Drug Information Update- Exondys 51 (eteplirsen)

New Drug Approval:

On September 19th, 2016 the FDA approved Exondys 51 (eteplirsen) for the treatment of Duchenne Muscular Dystrophy (DMD) in patients who have a confirmed mutation of the DMD gene that is amenable to exon 51 skipping.   

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Drug Overview & Place in Therapy:

Exondys 51 (eteplirsen), the first drug approved for treatment of DMD, binds to dystrophin mRNA and results in production of a truncated dystrophin protein. Exondys 51 is administered as an intravenous infusion once weekly. The currently available therapeutic options to treat patients with DMD are mainly symptomatic measures, including physical therapy and management of respiratory and cardiac issues. Only glucocorticoid therapy has been shown to delay loss of ambulation and respiratory decline, but continuous therapy is associated with a variety of detrimental side effects. There is no cure for DMD and the disorder leads to loss of independence and early mortality for patients.

Duchenne Muscular Dystrophy (DMD) is a rare genetic disorder seen predominately in young males that results in a near total lack of dystrophin production, a protein essential for muscle integrity, which leads to a progressive loss of muscle function. It is estimated there are nearly 20,000 DMD patients in the United States.  DMD mutations that are treatable by skipping exon 51 are thought to comprise 13% of DMD patients which accounts for roughly 1500 patients.

The approval of Exondys 51 is based on an increase in dystrophin seen in some patients treated on Exondys 51.  The FDA noted that clinical benefit of Exondys 51 has not been established in clinical trials.  The FDA will require an additional clinical trial to demonstrate clinical benefit of this drug and has noted that if the drug fails to show clinical benefit it will withdraw approval of the drug.  The results of those trials will not be available for several years. Earlier this year there were three agents under review at the FDA for DMD; one of them received a complete response letter and clinical development of the drug ceased, the other agent received a refusal to file from the FDA.  The DMD community has been eagerly awaiting approval of an agent and will likely support and demand this drug for all patients with DMD amendable to exon 51 skipping.  In a company press release, Sarepta, the manufacturers of Exondys 51 noted that the U.S. launch will occur very soon.  The manufacturer has stated that an estimated cost for a child weighing 25-30 kilograms will be roughly $300,000 per year.  

Utilization Management Strategies:

A Prior Authorization Guideline will be available for use when the drug becomes commercially available.  A full clinical review of Exondys 51 (eteplirsen) was conducted during the MedImpact 1st Quarter 2016 Pharmacy & Therapeutics (P&T) Committee Meeting in February.  Upon receiving pricing information and reviewing effective cost management strategies, MedImpact will make final recommendations regarding formulary placement and utilization management.

For more information, please contact the MedImpact Drug Information Team


Please note: The views expressed in the above reflect the opinions of the MedImpact Drug Information team.

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