SGT-003 gene therapy for ambulant boys and young men with Duchenne muscular dystrophy (IMPACT DUCHENNE)

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

This trial will test whether a single intravenous infusion of SGT-003 can help ambulatory boys and young men with Duchenne muscular dystrophy maintain or improve walking and motor function.

Quick facts

• Phase: Phase 3
• Study type: Interventional
• Enrollment: 80 (estimated)
• Ages: 7 Years to 11 Years
• Sex: Male
• Sponsor: Solid Biosciences Inc. (Industry-sponsored)
• Drugs / interventions: prednisone
• Locations: 2 sites (Sydney, New South Wales and 1 other locations)
• Trial ID: NCT07160634 on ClinicalTrials.gov

What this trial studies

This is a Phase 3, double-blind, placebo-controlled trial testing a single IV infusion of the AAV-based gene therapy SGT-003 in ambulant pediatric males with genetically confirmed DMD. Participants are randomized 1:1 to receive SGT-003 in Part 1 followed by placebo in Part 2, or placebo in Part 1 followed by SGT-003 in Part 2, with each participant observed across both parts. Key eligibility includes ambulatory status, weight ≤50 kg, negative anti-AAV antibodies, and stable corticosteroid treatment, and participants will be followed for safety and efficacy measures with at least five years of long-term follow-up after SGT-003 dosing. Primary outcomes focus on the effect of the single infusion on motor function while secondary outcomes and safety endpoints capture additional clinical effects and adverse events.

Who should consider this trial

Good fit: Ideal candidates are ambulatory boys or young men with genetically confirmed DMD who weigh ≤50 kg, are negative for anti-AAV antibodies, meet the walking and rise-time criteria, and have been on a stable corticosteroid regimen.

Not a fit: Patients who are non-ambulatory, have prior AAV gene therapy or gene editing exposure, have high anti-AAV antibody titers, weigh more than 50 kg, or recently received other dystrophin-modifying treatments are unlikely to be eligible or receive benefit.

Why it matters

Potential benefit: If successful, SGT-003 could restore some dystrophin production and help preserve or improve motor function, potentially slowing disease progression.

How similar studies have performed: Other AAV-based micro-dystrophin gene therapy programs have shown proof-of-concept with dystrophin expression and early functional signals in smaller trials, but results have been mixed and long-term benefit remains unproven.

Eligibility criteria

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.

Where this trial is running

Sydney, New South Wales and 1 other locations

• The Children's Hospital of Westmead — Sydney, New South Wales, Australia (Recruiting)
• BC Children's Hospital — Vancouver, British Columbia, Canada (Recruiting)

Study contacts

• Study coordinator: Solid Bio Clinical Trials

Conditions Duchenne Muscular Dystrophy; SGT-003; adeno-associated virus; IMPACT DUCHENNE