The FDA has approved a product label change for Biogen Idec/Elan’s Tysabri that will help enable individual benefit-risk assessment for patients with 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). PML marks the third risk factor identified to help physicians and people with MS have more confidence in their treatment decisions when considering Tysabri, a highly effective treatment for relapsing forms of MS.

“This label change marks an important advance in assisting people with MS and their physicians to make better-informed decisions concerning the challenges of balancing effectiveness with safety,” said Dr. Nicholas LaRocca, vice president, health care delivery and policy research at the National MS Society.

The label update was based on analysis of data from Biogen Idec/Elan's quantitative risk stratification algorithm. In the analysis, patients who were anti-JCV antibody positive were at an increased risk for developing PML with varying degrees of risk depending on prior IS use and Tysabri treatment duration. Irrespective of MS treatment, approximately 55% of MS patients are anti-JCV positive.

The FDA has granted Quest Diagnostics a de novo classification petition for the Stratify JCV antibody Elisa testing service. Stratify JCV allows neurologists to determine their MS patients' anti-JCV antibody status and is the first blood test to be FDA authorized for the qualitative detection of antibodies to the polyomavirus JC virus.

The U.S. label update follows European Commission approval of anti-JCV antibody status as an additional factor to aid in stratifying patients at risk for developing PML in the summary of product characteristics for Tysabri in the European Union.