Track 1: a therapeutic vaccine
Motor symptoms of Parkinson disease (stiffness, slowness of movement, tremors) appear when at least 50 to 70% of the neurons producing dopamine are destroyed.
By understanding the exact origin of their disappearance, it would probably be possible to curb the pathology. Today, we mainly suspect alpha-synuclein. “This protein, which is usually present in neurons, can, for reasons still poorly understood, become indestructible by accumulating in the form of deposits potentially toxic to neurons”, specifies Professor Philippe Damier, neurologist, at the Nantes University Hospital.
To eliminate these deposits, two types of drugs are developed: the first is a vaccine promoting the production of antibodies against alpha-synuclein. The second, more advanced, is based on the direct injection of such antibodies: two experimental treatments (PRX002 and BIIB054) are currently being tested in patients at the very beginning of the disease, who do not yet require treatment. Their efficacy will be demonstrated if the progression of the disease is delayed compared to that of subjects on placebo. Results within 4 to 5 years.
Track 2: cell transplants
Replacing destroyed neurons with others that function normally would also avoid symptoms of the disease. Dr Erwan Bézard says: “A few years ago, a clinical trial was conducted in patients, who received a local transplant of embryonic cells. They developed into new neurons, but they were taken from embryos, a complex method, incompatible with large-scale use. This approach was therefore abandoned “. Since then, researchers have successfully reprogrammed adult cells in stem cells, which has revived interest in this technique: clinical studies should be initiated by Nectar, a European network specializing in cell therapy.
Track 3: “drug” genes
Gene therapy is based on a similar idea, but it involves injecting the genes of a protein essential for the survival or functioning of neurons. Trials with nerve growth factors have not been conclusive.
On the other hand, those who used genes essential for the production of dopamine (Pro-Savin) succeeded: this world first, conducted at the CHU Henri Mondor (Créteil), made it possible to reduce the symptoms during the first year in the fortnight of patients treated.
Long-term follow-up and then confirmatory studies are now necessary.
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