PATIENT & CAREGIVER RESOURCES

Letter to the Duchenne Community

Dear Duchenne Community,

Today at the 2026 MDA Clinical & Scientific Conference, we announced a positive clinical update on the SGT-003 gene therapy program. This update includes interim safety and biomarker data from the ongoing Phase 1/2 INSPIRE DUCHENNE clinical trial.

To date, 40 participants have been dosed with SGT-003. The data include robust expression of microdystrophin, the shortened version of the dystrophin protein delivered by SGT-003 that is designed to help support and protect muscle cells during movement. The data also show restoration of proteins such as beta-sarcoglycan and nNOS, which normally work together with dystrophin as part of the muscle cell support system known as the dystrophin-associated protein complex (DAPC).

The update also includes signals related to muscle health. For example, fewer eMHC fibers in muscle tissue, which appear when muscle is repeatedly injured and repairing itself, may suggest less ongoing muscle damage. In addition, reductions in several proteins measured in the blood including CK, ALT, AST, LDH, and titin can provide insight into muscle cell integrity because these proteins can leak into the bloodstream when muscle cells are injured.

The data include measures of heart function, including left ventricular ejection fraction (LVEF), a measure of how well the heart pumps blood.

SGT-003 continues to demonstrate an encouraging safety profile and has been generally well tolerated in the 40 participants dosed as of March 11, 2026, and is administered using a lower-burden, steroid-only prophylactic immunomodulation regimen.

We are indebted to the participants, their families, and the clinical study teams whose commitment makes this progress possible.

We are actively engaged in a series of meetings with the FDA to receive guidance on a potential accelerated approval pathway for SGT-003 and expect to provide additional regulatory updates following these interactions.

For additional details, please refer to today’s press release and our 2026 MDA presentations (available following the close of the conference).

We are looking forward to keeping the Duchenne community informed through regular and transparent communication, including both written updates and dedicated community webinars. Families who would like to learn more about the INSPIRE DUCHENNE and IMPACT DUCHENNE studies can visit: https://www.solidbio.com/patient-caregiver-resources/resources-policies/clinical-trials/

With gratitude,
Annie Ganot
Co-founder, SVP Patient Advocacy
Solid Biosciences

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