As Sarepta (formely AVI) announces promising results from its phase II interim data and GSK follows up its promising phase II data with a phase III study, things are looking good for an exon-skipping based therapy for Duchenne…if you happen to be in the 13% of those with Duchenne who have a mutation that can be improved by skipping exon 51. For quick reference, this group includes out-of-frame deletions in exons 45-50, 47-50, 48-50, 49-50, 50, and 52.
But for the other 77% of families out there dealing with other types of mutations including other deletions, duplications or point mutations, what does an exon 51 success mean? From the big picture standpoint a success with a drug focused on exon 51 means that we will have, for the first time, a “proof of principle” that the course of the disease can be modified beyond the effect gained by steroids. It means that work on skipping additional exons to include a broader range of mutations will speed up dramatically. It also means that companies working on other types of therapy that are not mutation-specific and their investors will gain confidence from knowing that the disease is not intractable. It means that there will have been established a “regulatory path” or roadmap that can be used by other companies to approve additional drugs. It means that new born screening will become ethically acceptable and we will identify all affected children earlier, which will in turn allow those children to participate in trials of new drugs at even earlier ages.
Not feeling altruistic? Keep in mind that:
Not fast enough? The good news is that it looks like there may be a number of existing approved drugs that may be useful in slowing the progress of Duchenne.
Parent Project Muscular Dystrophy’s mission is to support all those affected by the lack of dystrophin—boys and girls, Duchenne-like symptoms and Becker-like symptoms. We will continue to fund a wide portfolio of research projects that includes both mutation-specific and non-mutation-specific approaches. And we will support the back-up approaches to those approaches. This strategy dovetails with our research plan characterized by the phrase “Better, Faster, Now!” We will put better drugs into clinical testing, we will improve the speed of clinical testing and we will test approved drugs in parallel now. And we will still be in this business until meaningful treatments are available for all of those with Duchenne.
Blog by Sharon Hesterlee, Ph.D.
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