Prosensa Announces 48-Week Data from a U.S. Phase II Placebo-Controlled Study of Drisapersen in 51 DMD Boys

Clinically mean­ing­ful improve­ment from 24-week treat­ment peri­od was main­tained for 24 weeks after dris­apersen admin­is­tra­tion ceased

Chicago, IL, March 17, 2014 (GLOBE NEWSWIRE) — Prosensa Holding N.V. (NASDAQ: RNA), the Dutch bio­phar­ma­ceu­ti­cal com­pa­ny focus­ing on RNA-mod­u­lat­ing ther­a­peu­tics for rare dis­eases with high unmet need, today report­ed encour­ag­ing 48-week data from its U.S.-based, Phase II place­bo-con­trolled study (DMD114876 or DEMAND V) of its lead com­pound, dris­apersen, for the treat­ment of Duchenne Muscular Dystrophy (DMD).
The results of this study indi­cate that, com­pared to place­bo, boys in the high­er-dose dris­apersen group (6 mg/kg once week­ly) expe­ri­enced sta­bi­liza­tion and even improve­ments in their mus­cle func­tion and phys­i­cal activ­i­ty as mea­sured by the six-minute walk test (6MWT) for the 24-week treat­ment phase and main­tained this improve­ment dur­ing the 24-week fol­low-up peri­od. Additionally, when eval­u­at­ing the per­cent-pre­dict­ed six-minute walk dis­tance (6MWD), a clin­i­cal­ly mean­ing­ful treat­ment dif­fer­ence of 5.2% was observed at week 24 and 4.8% at week 48.
Principal inves­ti­ga­tor, Craig M. McDonald, M.D., Professor and Chair of Physical Medicine & Rehabilitation and Professor of Pediatrics at the University of California, Davis School of Medicine, will report the 48 week results in a poster ses­sion (Abstract #50) today at the Muscular Dystrophy Association 2014 Clinical Conference in Chicago, Illinois (March 16-19).
“Given the sever­i­ty of the dis­ease and the lack of dis­ease mod­i­fy­ing treat­ment options avail­able, the results of this impor­tant study sup­port the use of dris­apersen at a dose of 6 mg/kg once week­ly in the treat­ment of boys with DMD eli­gi­ble for exon 51 skip­ping” Dr. McDonald said. “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 and may indi­cate that, at the 6 mg/kg once week­ly dose, the drug has a long term treat­ment effect that helps delay dis­ease pro­gres­sion in younger, less severe boys.”
The study includ­ed 51 boys with DMD who were at least five years old, still able to walk and stand up from the floor with­out help in less than 15 sec­onds. As pre­vi­ous­ly report­ed, boys in the group who received a 6mg/kg dose of dris­apersen each week for the 24-week treat­ment peri­od show a 27.1 meter improve­ment in the 6MWT (includ­ing a 16.1 m increase from base­line) over the boys in the place­bo group at the end of the treat­ment peri­od (p=0.069), indi­cat­ing a clin­i­cal­ly mean­ing­ful out­come for the pri­ma­ry end­point. This study com­pared 6mg/kg/week with 3mg/kg/week and place­bo and was not sta­tis­ti­cal­ly pow­ered to show a sig­nif­i­cant dif­fer­ence between the arms. A clin­i­cal­ly mean­ing­ful treat­ment dif­fer­ence of 27.9 m over place­bo (p=0.177) was main­tained for 24 weeks after dris­apersen admin­is­tra­tion ceased. This includes an over­all mean increase from base­line of 14.7 m. In the dris­apersen 6 mg/kg/week group, an improve­ment was seen in the per­cent-pre­dict­ed 6MWD of 5.2% (p=0.051) and 4.8% (p=0.154) when com­pared to place­bo at weeks 24 and 48, respec­tive­ly.
Drisapersen at week­ly dos­es of 3 and 6 mg/kg/week was gen­er­al­ly well tol­er­at­ed, although the major­i­ty of sub­jects treat­ed with dris­apersen report­ed injec­tion-site reac­tions (none severe or seri­ous). Renal abnor­mal­i­ties were com­mon and occurred both in the place­bo and dris­apersen groups.
“Our pri­or­i­ty remains improv­ing the lives and out­comes of boys afflict­ed with this dev­as­tat­ing dis­ease. We are encour­aged by these results, and are active­ly con­tin­u­ing with the analy­sis of the total dris­apersen data set, which includes 300 patients and com­bined data rep­re­sent­ing 450 patient years to put these results into con­text,” said Hans Schikan, CEO of Prosensa. “As we report­ed ear­li­er this year, ini­tial find­ings from fur­ther analy­ses of the aggre­gate dris­apersen data sug­gest that treat­ing ear­li­er in DMD and treat­ing longer shows a delay in the pro­gres­sion of the dis­ease.”
A copy of the poster can be accessed (start­ing March 18) under “Events & Presentations” through the Investors & Media sec­tion of the Prosensa cor­po­rate web­site at www.prosensa.com.

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