Eteplirsen is safe and well tolerated in boys with Duchenne muscular dystrophy (DMD) as young as 6 months of age, a study published in Neuromuscular Disorders reported.

This finding is based on an analysis of the results of the first clinical trial of the treatment in patients aged 6 months to 4 years.

The phase 2, multicenter, open-label, dose-escalation trial assessed the safety, tolerability, and pharmacokinetics of once-weekly intravenous infusions of eteplirsen in 15 boys with the disease.

Continue Reading

Participants were divided into 2 groups based on age. The first group consisted of 9 boys, aged 2 to 4 years, and the second consisted of 6 boys, aged 6 months to 2 years.

They were administered ascending doses of eteplirsen intravenously once a week over 10 weeks ranging from 2 to 30 mg/kg and then the highest dose for up to 96 weeks.

The primary endpoint was safety as measured by the number of participants with treatment-emergent adverse events, among other parameters, and the secondary endpoint was pharmacokinetics.

Read more about eteplirsen

The results showed that all boys tolerated eteplirsen well. There were no treatment-related discontinuations, deaths, or evidence of kidney toxicity. 

Most treatment-emergent adverse events were mild and included fever, cough, nasopharyngitis, vomiting, and diarrhea. 

Pharmacokinetics were consistent with previous findings in boys over 4 years of age, and there were no differences between the 2 groups of patients. 

“These data support the safety and tolerability of eteplirsen at the approved 30-mg/kg dose in boys as young as 6 months old,” the authors concluded.

Eteplirsen, marketed under the brand name Exondys 51, is an exon-skipping treatment for patients with DMD approved by the US Food and Drug Administration (FDA). It is intended for patients amenable to exon 51 skipping, aged 4 years and above, who are still able to walk.


Mercuri E, Seferian AM, Servais L, et al. Safety, tolerability and pharmacokinetics of eteplirsen in young boys aged 6–48 months with Duchenne muscular dystrophy amenable to exon 51 skipping. Neuromuscul Disord. Published online March 24, 2023. doi:10.1016/j.nmd.2023.03.008

Study of eteplirsen in young participants with Duchenne muscular dystrophy (DMD) amenable to exon 51 skipping. July 17, 2017. Updated December 9, 2021. Accessed April 6, 2023.