FDA slaps down BioMarin's Duchenne's drug as rival nears a moment of truth

After outlining its objections to BioMarin's ($BMRN) application for its experimental Duchenne muscular dystrophy drug drisapersen in an internal review and hearing clear objections from outside experts, the FDA has rejected the biotech's marketing application, saying it has yet to see real evidence of efficacy.

The move comes just days before another FDA panel is scheduled to sit down to review an application from Sarepta ($SRPT) for eteplirsen, another exon-skipping drug that looks to provide the dystrophin needed to delay the lethal disease that slowly but surely kills young patients. And with a rival put on the shelf, Sarepta's chances of gaining an approval--despite facing a major challenge to its own limited data set--likely just got better as patients and their families clamor for an approval.

The FDA didn't ask its outside experts to vote directly for or against approval, but the sentiment was clear as panelist after panelist concluded that BioMarin never could make its case with the three studies at hand. In addition, there were cases of fatal blood-platelet deficiency, renal injury and severe injection-site reactions to consider, adding to BioMarin's woes. 

BioMarin, which has previously enjoyed a strong track record in the rare-disease field, landed the drug in its acquisition of the Dutch biotech Prosensa ($RNA) in an $840 million deal in late 2014, after GlaxoSmithKline ($GSK) had walked away from the drug following a key clinical trial failure. That buyout deal included a $160 million set of milestones for an early approval of drisa, which will now be seriously delayed before a return trip to U.S. regulators.

"We are disappointed that the FDA did not approve drisapersen, given the significant benefit that many Duchenne boys experienced when they were on an early and consistent treatment protocol of the drug," responded the nonprofit CureDuchenne after the FDA's decision was announced. "Duchenne is progressive and relentless muscle wasting disease, and we cannot lose time finding therapies."

BioMarin is showing no signs of backing away, though. It will now ponder the rejection and pursue new talks with regulators, while pursuing new clinical work in the field. "The ongoing Kyndrisa extension studies will continue," the company said in a statement, "as will the ongoing clinical trials for other exon-skipping oligonucleotides, BMN 044, BMN 045 and BMN 053, while BioMarin is exploring next steps for this application. Patients currently receiving Kyndrisa, BMN 044, BMN 045 and BMN 053 will remain on therapy."

- here's the release