An update on the evidence base for peginterferon β1a in the treatment of relapsing-remitting multiple sclerosis.

Peginterferon β1a is a modified form of interferon β1a with a polyethylene glycol (PEG) group attached to the α-amino group of the N terminus of the interferon molecule. This modification alters the pharmacokinetic and pharmacodynamic properties of interferon β1a, enabling reduced frequency of dosing and may also result in reduced immunogenicity of the interferon β1a molecule. The efficacy of peginterferon β1a 125 µg administered subcutaneously every 2 or 4 weeks was demonstrated at the end of the placebo-controlled period in the phase III ADVANCE study; both dosing regimens met their primary endpoint of reducing annualized relapse rate (ARR) compared with placebo. Peginterferon β1a administered every 2 weeks resulted in a more robust treatment effect on ARR, sustained disability progression and magnetic resonance imaging endpoints (new or enlarging T2 lesions and gadolinium-enhanced lesions) than peginterferon β1a every 4 weeks. Further reductions in the ARR with additional positive impact on magnetic resonance imaging outcomes were noted in year 2 of the ADVANCE study with the every 2-week dosing regimen. An adverse-effect profile similar to other interferon β formulations coupled with the advantage of a significant reduction in the number of injections, could lead to improved long-term adherence to peginterferon β1a. We review the evidence base for the role of peginterferon β1a in the treatment of relapsing-remitting multiple sclerosis.