MS Drug Tysabri Update

An intravenous MS drug, Tysabri, was pulled from the market in 2005 due to safety concerns. The U.S. FDA Advisory Committee is trying to get it reapproved for use.

The medication Tysabri, an intravenous monoclonal antibody, was at first seen to be a wonder drug by MS specialists in the United States. It seemed to help with relapsing multiple sclerosis at a higher rate than any of the current injectable medications. Unfortunately, three people who used Tysabri in clinical trials developed a rare but serious disease called progressive multifocal leukoencephalopathy. Two individuals died, including one person with MS (Tysabri was also being tested on patients with Crohn's disease, another autoimmune disorder.) Although speculative, it is believed that the two people using the medication for MS were also taking another immune suppressing drug, Avonex, and could have possibly developed PML because of very suppressed immune systems. Tysabri was only on the market for four months before it was pulled.

In March of 2006, the U.S. FDA Advisory Committee recommended that Tysabri be put back on the market. The FDA is reviewing the information and has asked for a ninety day extension for the decision. Some possible new regulations include:

• registering patients and physicians who use Tysabri in order to track its use
• Tysabri not being used for people with compromised immune systems or those already taking immunosuppressive agents
• screening for symptoms of PML before each infusion
• a warning label on Tysabri, concerning the risks of developing PML

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