MDA 2026: SGT-003 gene therapy shows early promise for DMD in trial
One-time treatment boosts levels of muscle-protecting protein
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SGT-003, an investigational gene therapy for Duchenne muscular dystrophy (DMD), worked as expected to increase levels of microdystrophin — a version of the muscle-protecting protein that’s deficient in DMD — and preserve muscle health for boys in a clinical trial, according to new data.
The one-time treatment was also well tolerated, avoiding the signs of liver injury sometimes seen with gene therapies.
These data, from the ongoing Phase 1/2 INSPIRE DUCHENNE trial (NCT06138639), were presented in a talk at the 2026 Muscular Dystrophy Association (MDA) Clinical & Scientific Conference, held earlier this week in Orlando, Florida, and online.
The talk was presented by the study’s principal investigator, Aravindhan Veerapandiyan, MD, of the Arkansas Children’s Hospital. It was titled, “Update on the INSPIRE DUCHENNE Phase 1/2 Study of the Next-Generation Microdystrophin Gene Therapy Candidate SGT-003 for Duchenne Muscular Dystrophy.”
“These interim results reinforce our confidence in the potential of SGT-003 to meaningfully impact the disease course of Duchenne,” Bo Cumbo, president and CEO of Solid Biosciences, the company developing the gene therapy, said in a company press release.
INSPIRE is still recruiting boys with DMD younger than age 12 at sites in the U.S., Canada, the U.K., and Italy. It may eventually enroll additional groups of older patients and patients who cannot walk.
Solid also recently launched a Phase 3 trial to further establish the benefits of SGT-003 in Duchenne. Called IMPACT DUCHENNE (NCT07160634), the study is seeking about 80 boys with DMD, ages 7-11, who can walk. It is currently enrolling at two sites in Australia and Canada, although the trial may later expand to Europe and the U.S.
“We are pursuing guidance on a potential accelerated approval pathway for SGT-003 and look forward to continued engagement with the [U.S. Food and Drug Administration] as we work toward that goal,” Cumbo said. “Our focus remains on urgently advancing SGT-003 to provide the Duchenne community with an additional therapeutic choice.”
SGT-003 delivers version of DMD gene
Due to mutations in the DMD gene, people with DMD lack dystrophin, a protein that helps protect muscles from use-related damage. Over time, muscles progressively weaken and waste away.
SGT-003 is a gene therapy that delivers a version of DMD that produces a shorter-than-normal, yet still functional, dystrophin protein called microdystrophin. It is specifically designed to improve gene delivery to muscle tissue, including the heart, while avoiding the liver. This could help prevent some of the serious liver-related side effects that have been seen with other gene therapies.
In INSPIRE, boys with DMD are receiving a single dose of SGT-003 via an infusion into the bloodstream. For the first month, all participants receive a high-dose steroid regimen to prevent immune-related side effects, which is then tapered down.
In the recent presentation, Veerapandiyan discussed trial findings from 39 participants, ranging in age from 1 to 10 years at enrollment, who had been dosed as of February.
Muscle biopsies from 20 participants demonstrated that the therapy was effectively taken up by muscle cells after three months, where it worked as expected to produce microdystrophin.
On average, about 60% of muscle fibers were positive for microdystrophin after three months, and this was sustained for a year in three patients with available data. Other proteins that normally form a muscle-protecting complex with dystrophin were also increased.
Various markers of muscle fiber degeneration and injury also showed sharp declines after three months, reflecting improvements in muscle health and integrity, according to Veerapandiyan.
“What stands out in these data is the biological consistency observed across multiple independent measures of muscle structure, health, and preservation,” Veerapandiyan noted in the press release.
Videos show improvements in performing daily activities
On average, the boys’ heart function remained stable or improved over time after receiving SGT-003, with improvements particularly evident in those with lower heart function at the study’s start.
Veerapandiyan indicated that the data are still preliminary, and more work is needed to determine how much of the gene therapy reaches the heart and “how does it … translate into safety and efficacy.”
To put improvements in muscle health into perspective for families, Veerpandiyan showed videos of boys performing daily activities before and after receiving gene therapy.
One boy, initially struggling to get into a car, could easily hop in and sit down a year after SGT-003. Another, who struggled to walk up the stairs before treatment, was shown running up the stairs and doing a headstand in the grass six months later.
“Early signs … but promising to look at the treatment-related changes,” Veerapandiyan said.
Functional assessments to quantify motor gains across trial participants will be analyzed at a later date after guidance from regulators, and Veerapandiyan says these should provide more data on the treatment’s functional effects.
Based on these findings, I believe this therapy has the potential to become an important treatment option for patients living with Duchenne.
Veerapandiyan also discussed safety findings, which were similarly described in a poster titled, “Positive Preliminary Safety and Liver Toxicity Profile Using SGT-003, Solid Biosciences’ Next-Generation Investigational Gene Therapy for Duchenne Muscular Dystrophy.”
Importantly, no participants showed signs of medication-induced liver injury across multiple measures. The most common treatment-related side effects included nausea, vomiting, and appetite loss.
“Based on these findings, I believe this therapy has the potential to become an important treatment option for patients living with Duchenne,” Veerapandiyan said.
Note: The Muscular Dystrophy News Today team is providing live coverage of the 2026 MDA Clinical & Scientific Conference March 8-11 in Orlando, Florida. Go here to see the latest stories from the conference.
