FDA Approves Resumed Sale Of MS Drug

A multiple sclerosis (MS) drug withdrawn from the market for a year because of a rare but serious side effect will be allowed to return under a restricted distribution program designed to help ensure safe use of the product, federal health officials said on June 5.

FDA says Cambridge, Mass.-based Biogen Idec and Ireland's Elan Corp. can resume marketing Tysabri, a monoclonal antibody used by patients with relapsing forms of MS to reduce the frequency of flare-ups, which can complicate walking and seeing. Biogen makes the drug, and Elan distributes it.

Tysabri was initially approved by FDA in November 2004, but it was pulled off the market by Biogen in February 2005 after three patients in the drug's clinical trials developed progressive multifocal leukoencephalopathy (PML), a serious and rare viral infection of the brain. Two of the cases were fatal.

FDA allowed a trial of Tysabri to resume in February 2006, following a reexamination of the patients who had participated in the previous clinical trials, confirming that there were no additional cases of PML. In March, FDA advisers recommended that the agency allow Tysabri sales to resume, with restrictions.

Under a risk management plan worked out with Biogen and Elan, FDA is requiring that the drug be labeled with the warning that it can cause PML in patients suffering from immune system conditions. Prescribing doctors, as well as patients, must also join a registry program, and patients must be evaluated at various intervals for signs of PML.

Biogen says Tysabri could be available as soon as July. "The reintroduction of Tysabri offers new hope as an important therapeutic choice for patients living with this disabling disease," says James C. Mullen, Biogen's CEO. "Tysabri has demonstrated compelling efficacy in MS."

FDA says Tysabri is only for patients who have not responded adequately to, or cannot tolerate, other treatments for MS, which affects about 350,000 Americans. Its cause is unknown, and there is no cure.