Announcement • May 09
Solid Biosciences Doses First Participant in Phase 3 Impact Duchenne Clinical Trial Evaluating Sgt-003 in Duchenne Muscular Dystrophy
Solid Biosciences Inc. announced that the first participant has been dosed in IMPACT DUCHENNE, the Company’s multi-country, placebo-controlled, randomized, double-blind, Phase 3 clinical trial investigating SGT-003 for the treatment of Duchenne muscular dystrophy (Duchenne). IMPACT DUCHENNE and the ongoing Phase 1/2 INSPIRE DUCHENNE clinical trials are components of an integrated, multi-trial clinical development program designed to evaluate the safety and efficacy of a single intravenous dose of SGT-003 in individuals living with Duchenne. Since the initiation of the INSPIRE DUCHENNE trial in June 2024, SGT-003 has been administered to 46 participants, with approximately 30 participants dosed as of year-end 2025. As of a May 4, 2026, safety cutoff, SGT-003, which is administered using a steroid-only prophylactic immunomodulation regimen, has been generally well tolerated with no observed cases of drug induced liver injury, myocarditis, thrombotic microangiopathy or atypical hemolytic uremic syndrome. The first participant was dosed in Australia at The Children’s Hospital at Westmead. In the US, Solid previously announced the outcome of a Type C meeting with the FDA during which alignment was reached on the overall IMPACT DUCHENNE trial design, including the pre-specified primary endpoint of change from baseline at 18 months in time to rise from supine (TTR) velocity. The Phase 3 trial is designed to play a key role in supporting various US and ex-US regulatory pathways. Additionally, SGT-003 has received FDA Fast Track, Rare Pediatric and Orphan Drug designations. Solid has also made significant progress in advancing the regulatory strategy for SGT-003 across the globe. The Company has received a positive opinion from the EMA’s Paediatric Committee on its Pediatric Investigation Plan (PIP), providing alignment on the proposed pediatric development framework for SGT-003 in Europe. Approval of a PIP is required for a future marketing authorization application. The finalization of the PIP, together with receipt of Orphan drug designation from the European Commission, reflect Solid’s progress in advancing SGT-003 in Europe. In addition, Solid was one of only three recipients of the newly relaunched Innovation Passport under the UK’s Innovative Licensing and Access Pathway (ILAP), which focuses more selectively on transformative products that address unmet clinical needs. Solid has had multiple engagements under this designation with the goal of mapping an accelerated time to market as well as expedited patient access. SGT-003 is an investigational gene therapy containing a novel microdystrophin construct and a proprietary, next-generation capsid, POLARIS-101TM (formerly known as AAV-SLB101), which was rationally designed to target integrin receptors, and has shown enhanced cardiac and skeletal muscle transduction with decreased liver targeting in data from the Phase 1/2 INSPIRE DUCHENNE clinical trial and in nonclinical studies. SGT-003’s microdystrophin construct uniquely includes the R16/17 domains, which localize nNOS to the muscle. Nonclinical studies have shown that nNOS can improve blood flow to the muscle thereby reducing muscle breakdown from ischemia and muscle fatigue. Together, these design features suggest that SGT-003 could be a potential best-in-class investigational gene therapy for the treatment of Duchenne. The SGT-003 clinical development program consists of two multinational clinical trials – the Phase 1/2 INSPIRE DUCHENNE trial and the Phase 3 IMPACT DUCHENNE trial – which together were designed to generate a comprehensive data package to support potential global regulatory authorizations. INSPIRE DUCHENNE is a first-in-human, open-label, single-dose, multicenter Phase 1/2 clinical trial evaluating the safety, tolerability and efficacy of a single dose of SGT-003 in pediatric participants with a genetically confirmed Duchenne diagnosis. The trial is being conducted at clinical sites in the United States, Canada, the United Kingdom and Italy. IMPACT DUCHENNE is a Phase 3 placebo-controlled, randomized, double-blind clinical trial evaluating the efficacy of a single dose of SGT-003 in ambulatory participants with a genetically confirmed Duchenne diagnosis. Clinical trial sites are currently active in Australia and Canada and additional clinical site activations in the UK and US are expected in the second half of 2026, with sites in the EU anticipated to follow, subject to regulatory clearances.
