Open-Label Access to ATH434 for Patients Who Completed Study ATH434-201 in France

Open-Label Extension Study to Provide Access to ATH434 in Patients With Multiple System Atrophy

This multicenter open-label extension study conducted in France is designed to provide ATH434 orally BID to eligible patients who completed the Phase 2 study ATH434-201, and who may benefit from this treatment according to the evaluation by the Investigator.

Study Overview

• Status: Not yet recruiting
• Conditions: Multiple System Atrophy
• Intervention / Treatment: Drug: ATH434

Detailed Description

This is a multicenter, open-label extension (OLE) study designed to provide continued access to the investigational product ATH434 for eligible participants with Multiple System Atrophy (MSA) who have successfully completed the prior Phase 2 clinical trial (ATH434-201) in France. Up to 5 participants will be enrolled. No new participants will be recruited or enrolled in this study.

The primary objective is to monitor long-term safety, tolerability, and clinical response. Eligible participants will receive ATH434 at a dose of 75 mg twice daily (BID) to be taken with food.

The study is divided into two operational phases:

Initial Treatment Phase: Participants will receive treatment for a planned duration of 12 months.

Extension Phase: Participants may continue treatment beyond the initial 12 months based on the investigator's clinical judgment of ongoing benefit, safety, and tolerability. Continued eligibility will be re-evaluated and documented every 3 months.

Participants will undergo a combination of in-clinic and remote visits to perform safety monitoring, clinical evaluations, and investigational product accountability.

• Study Type: Interventional
• Enrollment (Estimated): 5
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Alterity Clinical Trials; Phone Number: +1 888-556-7582; Email: clinicaltrials@alteritytx.com

Study Locations

• France
  • Midi-Pyrenees
    • Toulouse, Midi-Pyrenees, France, 31300
      • Hôpital Pierre-Paul Riquet
  • New Aquitaine
    • Bordeaux, New Aquitaine, France, 33076
      • Centre Hospitalier Universitaire de Bordeaux
  • Provence-Alpes-Côte d'Azur Region
    • Marseille, Provence-Alpes-Côte d'Azur Region, France, 13005
      • Hôpital de la Timone
  • Île-de-France Region
    • Paris, Île-de-France Region, France, 75013
      • Hôpital Universitaire Pitié Salpêtrière

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Completed Alterity protocol ATH434-201.
• Expected to benefit from treatment from treatment with ATH434, in the opinion of the Investigator.

Exclusion Criteria:

• Discontinued prior ATH434 treatment (ATH434-201) for any reason.
• Significant medical or psychiatric condition that may decrease the benefit-risk ratio of participation in this program to an unacceptable level, as per the Investigator's opinion.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: ATH434 75mg BID; Participants who completed the prior ATH434-201 Phase 2 trial will receive ATH434 75 mg orally twice daily (BID). Treatment consists of an initial 12-month treatment phase, followed by an ongoing extension phase based on investigator assessment of continued clinical benefit, safety, and tolerability	Drug: ATH434; ATH434 75 mg tablets administered orally twice daily (BID).; Other Names: PBT434

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence, Severity, and Relationship of Adverse Events (AEs) and Serious Adverse Events (SAEs)	All AEs will be reviewed at every participant contact and documented in the CRF. All SAEs will be reported within 24 hours of awareness in accordance with local regulatory requirements.	Baseline to completion of study treatment, an average of 1 year.
Change From Baseline in Clinical Laboratory Parameters	Clinical laboratory parameters include hematology and blood chemistry panels.	Baseline to completion of study treatment, an average of 1 year.
Change From Baseline in Vital Signs	Vital signs include blood pressure, pulse, temperature, and respiration rate.	Baseline to completion of study treatment, an average of 1 year.
Duration of Exposure to ATH434	Total duration of treatment with investigational product per participant.	Baseline to completion of study treatment, an average of 1 year.
Cumulative Dose of ATH434	Total cumulative dose of investigational product administered per participant.	Baseline to completion of study treatment, an average of 1 year.

Collaborators and Investigators

• Sponsor: Alterity Therapeutics

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): July 1, 2029
• Study Completion (Estimated): July 1, 2029

Study Registration Dates

• First Submitted: July 16, 2026
• First Submitted That Met QC Criteria: July 22, 2026
• First Posted (Actual): July 28, 2026

Study Record Updates

• Last Update Posted (Actual): July 28, 2026
• Last Update Submitted That Met QC Criteria: July 22, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Synucleinopathies; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurodegenerative Diseases; Movement Disorders; Basal Ganglia Diseases; Primary Dysautonomias; Autonomic Nervous System Diseases; Multiple System Atrophy; ATH434; 8-hydroxyquinazolin-4(3H)-one
• Other Study ID Numbers: ATH434-203; 2025-524317-88-00 (Ctis)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes