Testing positive for anti-JC virus (JCV) antibodies is a newly identified risk factor for a rare, but serious brain disorder associated with the drug Tysabri® (natalizumab), according to a U.S. Food and Drug Administration (FDA) Safety Announcement.
Tysabri® is prescribed to treat multiple sclerosis or Crohn’s disease. Progressive multifocal leukoencephalopathy (PML) is a rare brain infection in which the coating of some brain nerve fibers called myelin is damaged. Tysabri® has been associated with increasing the risk of getting PML.
Two hundred and one patients with PML have been reported among about 96,582 patients given Tysabri® worldwide through Jan. 4, 2012. Patients who have taken Tysabri® for between 25 and 48 months number 11 in 1,000 if they have been treated previously with an immunosuppressant.
Doctors and patients are warned in the FDA announcement to carefully weigh the risks versus the benefits of continuing treatment with Tysabri® in patients who have:
- JCV antibodies
- Been treated longer with Tysabri®, especially longer than two years
- Have had prior treatment with an immunosuppressant drug such as mitoxantrone, azathioprine, methotrexate, cyclophosphamide, or mycophenolate mofetil.
The risk of getting PML is greatest if you have all three known risk factors.
The new information has been added to the Tysabri® drug label. A new anti-JCV detection test was approved by the FDA on January 20, 1012.
Because of this new information, your doctor may recommend a blood test to see if you have ever been exposed to JCV, which is the virus that causes PML. This test measures the presence of antibodies to the virus. These antibodies often are called anti-JCV antibodies.
PML symptoms are varied and progress over a matter of days to weeks. They include
- Progressive weakness on one side of the body
- Disturbed vision
- Changes in thinking, memory and orientation, leading to confusion and personality changes
The progression of the disease can lead to death or severe disability over weeks or months.
For more information, contact a progressive multifocal leukoencephalopathy lawyer today.