Clinical Trial in Patients With Barth Syndrome- 4TAZPower

NCT07531251 | Not Yet Recruiting Phase 4 DMC FDA Drug

• 1 other identifier: SPIBA-401
• Study Type: interventional
• Target: 48
• Locations: 2 countries
• Sites: 2

Brief Summary

Phase 3b/4, randomized, double-blind, parallel-group, placebo-controlled clinical trial to evaluate the efficacy, safety, and pharmacokinetics of a once daily SC injection of elamipretide in subjects with genetically confirmed BTHS for 72 weeks. The primary trial objective is to confirm the efficacy of elamipretide which is approved in the United States(FORZINITY™) under the accelerated approval based on an improvement in knee extensor muscle strength, an intermediate clinical endpoint.

Conditions

Barth Syndrome

Keywords

BTHS; Ultra Rare X-Linked Mitochondrial Disorder; Genetic Defect in TAZ Gene

Outcome Measures

Primary Outcomes (1)

• Primary Efficacy End Point

  -change in the composite normalized score of the three functional tests: Six-minute walk test (6MWT), the triple-timed up and go test (3TUG), and the Five times sit-to-stand test (5XSST) from baseline to 72 weeks of treatment

  72 weeks

Secondary Outcomes (7)

• Secondary Efficacy End Point 1

  72 weeks

• Secondary Efficacy End Point 2

  72 weeks

• Secondary Efficacy End Point 3

  72 weeks

• Secondary Efficacy End Point 4

  72 weeks

• Secondary Efficacy End Point 5

  72 weeks

Other Outcomes (1)

• Safety End Point Adverse Event Reporting

  72weeks

Study Arms (2)

Elamipretide

ACTIVE COMPARATOR

Elamipretide - aqueous, sterile 5.0 mL single-patient, ready to use, multi-dose glass vial containing 3.5 mL of elamipretide solution (elamipretide \[80 mg/mL\],

Drug: Elamipretide

Placebo

PLACEBO COMPARATOR

Matching Placebo-aqueous, sterile 5.0 mL single-patient, ready to use, multi-dose glass vial containing will be composed of 3.5mL of sodium chloride, phosphate buffer, and benzyl alcohol similar to excipients in active drug but without the active drug substance

Drug: Placebo

Interventions

Elamipretide DRUG

sub cutaneous injection

Also known as: elamipretide hydrochloride

Elamipretide

Placebo DRUG

sub cutaneous injection

Placebo

Eligibility Criteria

• Age: 5 Years - 55 Years
• Gender Eligibility Details: Male
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• Willing and able to provide signed informed consent form (ICF) prior to participation in any trial-related procedures. If applicable, informed consent in writing from parent(s) or legally-acceptable representative(s) and, informed assent from subject (if age appropriate according to local requirements) should be provided.
• Agrees to adhere to the trial requirements for the length of the trial.
• Must have genetically confirmed Barth Syndrome (pathogenic variant in the TAZ gene)
• Male aged ≥ 5 years at time of the Screening Visit
• Left Ventricular Ejection fraction of ≥ 50% by 3-D Echocardiogram at the Screening Visit.
• For subjects with a medical history of cardiomyopathy, must be on a stable regimen (unchanged and constant) of background heart failure medications for at least 3 months prior to the Screening Visit.
• Able to administer Investigational Medicinal Product (IMP) or have an appropriate designee who can administer the IMP (i.e., a capable family member or a caregiver).
• Subjects with female partners of childbearing potential must be willing to use a highly effective method of contraception (e.g., abstinence, dual method of contraception) from the date they sign the ICF until 28 days after the last dose of IMP.

You may not qualify if:

• Unable to perform the required functional tests or undergo echocardiography.
• History of solid organ transplant, except successful cardiac transplantation \> 12 months prior to screening, if, in the opinion of the Investigator, there is no evidence of organ rejection and post-transplant pharmacotherapy, is stable, and does not pose additional safety risk to participant.
• Patients with an implantable cardioverter defibrillator (ICD) and with a known occurrence of ICD discharge in the 3 months prior to the Screening Visit.
• Current placement on the waiting list for heart transplantation.
• Hospitalization for heart failure within 6 months prior to the Screening Visit.
• Any disease or medical condition that in the opinion of the Investigator would prevent the subject from successfully participating in the trial and reliably completing the assessments or might confound trial results.
• Has a history of a systemic eosinophilic illness
• Estimated Glomerular Filtration Rate (eGFR) of \< 30 mL/min at the Screening Visit (using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2021 formula for subjects \>16 years of age and the Schwartz 2009 formula for subjects 5-16 years of age).
• Active malignancy or any other cancer from which the subject has been cancer-free for \< 2 years. Localized squamous or non-invasive basal cell skin carcinomas are allowed, if appropriately treated prior to Screening.
• Participation in other investigational drug or device clinical trials within 30 days or 5 half-lives (whichever is longer) of Screening; or is currently enrolled in a non-interventional clinical trial that, in the opinion of the Investigator, may be potentially confounding to the results of the current trial.
• History of allergic reaction to the IMP or any of its components.
• Prior participation in any elamipretide trial or expanded access programs.

Sponsors & Collaborators

• Stealth BioTherapeutics Inc.: lead

Study Sites (2)

Trial Not Offered in the U.S

Needham, Massachusetts, 02494, United States

Location

Bristol Royal Hospital for Children Upper Maudlin Street Paul O'Gorman Building

Bristol, United Kingdom

Location

MeSH Terms

Conditions

Barth Syndrome

Interventions

arginyl-2,'6'-dimethyltyrosyl-lysyl-phenylalaninamide

Condition Hierarchy (Ancestors)

Heart Defects, Congenital; Cardiovascular Abnormalities; Cardiovascular Diseases; Heart Diseases; Abnormalities, Multiple; Congenital Abnormalities; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Genetic Diseases, X-Linked; Genetic Diseases, Inborn; Lipid Metabolism, Inborn Errors; Metabolism, Inborn Errors; Lipid Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases

Study Officials

• Rekha Sathyanarayana

  Stealth BioTherapeutics Inc.

  STUDY DIRECTOR

Central Study Contacts

Rekha Sathyanarayana

CONTACT

617-762-2579; rekha.sathyanarayana@stealthbt.com

Lani Glennon

CONTACT

lani.glennon@parexel.com

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: Active treatment
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: 1:1 Randomization

Study Record Dates

• First Submitted: March 12, 2026
• First Posted: April 15, 2026
• Study Start (Estimated): June 30, 2026
• Primary Completion (Estimated): September 30, 2029
• Study Completion (Estimated): November 30, 2029
• Last Updated: May 6, 2026

Record last verified: 2026-05

Locations

US (1); GB (1)