Although the FDA does not have to follow the advice of its regulatory committees, in most cases the agency does. Tysabri is approved for multiple sclerosis, although the drug was taken off the market for a short time due to safety concerns – concerns which were also raised by the committee in documents released before the panel’s meeting.
Biogen Idec and Elan said that discussions with the FDA will include adapting the existing Tysabri risk management plan, which was introduced when the drug was allowed back to the market.
The drug was originally suspended due to a risk of progressive multifocal leukoencephalopathy associated with the drug, an opportunistic viral infection of the brain that usually leads to death or severe disability. As the risk appeared to increase when Tysabri was used with other immunosuppressive agents, the drug was allowed back on the market under strict conditions, one of which was that it should be prescribed as a monotherapy.
However, the committee said that this issue of concomitant immunosuppressive therapy is considerably more difficult to address in the CD population compared to the MS population because of differences in the clinical management of each of these diseases. CD patients are more likely to have been treated chronically with immunosuppressive therapies. Also, CD patients are more likely to be treated with high dose and/or chronic steroids, whereas MS patients are more likely to be treated with pulse steroids.