Tysabri video on FDA site.
First Monoclonal Antibody Treatment for MS
FDA recently approved the first monoclonal antibody treatment for patients with relapsing forms of multiple sclerosis. The product, called Tysabri (natalizumab), is intended to reduce the frequency of clinical exacerbations of the disease. Tysabri is marketed by Biogen Idec and Elan Pharmaceuticals.
The product is given intravenously every four weeks in a physician's office.
Tysabri appears to work by targeting part of the underlying inflammatory process in MS by inhibiting adhesion molecules on the surface of leukocytes. It's believed that this interaction prevents immune cells from migrating into the brain, where they can cause damage.
The drug's approval was based on positive results after the first year of treatment in two randomized, double-blind clinical trials. In one of the trials, in which Tysabri was compared to a placebo, it reduced the frequency of relapses by 66 percent. The manufacturer will continue these trials for another year.
Serious but uncommon side effects included infections, severe or life threatening allergic reactions, depression, and gallbladder problems. Common adverse reactions were generally mild and included non-serious infections, headache, and fatigue.
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