A 1-year analysis from a natural history study in Chinese individuals with Duchenne muscular dystrophy

Background Duchenne muscular dystrophy (DMD) is a disabling and life-threatening, X-linked recessive disorder caused by mutations in dystrophin. Natural history studies can inform the disease characteristics of DMD, and data from these studies can be used to plan and design clinical trials and as external controls for long-term studies. We report 12-month results from the largest natural history study of individuals with DMD in China receiving standard of care treatment.Methods This ongoing, multicentre, prospective, single-cohort study (ClinicalTrials.gov: NCT03760029) was conducted in Chinese male participants with DMD (ambulatory aged <6 years [Group 1; n = 99]; ambulatory aged >= 6 years [Group 2; n = 177], and non-ambulatory of any age [Group 3; n = 36]. The follow-up period is >24 months, with some participants followed for 30 months. The primary endpoint was time to clinical milestones due to DMD disease progression, and motor, pulmonary, and cardiac function. Secondary endpoints were quality of life (QoL) assessments.Findings Mean (standard deviation [SD]) age at screening was 3.4 (1.2), 8.6 (2.0), 12.3 (2.7) and 7.4 (3.5) years in Groups 1, 2, 3 and total respectively. Mean (SD) North Star Ambulatory Assessment (NSAA) total score at baseline was 21.2 (5.8) in Group 1, 19.5 (8.3) in Group 2 and 20.0 (7.7) in ambulatory total. Overall, the time to clinical milestones due to DMD disease progression was consistent with previous findings, in which loss of ambulation occurred at 13 years. There was a trend towards a decline over 12 months in NSAA and timed motor function from age 6 years, with the greatest reductions observed thereafter. There were no consistent trends in measures of QoL, although participants of any age generally had poorer outcomes at Month 12 versus their domain scores at baseline.Interpretation This study improves the understanding of DMD progression according to the current standards of care in the Chinese DMD population and may inform selected endpoints and patient populations in clinical trials.