Early treatment of Duchenne muscular dystrophy (DMD) patients is increasingly perceived as important. However, assessing ambulation in patients below 4 years old is challenging. There is thus an urgent need to develop tools to evaluate new drug efficacy in young patients. Using the ActiMyo/Syde wearable sensor, designed to accurately measure ambulation during daily living, we obtained primary endpoint qualification of SV95C (stride velocity 95th centile) by the European Medicines Agency, in ambulant DMD from the age of 4, and recently submitted a qualification plan to the Food and Drug Administration.
SV95C robustness and sensitivity to assess ambulation in subjects below 4 years old was evaluated in the 3-year ActiLiege-Next study. Patients were asked to wear two ankle sensors daily for the first 3 months and then for 1 month every 3 months, and age-matched controls for 1 month every 6 months. SV95C reliability was assessed by comparing 2 two-week periods of the first recording month using intraclass correlation coefficient (ICC). Ability to differentiate patients from controls was assessed using a Mann Whitney U test.
To date, 27 patients were enrolled (median age ± standard deviation [min-max]: 33±8.9 months [16-47]), including 5 initiating steroids after enrolment, and 39 healthy volunteers (29±10.9 months [12-47]). As of 08/23/2024, all but one patients (N=25) and all controls (N=32) showed good baseline compliance. SV95C reliability was excellent with ICC of 0.99 for patients (N=25) and controls (N=32). Median SV95C at baseline was significantly different in patients and controls (p<0.01). Median 6-month SV95C showed no significant change from baseline for both DMD (N=18) and controls (N=7). All available longitudinal data will be shared at the congress. These initial results suggest that SV95C could be used for ambulation assessment during daily living in all ambulant DMD, including below 4 years.