DMD: Prosensa Announces New Grant and Provides Exon-Skipping Update

In an Aug. 28, 2013, announcement, the Dutch biotechnology company announced favorable results for drisapersen and a new grant for continuing development of PRO045

Article Highlights:
  • Prosensa-GSK drug drispaersen, which targets exon 51 of the dystrophin gene, has shown encouraging results with respect to walking ability and dystrophin protein production.
  • Prosensa recently received an $8 million grant to continue developing PRO045, which targets exon 45 of the dystrophin gene.
  • Several other experimental compounds are in Prosensa's pipeline.
  • MDA has been supporting exon skipping as a strategy for Duchenne muscular dystrophy since the 1990s.
by Margaret Wahl on August 30, 2013 - 5:00am

Update (Oct. 15, 2013):  In an Oct. 15, 2013, webinar, Prosensa announced preliminary results for the phase 1-2 trial of PRO044, designed to target exon 44 of the dystrophin gene. Dystrophin production that is believed to have occurred in response to the drug was seen in 12 out of 21 muscle biopsies that could be evaluated. No drug-related serious adverse events have been reported.

Update (Sept. 6, 2013): According to a Sept. 6 press release from Prosensa, the first patient in the PRO053 trial has received this medication. Prosensa says the initial portion of this trial will be conducted at several sites in Europe and that the trial may later be expanded to include additional sites in Europe and elsewhere.

Dutch biotechnology company Prosensa, developer of experimental drugs to treat Duchenne muscular dystrophy (DMD) using exon skipping, announced encouraging developments in an Aug. 28, 2013, press release.

Drisapersen looks promising

Included in the announcement are summaries of 2013 progress related to drisapersen, an experimental drug that targets exon 51 of the dystrophin gene and is being developed by Prosensa in collaboration with GlaxoSmithKline (GSK).

Drisapersen is intended to treat approximately 13 percent of DMD patients — those with deletions of dystrophin exons 50, 52, 45-50, 48-50 or 59-50.

It has recently shown encouraging results in terms of walking ability and dystrophin protein production in a phase 2 trial outside the U.S. Studies are continuing for those who already have been in a drisapersen trial. (Enter "drisapersen" at to learn more.)

More data are expected at forthcoming scientific meetings.

Large grant for PRO045

In addition, the Aug. 28 announcement notes that Prosensa recently received a grant of 6 million euros (about $8,022,462) for continued development of PRO045, an exon-skipping drug for DMD that targets exon 45 of the dystrophin gene.

PRO045 is intended to treat approximately 8 percent of DMD patients — those with deletions of dystrophin exons 44, 46, 46-47, 46-48, 46-49 or 46-51. It's being tested in a phase 2b trial outside the U.S.

The new award for PRO045 development is a Framework Programme 7 (FP7) grant from the European Commission, which gives financial support to European Union programs and policies.

In the pipeline

Prosensa's pipeline includes several additional compounds that target dystrophin exons to treat DMD.

PRO044 is aimed at approximately 6 percent of DMD patients — those with deletions of exons 43, 45, 38-43, 40-43, 42-43 or 45-54. A phase 1-2 trial outside the U.S. is ongoing but not recruiting new participants. The Aug. 28 announcement says Prosensa expects results from this study to be available in the fourth quarter of 2013.

Prosensa also is developing drugs that skip exon 53, exon 52 and exon 55, which are not yet being tested in clinical trials (see Pipeline).

The Aug. 28 announcement says Prosensa anticipates that the first patient in a safety study of PRO053 (to skip exon 53) will receive the drug in the third quarter of 2013.

In addition, the company has started a program called PROSPECT to target rarer mutations in the dystrophin gene. This research is in the laboratory phase.

MDA's role

MDA has supported research in exon skipping for DMD since the 1990s. A 2003-2006 MDA grant to Judith van Deutekom at Leiden (Netherlands) University Medical Center to develop exon skipping for DMD helped provide a foundation for DMD drug development at Prosensa, where van Deutekom is now vice president of drug discovery. For more history, see DMD: Exon-Skipping Timeline.

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