New data gives positive safety profile for Tysabri (natalizumab)

The Biogen Idec announced that no new cases of a PML (progressive multifocal leukoencephalopathy ) have been reported among patients taking Biogen Idec's multiple sclerosis drug Tysabri, since the FDA allowed it back into the market.

Tysabri was withdrawn in February 2005 after two deaths because of PML which were linked to this Multiple Sclerosis drug. Last June, the FDA approved Tysabri under the condition that any patients taking the drug register with a program designed to ensure its safe use. Currently drug is available under a strict surveillance TOUCH prescribing program.

Thursday's announcement by Biogen at the American Academy of Neurology's annual meeting was the first safety update since June. On Thursday, Biogen and its partner on Tysabri, Elan Corp. of Ireland, also released results of an extension of the original two-year study of Tysabri, which showed a 67 reduction in the relapse rate of MS patients who took the drug for a third year.

In the US, approximately 6,600 patients are on TYSABRI therapy commercially. Approximately 10,000 patients have enrolled in the TOUCH program and 1,500 physicians have enrolled patients.


In the US,
TYSABRI (natalizumab) is approved as a monotherapy treatment for relapsing forms of Multiple Sclerosis. TYSABRI increases the risk of PML, an opportunistic viral infection of the brain that usually leads to death or severe disability. Patients should be monitored at regular intervals for any new or worsening signs or symptoms suggestive of PML

Serious adverse events that occurred in TYSABRI-treated patients included hypersensitivity reactions (e.g., anaphylaxis), infections, depression and gallstones.

Seeji, Pharm House

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  1. Pradip says

    Even the second update released recently(July 07) supported the reinclusion of Tysabri.... FDA is gonna back it up with some prescribing restriction