A Study of TAK-341 in Treatment of Multiple System Atrophy

The drug being tested in this study is called TAK-341. The study will evaluate the efficacy, safety, tolerability, pharmacokinetics (PK), and pharmacodynamics of intravenous (IV) TAK-341 in participants with multiple system atrophy (MSA). The study will enroll approximately 158 participants. The study comprises a screening period of up to 42 days (6 weeks), a 52-week double-blind treatment period, and a follow-up safety visit. Participants will be randomly assigned (by chance, like flipping a coin) to one of the two treatment groups-which will remain undisclosed to the participant, care provider and investigator during the study: * TAK-341 * Placebo The change from baseline in UMSARS will be measured at Week 52 post-dose. This multi-center trial will be conducted worldwide. The duration of treatment in this study will be 52 weeks. Participants will make a follow-up visit to the site after approximately 90 days after the last dose of study treatment.