With global in-market sales growing 23 percent year over year to reach $1.5 billion, 2011 brought tremendous growth for TYSABRI, reflecting the therapy's efficacy.

In partnership with Elan Corp., we achieved several important milestones toward unlocking the value of TYSABRI. First, an assay to detect antibodies to the JC virus was made broadly available in both the United States and the European Union. Second, the TYSABRI product label was updated in the European Union and in early 2012 for the United States to include anti-JCV antibody status as a third risk factor for development of PML. We believe this more personalized approach will enable patients and prescribers to make informed treatment decisions.

There’s been tremendous interest from the MS community in risk stratification. We believe that the majority of TYSABRI patients now know their antibody status and that increasing numbers of patients considering TYSABRI are being tested as well.