Sarepta Therapeutics released the 168 week data for their exon skipping drug, eteplirsen, this morning. During a three year period, 7-13 year old boys with Duchenne (the age range of the boys who began the 201 study) would be expected to slow down considerably and many expected to lose ambulation entirely. After more than three years of treatment, results of the 6-minute walk test (at 168 weeks) showed continued ambulation across all patients evaluable on the test, with a decline in distance walked compared to that recorded at the week 144 timepoint. We are very encouraged to see a much smaller decline in distance walked during a 6 minute walk test compared to that anticipated based on our current understanding of the natural history of Duchenne.
In addition, pulmonary function continued to stabilize in all of the boys receiving eteplirsen. Progressive respiratory muscle decline leads to ventilation assistance in Duchenne and is a significant factor in mortality as well as quality of life. No serious adverse events were reported after more than three years of treatment, another very important consideration, since exon-skipping drugs will require chronic administration.
The intent of exon skipping is to transform the Duchenne phenotype into the milder form of dystrophy, Becker. Patients with Becker have a truncated, smaller form of the muscle protein, dystrophin, which stabilizes and protects the muscle cells from damage. Since Becker patients have this modified version of the protein from birth, their muscle cells have some protection as they grow. In the current exon skipping trials, boys begin treatment after the age of seven years old, well after significant damage has occurred and viable muscle cells have irreversibly converted to fibrosis and scar tissue.
Sarepta’s data this morning illustrates the need to begin treatment as early as possible. It also demonstrates that understanding the natural history of Duchenne is of paramount importance in evaluating the effectiveness of any drug. CureDuchenne has worked diligently this past year to create innovative methods which will help companies as they address regulatory and clinical design issues in order to accurately analyze the data for the greatest chance of drug approvals.
For the full press release, please visit Sarepta’s website: https://investorrelations.sarepta.com/phoenix.zhtml?c=64231&p=irol-newsArticle&ID=2006709