Prosensa Holding N.V. (NASDAQ:RNA) might have good news that was made possible through insightful observation following past results that almost condemned the Dutch biopharmaceutical company's compound drisapersen for the treatment of Duchenne Muscular Dystrophy (DMD).
Following the previously published negative results, further analysis by Prosensa led scientists to conclude that drisapersen data suggest that treating earlier in DMD and treating longer shows a delay in the progression of the disease. The firm acted upon that observation.
As a matter of fact, 48-week data from its U.S.-based, Phase 2 placebo-controlled study (DMD114876 or DEMAND V) with drisapersen on DMD were positive. The data indicate that boys with DMD 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. Important is the finding that boys 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) 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. Boys in the group who received a 6mg/kg dose of drisapersen each week for the 24-week treatment period showed 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). These results indicate a clinically meaningful outcome for the primary endpoint.
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 groups, 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.
The results are encouraging. Prosensa is 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. Hans Schikan, CEO of Prosensa, confirmed his firm will continue its efforts to confirm its early observation that earlier and longer treatment with disapersen will indeed delay the progression of the disease.
Our Observation: Of the specialists in the field of RNA modulation whom we know and ask advice about subjects that relate to their specialty, no one doubted the value of Prosensa's RNA modulation technology. However, almost all of them admitted having been surprised to learn about disapersen negative results following prior trials that demonstrated a statistically significant positive outcome on DMD. Prosensa technology has been validated time and time again in preclinical and clinical testing. Unfortunately, the final phase trial announced in 2013 fell short of showing meaningful statistical clinical improvement.
Prosensa's courageous and wise decision to pursue its observation that treating DMD children earlier and for a long period could stop the progression of Duchenne muscular dystrophy in children seems to bring back disapersen into the limelight.
We are optimistic.
Disclosure: We own no shares in Prosensa.
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