Long-Term Evaluation of Givinostat in Duchenne Muscular Dystrophy, and Natural History Comparisons.

OBJECTIVES: This ongoing, open-label extension study is evaluating the long-term safety, tolerability, and efficacy of givinostat, a Class I and II histone deacetylase inhibitor, in patients with Duchenne muscular dystrophy (DMD). METHODS: The recruited patients completed one of two prior clinical studies (one Phase 2 and one Phase 3 [EPIDYS]), receiving givinostat or placebo, or were successfully screened but not randomized into EPIDYS. All receive givinostat oral suspension open-label at a flexible, weight-based dose in addition to systemic corticosteroids, and attend visits every 4 months. RESULTS: A total of 194 patients are included in the current analyses, with a mean duration of givinostat exposure (excluding use in prior studies) of 559.6 days (SD 373.0); when including use in the prior studies, the maximum exposure to givinostat was > 8 years. Although the majority of patients reported ≥ 1 adverse event (169/194 [87.1%]), most were mild/moderate in severity, and the safety profile of givinostat was consistent with prior studies. Post hoc comparisons with natural history datasets (ImagingDMD and CINRG) suggest, in propensity matched populations, givinostat added to systemic corticosteroids significantly delayed the loss of the ability to rise from the floor, the loss of the ability to complete the 4-stair climb test, and the loss of ambulation (by medians of 2.0-3.3 years; all nominal p < 0.05). INTERPRETATION: Overall, the safety and tolerability of long-term administration of givinostat in patients with DMD was consistent with previous studies. Comparisons with natural history data suggest that givinostat delays the occurrence of major disease progression milestones. TRIAL REGISTRATION: EudraCT number: 2017-000397-10; ClinicalTrials.gov identifier: NCT03373968.