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

A Randomized, Double-blind, Placebo-Controlled, Phase 2 Study to Evaluate the Efficacy, Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Intravenous TAK-341 in Subjects With Multiple System Atrophy

The main aim is to see how TAK-341 works after 52 weeks in participants with multiple system atrophy as measured by the Unified Multiple System Atrophy Rating Scale Part I (UMSARS).

The study will enroll approximately 138 patients. Participants will receive a total of 13 intravenous infusions every 4 weeks approximately, these may be either of TAK-341 or placebo, after each infusion some blood samplings will be taken and other assessments completed.

This trial will be conducted in North America, Europe and Asia.

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.

Inclusion criteria:

Diagnostic:

1. The participant has a diagnosis of possible or probable MSA using the modified Gilman et al, 2008 diagnostic criteria.
2. The participant's onset of first MSA symptoms occurred ≤4 years before screening, as assessed by the investigator.
3. Evidence of MSA specific symptoms and deficits as measured by the UMSARS scale.

Exclusion criteria:

Medical History:

1. The participant has any contraindication to study procedures.

Diagnostic Assessments:

1. Presence of confounding diagnosis and/or conditions that could affect participant's safety during the study per investigator judgement.
2. The participant's participation in a previous study of a disease-modifying therapy (with proven receipt of active treatment) will compromise the interpretability of the data from the present study, per consultation with medical monitor or designee.

Other:

1. The participant has participated in another study investigating active or passive immunization against α-synuclein (αSYN) for progressive disease (PD) or MSA, or has had immunoglobulin G therapy, within 6 months before screening.