Immunogenicity and Safety of Subcutaneously-administered Avonex (Interferon Beta-1a) in Multiple Sclerosis (MS) Patients

Inclusion Criteria: * Ability to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information (PHI) in accordance with national and local subject privacy regulations. * Male or female aged 18- to 60-years-old, inclusive, at the time of informed consent. * Must have a diagnosis of relapsing MS. * Must have a screening Expanded Disability Status Scale (EDSS) score between 0 and 6.0, inclusive. * All male subjects and female participants of child-bearing potential must practice effective contraception during the study and be willing and able to continue contraception for 30 days after their last study dose of Avonex. Exclusion Criteria: * History of severe allergic or anaphylactic reactions. * Diagnosed with Primary progressive, secondary progressive, or progressive relapsing MS. * Known allergy to any component of the Avonex formulation. * History of any clinically significant (as determined by the investigator) cardiac, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric renal, or other major disease. * Subjects with history of malignant disease, including solid tumors and hematologic malignancies. * History of seizure disorder or unexplained blackouts OR history of a seizure within 3 months prior to Day 1. * History of suicidal ideation within 3 months prior to Day 1 or an episode of severe depression within 3 months prior to Day 1. Severe depression is defined as any episode of depression that requires hospitalization, or the initiation of antidepressant therapy, or an increase in the dose of an existing regimen of antidepressant therapy. * Clinically significant abnormal electrocardiogram (ECG) values as determined by the investigator. * Known history of, or a positive test result for, human immunodeficiency virus (HIV). * Known history of, or a positive test result for hepatitis C virus. * Abnormal screening blood tests exceeding any of the limits defined below: 1. Alanine transaminase/serum glutamate pyruvate transaminase (ALT/SGPT) greater than 2 times the upper limit of normal or aspartate transaminase/serum glutamic oxaloacetic transaminase or bilirubin. 2. Total white blood cell count (WBC) \<3700 cells/mm 3. Platelet count \<150,000 cells/mm 4. Hemoglobin \<10 g/dL in female subjects; \<11 g/dL in male subjects 5. Serum creatinine \>upper limit of normal (ULN) 6. Prothrombin time (PT) or activated partial thromboplastin time (aPTT) \> 1.2\*ULN