Assay Evaluated for Potential in Tysabri Patients

Biogen Idec and Elan Pharmaceuticals are evaluating an investigational, two-step assay in a clinical trial to determine its potential to detect anti-JC virus antibodies in multiple sclerosis (MS) patients and to identify those at higher risk of developing progressive multifocal leukoencephalopathy (PML). The antibodies are thought to be a factor in developing PML, Biogen says. If successful, the diagnostic could be used to evaluate PML risks for patients treated with Biogen and Elan’s MS drug Tysabri (natalizumab).