FDA Warns Drug Maker For Minimizing Risk of Brain Infection from Tysabri

Federal regulators have cited Biogen Idec, Inc. for attempting to downplay the risks of a rare, but often fatal, brain infection that has been linked to the multiple sclerosis drug Tysabri. 

The FDA sent a warning letter (pdf) to the company on March 25, accusing the company of misleading statements made in a series of webcasts used to promote Tysabri. According to the FDA, Biogen aired the webcast eight times between late October and early November of 2009.

In the webcasts, the FDA says Biogen played down the risk of contracting progressive mutifocal luekoencephalopathy (PML), which is a serious infection in the brain that can be caused by side effects of Tysabri. In addition, the FDA said that the webcasts failed to inform the viewer of Tysabri’s approved uses.

Tysabri (natalizumab) is an intravenous injection given every 28 days to treat MS and Crohn’s Disease. Manufactured by Biogen Idec Inc. and marketed with Elan Corp PLC, Tysabri has been shown to prevent relapse, cognitive decline and vision loss associated with MS. Sales of Tysabri bring in about $1 billion annually.

A Tysabri recall was issued in 2005 after three users developed the rare and life-threatening brain infection, which attacks the central nervous system, damaging and inflaming the white matter areas of the brain. The drug was reintroduced in July 2006 with stronger warnings about the potential risk of a PML brain infection from Tysabri and the drug was only made available under strict usage guidelines.

PML is believed to be caused by the common JC virus, and Tysabri may reduce the ability of the immune system to combat the virus. There have been 31 cases of Tysabri brain infections since the drug was reintroduced.

In February, the FDA issued a Tysabri PML warning saying that it now appears that the risk of developing PML increases with the number of Tysabri infusions patients receive.

“We are particularly concerned with this webcast because it presents numerous statements that seriously minimize the risk of PML,” the FDA said in its warning letter. “This presentation misleadingly implies that Tysabri patients who developed PML and received treatment…experienced lessened effects of PML and that patient outcomes will necessarily be improved if Tysabri treatment is stopped at the first sign of PML; this has not been established.”

The FDA said that, in truth, no one knows if early detection of PML or discontinuing use of Tysabri once it’s been detected will mitigate the disease. The FDA also points out that there is no evidence that plasma exchanges, a treatment touted in the webcasts, have any benefit in treating PML or other opportunistic infections.