Evidentiary basis of the first regulatory qualification of a digital primary efficacy endpoint.

Stride velocity 95th centile (SV95C) is a wearable-derived endpoint representing the 5% fastest strides taken during everyday living. In July 2023, SV95C received European Medicines Agency (EMA) qualification for use as a primary endpoint in trials of patients with Duchenne muscular dystrophy (DMD) aged ≥ 4 years-becoming the first digital endpoint to receive such qualification. We present the data supporting this qualification, providing insights into the evidentiary basis of qualification as a digital clinical outcome assessment. Clinical trials, natural history studies, and patient surveys (ages 5 - 14 years) showed that SV95C is accurate, valid, reliable, sensitive, and clinically meaningful. SV95C significantly correlated with traditional DMD assessments, increased rapidly after steroid initiation (0.090 m/s 3 months post-treatment), and declined steadily in patients on stable steroid regimens. Compared with traditional assessments, SV95C demonstrated earlier sensitivity to disease progression (3 vs 9 months) and greater sensitivity at 12 months. Distribution- and anchor-based approaches revealed a change of - 0.10 to - 0.20 m/s as clinically meaningful. The EMA qualification of SV95C illustrates the willingness of regulators to accept novel digital endpoints for drug approval, setting an important precedent for the evidentiary basis of regulatory digital endpoint qualification that could transform clinical development in disorders affecting movement.