那他珠单抗(Tysabri)：药物安全通报-进行性多灶性白质脑病（PML）的新风险因素

Target Audience: Neurology, Gastroenterology

Published: January 20, 2012

Question

The U.S. FDA notifies healthcare professionals that a positive test for anti-JC virus antibodies has been identified as a risk factor for progressive multifocal leukoencephalopathy (PML). PML is a rare but serious brain infection associated with use of natalizumab (Tysabri) to treat multiple sclerosis (MS) or Crohn's disease.

A patient's anti-JCV antibody status can be determined with an analytically and clinically validated anti-JCV antibody test prescribed by a healthcare professional. StratifyJCV antibody ELISA detection reagent was approved by the FDA on January 20, 2012. A positive anti-JCV antibody test means the person has been exposed to JC virus in the past.

Background

Natalizumab (Tysabri) belongs to a class of drugs called immunomodulators. Its mechanism of action is to prevent certain cells in the immune system from causing damage to the body. Natalizumab (Tysabri) has been approved for the treatment of relapsing forms of multiple sclerosis since November 2004 and for the treatment of moderately to severely active Crohn's disease since January 2008.

Recommendations

For patients who are found to be positive for anti-JCV antibodies and have one or more other known risk factors for PML, the risks and benefits of continued treatment with Tysabri should be carefully considered. The estimated risk of developing PML for patients with all three known risk factors is approximately 11 cases per 1,000 users. For more information, see the Data Summary section of the Drug Safety Communication.