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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