MS Patients who were previously treated with the drug under an investigational study can now resume treatment.
In February 2005, Biogen-IDEC suspended marketing and clinical trials of Tysabri after three patients developed progressive multifocal leukoencephalopathy (PML), an often fatal infection of the brain.
Two patients developed PML following treatment with natalizumab for MS, and one patient got it after being treated for Crohn's Disease. Two of these cases were fatal.
FDA has worked with Biogen-IDEC over the ensuing months to assess whether any other patients exposed to natalizumab had developed an early stage of PML.
They also examined what factors might have contributed to the three PML cases that did occur, and considered what procedures could be utilized to potentially decrease the risk of PML in the future.
Additionally, the FDIA and Biogen worked on how to suitably monitor patients to detect a PML infection as early as possible.
The drug is not being placed back on the market at this time. FDA has scheduled an Advisory Committee Meeting on March 7 and 8, 2006 to discuss an application for Tysabri for use in treating patients with relapsing forms of multiple sclerosis.
