Eteplirsen (Exondys 51) is an antisense oligonucleotide that targets the skipping of exon 51 in the DMD gene. Eteplirsen was developed by Sarepta Therapeutics and is conditionally authorised in the United States; it allows dystrophin to be produced in the muscle.
Ability to walk preserved over the long-term
A published article from the Journal of Neuromuscular Diseases describes new results from one of the very first trials of eteplirsen, which included 12 participants with DMD aged 7 to 13 years who were able to walk at the time of enrolment. These results relate to data obtained for the 6-minute walk test among these boys after 4 years of weekly treatment with eteplirsen, compared with natural history data for children with DMD who were not being treated, from the Italian and Belgian DMD registries.
After one year of treatment, 17% of participants (2/12) had lost the ability to walk, but after 4 years of treatment, all the other participants could still walk, including those over 14 years of age (4/12). On average, these participants could walk 196.3 m further than the non-treated cohort, a significant difference. In comparison, the mean age for loss of ability to walk was 13 years in the non-treated cohort taken from the registries.
On the other hand, the difference in NSAA functional scores obtained after 3 years of treatment, between the trial participants and the registry cohort, was not significant. It was not possible to obtain data from after the 4-year treatment period.
The results of this study should be weighed up carefully, because the comparison was not a direct one, to a placebo group, but to a non-treated group external to the study.
Other trials to evaluate the efficacy of eteplirsen are currently ongoing, including one in France.
