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Clinical trials

Elamipretide confirmatory trial appears after accelerated approval

Why the 4TAZPower trial matters for Forzinity's narrow Barth syndrome approval.

By the PeptideFactSheets Editorial Team. Claims are source-checked under our editorial policy; clinician review is identified only when a named reviewer is shown.

What happened?

ClinicalTrials.gov posted 4TAZPower, a Phase 3b/4 randomized, double-blind, placebo-controlled study in people with genetically confirmed Barth syndrome.

The registry describes the trial as a post-marketing confirmatory study for elamipretide after Forzinity's accelerated FDA approval. As of the May 6, 2026 registry update, the study was not yet recruiting and had no posted results.

Why it matters

  • Forzinity's FDA approval was accelerated and narrow: it covers improving muscle strength in adults and pediatric patients with Barth syndrome who weigh at least 30 kilograms.
  • Accelerated approval can rest on an endpoint considered reasonably likely to predict clinical benefit. The FDA announcement and label both state that continued approval may depend on confirmatory evidence.
  • A registered confirmatory trial helps readers distinguish the approved intermediate-endpoint claim from broader mitochondrial, fatigue, performance, or healthy-aging claims that remain unproven.

What changed for patients or consumers?

  • The elamipretide fact sheet can now point to a specific confirmatory trial record instead of referring only generally to future confirmatory research.
  • Nothing changed about the approved use: Forzinity remains approved only for the labeled Barth syndrome population, not for general mitochondrial support or athletic performance.
  • The trial registration is not a result. It should not be read as proof that patient-centered benefit has been verified.

What remains uncertain?

  • Whether the confirmatory trial will start, complete, and post results on the estimated timeline
  • Whether functional outcomes will verify a patient-centered clinical benefit
  • How the benefit-risk profile will look with more participants and longer follow-up
  • Whether any other mitochondrial-disease research will support separate indications

Related fact sheets

ElamipretideMOTS-cHumanin

Source links

  1. 1
    ClinicalTrials.gov: 4TAZPower

    Registered post-marketing confirmatory trial for elamipretide in genetically confirmed Barth syndrome.

  2. 2
    FDA prescribing information: Forzinity

    Official label describing the approved use, accelerated-approval basis, and confirmation requirement.

  3. 3
    FDA accelerated approval announcement

    FDA announcement describing the September 19, 2025 approval and post-approval trial requirement.