Today the US Food and Drug Administation (FDA) released a warning to doctors that the Biogen Inc. drug Tysabri (natalizumab) causes a rare brain infection that could be fatal to patients. The drug is used to treat relapsing multiple sclerosis patients. Multiple sclerosis is an autoimmune disease that affects the brain and spinal cord (central nervous system. Doctors also use it to treat Crohn”s disease, an uncomfortable inflammatory bowel disease.
What’s the Cause?
Tysabri is proven to cause progressive multifocal leukoencephalopathy (PML) due to a low autoimmune system. According to the Nation Institute of Health (NIH), PML is caused by the reactivation of a common virus in the central nervous system of immune-compromised individuals. Mortality is around 50% and those who do not die from the disease are generally left severely mentally impaired.
Problems From the Start
The FDA approved the drug in 2004, but Tysabri was pulled in 2005 due to those in the clinical trials coming down with PML. In the FDA report it said that the onset of PML became much higher after Tysabri, usually dispensed under supervised infusion, had been administered regularly for 12 months.
According to the Wall Street Journal, 66,000 people around the world take the drug. Only 1 in 1000 people contract PML. There have been 31 cases reported since it was reintroduced by Biogen in 2006. Biogen attributes the lower number to close monitoring of the patient during the infusion. Also, few patients have received more than 36 infusions.
Warning the Public
On the Tysabri website in the side effects section, it specifically states,
TYSABRI increases your chance of getting a rare brain infection that usually causes death or severe disability. This infection is called progressive multifocal leukoencephalopathy (PML).
The actions of the FDA today specifically require a change in the instructions on the bottle and with the packaging of the drug, warning the public of the chances and risks of PML.
The FDA further deemed that it would not reduce or restrict production because the occurrence of PML in patients is low enough not to outweigh the benefits over all to patients using the drug.
What To Do If You Contract PML from Tysabri
If you or a loved one contracts PML or shows symptoms of PML from taking Tysabri infusions please:
- Talk to your doctor.
- Request to be immediately taken off of the drug (as per Biogen’s instructions)
- Seek legal council by calling Phillips Webster to learn about your legal options.

