What Dosage of Subcutaneous Interferon Beta-1a Is Best for Clinically Isolated Syndrome?

To gain regulatory approval to label subcutaneous interferon beta-1a (IFN-β-1a) for use in clinically isolated syndrome, investigators compared the effects of two different dosages of the drug in a multicenter, industry-sponsored, randomized, double-blind, placebo-controlled trial. Participants were aged 18 to 50, had a recent first demyelinating event typical of multiple sclerosis (MS), and had baseline T2 magnetic resonance imaging (MRI) abnormalities suggestive of MS. Participants were randomized to placebo, weekly subcutaneous IFN-β-1a, or thrice-weekly subcutaneous IFN-β-1a. Upon conversion to clinically definite MS (by having a second clinical event or new MRI activity on quarterly scans), patients were switched to open-label, thrice-…