Prosensa Announces Regulatory Path Forward for Drisapersen as a Potential Treatment for DMD

Plans to Submit a New Drug Application to the FDA this Year; Dialogue with EMA continues with intent to seek approval

Leiden, The Netherlands, June 3, 2014 (GLOBE NEWSWIRE) — Prosensa Holding N.V. (NASDAQ: RNA) the Dutch biopharmaceutical company focusing on rare diseases with a high unmet medical need, today announced that the United States Food and Drug Administration (FDA) has outlined a regulatory path forward, under an accelerated approval pathway, for drisapersen, the Company’s lead program for the potential treatment of Duchenne Muscular Dystrophy (DMD). In addition, the company has been interacting with the European Medicines Agency (EMA) and based on these interactions intends to file in Europe as well.
Following the positive feedback from the FDA, Prosensa has confirmed that it will pursue a New Drug Application (NDA) filing for drisapersen with the FDA, under an accelerated approval pathway based on existing data. The company plans to submit a file later this year and will commit to the initiation of two confirmatory post-approval studies. “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” said Hans Schikan, Chief Executive Officer of Prosensa.
“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” he said.
The FDA has outlined the following approaches for confirmatory trials, which the Company is urged to initiate both as soon as possible, as quoted from the guidance letter:
1. “A historically-controlled trial might be acceptable to confirm clinical benefit following accelerated approval. We note that a historically-controlled study is likely to provide interpretable evidence of efficacy only if the beneficial effect of drisapersen is large, by clearly showing that performance is better in drisapersen-treated subjects than could be reasonably expected, based on knowledge of the natural history of the disease. The effect size would have to be sufficient to overcome the uncertainty inherent in historically controlled trials, and motivational factors that can affect the results.
2. A randomized, placebo-controlled trial of another exon-skipping drug with a similar mechanism of action, directed at a different exon (e.g., PRO044 or PRO045), with demonstration of a correlation between dystrophin protein production and definitive clinical benefit on 6-minute walk or another measure, could provide confirmatory evidence of drisapersen’s clinical benefit if approval were based on a surrogate endpoint.”
In conjunction with commencing confirmatory post-approval studies of drisapersen, Prosensa will continue with its plans to re-dose an initial cohort of boys in the third quarter of 2014 who have previously participated in clinical studies with drisapersen. Based on the guidance, one option is to enroll a number of previously treated patients in these confirmatory studies. Moreover, Prosensa’s natural history study, which has enrolled 250 patients, can serve as a historical control.
“Improved understanding of the natural history of DMD and developing effective therapies takes the commitment of pioneers such as Prosensa, and we welcome the news that the FDA is committed to accelerating the pathway for approval of drisapersen and potentially for follow-on exon-skipping therapies” said Dr. Nathalie Goemans, Head of the Neuromuscular Reference Center for Children at the University Hospitals Leuven (UHL) in Belgium and one of the key investigators in various drisapersen studies.
Prosensa has the most comprehensive pipeline of targeted RNA-based products in development for the treatment of DMD, with three other exon skipping therapies in Phase I/II clinical studies and two programs in pre-clinical development, all of which have been granted orphan drug designation in the US and EU. Dose finding studies for PRO044 have been completed and are ongoing for PRO045 and PRO053.
Conference Call / Webcast Information
Prosensa will host a conference call on June 3, 2014 at 8:00 a.m. US Eastern Time, 2:00 p.m. Central European Time to discuss this regulatory update. In order to participate in the conference call, please dial +1-877-407-9170 (US domestic toll-free). International dial-in numbers and an audio webcast can be accessed under “Events & Presentations” through the Investors & Media section of the Prosensa corporate website at

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