On March 12, 2018 Sarepta Therapeutics, Inc. (NASDAQ: SRPT), a commercial-stage biopharmaceutical company focused on the discovery and development of precision genetic medicine to treat rare neuromuscular diseases, reported that it recently received final minutes from a February 2018 Type C meeting held with the Division of Neurology Products, United States Food and Drug Administration (the Division), to solicit the Division’s guidance on the development pathway for Sarepta’s therapeutic candidate, golodirsen, a phosphordiamidate morpholino oligimer engineered to treat those patients with Duchenne muscular dystrophy (DMD) who have genetic mutations subject to skipping exon 53 of the DMD gene (Press release, Sarepta Therapeutics, MAR 12, 2018, View Source [SID1234524681]).
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"Sarepta is thankful for the FDA Neurology Division’s thoughtful and direct guidance regarding golodirsen," said Doug Ingram, Sarepta’s president and chief executive officer. "Obviously, whether golodirsen will obtain accelerated approval is a review decision that will come after the submission and review of our NDA. But we greatly appreciate the willingness of the Neurology Division to engage and provide clear direction to us on the steps necessary to support an NDA submission for accelerated approval."
As previously announced in the third quarter of 2017, Sarepta’s 4053-101 study – a Phase 1/2 study to assess the safety, tolerability, pharmacokinetics and efficacy of golodirsen in 25 boys with confirmed deletions of the DMD gene amenable to exon 53 skipping – demonstrated statistically significant results in favor of golodirsen on all biological endpoints, including properly exon-skipped RNA transcript using reverse transcription polymerase chain reaction, quantity of dystrophin expression using Western blot and dystrophin intensity pursuant to immunohistochemistry.
Based on the results of Study 4053-101 and informed now by FDA’s feedback, Sarepta intends to complete a rolling submission of a golodirsen NDA by year-end 2018, seeking accelerated approval of golodirsen based on an increase in dystrophin protein as a surrogate endpoint.
Among other guidance:
The Division reported that in light of the precedent of eteplirsen’s approval, based on an increase in dystrophin protein as a surrogate endpoint reasonably likely to predict clinical benefit, a statistically significant increase in de novo, truncated dystrophin protein in Study 4053-101, based on a scientifically sound experimental design and rigorous analytical methods, may serve as a basis for accelerated approval of golodirsen for the treatment of Duchenne muscular dystrophy, assuming that Sarepta provides substantial evidence of the effect of golodirsen on dystrophin from a single study.
Sarepta proposed that its Study 4045-301 (ESSENCE), a Phase 3 ongoing placebo-controlled clinical trial assessing the efficacy of golodirsen and casimersen, serve as the post-marketing confirmatory study. The Division confirmed that ESSENCE could possibly serve as a confirmatory study if golodirsen is granted accelerated approval, with the understanding that it is incumbent upon Sarepta to describe how it will successfully enroll and complete the ESSENCE study in light of an accelerated approval.
The Division indicated that it is willing to accept a rolling submission of the NDA. The complete submission must include long-term animal toxicology studies, which will be completed in the fourth quarter of 2018. Hence, Sarepta anticipates the NDA submission will be complete in late 2018.
About Golodirsen
Golodirsen uses Sarepta’s proprietary phosphorodiamidate morpholino oligomer (PMO) chemistry and exon-skipping technology to skip exon 53 of the DMD gene. Golodirsen is designed to bind to exon 53 of dystrophin pre-mRNA, resulting in exclusion, or "skipping," of this exon during mRNA processing in patients with genetic mutations that are amenable to exon 53 skipping. Exon skipping is intended to allow for production of an internally truncated but functional dystrophin protein.
Golodirsen is one of the investigational candidates currently being evaluated in the ESSENCE study, a global, randomized double-blind, placebo-controlled study evaluating efficacy and safety in patients amenable to skipping exons 45 or 53.
Dystrophin is a protein found in muscle cells that, while present in extremely small amounts (about 0.002 percent of total muscle protein), is crucial in strengthening and protecting muscle fibers. A devastating and incurable muscle-wasting disease, DMD is associated with specific errors in the gene that codes for dystrophin, a protein that plays a key structural role in muscle fiber function. Progressive muscle weakness in the lower limbs spreads to the arms, neck and other areas of the body. The condition is universally fatal, and death usually occurs before the age of 30 generally due to respiratory or cardiac failure.
About Duchenne Muscular Dystrophy
DMD is an X-linked rare degenerative neuromuscular disorder causing severe progressive muscle loss and premature death. One of the most common fatal genetic disorders, DMD affects approximately one in every 3,500 – 5,000 male births worldwide.