Europe Looking Again at Tysabri for Link to Fatal Brain Infection

The multiple sclerosis and Crohn’s disease drug Tysabri is going back under the microscope in Europe for a possible link to cases of a rare but potentially deadly brain infection called progressive multifocal leukoencephalopathy (PML), according to various news reports.

Tysabri is the controversial Biogen Idec Inc. and Elan PLC medication that has long been suspected of causing PML. At least 13 patients taking the drug since its approval in 2004 have developed the infection. Tysabri was even taken off the market soon after it was approved because of reports of PML in users.

The drug was later allowed back in circulation after stronger warnings were added to its labeling to caution users and doctors about the risks of PML from taking it. All of the cases of PML have been reported in patients taking the drug for multiple sclerosis. No cases have been associated with use of the drugs in patients with Crohn’s disease.

PML: Deadly and Severe Brain Infection

PML is an infection of the brain and central nervous system that is caused by a polyomavirus, also called the JC virus. The virus may be carried and remain inactive inside people for years without triggering PML, but when patients take immunosuppressive drugs to treat a variety of conditions and diseases, the virus can result in the potentially fatal disease.

The European Medicines Agency’s Committee for Medicinal Products for Human Use has now launched a review of Tysabri because of a higher rate of PML than has previously been disclosed. The agency says there have been 23 cases of PML in Tysabri users.

Rituxan Also Linked to PML

Also, just last week, the rheumatoid arthritis drug Rituxan was linked to three reports of PML. One new report of the infection in a woman taking the drug was added to two earlier cases, prompting concerns about the safety of Rituxan.

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