BIIB019

Relapses are defined as new or recurrent neurological symptoms not associated with fever or infection, lasting at least 24 hours, and accompanied by new objective neurological findings upon examination by the examining neurologist. Only relapses confirmed by Independent Neurology Evaluation Committee (INEC) are included in this analysis. Adjusted ARR was estimated from a negative binomial regression model adjusted for the baseline relapse rate, history of prior IFN beta use, baseline Expanded Disability Status Scale score (EDSS; ≤ 2.5 vs \> 2.5) and baseline age (≤ 35 vs \> 35 years). Data after participants switched to alternative MS medications are excluded.

An AE is defined as any untoward medical occurrence in a clinical investigation participant administered a drug; it does not necessarily have to have a causal relationship with this treatment. A SAE is any untoward medical occurrence or effect that at any dose results in death, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability / incapacity, is a congenital anomaly / birth defect or is medically important due to other reasons than the above mentioned criteria.

Treatment-emergent AE: any untoward medical occurrence after the first dose of study treatment that did not necessarily have a causal relationship with this treatment. Serious AE (SAE): any untoward medical occurrence that at any dose: resulted in death; in the view of the Investigator, placed the subject at immediate risk of death (a life-threatening event); required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability/incapacity; resulted in a congenital anomaly/birth defect. An SAE could also have been a medically significant event that, in the opinion of the Investigator, jeopardized the subject or required intervention to prevent one of the other outcomes listed in the definition above.

For participants who took DAC HYP during 205MS201 (NCT00390221) the baseline is defined as the baseline from 205MS201, and for participants who took placebo during 205MS201 the baseline is defined as the baseline from 205MS202 (NCT00870740). All post-baseline data are taken after first dose in 205MS202 only. SBP=systolic blood pressure; DBP=diastolic blood pressure; bpm=beats per minute; ↑ BL=increase from baseline; ↓ BL=decrease from baseline.

Hematology parameters evaluated include: white blood cells, lymphocytes, neutrophils, red blood cells (RBC), hemoglobin, and platelets.

For each abnormality a subject can be counted once. If a subject has more than one occurrence of the same abnormality the highest toxicity grade is counted. ALT=alanine aminotransferase; AST=aspartate aminotransferase; ALP=alkaline phosphatase; GGT=gamma-glutamyl transferase; TSH=thyroid stimulating hormone, ULN=upper limit of normal.

Number of participants positive and negative for ADAb and NAb, based on all post-baseline immunogenicity assessments during treatment period and follow-up. Participants are stratified differently in this Outcome Measure as per the pre-specified statistical analysis plan.

Relapses are defined as new or recurrent neurologic symptoms not associated with fever or infection, lasting at least 24 hours, and accompanied by new objective neurological findings upon examination by the examining neurologist. The annualized relapse rate was calculated as the total number of relapses that occurred during the study divided by the total number of subject-years followed in the study.