A Phase 1 Randomized, Double-Blinded, Placebo-Controlled Single-Ascending Dose Study of the Safety, Tolerability, and Pharmacokinetics of BIIB054 in Healthy Subjects and Subjects With Early Parkinson's Disease

The primary objective of the study is to evaluate the safety and tolerability of a range of
single BIIB054 doses, administered as a single intravenous (IV) infusion, in healthy
participants and participants with early Parkinson's disease (PD). Secondary objectives of
the study are to assess the serum pharmacokinetics (PK) profile of BIIB054 after single-dose
administration and to evaluate the immunogenicity of BIIB054 after single-dose
administration.