The new label identifies anti-JCV antibody status as a risk factor for developing an infrequent but serious brain infection known as progressive multifocal leukoencephalopathy (PML).
The new label states that anti-JCV antibody negative status indicates that exposure to the JC virus has not been detected.
Patients who are anti-JCV antibody positive have a higher risk of developing PML.
Patients who are anti-JCV antibody positive, have received prior immunosuppressant (IS) therapy and received treatment with TYSABRI for more than two years have the highest risk of developing PML.
Biogen CEO George Scangos said TYSABRI has benefited thousands of patients worldwide who are living with multiple sclerosis, an often devastating disease affecting people in the prime of their lives.
"Biogen Idec and Elan’s use of novel research and scientific expertise has allowed us to gain a better understanding of the benefit-risk profile for TYSABRI," Scangos added.