A study recently published in the Journal of Neuromuscular Diseases evaluated several clinical trials of eteplirsen in patients with Duchenne muscular dystrophy (DMD) and found that patients who receive the drug may have slower cardiac decline than those who do not.
“This study is the first to demonstrate significant change in measured cardiac function with an innovative therapy that aims to increase dystrophin expression, suggesting clinically meaningful multi-year delays in reaching cardiomyopathy milestones,” the authors wrote.
Eteplirsen, marketed as Exondys 51, is a therapy designed for patients with DMD who have mutations that can be treated by skipping exon 51 of the DMD gene (about 13% of patients). Individuals who receive eteplirsen produce a shorter yet still-functional version of the dystrophin protein. The drug was approved by the U.S. Food and Drug Administration in 2016. While research has shown that eteplirsen can help prolong walking and slow DMD’s impact on breathing, its impact on heart function is not as well-known.
The study included 122 patients who received eteplirsen and 122 controls with DMD who did not receive the therapy. The main outcome was changes in left ventricular ejection fraction (LVEF), a measure of how well the left ventricle of the heart can pump blood.
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Treated patients had a mean age of 9.1 years and were followed for an average of 26.5 months. Controls had a similar mean age of 9.6 years but were followed for an average of 69.3 months.
At follow-up, zero treated patients and 27 controls had an LVEF less than 50%. Additionally, 13 treated patients and 60 controls had an LVEF below 60%. Patients who were treated experienced an average decline in LVEF of 0.66 percentage points per year, compared to 1.38 percentage points per year among controls.
The authors projected that eteplirsen-treated patients would reach a median LVEF below 55% at 27.6 years of age, whereas controls would reach the same threshold at a median age of 19.2 years. Although these values are only estimates, they suggest that treated patients may have an additional 8.4 years before their LVEF drops below 55%.
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