Information on Natalizumab (marketed as Tysabri)

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The FDA continues to receive reports of progressive multifocal leukoencephalopathy (PML) in patients receiving Tysabri. Tysabri was approved by the FDA for the treatment of relapsing forms of multiple sclerosis (MS) in November 2004 and for moderately to severely active Crohn’s disease in January 2008. From July 2006, (when Tysabri marketing resumed) to September 8, 2009, 13 reported cases of Tysabri-related PML were confirmed worldwide in patients being treated for MS with Tysabri monotherapy. Of these, four cases were patients in the United States (U.S.). There have been no postmarketing reports of PML in patients treated with Tysabri for Crohn’s disease. Less than 2% of Tysabri use in the U.S. has been in patients with Crohn's disease.

Information on Natalizumab (marketed as Tysabri)
Updated Information: [9/2009]

The FDA continues to receive reports of progressive multifocal leukoencephalopathy (PML) in patients receiving Tysabri. Tysabri was approved by the FDA for the treatment of relapsing forms of multiple sclerosis (MS) in November 2004 and for moderately to severely active Crohn’s disease in January 2008. From July 2006, (when Tysabri marketing resumed) to September 8, 2009, 13 reported cases of Tysabri-related PML were confirmed worldwide in patients being treated for MS with Tysabri monotherapy. Of these, four cases were patients in the United States (U.S.). There have been no postmarketing reports of PML in patients treated with Tysabri for Crohn’s disease. Less than 2% of Tysabri use in the U.S. has been in patients with Crohn's disease.

The risk for developing PML appears to increase with the number of Tysabri infusions received. The number of monthly infusions of Tysabri in the 13 patients who developed PML ranged from 12 to 35 infusions. The average number of infusions received before the diagnosis of PML was 25. There is minimal experience in patients who have received more than 35 infusions of Tysabri.

The overall rate of developing PML with Tysabri therapy in patients who have received at least one infusion remains below one per 1,000 patients. Based on available data from the U.S. and outside of the U.S., the current rate of PML in patients who have received at least 24 infusions ranges from 0.4 to 1.3 per 1,000 patients.

At this time, the FDA is not requiring changes regarding PML to the Tysabri prescribing information or to the Tysabri risk management plan, called the TOUCH Prescribing Program. All patients receiving Tysabri therapy in the U.S. must be enrolled in the TOUCH Prescribing Program. Under this program, every patient who receives Tysabri is closely monitored for the occurrence of PML and other serious opportunistic infections.



Current FDA Alert: [issued 8/2008]

The FDA has recently received information from the manufacturer about two new cases of progressive multifocal leukoencephalopathy (PML) in patients receiving Tysabri monotherapy for multiple sclerosis in Europe. Both patients had received Tysabri for more than one year. PML, which is usually fatal, is a known risk of Tysabri treatment, but previous cases in patients with multiple sclerosis were seen in combination with other immunomodulatory therapies. About 39,000 patients have received treatment with Tysabri worldwide, with about 12,000 patients having been treated for at least one year. No new cases have been seen in the US, where about 7,500 patients have received the drug for longer than one year and about 3,300 patients have received the drug for at least one and a half years. Healthcare Professional Sheet
Previous FDA Alert: [issued 2/2006]

The FDA has lifted the clinical hold on Biogen-IDEC's trials of natalizumab for patients with multiple sclerosis (MS). Biogen-IDEC can now resume administration of natalizumab to patients with relapsing-remitting MS who had previously been treated with the drug in clinical trials. Biogen-IDEC had previously suspended marketing of natalizumab and all further dosing of patients in on-going clinical trials. This decision was made after confirmation of one fatal case and one additional case of severely disabling progressive multifocal leukoencephalopathy (PML) in patients receiving natalizumab for MS. A third case of PML, this one fatal, in a patient with Crohn's Disease had been identified shortly thereafter. Healthcare Professional Sheet


To report any serious adverse events associated with the use of this drug, please contact the FDA MedWatch program using the contact information at the bottom of this sheet.

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Information on Natalizumab (marketed as Tysabri)