A large-scale, phase 3 trial of the experimental exon-skipping drug drisapersen, in development to treat Duchenne muscular dystrophy (DMD), found no statistically significant differences on tests of walking distance or motor function between trial participants treated with the drug and those treated with a placebo.
The results were jointly announced in a Sept. 20, 2013, press release from drisapersen's developers, multinational pharmaceutical company GlaxoSmithKline (GSK) and Dutch biotechnology company Prosensa.
"Today’s news is very disappointing," said neurologist Valerie Cwik, executive vice president and chief medical and scientific officer at MDA. "We’re eager to see the data to better understand why the drug failed in this trial."
A Sept. 20, 2013, conference call, available for replay on the Prosensa website, provides further details. In the approximately 30-minute call, Prosensa's CEO Hans Schikan and Giles Campion, chief medical officer at Prosensa, noted that today's announcement represents "top-line" (preliminary) results and that full results of the phase 3 trial of drisapersen will be presented at upcoming medical conferences in October.
The conferences are the World Muscle Society meeting to take place Oct. 1-5, 2013, in Asilomar, Calif., and the Oligonucleotide Therapeutics Society meeting, which will take place in Naples, Italy, Oct. 6-8.
MDA says DMD drug portfolio is deep
MDA has been supporting the development of exon skipping for DMD since the 1990s, largely through basic science research.
"MDA remains committed to a deep and comprehensive portfolio of experimental drugs in the pipeline for DMD, including other exon-skipping drugs," Cwik said. "Drisapersen results do not affect the prospects for other Duchenne drug candidates in clinical trials or early development. While the setback for this trial is unfortunate, we remain hopeful that breakthroughs are on the horizon."
Phase 3 trial found drisapersen not better than placebo
The phase 3 trial of drisapersen took place at some 50 sites (none of which were in the U.S.) and involved 186 boys (125 on the drug, 61 on a placebo) with DMD who were more than 5 years old, able to walk, and had mutations in the dystrophin gene that potentially could be treated by coaxing cells to skip exon (section) 51 of the dystrophin gene.
Trial participants received weekly injections of drisapersen at a dosage level of 6 milligrams per kilogram of body weight or weekly injection of a placebo for 48 weeks (nearly a year).
Results for this 48-week, phase 3 trial showed that:
Phase 2 results had been encouraging
"These results demonstrate that the clinical trial process works," Cwik said. "Researchers will gain valuable insight from this trial that will shape future trials."
In a Sept. 20, 2013, email to patient groups, Rohit Batta, global medical affairs leader for GSK's neuromuscular disorders unit, said the following:
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