FDA label change for Tysabri (Biogen IDEC) for Multiple Sclerosis and approval of JCV antibody test

The FDA has approved a product label change for Tysabri(natalizumab) from Biogen IDEC/Elan that will help enable individual benefit risk assessment for patients with relapsing remitting Multiple Sclerosis (MS).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). Infection with the JC virus (JCV) is required for the development of PML and 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 therapy and received treatment with Tysabri for more than two years have the highest risk of developing PML. The FDA also has allowed marketing of the first test, Stratify JCV Antibody ELISA test,from Focus Diagnostics, to help determine the risk for PML in people using Tysabri for Multiple Sclerosis or Crohn�s disease.