Approval for exon skipping drug discussed by the FDA

Published Date
Dr Marita Pohlschmidt
Claire and luke o'hanlon

Next week on Monday 25 April, the Food and Drug Administration’s (FDA) Advisory Committee will meet to discuss whether to recommend approval for eteplirsen, a potential drug for people with Duchenne muscular dystrophy whose mutation is amenable to exon 51 skipping.

The FDA convenes meetings of their Advisory Committees to receive independent advice from experts on questions such as safety and efficacy of a potential treatment or drug.  The companies developing the drugs are generally invited to present their data but they also have the option to invite participants to present on their behalf. Following the companies’ presentation, an open public hearing will take place that allows members of the public to bring forward their views. The members of the Advisory Committee then vote on whether the discussed evidence warrants approval and their recommendation will be considered by the FDA. However this vote is not binding and the FDA will make the final decision.

Claire O’Hanlon’s son, Luke (pictured), has Duchenne muscular dystrophy. Claire is Vice-Chair of our Northern Ireland Council and is representing Muscular Dystrophy UK at the meeting. Claire says:

This is a really big day for Duchenne families and important we all come together to show our support for FDA approval of this drug. We also need approval in Europe to get the drug to our children in the UK, so it’s crucial we persuade the drug company to apply to the European Medicines Agency.

In preparation for the meeting, an open letter that was signed and supported by 36 researchers and clinicians was sent to the FDA. The letter outlined their reasoning why the submitted data by Sarepta Therapeutics should be sufficiently compelling to warrant approval of the drug.

The main points of the letter are:

  • The clinical data submitted by Sarepta Therapeutics relies on change of the six minute walk test (6MWT, the distance the boys can walk in six mins). The FDA questioned the fact that the results of this test of the 12 boys taking part in the trial were compared to natural history data. The authors of the letter, however, state that this external control group was carefully chosen and was well-matched to the clinical criteria of the boys taking part in the trial.
  • After three years of treatment, the difference of the 6MWT between boys treated with eteplirsen and the external control group was 151m, which the authors claim is a ‘clinically significant difference’.
  • After four years of treatment, the age at which ambulation was lost was compared. All boys with Duchenne muscular dystrophy that were treated with eteplirsen and had reached an age of 14 years, could still walk compared to two out of ten boys that could still walk at the same age in the control group.
  • After four years of treatment, eteplirsen has been shown to be safe.

Muscular Dystrophy UK has supported the development of exon skipping technology for over 20 years. We fully support the request of the authors of this letter, urging the FDA to carefully consider the compelling evidence of the submitted clinical trial data. There is currently very little treatment available for boys with Duchenne muscular dystrophy and granting approval for eteplirsen might delay the progression of this devastating condition for many boys, improving their quality of life. It will also send a signal to regulatory bodies here in Europe so that they will look favourable should a drug application be brought forward by Sarepta Therapeutics.

The FDA has today released documents in which they commented on the clinical data and stated they do not feel it provides sufficient statistical evidence to support the use of eteplirsen. However, if the drug were to receive FDA approval this would allow for more evidence to be gathered on a much greater scale, whilst also ensuring that eligible boys can access the treatment.

As part of our campaign to secure a green light for the drug in Europe, our Chief Executive, Robert Meadowcroft, is writing to the drug’s manufacturer, Sarepta Therapeutics, to press them for more detail on their plans to seek European Medicines Agency approval.

Dr Marita Pohlschmidt, Director of Research at Muscular Dystrophy UK, said: 

Having invested in exon skipping research since the early 90s, we’re delighted to see Eteplirsen reach the stage of potential FDA approval. In the interest of all families affected by Duchenne muscular dystrophy, we are calling on the FDA to look carefully at the clinical evidence for Eteplirsen.

As founders of the MDEX consortium – a group of expert scientists – we are pleased to see the potential impact the group has had in successfully bringing this technology into clinical trial.

Professor Matthew Wood, who is currently developing exon skipping approaches at Oxford University, said:

Muscular Dystrophy UK has played a critical role over almost two decades supporting the development of exon skipping drugs, which have real potential to bring significant clinical benefit to Duchenne patients. First generation exon skipping drugs such as eteplirsen are very important as they have helped to build knowledge and understanding of how such drugs can be successfully developed and evaluated in patients. A positive FDA review of eteplirsen will galvanise patients, families, charities and the entire Duchenne scientific community to redouble their efforts in work towards the development of improved second generation compounds.

Further information and links

For more information, please contact Dr Ozge Ozkaya on 020 7803 4813 or email

To find out more about exon skipping, read our feature article

Read the latest research news on Duchenne muscular dystrophy

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