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  • Writer's pictureSaeed Anwar Anuj

On the horizon: Sarepta's micro-dystrophin gene therapy for DMD awaits FDA approval

Updated: Jun 12, 2023

Duchenne muscular dystrophy (DMD) is a severe and debilitating disease that primarily affects young boys. It occurs due to a genetic mutation that results in the lack of dystrophin, a crucial protein for proper muscle function. The absence of dystrophin causes muscle damage, weakness, loss of mobility, and eventually death, typically in the late teens or early twenties.

Unfortunately, there is no cure for DMD. However, there are four therapies approved by the U.S. FDA that can help slow down its progression. These therapies - Eteplirsen, Golodirsen, Viltolarsen, and Casimersen - use a technique called exon skipping to convert DMD into a milder form of the disease called Becker Muscular Dystrophy (BMD). Exon skipping involves the use of synthetic antisense oligonucleotides (AONs) to target and remove the mRNA of the dystrophin gene, leading to the production of a partially functional protein that compensates for the full-length protein's function. These four treatments benefit approximately 30% of DMD patients.

However, the most exciting news in the DMD community recently comes in the form of gene therapy. Originally developed at Children's National Hospital, this therapy aims to artificially introduce the correct genetic code into muscle cells, enabling the production of a miniaturized version of the dystrophin protein, called micro-dystrophin. The full-length dystrophin is too large to be transferred into the body, so the smaller micro-dystrophin is used instead. Micro-dystrophin is expected to perform at least the essential functions of healthy dystrophin. The gene therapy uses an adeno-associated virus (AAV) as a delivery vehicle, which deposits the genetic code for micro-dystrophin directly into the nucleus of muscle cells.

Sarepta Therapeutics, in partnership with the pharmaceutical giant Roche, owns the license for the treatment from Nationwide Children's Hospital and is sponsoring two clinical trials - EMBARK and ENDEAVOR - to test its efficacy. Last week, Sarepta announced that the U.S. FDA has accepted their Biologics License Application (BLA) for micro-dystrophin gene therapy for ambulant DMD patients. The BLA includes positive efficacy and safety results from multiple studies, including the EMBARK and ENDEAVOR trials, up to four years after treatment, with a consistent safety profile. Sarepta expects the FDA's decision by the end of May. If approved, this gene therapy has the potential to generate USD 4 billion in annual sales and change the course of the disease for those affected by DMD. The DMD community also eagerly awaits FDA's decision.

The development of gene therapy for DMD holds great promise for treating this severe and fatal disease. The use of AAV and micro-dystrophins has the potential to provide a cure and change the course of the disease for generations to come. While there is still much research to be done, the progress made so far is encouraging and offers hope for a brighter future for those affected by DMD.



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05 February 2023 Saeed Anwar Edmonton, Canada


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