The drug Tysabri marketed by Cambridge, Mass-based Biogen Idec and Elan pharamtecuticals is used for the treatment of Crohn’s disease (CD) and multiple sclerosis (MS) in some patients. Now, the US Food and Drug Administration (FDA) has approved the first test for gauging the risk of a rare brain infection known as progressive multifocal leukoencephalopathy (PML) in patients exposed to Tysabri for treating MS or CD.
This test namely Stratify JCV Antibody ELISA can be used with other clinical information of patients to determine the risk of PML in the aforesaid group. A specific virus known as John Cunningham virus (JCV) is considered to be harmless. But, it may lead to PML in people with weak immune systems possibly due to diseases and Tysabri treatment.
The team has put forward certain risk factors for PML such as presence of anti-JCV antibodies, exposure to Tysabri for more than 2 years and use of immunosuppressants. According to them, individuals with all the 3 risk factors are apparently at the highest risk for PML.
“PML is a fatal infection reported in patients undergoing immunomodulatory therapy. This test gives doctors an additional means to determine if MS or CD patients undergoing Tysabri therapy are at increased risk for developing PML,” commented Alberto Gutierrez, Ph.D., director of the Office of In Vitro Diagnostics in FDA’s Center for Devices and Radiological Health.
Notably, the Stratify JCV Antibody ELISA test is not to be used for diagnosis of PML and is for professional use only. The test is to be performed at Focus Diagnostics’ Reference Laboratory by means of a prescription. It is not to be used for blood donor screening.
Focus Diagnostics of Cypress, Calif have manufactured the Stratify JCV Antibody ELISA test.