Elevidys (delandistrogene moxeparvovec-rokl), the first gene therapy approved for Duchenne muscular dystrophy (DMD), continues to show promise in treating a condition long considered incurable, according to a webinar presented recently by Sarepta Therapeutics and hosted by Parent Project Muscular Dystrophy.
By delivering a shortened version of the dystrophin gene through a single intravenous infusion, Elevidys enables the body to produce micro-dystrophin, a crucial protein for muscle stability. Sarepta Therapeutics, which developed Elevidys, says over 275 patients have received the therapy in clinical trials, and more than 550 boys have been treated in real-world settings.
Approved by the FDA for DMD patients aged 4 and older — whether walking or not — Elevidys uses a precise combination of a viral vector (AAVrh74), a muscle-specific promoter (MHCK7), and the micro-dystrophin gene. This combination gives the therapy its distinct safety and effectiveness profile, according to Sarepta’s chief medical officer, Dr. James Richardson. Most clinical trial participants experienced mild side effects such as vomiting, fever and elevated liver enzymes, typically within the first 90 days post-treatment.
“The choices of vector, promoter, and transgene are a major determinant for the safety, expression, and function of gene therapies, respectively,” explained Richardson in the webinar. “The combination of the AAVrh74 vector, MHCK7 promoter, and the micro-dystrophin transgene result in a distinct safety and efficacy profile for Elevidys.”
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In its early trials, Elevidys showed statistically significant benefits in boys ages 4 to 5, forming the foundation for its accelerated approval. Now, research has expanded to include studies on non-ambulatory patients and the long-term effects across five years. Additional trials like MISSION, ESSENCE and ENVISION aim to explore the therapy’s full potential across the DMD community.
The safety profile of Elevidys remains under careful review. While a death due to liver failure in a 16-year-old patient raised serious concerns, an independent monitoring board determined that U.S. trials could continue unchanged. The incident was linked to both the therapy and a cytomegalovirus infection. Sarepta is now working with global experts to analyze the data and determine whether screening or new treatment protocols are needed.
“Multidisciplinary treatment has to play a role,” explained Dr. Chet Villa, a pediatric cardiologist and associate faculty member at Cinncinnati Children’s Hospital, when discussing assessing heart function before and after dosing. Dr. Craig McDonald, chair of the department of physical medicine and rehabilitation, further emphasized in the webinar the importance of assessing remaining functional muscle mass that could be preserved with this treatment. He suggested evaluating hand-to-mouth function and distal hand function to make informed decisions regarding risk-to-benefit ratios.
Despite the therapy’s high cost — approximately $3.2 million per treatment — Sarepta emphasizes its commitment to safety, education and collaboration with physicians. The company continues to share real-world safety data and trial results with regulators and the wider medical community.
For families facing the daily reality of DMD, Elevidys offers a one-time treatment option that could help preserve muscle function and delay disease progression, with ongoing studies refining how best to use it.
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