Eteplirsen May Be a Promising Therapy for Duchenne Muscular Dystrophy

A late-stage clinical trial performed by researchers at the University of Florida Health (UF Health) led to a new promising treatment for children with the most common form of muscular dystrophy, Duchenne Muscular Dystrophy. This condition causes the loss of mobility when the patients reach 12 years old, and life expectancy is averaged in their twenties.

Duchenne muscular dystrophy is an inherited disorder that occurs when a gene located on the X chromosome is mutated and does not produce its coded protein called dystrophin. Dystrophin has an important role in enabling muscles to remain intact and protected from injury. This condition only affects young males because they carry only one X chromosome while young females have two, giving them an additional dystrophin gene that compensates for the other mutated gene.

Dr. Barry Byrne, principal investigator for the hub site at UF Health, said in a news release that previous results from the first two phases of the clinical trial for eteplirsen, a drug that improves dystrophin production and leads to a shorter but functional protein, showed promising results like prolonging mobility in some patients with the condition Duchenne when compared with the control group that was not treated with the drug. This drug is not a cure but may potentially retard the loss of function in Duchenne patients.

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“The strategy is borrowed from the observation that patients with Becker muscular dystrophy have a truncated protein,” said Dr. Byrne, Director of UF’s Powell Gene Therapy Center. “Dystrophin is the largest protein in the body. Regions of it are repeated. These long, repeated segments of the protein can be shortened and still maintain function.”

Dr. Byrne said that if the current clinical trial is a success and is approved by the FDA only 15% of patients with Duchenne could be candidates for this therapy since patients with dystrophin genes containing long segments with errors cannot. The success of this trial will potentially help some patients with Duchenne to maintain mobility and prolong maintenance of pulmonary function.

Phase III of clinical testing will be performed in UF Health, which will be supported financially with $1.6 million in funding by Sarepta Therapeutics. During the trial, researchers will evaluate the effectiveness of the therapy, its adverse effects and its performance compared to other available therapies. This phase of the study is crucial for approval from the Food and Drug Administration.