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Prosensa gets an FDA green light for its once-failed DMD drug

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Prosensa CEO Hans Schikan

After a late-stage failure and a kiss-off from partner GlaxoSmithKline ($GSK), Prosensa ($RNA) and its innovative treatment for Duchenne muscular dystrophy seemed to be on a downward slope. But now, after a series of "positive" meetings with the FDA, the company says it plans to submit its breakthrough-designated drug for approval this year, taking advantage of the agency's accelerated pathway.

In Phase III results revealed in the fall, Prosensa's treatment, called drisapersen, failed to beat out placebo in improving walking distance in boys with the muscle-destroying disease. Months later, however, the company came back with new analysis and extension-study data suggesting administering the drug earlier in the disease and lengthening treatment can delay the progression of DMD.

Those results, along with some mid-stage data Prosensa dubbed "clinically meaningful," will make up drisapersen's new drug application, the company said, which, under the FDA's accelerated review program, can be approved based on surrogate endpoints. At the agency's behest, Prosensa has committed to run two post-approval studies to confirm drisapersen's efficacy.

Over the past year, Prosensa has become something of a bellwether for the DMD field. After September's Phase III failure for drisapersen, the FDA seemed to tighten up on exon-skipping therapies, giving word to competitor Sarepta Therapeutics ($SRPT) that it would no longer consider an early approval for the similar eteplirsen. In January, PTC Therapeutics' ($PTCT) ataluren, another DMD drug with a different mechanism of action, endured a rejection at the hands of European regulators, who declined its application for conditional approval.

Since then, however, DMD drug developers have had better fortune--or have at least gotten more optimistic. In April, Sarepta announced that it had come to terms with the FDA and now planned to file for an early eteplirsen approval by year's end. And, last month, the European Medicines Agency changed its tune on PTC's ataluren, recommending in favor of an early nod.

And now Prosensa is back on solid ground, at least in the short term, news that sent its shares up about 5% in premarket trading and its CEO on something of a victory lap.

"Given the urgent need to find effective therapies for boys afflicted with this devastating disease, we could not be more pleased with this favorable outcome and with the regulatory authorities' willingness to advance investigational products for the treatment of DMD" Hans Schikan said in a statement. "We have been diligently preparing for multiple scenarios since acquiring the rights back from GSK in January and completing our more detailed analysis of the drisapersen dataset. The progress announced today is remarkable news for boys and their families, and we remain dedicated to enabling long term patient access to drisapersen and our follow-on products as novel treatments for DMD."

- read the statement

Related Articles:
Upbeat review of PhII DMD trial earns Prosensa a big boost to shares
PTC soars as EU changes its tune on the DMD-treating ataluren
Sarepta rockets up after mapping a shortcut to the FDA with DMD hopeful eteplirsen