Prosensa Shares Jump on 'Encouraging' Phase II Drug Study

By Dow Jones Business News, March 17, 2014, 07:28:00 PM EDT

By John Kell

Shares of Prosensa Holding NV ( RNA ) jumped Monday after the Dutch biotechnology company reported "encouraging" data from a Phase II study for a Duchenne muscular dystrophy treatment.

The compound, drisapersen, is in development to treat DMD, a rare, fatal muscular disorder. DMD is one of the most prevalent rare genetic diseases globally, according to Prosensa, which said the disorder affects as many as 1 in 3,500 boys. The disorder is almost always fatal, and there is no approved disease-modifying therapy.

On Monday, Prosensa disclosed data from a 48-week U.S. study in 51 boys with DMD. The results indicated that boys in the higher-dose drisapersen group experienced stabilization and even improvements in their muscle function and physical activity for the 24-week treatment period and maintained that improvement during the 24-week follow-up phase.

"The maintenance of the clinically meaningful treatment benefit in the 24-week follow-up phase is very encouraging evidence for the drug's ability to produce prolonged stabilization of disease," said Craig M. McDonald, principal investigator and a professor of pediatrics at the University of California.

Investors cheered the news, sending Prosensa's shares up 34% to $9.05 in after-hours trading.

Prosensa went public in June at $13 a share and traded as high as $34.55 in early August. But the stock plummeted 70% in September after Prosensa said the DMD treatment didn't meet a primary endpoint in a Phase III study.

The company earlier this year regained the rights to drisapersen from GlaxoSmithKline PLC (GSK), which in 2009 had obtained an exclusive world-wide license to develop and commercialize the treatment. As a result of a termination of that collaboration pact, Prosensa has full rights to develop its DMD pipeline.

Meanwhile, a potential competing treatment made by Sarepta Therapeutics Inc. ( SRPT ) in November was delayed at least two years, after U.S. regulators suggested the company's study data was inadequate. Some analysts at the time had predicted an approval for Sarepta's treatment late this year or early in 2015.

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Prosensa Shares Jump on 'Encouraging' Phase II Drug Study