Duchenne muscular dystrophy (DMD) is a fatal, X-linked disease, characterized by progressive muscle weakness. Loss of ambulation is a major milestone in disease progression. Approximately 10–15% of cases of DMD are caused by a nonsense mutation (nmDMD) in the dystrophin gene, which leads to translation of truncated, non-functional dystrophin. Ataluren is the first approved therapy to target the underlying cause of nmDMD, enabling formation of full-length, functional dystrophin.

In this study, age at loss of ambulation was evaluated in patients with nmDMD taking ataluren for at least 12 months while enrolled in the international, multi-center STRIDE (Strategic Targeting of Registries and International Datasets of Excellence) Registry (N=207). Data were extracted from the registry on 9 July 2018. Kaplan–Meier analyses were used to investigate age at loss of ambulation.

Mean (standard deviation, SD) age of registry participants starting ataluren treatment was 9.8 (3.7) and 89.2% were being treated with corticosteroids in addition to ataluren. At the date of data extraction, registry participants had a mean (SD) age of 11.6 (3.6) years. Mean (SD) exposure to ataluren within the registry was 372.6 (211.6) patient-years and 44.6% of patients had been on ataluren for more than 720 days. Mean (standard error) age at loss of ambulation in registry participants was 15.5 (0.3) years, and 50% of patients were still ambulatory at the age of 16.5 years. Safety outcomes were consistent with the known safety profile of ataluren.