FDA Sets Action Date for Hemophilia B Gene Therapy

The FDA has accepted Pfizer’s biologics license application (BLA) for fidanacogene elaparvovec to treat adults with hemophilia B, and assigned a PDUFA date in the second quarter of 2024. In parallel, the European marketing authorization application (MAA) for fidanacogene elaparvovec has also been accepted and is under review by the European Medicines Agency (EMA).

Hemophilia is a rare genetic bleeding disorder caused by a deficiency in one of several blood clotting factors. People with hemophilia B have a deficiency in clotting human coagulation Factor IX, a specific protein in the blood. The current standard of care requires recurrent intravenous infusions of either plasma-derived or recombinant Factor IX. More than 38,000 people worldwide were living with hemophilia B in 2021, according to the World Federation of Hemophilia.

Fidanacogene elaparvovec is a one-time gene therapy that contains a bio-engineered adeno-associated virus (AAV) capsid and a high-activity variant of the Factor IX gene. Pfizer licensed the gene therapy from Spark Therapeutics.

Chris Boshoff, M.D., Ph.D.

“Gene therapy marks a new era of scientific advancement, and if approved, we believe fidanacogene elaparvovec has the potential to transform the lives of people living with hemophilia B who are eligible for treatment,” Chris Boshoff, M.D., Ph.D., chief development officer, Oncology and Rare Disease, Pfizer Global Product Development, said in a press release.

The submissions are based on efficacy and safety data from the phase 3 BENEGENE-2 study (NCT03861273), which met its primary endpoint of non-inferiority in the annualized bleeding rate (ABR) of total bleeds post-fidanacogene elaparvovec infusion versus prophylaxis regimen with Factor IX, administered as part of usual care. Study results, which were reported in December 2022, also showed that key secondary endpoints demonstrated a 78% reduction in treated annualized bleeding rate and a 92% reduction in annualized infusion rate.

Fidanacogene elaparvovec was generally well-tolerated. Fourteen serious adverse events (SAEs) were reported in seven (16%) patients, including one case with two events assessed as related to treatment: a duodenal ulcer hemorrhage and anemia occurring in the setting of corticosteroid use