GSK and Prosensa announce failure of Phase III DMD trial

LONDON & LEIDEN, The Netherlands—GlaxoSmithKline(GSK) and Prosensa recently announced that GSK's Phase III clinical study ofdrisapersen, an investigational antisense oligonucleotide, for the treatment ofDuchenne muscular dystrophy (DMD) patients with an amenable mutation, did notmeet the primary endpoint of a statistically significant improvement in the six-minutewalking distance (6MWD) test compared to placebo.

Drisapersen is not yet approved or licensed for anyuse anywhere in the world.

Although he acknowledged that the news of thestudy's failure will be disappointing for those suffering from DMD and theirfamilies, Carlo Russo, senior vice president at GSK and head of rare diseasesresearch and development, said, "We are committed to evaluating the outcome ofthis study in the context of the overall development program with experts inthe field, and we expect such evaluation to help inform our next steps fordrisapersen. It is our hope that progress will be made in an effort to helpboys with DMD."

"While we are disappointed that this study did notmeet its primary endpoint, we remain committed to the overall program and willcontinue to work closely with GSK." said Hans Schikan, CEO of Prosensa. "Withno long-term disease modifying therapies available for DMD patients, researchand development of possible treatment options is of critical importance forboys and their families affected by this debilitating disease."

A total of186 boys were randomized to this double-blind, placebo-controlled study(DMD114044) and received drisapersen at a dose of 6mg/kg/week (N=125) orplacebo (N=61) via subcutaneous injection over 48 weeks. The difference in 6MWDbetween drisapersen and placebo groups did not reach statistical significance.There was also no treatment difference in key secondary assessments of motorfunction: a 10-meter walk/run test, a four-stair climb and North StarAmbulatory Assessment.

Full evaluation of the benefit-to-risk profile ofdrisapersen treatment across all studies is anticipated to be completed by yearend. This may include analyses of pooled results from various drisapersenstudies.

GSK obtained an exclusive worldwide license todevelop and commercialize drisapersen from Prosensa in 2009. Drisapersen hasbeen designated with orphan drug status in the European Union, United States andJapan. In June 2013, drisapersen was granted Breakthrough Therapy designationby the U.S. Food and Drug Administration.

DMD is a severely debilitating childhoodneuromuscular disease that affects up to one in 3,500 live male births. Thisrare disease is caused by mutations in the dystrophin gene, resulting in theabsence or defect of the dystrophin protein. Patients suffer from progressiveloss of muscle function due to the absence or defect of the dystrophin protein,often making them wheelchair-bound before the age of 12. Respiratory andcardiac muscle can also be affected by the disease. Few patients survive to theage of 30.

SOURCE: GSK/Prosensa news release