Une étude clinique de grande envergure montre que le THC ne ralentit pas la progression de la sclérose en plaques

Science/Homme : une étude clinique de grande envergure montre que le THC ne ralentit pas la progression de la sclérose en plaques
| cannabis-med.org | vendredi 8 juin 2012

Une étude clinique de grande envergure réalisée en Angleterre sous la direction du Docteur John Zajicek, professeur de neurologie au Peninsula College of Medicine and Dentistry de l’Université de Plymouth, Royaume-Uni a montré que l’administration de capsules de THC n’a pas ralenti la progression de la sclérose en plaques. Malgré les résultats prometteurs d’une étude précédente sur douze mois, les chercheurs ont trouvé que les patients traités avec des capsules de THC ne se portaient pas mieux que ceux à qui l’on avait donné un placébo pendant 3 ans.

Les chercheurs espéraient démontrer que le THC, non seulement procure un soulagement de la spasticité due à la sclérose, mais aussi constitue une thérapie du développement secondaire de la maladie dans les cas où peu d’options de traitement existent. Les patients atteints de sclérose en plaques ont été évalués lors d’un essai nommé CUPID (cannabinoid use in progressive inflammatory brain disease) par les neurologues qui ont mesuré l’invalidité d’une part et par les patients qui ont fourni leurs propres informations d’autre part. « L’étude, en moyenne, n’a pas montré d’effet du THC sur la progression de la maladie, dans aucun de ces développements, » a indiqué le Dr Zajicek. En revanche l’étude a montré un effet bénéfique du THC sur les patients les moins malades. Comme ces patients étaient peu nombreux dans l’étude, l’efficacité de ce traitement n’a pu être mesurée. L’équipe ayant réalisée l’étude ajoute « que l’ensemble des patients a pu voir une diminution de la progression de la maladie, ce qui laisse croire une différence d’effet entre le traitement placébo et le THC. Les résultats de l’étude n’ont pas encore été publiés dans une revue médicale.

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Cannabis fails to slow progress of multiple sclerosis in UK study
Ben Hirschler | reuters.com | Mon May 28, 2012

(Reuters) - Cannabis capsules failed to slow the progression of multiple sclerosis in a large British study, dealing a blow to hopes that the drug could provide long-term benefits for patients with the debilitating nerve disease.

Despite promising signs in earlier, shorter studies, researchers found patients who took capsules containing tetrahydrocannabinol (THC), a key active ingredient in cannabis, fared no better than those given a placebo.

The finding is a disappointment for researchers who thought cannabis might provide a viable therapy in the disease’s secondary progressive stage, when patients have few treatment options.

Multiple sclerosis (MS) patients were assessed in the trial known as CUPID (cannabinoid use in progressive inflammatory brain disease) on both a disability scale administered by neurologists and another based on their own reporting.

"Overall the study found no evidence to support an effect of THC on MS progression in either of the main outcomes," researchers led by John Zajicek of the Peninsula College of Medicine and Dentistry, Plymouth University, said.

Results from the study, which was funded by Britain’s Medical Research Council, will be presented at the Association of British Neurologists’ annual meeting in Brighton later on Tuesday.

Cannabis contains more than 60 different cannabinoids, of which THC is thought to be the most active, and many MS patients have long said the drug helps them cope with the effects of the disease.

Drug companies, too, have been interested in cannabis as a medicine. Britain’s GW Pharmaceuticals, working with Bayer and Almirall, recently started selling an under-the-tongue cannabis spray called Sativex to relieve spasticity.

David Nutt, professor of neuropsychopharmacology at Imperial College London, who was not involved in the latest research, said the study’s failure did not mean cannabis had no role in helping MS patients.

"It would be wrong to interpret these preliminary findings to mean that cannabis does not achieve its licensed use. Cannabis is not licensed for limiting disease progression, it is licensed for dealing with spasticity and pain," he said.

Zajicek’s study did find some evidence to suggest a beneficial effect in less disabled patients but because this was seen in only a small group of people it was unclear how strong the effect was.

The overall study population also experienced slower disease progression than had been expected, making it more challenging to detect any treatment effect, the research team added.

MS is a disease in which immune system cells destroy the myelin sheath that protects the nerve cells in the brain and spinal cord.

The most common type is relapsing remitting MS, affecting around 85 percent of patients at the time of diagnosis. Several drugs are available to treat this stage of the disease, including injections of beta-interferons and a new pill from Novartis called Gilenya.

Secondary progressive MS comes later and involves a sustained build up of disability.

(Reporting by Ben Hirschler ; Editing by Helen Massy-Beresford)