New Phase 3 trial of Duchenne gene therapy SGT-003 to begin dosing
FDA agreement supports launch of Solid Biosciences’ pivotal study
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A Phase 3 trial testing SGT-003, a gene therapy candidate for Duchenne muscular dystrophy (DMD), will start dosing before the end of March, according to Solid Biosciences.
The trial follows a successful meeting with the U.S. Food and Drug Administration (FDA), during which the company and the agency aligned on the study’s design.
The IMPACT DUCHENNE trial (NCT07160634) is expected to enroll about 80 boys with DMD, ages 7 to 11, who are able to walk, at sites in Australia, Canada, the European Union, and the U.K. Solid is also evaluating whether to open sites in the U.S.
Solid plans discussions with FDA on accelerated approval pathway
Solid expects to meet again with the FDA to discuss what evidence would be needed to pursue accelerated approval for SGT-003. Under this pathway, the FDA can allow a therapy to be marketed based on early clinical data suggesting it is likely to be effective, with additional studies required to confirm benefit.
“We have structured our U.S. regulatory strategy around engaging with the FDA regarding a potential accelerated approval pathway for SGT-003, and the successful alignment on the design of our Phase 3 IMPACT DUCHENNE trial marks a critical first step in that plan,” Bo Cumbo, president and CEO of Solid, said in a company press release.
DMD is caused by mutations in the DMD gene that result in a lack of functional dystrophin, a protein that helps protect muscles from damage during muscle movements. The loss of dystrophin leads to progressive muscle weakness and wasting.
SGT-003 delivers a gene encoding a shorter yet functional version of the dystrophin, called microdystrophin, to muscle cells. The gene therapy uses a newly designed viral vector intended to improve delivery to muscle tissue while limiting exposure to the liver, an important consideration because some infused gene therapies can trigger liver inflammation and serious side effects.
The treatment’s safety and efficacy are currently being evaluated in the open-label Phase 1/2 INSPIRE DUCHENNE trial (NCT06138639), which is still recruiting boys with DMD, up to age 17, at sites in the U.S., Canada, Italy, and the U.K.
Early trial testing safety and microdystrophin expression
Participants received a single treatment dose through an intravenous (into the vein) infusion. According to the company, results from the 36 participants treated so far show that the therapy has been generally well tolerated. The trial is also evaluating changes in microdystrophin protein levels in muscle tissue and in multiple measures of motor abilities for up to 1.5 years.
In the IMPACT trial, children will be randomly assigned to receive a single treatment infusion followed by placebo, or placebo followed by SGT-003, ensuring that all participants eventually receive the gene therapy. The main goal is to assess changes in how long it takes participants to stand up from a lying position (face and torso facing up) after about 1.5 years.
Secondary goals include measures of walking and stair-climbing speed, other aspects of motor function, lung function, and safety.
“Our dedication to the Duchenne community remains unwavering: they deserve therapeutic options, and we are committed to collaborating with the FDA to help make that a reality,” Cumbo said.
SGT-003 has received rare pediatric disease status by the FDA, a designation given to therapies intended to prevent or treat rare diseases that mainly affect children and adolescents.
