Sarepta Launches Gene Therapy Trial for Duchenne Muscular Dystrophy

Motor neuron connecting to muscle fiber, 3D illustration
Motor neuron connecting to muscle fiber, 3D illustration. A neuromuscular junction allows the motor neuron to transmit a signal to the muscle causing contraction. It is affected by toxins and diseases. [Source: Dr_Microbe/Getty Images]

Sarepta Therapeutics has announced the initiation of a new global study of SRP-9001 for the treatment of Duchenne Muscular Dystrophy (DMD). The study, known as EMBARK, will be carried out in partnership with Roche. SRP-9001 is an investigational gene transfer therapy intended to deliver a micro-dystrophin-encoding gene to muscle tissue for the targeted production of that protein.

This is the company’s second high profile attempt to prove that dystrophin replacement can be an “all-comers” treatment for DMD.

Sarepta is focused on DMD and limb-girdle muscular dystrophies (LGMDs). The company has three approved drugs on that market, and reports it currently has “More than 40 programs in various stages of development. Our vast pipeline is driven by our multi-platform Precision Genetic Medicine Engine in gene therapy, RNA and gene editing.”

The company’s first gene-based treatment was conditionally approved in Europe in 2014 and received accelerated approval in the US in 2016: Exondys 51 is a read-through-based drug that addresses about 13% of Duchenne patients. Other such gene editing therapies, which all address subsets of patients, have since been fast-tracked in the US or conditionally approved in EU. However, the EMA has rejected production of dystrophin as a viable endpoint for conditional approval.

It seemed as if Sarepta was going to answer the question of whether dystrophin replacement was sufficient to treat this disease with their earlier trial of SRP-9001. But that trial (Part I of Study 102), whose results were released in January of this year, did not met the primary functional endpoint even though it did meet the biological endpoint of increasing dystrophin levels.

DMD is a rare, fatal neuromuscular genetic disease that occurs in approximately one in every 3,500-5,000 males worldwide. DMD is caused by a change or mutation in the gene that encodes instructions for dystrophin.

Symptoms of DMD usually appear in infants and toddlers. Affected children may experience developmental delays such as difficulty in walking, climbing stairs or standing from a sitting position. As the disease progresses, muscle weakness in the lower limbs spreads to the arms and other areas.

Most patients require full-time use of a wheelchair in their early teens, and then progressively lose the ability to independently perform activities of daily living such as using the restroom, bathing and feeding. Eventually, increasing difficulty in breathing due to respiratory muscle dysfunction requires ventilation support, and cardiac dysfunction can lead to heart failure. The condition is universally fatal, and patients usually succumb to the disease in their twenties.

“We are delighted to announce the initiation of EMBARK, representing the first pivotal double-blind gene therapy trial in Duchenne which will be initiated in US, Europe and Asia,” said Doug Ingram, president and chief executive officer, Sarepta. “The initiation of EMBARK represents the culmination of enormous effort and success from a research, development and manufacturing perspective and is an extraordinarily important moment for the patient community and a leap forward in our effort to change the course of Duchenne’.”

Sarepta is responsible for global development and manufacturing for SRP-9001 and plans to commercialize SRP-9001 in the United States upon receiving FDA approval. In December 2019, Roche partnered with Sarepta to accelerate access to SRP-9001 for patients outside the United States. Sarepta has exclusive rights to the micro-dystrophin gene therapy program initially developed at the Abigail Wexner Research Institute at Nationwide Children’s Hospital.

The Company will host an SRP-9001 Micro-dystrophin R&D Day on Monday, Oct. 11, 2021, at 8:30 am Eastern Time. The presentation will be webcast live under the investor relations section of Sarepta’s website at and slides will be archived there following the call for one year.

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