GlaxoSmithKline, Propensa's experimental Duchenne muscular dystrophy drug drisapersen achieved main goal in mid-stage study

GlaxoSmithKline and Propensa's experimental therapy drisapersen achieved the main goal in a Phase II trial of a clinically meaningful and significant difference in the six-minute walking text with continuous treatment compared to placebo in patients with Duchenne muscular dystrophy (DMD). At 24 weeks, patients in the continuous drisapersen treatment arm walked over 35 meters more than those in the placebo arm, and this difference was maintained at 48 weeks. Shares of Sarepta Therapeutics, which is developing the similar drug eteplirsen, climbed as much as 11 percent on the news, with Deutsche Bank analyst Robyn Karnauskas noting that the study "validates Sarepta's platform," adding that the former's better safety profile potentially differentiating it from GlaxoSmithKline and Propensa's agent.

The Phase II study randomised 53 boys with DMD who were at least 5 years old. Unlike continuous treatment, no significant difference in walking distance was observed between the intermittent drisapersen and placebo groups at 24 weeks, although a trend towards a longer walking distance in the treatment group was observed at 48 weeks. No difference in muscle strength was observed in either treatment group compared to placebo after 24 or 48 weeks. Although Rohit Batta, head of global medical affairs at GlaxoSmithKline's rare disease unit, had previously noted that a "small" number of boys receiving drisapersen were hospitalised due to proteinuria and thrombocytopaenia, company spokeswoman Melinda Stubbee confirmed that none of the four hospitalisations occurred in the Phase II trial.

Data from a late-stage study that began in 2011 are expected to be released later this year. Drisapersen has been designated orphan drug status by the US and European regulators and Kepler Capital Markets analyst Fabian Wenner estimates that the medicine, if approved, could have peak sales of as much as 500 million pounds ($766 million).

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