Closer Than Ever Before
The landscape for Duchenne muscular dystrophy (DMD) has changed significantly over the last six decades, with advances in comprehensive and supportive care — particularly respiratory and cardiac care — influencing the natural course of the disease and resulting in better quality of life and a longer lifespan. Children with this devastating disease used to live into their late teens. Now they’re routinely living into their late 20s and longer. They’re going to college, advancing their careers and starting families of their own.
MDA is proud to have supported foundational research that many of today’s advances are built upon. We’re gratified to see our work and investment paying off in the form of better outcomes for the DMD community and ongoing progress in other disease spaces. We’re excited to continue pushing science to its very limits in the search for treatments and cures — and today we’re on the verge.
Today, the immediate hope on the horizon — closer than ever before — is tied to a trio of promising drugs in late-stage development that are designed to treat not only symptoms, but the underlying genetic cause of DMD itself.
As we close in on the day when we’ll have an approved treatment for DMD that can modify the course of the disease in patients, I want to take a moment to share the latest on the status of the three drugs that are closest to hitting that mark. It’s taken MDA 65 years of unwavering resolve, $209 million — more than any other organization aside from the federal government — as well as countless hours in the labs and clinics, and in the lives of MDA staff, researchers, clinicians and the families fighting this disease, to get to where we are today. Closer than ever. Closer to treatments. Closer to cures.
Two potential therapies “skip” exons
In 1986, MDA-supported researchers identified the gene that, when flawed, leads to DMD. Not long after, in the early 1990s, we began supporting research into a promising treatment strategy called exon skipping. The strategy causes cells to “skip” (splice out, or leave out) certain sections of genetic code called exons during the protein production process. Leaving out these sections allows for the creation of shorter-than-normal, but partially functional, dystrophin — the muscle protein missing in DMD.
Today our investment is paying off, as there are a number of different exon skipping drugs in development designed to treat various mutations affecting different sections of the dystrophin gene — and, therefore, different sub-populations of kids with DMD. Furthest along in development are the two exon skipping drugs drisapersen and eteplirsen. Despite subtle differences in their chemical composition, both target exon 51 and may be effective in up to 13 percent of boys with DMD.
Drisapersen, under development by BioMarin Pharmaceutical to treat DMD, is poised to enter the market pending approval by the U.S. Food and Drug Administration (FDA). The next step for this drug will be review by an FDA advisory committee, scheduled for Nov. 24, 2015. The action date by which the FDA must make a decision on whether or not to approve the drug is Dec. 27, 2015.
SareptaTherapeutics, developer of eteplirsen, has announced that the advisory committee to review eteplirsen is tentatively scheduled for Jan. 22, 2016. The FDA decision date for eteplirsen is Feb. 26, 2016.
These could become the first two therapies on the market in the United States to treat the underlying cause of DMD in a subset of patients. And, if successful, they could lead the way for similar drugs currently under development to skip different exons and treat additional children with the disease.
One promising drug “reads through” genetic errors
Ataluren, in development by PTC Therapeutics, is another drug that’s generating a great deal of excitement in the DMD community as it moves through the late stages of development toward potential FDA approval. The compound is an experimental “stop codon read-through” drug, whose development MDA has long supported.
It’s designed to work by coaxing cells to ignore (“read through”) erroneous, premature stop codes in the gene for the dystrophin protein so that functional dystrophin can be produced. As with the exon-skipping drugs, drisapersen and eteplirsen, ataluren may be effective in approximately 13 percent of DMD patients.
PTC announced results last month from its phase 3 “ACT DMD” trial of ataluren in patients with DMD, demonstrating the drug’s strong safety profile and ability to slow disease progression.
Ataluren was granted conditional approval (under the brand name Translarna) by regulatory authorities in the European Union in August 2014. PTC announced Dec. 23, 2014, that it had begun the process of an NDA submission to the FDA. Completion of the application is slated for late 2015.
Marking out milestones
We’ve never lived in a time where even one drug to treat the genetic defect that causes DMD has been under consideration for approval. Now we’re seeing the culmination of decades of work and unwavering dedication as we face the distinct possibility that three candidates will reach that benchmark all within a relatively short period of time.
It’s a historical time for the MDA community, and an important milestone for DMD treatments. And as we make our way through it, MDA refuses to slow down even for a second.
We’re working harder than ever to bring effective treatments to our families, and we share in the excitement flowing through the DMD community right now as we look forward to positive outcomes not only for drispersen, eteplirsen and ataluren, but for numerous other therapies that surely will follow in their wake.
Please visit mda.org to learn more.
Laura Hagerty, Ph.D.
MDA Scientific Program Officer