BioMarin Duchenne Drug Receives Harsh Review From FDA

The FDA is highly critical of BioMarin Pharmaceuticals' drisapersen, concluding that efficacy data from three clinical trials do 'not reach the level of substantial evidence' necessary for approval.
By Adam Feuerstein ,

The U.S. Food and Drug Administration is highly critical of BioMarin Pharmaceuticals' (BMRN) - Get Report drisapersen, concluding that efficacy data from three clinical trials "does not reach the level of substantial evidence" necessary for approval.

The FDA's review of drisapersen was posted Friday morning to the agency's Web site ahead of Tuesday's advisory committee meeting. BioMarin is seeking FDA approval for drisapersen to treat Duchenne muscular dystrophy, a rare, genetic muscle-wasting disease.

BioMarin shares are down 7% to $95.70 in premarket Friday trading.

Here's how the FDA review team summed up the efficacy data from three clinical trials submitted by BioMarin to support drisapersen's approval:

"This review concludes that, while there may be some evidence suggestive of efficacy of drisapersen, the evidence is inconsistent and in some cases contradictory, and does not reach the level of substantial evidence."

In addition to raising serious questions about drisapersen's efficacy, the FDA reviewers also have concerns about the drug's safety

"Even in the context of an invariably disabling and fatal disease such as DMD, the safety profile of drisapersen is concerning ... Severe toxicity across many organ systems was encountered in the nonclinical studies, and appeared to predict a number of the adverse events that were subsequently observed in the clinical studies."

FDA drug reviews are known to be harsh, so the concerns raised about drisapersen do not necessarily spell doom for BioMarin at Tuesday's advisory panel meeting. The experts on the panel will be weighing drisapersen's efficacy and safety data in the context of Duchenne being a fatal disease with no currently approved treatments. The panel might also be swayed by two hours of testimony from DMD patients, their families and advocates -- most, if not all, will be urging the FDA to approve drisapersen.

Interestingly, the voting questions posed to the panel Tuesday by the FDA do not specifically ask for a yes or no vote on a recommendation for approval. The FDA wants the panel to address each of the three clinical trials individually and assess if they add, substract or have no impact on the overall strength of evidence necessary for approval.

Sarepta Therapeutics (SRPT) - Get Report is developing a competing Duchenne drug, eteplirsen, which will undergo its own FDA advisory panel review in January.

Shares of Sarepta are up 28% to $33.43 in reaction to the negative FDA review of drisapersen.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.

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