DMD: Drisapersen Dosing Planned for Later in 2014

In a May 22, 2014, letter, Prosensa provides updates on drisapersen and other Duchenne MD compounds in its pipeline, and on its natural history study

Article Highlights:
  • Prosensa, developer of drisapersen and other exon-skipping compounds to treat Duchenne muscular dystrophy, says it will begin re-dosing patients with drisapersen in the third quarter of 2014.
  • The company is developing exon-skipping compounds for DMD and has provided updates about them.
  • Prosensa's natural history study of DMD has nearly completed its enrollment goal of 250.
by Margaret Wahl on May 28, 2014 - 8:12am

Dutch biopharmaceutical company Prosensa, developer of the experimental Duchenne muscular dystrophy (DMD) drug drisapersen, says it is moving the compound forward through regulatory agencies in the U.S. and Europe and will resume administering it to a first group of trial participants in the third quarter of 2014.

The company announced these plans in a May 22, 2014, letter to patient groups. In this same communication, Prosensa introduced its new web page Drisapersen Re-Dosing, which will provide updated tracking of information on administration ("re-dosing") of drisapersen in ongoing studies.

Drisapersen is an exon-skipping drug, designed to cause muscle cells to reinterpret flawed instructions for the dystrophin protein and produce short, but functional, dystrophin. Lack of dystrophin protein in muscle cells is the underlying cause of DMD. Drisapersen is given by injection and targets a section of the dystrophin gene called exon 51.

MDA has funded the development of exon skipping for DMD since the 1990s. A current grant to Steve Wilton at Murdoch University in Australia aims to develop exon-skipping drugs for the rarer DMD-causing mutations in the dystrophin gene

Encouraging data

Dosing with drisapersen was halted in September 2013, after a large-scale, phase 3 trial of the drug failed to show a difference on tests of walking distance or other motor function between treated and placebo participants.

However, release of additional data since then has yielded more encouraging results, which Prosensa says support the idea that "treating earlier in the disease and treating for a longer duration confers a treatment benefit for boys with DMD."

Several compounds in development; natural history study underway

The May 22 letter from Prosensa also delivers news about the company's additional exon-skipping compounds in development for DMD and its large-scale natural history study, now being conducted to refine understanding of usual disease progression. The letter offers the following updates.

  • PRO044, targeting dystrophin exon 44, has completed a phase 1-2 study in Europe, and an extension study is planned for the second half of 2014.
  • PRO045 and PRO053, targeting exons 45 and 53 respectively, are in phase 1-2 clinical trials and are expected to enter confirmatory studies during the first half of 2015.
  • PRO052 and PRO055, targeting exons 52 and 55 respectively, are in advanced laboratory development.
  • PROSPECT, targeting multiple dystrophin exons in the exon 10-30 region, is in early-stage laboratory development.
  • Prosensa's natural history study of DMD remains open to recruitment but has almost completed enrollment. (As of May 22, the study had enrolled 247 participants out of a planned 250.)

For more information

Families are invited to send questions to Claire Leyten, manager of patient group relations at Prosensa, at patientinfo@prosensa.nl.

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