drug_prevents MS Brain Damage

A front-line drug against multiple sclerosis (MS) has recently passed a long-anticipated, critical test of its effectiveness, according to a report in the March 2001 issue of Annals of Neurology, the research publication of the American Neurological Association. Brain scans of patients taking glatiramer acetate (GA), sold in the United States as Copaxone, indicate that the drug significantly curtails the number of new brain lesions (injuries) caused by flare-ups of the disease and reduces the overall volume of damaged brain tissue.

Multiple sclerosis is a disorder of the nerve fibers of the brain and spinal cord. In MS, scarring (sclerosis) replaces myelin, a substance that normally surrounds the nerves and speeds electrical conduction through the fibers. Depending on which nerve fibers are hindered, patients can experience problems ranging from weakness and clumsiness to numbness, visual disturbances, and even emotional and intellectual alterations. In some patients, MS manifests itself in cycles of relapse and remission; in other patients, the disease may progress to a stage of severe debilitation.

Although the cause of MS is not known, most circumstantial evidence has suggested that it is an autoimmune disorder wherein the immune system's defense mechanisms erroneously destroy the myelin. Interferon-beta and GA, two drugs that act very differently on the immune system, both reduce the frequency of MS relapses by approximately 30%. Unlike interferon-beta, however, GA is a treatment specific for MS and has the advantage of not causing major side effects, such as the flu-like symptoms and depression that have been associated with interferon-beta.

Up until now, one key outcome measure--magnetic resonance imaging (MRI)--was missing for GA, however. MRI allows researchers to measure the number and volume of the lesions that accumulate in the brains of MS patients and is used to evaluate the effects of new treatments. This technique has demonstrated clearly the positive effects of interferon-beta but has never been used to test the effects of GA.

In the current study, 239 patients with relapsing/remitting MS were enrolled from 29 medical centers in six European countries and Canada. Half of the patients received daily GA injections and half were given a placebo substance for nine months. The researchers used monthly MRI scans to examine the subjects' brains for evidence of new lesions.

Glatiramer acetate had a significant effect in reducing the activity of the disease, as measured by the appearance of new lesions. The drug also significantly reduced the burden of the disease, as measured by the volume of the damaged tissue.

A secondary objective of the study was to determine the time course of the protective effect. The researchers found that the therapeutic effects of GA, both in terms of preventing relapses and protecting the brain, appeared three to four months after initiation of the treatment. This observation confirms scientists' prior understanding of how GA exerts its influence - by gradually inducing the immune system to protect, rather than to destroy, brain tissue.

© American Neurological Association (ANA)

Submission date: 16/03/01