Long-Term Assessment of Remyelinating Therapy

A Multicenter, Follow-Up Study to Assess Long-Term Electrophysiologic and Clinical Outcomes in Subjects Previously Enrolled in Study 215ON201

The primary objective of the study is to assess full-field visual evoked potential (FF-VEP) latency in subjects who were enrolled in Study NCT01721161 2 years (+ up to 12 months) after the last study visit. The secondary objective is to assess clinical progression and severity of central nervous system (CNS) demyelinating disease in subjects who were enrolled in Study NCT01721161 2 years (+ up to 12 months) after the last study visit. Intervention was administered in the previous study. The participants, investigator and outcome assessors remain blinded in this follow-up study.

Key Inclusion Criteria:

• Must have participated in Study NCT01721161 and received at least 1 dose of BIIB033 or placebo, as per protocol, within 2 years (+ 4 months) from Day 1 of this study (2 years from Week 32 or projected Week 32 visit, if the subject did not complete all visits in Study NCT01721161).

Key Exclusion Criteria:

• Not previously enrolled in Study NCT01721161
• Subjects with recent kidney function, such as serum creatinine above upper limit of normal range, will not be allowed to receive administration of Gd but will otherwise be allowed to participate in the study, including magnetic resonance imaging (MRI) assessments not requiring the use of Gd.
• Female subjects must have had a recent pregnancy test and must not be breastfeeding prior to MRI assessments with Gd.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.