Sarepta Therapeutics, Inc., announced that a U.S. Food and Drug Administration (FDA) advisory committee has been forced to postpone Friday’s scheduled hearing to review the company’s New Drug Application (NDA) for eteplirsen, a potential treatment of Duchenne muscular dystrophy (DMD) amenable to exon 51 skipping.
A severe winter storm starting early Friday that is expected to dump up to two feet (0.6 meters) of snow in the Washington, D.C., area was the reason for the postponement. A replacement hearing date has not yet been announced.
The FDA’s Peripheral and Central Nervous System Advisory Committee is reviewing Sarepta’s application under the agency’s accelerated drug approval pathway, which allows for early approval of drugs with demonstrated benefits over current treatment for serious or life-threatening illnesses.
DMD, a rare and muscle-wasting genetic disorder that affects mainly boys, is an X-linked disease associated with mutations, or errors, in the gene that codes for dystrophin, a protein with a prime role in muscle fiber function. Eteplirsen is designed to address the disease’s underlying cause by restoring the dystrophin messenger RNA (mRNA), enabling the production of a shorter, functional form of the dystrophin protein. Simply put, it allows neighboring genes to correctly assemble by skipping the protein’s missing exon 51.
The dystrophin protein has 79 exons, all of which have a specific place. When one exon doesn’t exist, without “skipping” assistance the others cannot correctly link, and the protein fails to work.
A recent article published in the Annals of Neurology describes promising results from a Phase 2b study in DMD patients, boys ages 7-13, on eteplirsen treatment compared to a historical control group with typical DMD degeneration. At the three-year mark, according to the study, eteplirsen-treated patients were able to walk an additional 151 meters in the six-minute walk test compared to controls, and had a lower loss of ambulation (16.7%) compared to the historical group (46.2%).
The study, “Longitudinal effect of eteplirsen vs. historical control on ambulation in DMD,” was the result of a collaborative effort between researchers from the U.S., Belgium and Italy.
“As a clinician with extensive experience treating patients with Duchenne muscular dystrophy, it is apparent based on these data, that the boys treated with eteplirsen in this study are showing more signs of stability than would normally be expected at this stage of the disease. Remaining ambulatory is critical to greater independence over a longer period of time and a 151 meter difference indicates a marked slowing of disease progression,” Jerry Mendell, MD, director of the Center for Gene Therapy and Muscular Dystrophy at Nationwide Children’s Hospital, in Columbus, Ohio, and the study’s first author, said in a press release.
“The safety and tolerability demonstrated by eteplirsen is also important, as exon skipping therapies will require lifelong dosing to be effective. For over three years, it continues to be one of the safest drugs I have used in my career,” Dr. Mendell added.
Another hearing by the FDA advisory committee on the company’s NDA for eteplirsen, previously scheduled, is set for Feb. 26, 2016.
Sarepta, based in Cambridge, Massachusetts, is a biopharmaceutical company working toward the discovery and development of RNA-targeted therapies for rare, infectious, and other diseases. Eteplirsen is its lead DMD treatment candidate.
Duchenne muscular dystrophy, which is currently incurable, is estimated to affect one in every 3,500 to 5,000 boys worldwide. Sarepta estimates that about 13 percent of this DMD population is amendable to exon 51 skipping.