GlaxoSmithKline (GSK) and Prosensa's investigational drug 'drisapersen' being developed for the treatment of patients with Duchenne muscular dystrophy (DMD) has failed to meet the primary endpoint in a Phase III clinical trial (DMD114044).
In the double-blind, placebo-controlled study, drisapersen did not show a statistically significant improvement in the six minute walking distance (6MWD) test conducted in patients compared to placebo.
A total of 186 boys were randomised to the study and received drisapersen, an investigational antisense oligonucleotide, at a dose of 6mg/kg/week (N=125) or placebo (N=61) via subcutaneous injection over 48 weeks.
According to the companies, the difference in 6MWD between drisapersen and placebo groups did not reach statistical significance as there was no treatment difference in key secondary assessments of motor function: 10m walk/run test, four-stair climb and north star Ambulatory Assessment.
Complete assessment of the benefit-to-risk profile of the drug across all studies, which might include analyses of pooled results from several drisapersen studies, is expected to be completed by the end of 2013.
GSK senior vice-president Carlo Russo said the companies expect that progress will be made in an effort to help boys with DMD.
"We are committed to evaluating the outcome of this study in the context of the overall development programme with experts in the field, and we expect such evaluation to help inform our next steps for drisapersen," Russo said.
Results of the Phase III clinical trial have been submitted for presentation at future scientific meetings and will also be submitted for publication in a scientific peer-reviewed journal.
Drisapersen, which induces exon skipping of exon 51, is currently in late-stage development for DMD and its most commonly reported adverse events included injection site reactions and renal adverse events.
DMD is a severely debilitating childhood neuromuscular disease that affects up to one in 3,500 live male births mainly caused by mutations in the dystrophin gene, resulting in the absence or defect of the dystrophin protein.
Prosensa CEO Hans Schikan said: "With no long-term disease modifying therapies available for DMD patients, research and development of possible treatment options is of critical importance for boys and their families affected by this debilitating disease."
In 2009, GSK acquired exclusive worldwide license to develop and commercialise drisapersen from Prosensa.
The drug, which is currently not approved or licensed for use anywhere in the world, has been designated orphan drug status in the EU, the US and Japan.
In addition, the US Food and Drug Administration (FDA) granted breakthrough therapy designation for the drug in June.
Image: In the muscular dystrophy affected muscle (left), the tissue has become disorganized and the concentration of dystrophin (green), an important protein in normal muscle functioning, is greatly reduced. Photo: courtesy of Cbenner12.