Sarepta Therapeutics of Cambridge, Mass., has received word from the U.S. Food and Drug Administration (FDA) that the agency will consider an accelerated approval pathway for eteplirsen, an experimental drug the company is developing for boys and young men with Duchenne muscular dystrophy (DMD) who can potentially be treated by skipping of exon 51 of the dystrophin gene.
MDA has provided support for the development of exon skipping, a gene modification strategy for treating DMD and potentially other muscle diseases, since the 1990s. It has funded foundational research that has made drugs like eteplirsen possible.
The application for approval of eteplirsen to treat DMD will be filed by Sarepta under an FDA program that allows a promising drug for a serious disease to be approved on the basis of evidence that the drug is "reasonably likely to predict clinical benefit," rather than providing evidence of actual clinical benefit, such as lengthened life span or clearly improved function.
The FDA requires that at least one additional, confirmatory study be conducted when a drug is approved in this accelerated manner, but patients can have access to the drug while that confirmatory study is being conducted.
Sarepta says it plans to begin an open-label, large-scale, confirmatory study of eteplirsen in DMD patients who can walk and have dystrophin gene mutations near exon 51 during the third quarter of this year. Trial sites in the U.S. and Canada are anticipated, and a historical control group, instead of a placebo group, will be used to measure drug effects. All trial participants will receive eteplirsen.
Reversal of earlier FDA decision
In November 2013, the FDA had said it considered a new drug application for eteplirsen via the accelerated approval pathway to be premature. This decision has now been reconsidered by the agency, based on additional data supplied by Sarepta about eteplirsen between November 2013 and March 2014. Details of the adjusted decision are provided by Sarepta in an April 21, 2014, press release.
Additional trials for eteplirsen, other drugs are planned
In addition to the confirmatory study for eteplirsen, Sarepta plans to study the drug in patients who are younger than age 7 and in patients who are advanced in their disease progression to the point where they cannot walk a minimum distance or have lost the ability to walk entirely. Plans are to begin these trials later in 2014.
The company also plans to begin a placebo-controlled study with one or more of its follow-on DMD exon-skipping drug candidates (targeting exons of the dystrophin gene other than 51) by the end of the year.
MDA is working with Sarepta and other partners to facilitate a webinar for the patient community later this week and will provide details as soon as possible.
"We're thrilled that the FDA has decided to allow an accelerated approval pathway for eteplirsen," said Valerie Cwik, M.D., MDA's chief medical and scientific officer. "Given MDA’s mission to save and improve the lives of anyone fighting muscle disease, safe and effective drug development remains a critical priority as we work earnestly to find treatments and cures on behalf of the families we serve. We're especially pleased to see a clear path forward for this promising exon-skipping drug.
"Thanks to our supporters, MDA has had a rich and unparalleled role in funding the foundational research that has made the progress we’re seeing today possible. Our goal now is to finish the fight by moving from clinical trials into widespread drug deployment, and today’s development is an important mile marker in that journey.”