Comparing the change in 6-minute walk distance in nmDMD patients receiving ataluren: STRIDE Registry compared with phase 3 clinical trial

Objectives: We investigated whether ataluren-treated nonsense mutation Duchenne muscular dystrophy (nmDMD) patients in real-world practice (STRIDE Registry; NCT02369731) experienced a similar decline in 6-minute walk distance (6MWD) vs ataluren-treated patients in a phase 3 clinical trial (Study 020; NCT01826487). The 6-minute walk test is a motor function assessment that allows progressive loss of ambulation to be recorded.

Methods: STRIDE patients (n=42) were assessed by their first 48-week change (difference between their first ‘48-week assessment’ [between 40 and 72 weeks] and first assessment); Study 020 patients (ataluren [n=45] and placebo [n=50]) were assessed by change over 48 weeks. Only patients with a 6MWD of ≥300 to ≤400 metres (m) at first assessment were assessed. For patients who lost ambulation, 6MWD was imputed as 0 m the day ambulation was lost.

Results: Mean (95% CI) first baseline 6MWD assessment for STRIDE patients (349.7 [341.4, 358.0] m, n=42) was comparable to that for patients in Study 020 (ataluren, 356.7 [348.9, 364.5] m, n=47; placebo, 354.5 [346.3, 362.8] m, n=52). Mean (SD) age at first assessment was also comparable (STRIDE ataluren, 9.6 [3.1], n=42; 020 ataluren, 8.9 [1.8], n=47; placebo, 9.0 [1.5], n=52). STRIDE patients experienced a mean (95% CI) decline in 6MWD of −3.5 (−20.9, 13.8) m, performing better than ataluren-treated Study 020 patients (−28.3 [−45.1, −11.5] m). Placebo-allocated patients experienced a greater decline in 6MWD (−75.5 [−105.7, −45.3] m).

Conclusion: In both the real-world and clinical trial setting, ataluren delays motor function decline in nmDMD patients vs placebo, thus delaying disease progression.
Keywords: 6-minute walk distance; ataluren; Duchenne muscular dystrophy; STRIDE.