BioMarin's hopes in DMD fade after FDA panel pillories its case for approval

BioMarin's ($BMRN) odds of winning FDA approval for a Duchenne muscular dystrophy treatment got longer on Tuesday after a group of agency advisers picked apart the company's clinical evidence and raised serious concerns about its safety.

The committee, made up of independent experts, concluded that none of BioMarin's three supporting studies adequately made the case that its drug, drisapersen, offered a meaningful benefit to children with the muscle-wasting DMD. And on the safety side, panelists pointed to drisapersen's ties to potentially fatal blood-platelet deficiency, renal injury and severe injection-site reactions as alarming risks.

The FDA didn't ask the panel a yes-or-no question about whether to approve the drug but instead tasked the group with weighing in on four major issues in BioMarin's application. On each prompt, the vast majority voted that drisapersen's case for approval was either weakened or unaffected by the clinical data, with only one member voting that BioMarin's work strengthened the drug's profile.

The agency has promised to make a final decision on drisapersen by Dec. 27, taking into account the committee's advice.

Analysts have largely soured on BioMarin's prospects in DMD. Before Tuesday's panel, Baird's Brian Skorney said drisapersen's odds of winning approval were "near zero," and, after the vote, reaffirmed his prediction and added that "competitors of ours, citing probabilities of 50%, must have attended different committee meetings altogether."

Among those competitors is Evercore ISI analyst Mark Schoenebaum, who lowered his projected odds from 60% to 40%, and Barclays' Geoff Meacham, who wrote that BioMarin's drug still has a 50% chance. The Street's Adam Feuerstein, who has been following drisapersen closely and live-blogged the committee meeting, believes the drug has a 10% shot at approval.

Meanwhile, Sarepta Therapeutics ($SRPT) is awaiting a similar judgment process for its rival DMD drug, eteplirsen. The Cambridge, MA-based company is set to go before the same panel in January and will face similar scrutiny over its mixed bag of clinical data supporting eteplirsen. The ongoing worries over drisapersen, which began last week with some unfavorable FDA briefing documents, have sent Sarepta's shares up more than 30%.

Each drug targets the roughly 13% of DMD patients whose disease stems from a flaw in the gene responsible for producing the protein dystrophin. Drisapersen and eteplirsen work by getting the body to skip over that genetic defect, restoring the flow of dystrophin and alleviating symptoms of DMD.

- read BioMarin's statement
- here's The Street's story

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