Abstract
Duchenne muscular dystrophy (DMD) is an X-linked recessive disease characterized by mutations in the dystrophin gene, causing motor and pulmonary function decline. Viltolarsen is indicated for patients with dystrophin gene mutations amenable to exon 53 skipping. Here, we report safety, motor function, and the first pulmonary function results from the open-label, phase II Galactic53 trial of viltolarsen (NCT04956289). Male participants aged ≥ 8 years with DMD received 80 mg/kg intravenous viltolarsen once weekly for 48 weeks. Results from participants receiving viltolarsen were compared with an external control cohort group-matched for multiple variables. All treatment-emergent adverse events were mild or moderate, 4 were considered treatment-related, and no participants discontinued. Participants receiving viltolarsen experienced clinically meaningful benefits in pulmonary function with higher percent predicted forced vital capacity and higher peak cough flow at Week 49 compared with the control cohort for both ambulatory and nonambulatory participants. Viltolarsen also stabilized upper limb motor function over the Treatment Period. These results support viltolarsen as an important part of the treatment armamentarium for both ambulatory as well as nonambulatory patients with DMD.