A Randomized, Double-blind, Placebo-controlled Study of Delandistrogene Moxeparvovec (SRP-9001) for Duchenne Muscular Dystrophy (DMD)

Sarepta Therapeutics, Inc.41 enrolled

Overview

The purpose of this study is to evaluate the safety and efficacy of exogenous gene transfer in DMD participants by measuring biological and clinical endpoints in three parts: two 48-week randomized, double-blinded, placebo-controlled periods (Part 1 and Part 2), and an open-label follow-up period (Part 3). Participants who are randomized to placebo in Part 1 will have the opportunity for treatment with delandistrogene moxeparvovec in Part 2. In order to provide a uniform approach to monitoring long-term safety and efficacy in participants who received SRP-9001 in a clinical trial, the Sponsor has amended Study Completion for this study to occur at Week 130. Therefore, participants have transitioned and will complete the remainder of the Part 3 follow up visits in a long-term extension study, SRP-9001-305 (NCT05967351).

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

QUADRUPLE

Enrollment

Conditions

Muscular Dystrophy, Duchenne

Interventions

Eligibility

Sex: MALEMin age: 4 YearsMax age: 7 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Established clinical diagnosis of DMD and documented dystrophin gene mutation of DMD phenotype. * Indication of symptomatic muscular dystrophy by protocol-specified criteria. * Ability to cooperate with motor assessment testing. * Stable dose equivalent of oral corticosteroids for at least 12 weeks. * A frameshift mutation contained between exons 18 and 58 (inclusive). Exclusion Criteria: * Impaired cardiovascular function on echocardiogram. * Prior or ongoing medical condition on physical examination, electrocardiogram, or laboratory findings that could adversely affect participant safety, compromise completion of follow-up, or impair assessment of study results. * Exposure to another investigational drug or exon skipping medication within 6 months of screening. * Exposure to an investigational or commercial gene therapy product. * Abnormal liver or renal function by protocol-specified criteria. Other inclusion/exclusion criteria apply.

Locations (2)

David Geffen School of Medicine at UCLA

Los Angeles, California, United States

Nationwide Children's Hospital

Columbus, Ohio, United States

Outcomes

Primary Outcomes

Change From Baseline at Week 12 in Quantity of Delandistrogene Moxeparvovec Dystrophin Protein Expression as Measured by Western Blot Adjusted by Muscle Content

Baseline muscle biopsies with ultrasound guidance were performed pre-treatment and post-treatment (Week 12) on all participants. The change from baseline in delandistrogene moxeparvovec dystrophin expression in these muscle biopsy samples was determined by Western Blot. Dystrophin protein was measured and then adjusted based on the percentage of muscle content in the biopsy sample. An increase in protein expression indicates production of the delandistrogene moxeparvovec dystrophin protein.

Time frame: Baseline, Week 12 (Part 1)

Change From Baseline at Week 48 in NSAA Total Score

The NSAA is a healthcare provider administered scale that rates performance of various motor abilities in ambulant children with Duchenne Muscular Dystrophy and is used to monitor disease progression and treatment effects. During assessment, participants are asked to perform 17 different functional activities that are graded as: 2 - "Normal" - no obvious modification of activity; 1 - Modified method but achieves goal independent of assistance; 0 - Unable to achieve independently. The NSAA total score is defined as the sum of all 17 items, ranging from 0 (worst) to 34 (best). The response vector consists of the change from baseline in NSAA total score at the post-baseline visit. The model includes the covariates of treatment group, visit, treatment group by visit interaction, age group, baseline NSAA total score, and baseline NSAA total score by visit interaction. All covariates are fixed effects in this analysis. An increase in score indicates an improvement in motor function.