Gene therapy of Parkinson's disease: developing success
Gene therapy has helped patients with Parkinson's disease
Copper news based on the materials of The New Scientist:
Gene therapy for Parkinson's passes the ultimate test
American researchers report the successful completion of the next stage of clinical trials of gene therapy for Parkinson's disease. 45 patients participated in a double-blind, placebo-controlled study.
The technique developed by specialists of the Presbyterian Hospital of New York under the leadership of Andrew Feigin consists in introducing a harmless adenovirus into the subthalamic nucleus of the brain of patients carrying a gene encoding the enzyme glutamic acid decarboxylase (GAD). This enzyme controls the production of gamma-aminobutyric acid (GABA), which serves to suppress the hyperactivity of neurons. The lack of GABA in the subthalamic nucleus in Parkinson's disease leads to the development of tremor, impaired coordination of movement and other symptoms of the disease.
It is assumed that the introduction of additional copies of the gene responsible for the synthesis of GABA will lead to the normalization of the work of the brain departments that control motor functions.
The first stage of the study of a new method of gene therapy with the participation of 12 volunteers was conducted in 2007, and showed the safety of this technique. At the second stage, it was supposed to evaluate not only the safety, but also the effectiveness of the proposed method of therapy. To do this, however, it was necessary to conduct a double-blind placebo-controlled study, in which neither the participants nor the doctors observing them knew which treatment (real or placebo) a particular patient received. It was not easy to fulfill these requirements, since the gene therapy drug was injected directly into the brain through a hole in the skull.
For the new study, Feigin and his collaborators recruited 45 volunteers with Parkinson's disease aged 30 to 75 years. 22 participants of the experiment received gene therapy. The rest, who made up the control group, also drilled a hole in the skull and simulated the administration of the drug. The hole was not through to reduce the risk of complications, but no one knew about it except the surgeons who performed the manipulation.
The observation of the subjects continued for 6 months after the experiment. After that, they passed a standard test to assess motor abilities for patients with Parkinsonism. In patients who received gene therapy, they improved by an average of 23 percent. In the control group, the improvement averaged 12.7 percent.
According to the authors of the study, the results obtained indicate that gene therapy for Parkinson's disease is a safe and effective treatment method that deserves further research. However, the data available today is not enough to assess the effectiveness of gene therapy in comparison with other methods of treatment – in particular, with deep electrical stimulation of the brain.
The study report is published in the journal The Lancet Neurology (Peter A LeWitt et al., AAV2-GAD gene therapy for advanced Parkinson's disease: a double-blind, sham-surgery controlled, randomized trial).
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