Background: Duchenne muscular dystrophy (DMD) is a severe neuromuscular disorder caused by a lack of functional dystrophin. Ataluren promotes readthrough of an in-frame premature stop codon to produce full-length dystrophin and is indicated for the treatment of patients with nonsense mutation (nm) DMD. Study 041 (NCT03179631) is a phase 3, double-blind, placebo-controlled 72-week trial. The STRIDE Registry (NCT02369731) is an ongoing, long-term, real-world evidence study.
Objectives: To assess performance of upper limb (PUL) function in patients with nmDMD receiving ataluren plus standard of care (SoC) in Study 041 and in the STRIDE Registry.
Methods: In Study 041, boys with nmDMD aged ≥5 years, on a stable corticosteroid regimen, and with a 6-minute walk distance (6MWD) ≥150m were randomized 1:1, ataluren:placebo. The intention-to-treat (ITT) population comprised randomized boys who received at least one dose of study treatment (N=359; mean age 8.1 years); a key subgroup included those with baseline 300–400m 6MWD (n=169). STRIDE patients were propensity-score matched to patients receiving SoC alone in CINRG DNHS (NCT00468832), yielding a comparable population (N=261). Kaplan-Meier analyses estimated age at loss of upper limb function.
Results: Least-squares mean PUL total score change from baseline to week 72 (by MMRM analysis) numerically favored ataluren versus placebo (0.44, p=0.1059) in the Study 041 ITT population and was significant in the 300–400m 6MWD subgroup (1.02, p=0.0165).
In matched STRIDE versus CINRG patients (mean last assessment age, 13.1 versus 14.6), ataluren preserved hand-to-mouth function by 3.4 years (p=0.0046) assessed by entry level items of PUL versus Brooke Scale, respectively. Median age at loss of overhead reach favored STRIDE, consistent with the overall trend (15.8 versus 12.6; p=0.2872). Median age at loss of distal hand function was non-estimable for STRIDE patients.
Conclusions: These results indicate that ataluren may preserve upper limb function in patients with advanced nmDMD.