Gene Therapy May Improve Parkinson’s Symptoms

March 16, 2011 -- An experimental gene therapy injected into the brains of patients with Parkinson’s disease improved tremor, stiffness, and other movement symptoms and was safe with few side effects over six months of follow-up, a study shows.

The small study represents the first successful clinical trial comparing a gene-based treatment to sham treatment in Parkinson’s or any neurologic disorder, says Michael Kaplitt, MD, PhD, who developed the gene therapy more than a decade ago. He hopes to market it if phase III trials confirm its effectiveness.

Kaplitt is vice president for research in the department of neurological surgery at Weill Cornell Medical College in New York City. He is a co-founder of the company Neurologix, which is developing the treatment and funded the study.

“For almost two decades we have recognized that gene therapy holds great promise for treating neurological diseases like Parkinson’s and Alzheimer’s,” Kaplitt tells WebMD. “The problem has been translating that promise into reality.”

Testing Gene Therapy

Gene therapy involves the use of genes to treat or prevent disease. The genes are transferred into targeted cells via viruses that have been rendered harmless.

While other gene-based treatments have shown promise for the treatment of Parkinson’s disease in studies involving primates, the few that have made it to human trials have failed to show a clear benefit over sham treatments, Kaplitt says.

The 45 patients in the newly reported phase II study had moderate to advanced Parkinson’s symptoms that were not adequately controlled with conventional treatments. They were treated at seven medical centers in the U.S.

Half got the gene therapy, which involved the infusion of genetic material directly into a key brain regions associated with motor function through tiny holes drilled in the brain.

The gene used in the treatment, glumatic acid decarboxylase (GAD), makes a chemical called GABA, which helps reduce the excessive firing of neurons that lead to Parkinson’s symptoms.