The FDA has rejected approval of BioMarin's hemophilia A gene therapy drug, Roctavian, which was widely expected to be approved, according to STAT.
The drug would have been the first gene therapy for hemophilia A, a rare disease in which a patient's blood doesn't clot properly. The FDA had previously granted the drug priority review, which typically shortens a drug's time to approval.
In clinical trials, Roctavian demonstrated a 95 percent reduction in bleeding episodes over four years, and patients needed 96 percent fewer doses of medications to improve blood clotting.
But despite the positive trial results, the FDA said Aug. 19 that it wants two more years of data from clinical trials, meaning approval has been delayed until at least 2022.
The FDA is asking for the extra data because of uncertainty about how long the drug's effects last, according to STAT.
Roctavian is a one-time treatment for hemophilia A that works by repairing an inherited defect that stops patients from producing a protein needed for blood clotting. It is one of three gene therapies for hemophilia A in development.
The drug was widely expected to be BioMarin's biggest product, STAT reported.
BioMarin CEO Jean-Jacques Bienaimé said he was "surprised and disappointed" by the FDA's decision.
Read BioMarin's full news release here.