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NCT Number: NCT07160634

A Study of SGT-003 Gene Therapy in Ambulant Males With Duchenne Muscular Dystrophy (IMPACT DUCHENNE)

This is a Phase 3, double-blind, placebo-controlled study with the primary objective of evaluating the efficacy of a single IV infusion of SGT-003 in pediatric ambulant male participants with DMD. The secondary objectives include the evaluation of additional efficacy and safety outcomes. The study will be divided into 2 parts. Participants will be randomized 1:1 to either SGT-003 in Part 1 followed by placebo in Part 2 or to placebo in Part 1 followed by SGT-003 in Part 2. Participants will continue to be monitored in long term follow up (LTFU) for at least 5 years from their SGT-003 dosing date.

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Key information

Conditions

Duchenne Muscular Dystrophy Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn Genetic Diseases, X-Linked Muscular Diseases Muscular Disorders, Atrophic Muscular Dystrophies Muscular Dystrophy, Duchenne Musculoskeletal Diseases Nervous System Diseases Neuromuscular Diseases

Age range

7 year–11 year

Sex eligibility

Male

Study type

Interventional

Phase

Phase 3

Primary location

The Children's Hospital of Westmead, Sydney, New South Wales, Australia

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Participant is ambulatory.
  • Established clinical diagnosis of DMD and documented DMD gene mutation predictive of DMD phenotype.
  • Negative for antibodies against adeno-associated virus.
  • On a stable daily oral regimen of at least 0.5 mg/kg/day prednisone or 0.75 milligrams per kilogram per day (mg/kg/day) deflazacort for at least 6 months prior to entering the study, allowing for weight-based dose modifications in accordance with clinical practice.
  • Meet 10-meter walk/run time criteria.
  • Meet time to rise from supine criteria.
  • Participant has bodyweight ≤50 kg.

Exclusion criteria

  • Current or prior treatment with an approved or investigational gene transfer drug or gene editing therapy.
  • Exposure to vamorolone, givinostat, approved or investigational dystrophin- or disease-modifying drugs (such as eteplirsen, golodirsen, casimersen, viltolarsen, and ataluren), or another investigational drug for any indication within 6 months or 5 half-lives, whichever is longer, prior to enrollment.
  • Established clinical diagnosis of DMD that is associated with any deletion variant or variant predicted not to express exons 1 to 11, exons 42 to 45, or exons 57 to 69, inclusive of the DMD gene as documented by a genetic report.

Other Inclusion/Exclusion criteria to be applied as per protocol.

Treatment and study plan

SGT-003

Drug

Adeno-associated virus (AAV)-based gene therapy that delivers a codon-optimized and CpG island-minimized human 5-repeat microdystrophin (h-μD5)

Placebo

Drug

IV infusion

Primary outcomes

  1. Change From Baseline in Time to Rise (TTR) from Supine Velocity (rise/s) at Day 540

    Time frame: Baseline, Day 540

Secondary outcomes

  1. Change From Baseline in Stride Velocity 95th Centile (SV95C) (m/s) at Day 540

    Time frame: Baseline, Day 540

  2. Change From Baseline in 4-Stair Climb (4SC) Velocity (tasks/s) at Day 540

    Time frame: Baseline, Day 540

  3. Change From Baseline in 10-meter Walk/Run (10MWR) Velocity (m/s) at Day 540

    Time frame: Baseline, Day 540

  4. Change From Baseline in North Star Ambulatory Assessment (NSAA) total score at Day 540

    Time frame: Baseline, Day 540

  5. Cumulative Loss of Function in NSAA Items at Day 540

    Time frame: At Day 540

  6. Change From Baseline in Microdystrophin Protein Levels by western blot (% of normal dystrophin) at Day 90

    Time frame: Baseline, Day 90

  7. Change From Baseline in Microdystrophin Tissue Distribution by Immunofluorescence (% positive fibers) at Day 90

    Time frame: Baseline, Day 90

  8. Change from baseline in Percent Predicted Forced Vital Capacity (FVC) at Day 540

    Time frame: Baseline, Day 540

  9. Change from baseline in Percent Predicted Peak Expiratory Flow (PEF) at Day 540

    Time frame: Baseline, Day 540

  10. Change from baseline in Percent Predicted Forced Expiratory Volume in 1 second (FEV1) at Day 540

    Time frame: Baseline, Day 540

  11. Change from baseline in the Pediatric Outcomes Data Collection Instrument (PODCI) Global score at Day 540

    Time frame: Baseline, Day 540

  12. Number of Participants with Treatment Emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs), Adverse Events of special interest (AESIs), and clinically significant changes in Electrocardiogram (ECG) and Echocardiography (ECHO)

    Time frame: From first dose up to Day 540

Study contacts

Contact information is provided by the study sponsor or research team.

Solid Bio Clinical Trials

CONTACT

[email protected]

6173374680

Sponsors and collaborators

Lead sponsor

Solid Biosciences Inc.

Industry

Registry information

Official study title

A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled Study to Investigate the Efficacy of a Single Intravenous Dose of SGT-003 in Ambulant Males With Duchenne Muscular Dystrophy

Important dates

Study start
2025
Primary completion
2029
Study completion
2034
First posted
Sep 8, 2025
Registry last updated
Jul 16, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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