [the beginning]," Kaplitt says.