The primary objectives of the study are: To determine the mass balance and routes of elimination of BIIB074 and its known metabolites following administration of a single oral dose of BIIB074 in healthy male participants and To describe the pharmacokinetics (PK) of BIIB074 and its known metabolites and the disposition profiles of total radioactivity in whole blood and plasma following a single oral dose. The secondary objectives of this study are: To assess the safety and tolerability of BIIB074 in healthy participants and To identify and characterize any additional metabolites of BIIB074 in plasma, urine, and feces.

Key Inclusion Criteria:

• All subjects must practice effective contraception during the study and be willing and able to continue contraception for 90 days after the administration of study treatment.
• Must be in good health as determined by the Investigator, based on medical history and screening evaluations.

Key Exclusion Criteria:

• History of any clinically significant cardiac, endocrine, gastrointestinal, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, or renal disease, or other major disease, as determined by the Investigator.
• Previous exposure to BIIB074.
• Other unspecified reasons that, in the opinion of the Investigator or Biogen, make the subject unsuitable for enrollment.

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