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An advisory panel to the Food and Drug Administration gave an unfavorable review on Tuesday to drisapersen, an experimental drug for Duchenne muscular dystrophy, voting that inconsistencies in clinical trial data suggested the BioMarin Pharmaceutical treatment is unlikely to work.

There was no official up-down vote on whether to recommend approval. But 15 of 17 panel members did indicate that the lack of statistical significance in a late-stage study of 186 patients weakened positive outcomes seen in two smaller and earlier studies. The FDA is expected to make a final decision on the drug byDec. 27.

The vote came after FDA staff cited “life-threatening” side effects and a lack of “substantial evidence” of effectiveness in documents released last week.


It’s unclear what the reservations over the BioMarin drug may mean for Sarepta Therapeutics, which will go before an FDA review panel in January for its rival Duchenne drug called eteplirsen. One analyst wrote that the vote may not bode well for either company, despite impassioned pleas from some families during the panel meeting.

“We believe the result [poses] a significant amount of uncertainty and bearishness to persist” into the FDA approval dates for both drugs, wrote Leerink analyst Joseph Schwartz in an investor note. “We continue to believe that the most likely outcome is that the FDA approves either both or neither therapy based on currently submitted data, and it is unlikely that they approve just one.”


Nonetheless, he reiterated a view shared by other Wall Street analysts that the agency was very strategic in crafting questions for the panelists to answer. Many analysts believe that FDA officials sought panelist views on efficacy — as opposed to approval recommendations — in order to give themselves enough leeway “to do whatever they wish,” as Schwartz put it.

Yet another analyst, Evercore ISI’s Mark Schoenebaum, opined that this is “largely a coin flip.”

Meanwhile, one advocacy group urged the FDA to approve both drugs. “There are currently no treatments available for this fatal genetic disease, and there is a great sense of urgency for those living with the disease to have treatments that can slow its progression,” said Debra Miller of Cure Duchenne.