A Study of the Effect of BIIB023 on Muscle Atrophy in Healthy Male Volunteers

Key Inclusion Criteria:

• Deemed healthy as determined by the Investigator based on medical history, 12-lead electrocardiogram, vital signs, and clinical laboratory parameters at Screening, and physical examination at Baseline
• Body mass index (BMI) between 18.5 and 32 kg/m2, inclusive, at the time of Screening
• Willing to abstain from using tobacco and tobacco-containing products during the study
• Willing to limit the intake of alcohol to no more than 2 units per day throughout the study; exceptions are 48 hours prior to Screening, 48 hours prior to Day 1, and during the in-clinic immobilization period when no alcohol will be permitted. One unit of alcohol is defined as 12 fluid ounce (fl oz) of beer, 5 fl oz of wine, or 1.5 fl oz of liquor
• Willing to maintain a regular diet for the duration of the study and a recreational level of physical activity defined as participation in an exercise program or other physical activity at a level of intensity that does not exceed the level prior to study entry
• Practice effective contraception during the study and be willing and able to continue contraception for at least 6 months after the last dose of study treatment.

Key Exclusion Criteria:

• History of or positive test result at Screening for human immunodeficiency virus (HIV).
• History or positive test result at Screening for hepatitis C virus (HCV) antibody or hepatitis B virus (defined as positive for hepatitis B surface antigen [HBsAg] or hepatitis B core antibody [HBcAb]).
• History of tuberculosis (TB) or a positive QuantiFERON®-TB Gold test. There must be no other clinical evidence of TB on physical examination of the subject.
• Use of tobacco or tobacco-containing products within 3 months prior to Screening
• Known history of thrombophilia, hypercoagulopathy, or prior history of deep vein thrombosis (DVT) or pulmonary embolism (PE)
• History of physical activity consistent with endurance training or resistance training within 6 months prior to Screening
• Any back, leg, knee, or shoulder complaints that may interfere with the use of crutches
• Prolonged travel (more than 6 hours) within 2 weeks prior to randomization.

NOTE: Other protocol-defined inclusion/exclusion criteria may apply.