Efficacy and Safety of BIIB019 (Daclizumab High Yield Process) Versus Interferon β 1a in Participants With Relapsing-Remitting Multiple Sclerosis

Key Inclusion Criteria:

- Must have a confirmed diagnosis of Relapsing Remitting Multiple Sclerosis (RRMS), and
a cranial magnetic resonance imaging (MRI) demonstrating lesion(s) consistent with MS

- Must have a baseline Expanded Disability Status Scale (EDSS) between 0.0 and 5.0,
inclusive

- Male subjects and female subjects of childbearing potential must be willing to
practice effective contraception during the study and be willing and able to continue
contraception for 4 months after their last dose of study treatment

Key Exclusion Criteria:

- Known intolerance, contraindication to, or history of non-compliance with Avonex® 30
µg

- History of treatment with Daclizumab High Yield Process (Dac HYP)

- History of malignancy

- History of severe allergic or anaphylactic reactions

- Known hypersensitivity to study drugs or their excipients

- History of abnormal laboratory results indicative of any significant disease

- History of human immunodeficiency virus (HIV) or other immunodeficient conditions

- History of drug or alcohol abuse (as defined by the Investigator) within the 2 years
prior to randomization

- History of seizure disorder or unexplained blackouts OR history of a seizure within 6
months prior to Baseline

- History of suicidal ideation or an episode of clinically severe depression (as
determined by the Investigator) within 3 months prior to Day 1

- An MS relapse that has occurred within the 50 days prior to randomization AND/OR the
subject has not stabilized from a previous relapse prior to randomization

- Known history of, or positive screening test result for hepatitis C virus or
hepatitis B virus

- Varicella or herpes zoster virus infection or any severe viral infection within 6
weeks before screening

- Exposure to varicella zoster virus within 21 days before screening

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