Feb. 28, 2005 - The recently approved multiple sclerosis (MS) drug Tysabri has been voluntarily pulled from the market following reports of one death and one serious side effect in patients treated with the drug.
In cooperation with the FDA, the drug's makers, Biogen Idec and Elan Pharmaceuticals, today voluntarily suspended the drug. The companies have also suspended all studies involving Tysabri, which was approved by the FDA for the treatment of multiple sclerosis in November 2004.
The reports involved one confirmed and one suspected case of progressive multifocal leukoencephalopathy (PML), a rare but often fatal disease that affects the nervous system. In both cases, the patients had been taking Tysabri for more than two years in combination with another MS drug, Avonex.
PML is a progressive disease of the brain and spinal cord that primarily affects people with weakened immune systems. The condition is caused by a virus that destroys the sheath that covers the nerves. Symptoms include mental deterioration, vision loss, speech disturbances, and movement abnormities or paralysis.
In a letter sent to health care professionals, Biogen and Elan state they are suspending the supply of Tysabri from commercial distribution and advise doctors to stop prescribing or using the drug until further notice.
The companies state they are convening with experts to better understand the possible risk of PML in people taking Tysabri.
About 3,000 people have been treated with Tysabri in studies of the drug for the treatment of multiple sclerosis, Crohn's disease, and rheumatoid arthritis.
The two cases of PML that prompted the suspension occurred only in MS patients treated with both Tysabri and Avonex.