Eteplirsen for the Treatment of Duchenne Muscular Dystrophy (DMD) (S42.001)

TLDR: The present study used a double‐blind placebo‐controlled protocol to test eteplirsen's ability to induce dystrophin production and improve distance walked on the 6‐minute walk test.

Abstract: Objective: Phosphorodiamidate morpholino oligomers (PMOs) are synthetic nucleic acid analogs that can be designed to sequence-specifically block spliceosomes from binding to dystrophin pre-mRNA, resulting in omission of the targeted exon from the transcript and restoration of the reading frame with the goal of enabling synthesis of internally-shortened dystrophin. Background: DMD, a rare, X-linked genetic disease results in progressive muscle degeneration and premature death. DMD is primarily caused by whole exon deletions in the dystrophin gene resulting in a shift of the mRNA reading frame that prevents production of functional dystrophin protein. Design/Methods: As of June 3, 2016, 81 of 150 treated patients had received weekly eteplirsen for ≥1 year. Results: PMO eteplirsen received accelerated approval in the US for patients with a dystrophin gene mutation amenable to exon 51 skipping based on an increase in dystrophin in skeletal muscle in some patients. Mean dystrophin increases as measured by Western blot were observed following 180 weeks of treatment in the pivotal Phase II Studies 201/202 when compared to untreated DMD controls (N=11; +0.85%, p=0.007) and at Week 48 in Phase III Study PROMOVI when compared to baseline (N=12; +0.28%, p=0.008). Immunohistochemistry analysis at Week 180 in Study 201/202 also showed mean increases in dystrophin as measured by % dystrophin-positive fibers (N=11; +16.27%, p 4.5 years of treatment. Conclusions: Eteplirsen is the first exon skipping therapy approved for the treatment of Duchenne muscular dystrophy amenable to exon 51 skipping. Lessons learned from the eteplirsen clinical development program can aid in development of PMO therapies targeting additional exons. Study Supported by: Sarepta Therapeutics, Inc. Disclosure: Dr. Charleston has received personal compensation for activities with Sarepta Therapeutics as an employee. Dr. Schnell has received personal compensation for activities with Sarepta Therapeutics as a full time employee. Dr. Dworzak has received personal compensation for activities with Sarepta Therapeutics as an employee. Dr. Donoghue has received personal compensation for activities with Sarepta Therapeutics as an employee. Dr. Lynch has received personal compensation for activities with Sarepta Therapeutics, Inc. as an employee. Dr. Lewis has nothing to disclose. Dr. Chen has nothing to disclose. Dr. Rodino-Klapac has nothing to disclose. Dr. Sahenk has nothing to disclose. Dr. Voss has received personal compensation for activities with Sarepta Therapeutics as an employee. Dr. DeAlwis has received personal compensation for activities with Sarepta Therapeutics as an employee. Dr. Frank has received personal compensation for activities with Sarepta Therapeutics, Inc. as an employee. Dr. Eliopoulos has received personal compensation for activities with Sarepta Therapeutics as an employee. Dr. Mendell has received personal compensation for activities with Sarepta Therapeutics, Inc.