Efficacy and Safety of Daclizumab in Participants With RRMS Switching From Natalizumab

The primary objective of the study is to evaluate the effects of treatment with daclizumab on the proportion of participants relapse-free at 6 months in Relapsing-Remitting Multiple Sclerosis (RRMS) participants, who switched from treatment with natalizumab to daclizumab due to safety concerns. The secondary objectives of this study in this study population are to evaluate the effects of daclizumab on the following: 1) Multiple Sclerosis (MS) relapse activity including the annualized relapse rate (ARR) and the proportion of participants experiencing relapses requiring hospitalization and/or steroid treatment; 2) MS-related outcomes measured using magnetic resonance imaging (MRI); 3) Safety and tolerability in participants previously treated with natalizumab.