Prosensa (RNA) will seek FDA and European approval for drisapersen, its drug candidate for Duchenne Muscular Dystrophy, following correspondence with the US regulatory body and what appears to be a somewhat lackadaisical approach at the European equivalent, the EMA. As with competing DMD developer Sarepta Therapeutics (SRPT), the FDA requested that RNA run more trials to demonstrate drisapersen’s efficacy but is open to reviewing existing data towards an accelerated approval.
In a letter to the small Dutch company, however, the FDA indicated that while they are receptive to a NDA, the agency finds existing evidence of drisapersen’s efficacy inconclusive. No surprise here, as drisapersen failed a sizeable phase 3 study late last year. Partner GlaxoSmithKline (GSK) handed back rights to the drug shortly after. Here’s how the FDA describes the discrepencies in their letter to Prosensa, which the company admirably released in full in a regulatory filing:
We find some of your hypotheses about factors that might have led to a lack of statistically significant findings in the Phase 3 study (DMD114044), in contrast to the nominal findings in earlier studies, plausible but not conclusive. Although we have discussed with you our reservations about the persuasiveness of the available data, we are open to filing an NDA for drisapersen for consideration under an accelerated approval pathway (assuming the submitted application otherwise meets the applicable standards). As we are sure you appreciate, however, our willingness to consider an application for filing cannot be taken to suggest the outcome of our review . . . As noted above, we recognize that you have presented hypotheses concerning factors that might explain the failure of Study DMD114044 [mentioned above]. We also recognize that you have presented post-hoc integrated analyses of data from earlier studies and Study DMD114044 as well as data from the long-term extension of Study DMD114044 that you feel is supportive. We would expect such analyses and discussion to be of significant importance to your application, as the failure of Study DMD114044 is a major concern.
Prosensa committed in the Tuesday press release to two confirmatory studies: a historically-controlled trial, and a randomized, placebo-controlled trial of another Prosensa exon-skipping drug with a similar mechanism of action. Prosensa still plans to re-dose in the third quarter a cohort of boys who previously participated in clinical studies with drisapersen.
Interestingly, the FDA also encouraged Prosensa to get involved in the agency’s efforts to understand the appropriate methodology for assessment of dystrophin in DMD boys, referencing an effort that’s being spearheaded by Sarepta.
The news sets up an eventful 2015 if both companies head to the same FDA advisory panel meeting in the first half of next year, which the FDA has made clear will be in the works for these contentious treatments.
Sarepta hosts its annual investor meeting on Tuesday, June 3, the same day that Prosensa announced its plans to file.
