Gene therapy treats Parkinson’s disease in second clinical trial

Kathleen Blanchard's picture
Parkinson's disease
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In a first successful Phase II clinical trial, funded by Neurologix, Inc, researchers used a gene therapy called NLX-P101 to reverse symptoms of Parkinson’s disease. The success of the gene therapy is the result of 20 years of research and the first to be used for Parkinson’s disease or any neurological disorder.

Gene therapy normalizes chemical signals in Parkinson’s disease

The gene therapy works by normalizing chemical signals in the brain, eliminating symptoms of tremor, stiffness and difficulty moving. Typically, patients with the disease walk with a shuffling gait, finding it difficult to pick up their feet from rigidity of the limbs.

The treatment uses a gene known as glutamic acid decarboxylase (GAD). An inert virus is used to get the gene into the brain. GAD then signals brain cells to produce GABA that binds to the brain’s neurons, normalizing defects found in patients with Parkinson’s disease.

Dr. Matthew During, formerly at Yale University and current professor of molecular virology, immunology and medical genetics, neuroscience and neurological surgery at the Ohio State University explains, "In Parkinson's disease, not only do patients lose many dopamine-producing brain cells, but they also develop substantial reductions in the activity and amount of GABA in their brains. This causes a dysfunction in brain circuitry responsible for coordinating movement."

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Dr. Michael Kaplitt, vice chairman for research in the Department of Neurological Surgery at Weill Cornell Medical College and a neurosurgeon at New York-Presbyterian Hospital/Weill Cornell Medical Center pioneered a Phase I study that treated one side of the patient’s brain with the gene therapy, performed in the operating room. The Phase II trial delivered the gene to both sides of the brain that randomized 45 patients and performed at the bedside, using a delivery system developed by Dr. Kaplitt.

As a control, patients were given a sham therapy while they wereawake so they could respond to commands to move their limbs from the researchers, making them believe they were receiving the gene therapy. The control group was also given a saline injection instead of the gene, using the same delivery system as the therapy group.

The findings are published in the Lancet Neurology that could be a major advance for treating Parkinson’s disease, but longer trials would be needed to assess safety of the treatment.

In the study, the gene therapy dramatically improved symptoms of Parkinson’s disease in over half of the patients, compared to 14 percent of the control group at six months, with improvement seen at one month. Dr. During says the success of the Phase II trial means the NLX-P101 therapy is closer to being used in clinical practice for treatment of the debilitating neurological disorder. Neurologix, Inc., co-founded by Dr. Kaplitt, is seeking FDA approval for a Phase III clinical trial.

Lancet Neurology
doi:10.1016/S1474-4422(11)70039-4

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