Gene Therapy for Parkinson’s
Researchers are taking more interest in treating neurological disorders with gene therapy. A phase 2 clinical trial shows that this novel treatment may help people with Parkinson’s disease.
It has been known for some years now that gene therapy may be helpful for treatment of Parkinson’s, a common neurological disorder. But it wasn’t exactly clear how it can.
Researchers at the Feinstein Institute for Medical Research had reported in a 2011 trial that gene therapy improved motor functions in patients. They found that the treatment helped to reduce symptoms of the disorder for a minimum of a year. But they just didn’t understand completely why this was so.
Parkinson’s is a complex, incurable disorder that presents a wide range of symptoms. People who have it typically experience muscle stiffness, changes in speech and tremors. These are the effects of overstimulation of the subthalamic nucleus in the brain, a part which coordinates motor functions.
In the current study, the Feinstein Institute for Medical Research scientists set out to find out what mechanisms mediate the improvements that were observed in the 2011 trial.
In a Phase 2 trial reported in the journal Science Translational Medicine, they found that the observed improvements were the results of improved functional brain connectivity.
Reorganizing the brain
Gene therapy is a form of treatment involving DNA infusion into cells to fight medical conditions. The U.S. Food and Drug Administration has approved a number of its variants for treatment of diverse conditions.
The team in the current research, led by Dr. David Eidelberg, already knew that this therapy can produce therapeutic effects in people with Parkinson’s. The scientists had analyzed studies on gene therapy spanning several years.
To understand what led to beneficial effects, they made use of PET scans to assess the brains of people who received the treatment and those who were not given. It was found that the subjects given gene therapy developed new brain circuits that helped with better motor functions.
The researchers called this effect “adaptive rewiring.”
The treatment led to creation of new pathways. It caused the pathways between the motor regions of the brain and the subthalamic nucleus implicated in the disorder to be shut down.
The Feinstein Institute researchers called their gene therapy AAV2-GAD. It involves infusing a gene carrying the code for glutamic acid decarboxylate (GAD). The genes stimulate non-dopamine cells in the brain for production of that compound, thus improving Parkinson’s symptoms.
Positive attitude helps
One interesting, and probably unexpected, finding in the trial is that people with this disorder may notice improvement in their symptoms by being positive.
The subjects in the study appears not to be aware of whether they were receiving gene therapy or a placebo. The researchers found that people who thought they had been given new genes, when in reality they have not, also developed new brain circuits.
This effect was, however, not as significant as in people who truly got new genes. But it improved their motor functions.
Eidelberg said the observed improvements in the placebo group was a reflection of the power of positive thinking.
The researchers are now planning to start a Phase 3 trial toward the end of 2019. That study will involve testing the gene therapy for Parkinson’s in larger number of people than in the one just published.
The proposed trial will not be double-blind as is normally seen in drug studies, according to News Day. The researchers will be aware of those getting new genes or a placebo.
Gene therapy eases Parkinson’s symptoms by rewiring parts of the brain (https://www.newscientist.com/article/2186723-gene-therapy-eases-parkinsons-symptoms-by-rewiring-parts-of-the-brain/)
Long Island researchers: Gene therapy helps with Parkinson’s (https://www.newsday.com/news/health/gene-therapy-parkinson-s-disease-1.24036604)