FDA Approves Eteplirsen to Treat Duchenne Muscular Dystrophy

James Radke, PhD

The FDA has approved Sarepta’s eteplirsen ( Exondys 51) for the treatment of patients Duchenne muscular dystrophy (DMD)  who have a confirmed mutation of the dystrophin gene amenable to exon 51 skipping.
Eteplirsen was approved under the accelerated approval pathway. The FDA has concluded that the data submitted demonstrated an increase in dystrophin production that is ‘reasonably likely to predict clinical benefit in some patients with DMD who have a confirmed mutation of the dystrophin gene amenable to exon 51 skipping’.
Under the accelerated approval pathway, the FDA is requiring Sarepta Therapeutics to conduct a clinical trial to confirm the drug’s clinical benefit.  If the trial fails to verify clinical benefit, the FDA may initiate proceedings to withdraw approval of the drug.
The most common side effects reported by participants taking Exondys 51 in the clinical trials were balance disorder and vomiting.
In a press release, Janet Woodcock, M.D., director of the FDA’s Center for Drug Evaluation and Research. “In rare diseases, new drug development is especially challenging due to the small numbers of people affected by each disease and the lack of medical understanding of many disorders. Accelerated approval makes this drug available to patients based on initial data, but we eagerly await learning more about the efficacy of this drug through a confirmatory clinical trial that the company must conduct after approval.

Advocates, Patients, and Investors Very Very Happy

New of the approval has spread quickly through social media with most everyone being thrilled with the announcement.


$SRPT secures FDA approval for duchenne drug after long fight My quick story, will update. Wowza!!!

— Adam Feuerstein (@adamfeuerstein) September 19, 2016

WOO HOO! @US_FDA finally approved Sarepta's treatment for #Duchenne

— Stephanie Fischer (@RarePOV) September 19, 2016

BREAKING: Sarepta shares soar 85% after FDA grants accelerated approval for Duchenne Muscular Dystrophy drug

— CNBC (@CNBC) September 19, 2016

FDA grants accelerated approval for Eteplirsen for Duchenne Muscular Dystrophy

— Stand for Duchenne (@DuchenneCanada) September 19, 2016

Duchenne muscular dystrophy

Duchenne muscular dystrophy is caused by lack of a functional dystrophin protein, a protein that helps keep muscle cells intact. Patients with progressive muscle disorder experience symptoms in early childhood, losing the ability to walk as early as age 10. These patients, mostly boys, experience life-threatening heart and lung complications in their late teens and twenties.
There are many subsets of the Duchenne population based on the type of mutation found in the dystrophin gene. There are currently no drugs approved in the US to directly treat any of these groups.

Eteplirsen is designed to enable RNA to skip over the part of the DNA with a problematic mutation, enabling a functional (though shorter) dystrophin protein to be produced. Specifically, the drug skips a portion of the DNA known as exon 51. About 13% of the 35,000 DMD patients in the US and Europe have a mutation that might theoretically respond to a drug such as eteplirsen.
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