The Food and Drug Administration (FDA) has accepted for Priority Review the Biologics License Application (BLA) for etranacogene dezaparvovec, for the treatment of adults with hemophilia B.

Etranacogene dezaparvovec is an investigational gene therapy that uses a recombinant adeno-associated viral vector of serotype 5 (AAV5) to carry the Padua gene variant of factor IX. The single dose treatment generates factor IX proteins that are 5 to 8 times more active than normal.

The BLA is supported by data from the HOPE-B trial ( Identifier: NCT03569891), a phase 3, open-label, single arm study that included 54 male participants with severe or moderately severe hemophilia B. Patients were initially enrolled in a 6-month observational period during which they continued to receive current standard of care. After the lead-in period, patients received a single intravenous dose of etranacogene dezaparvovec.

The primary endpoint was 52-week annualized bleeding rate (ARB) following stable factor IX expression compared with the 6-month lead-in period. Results showed that after the 6-month lead-in period post infusion, the ABR was reduced by 64% (P =.0002) and 77% (P< .0001) for all bleeds (regardless of investigator adjudication as true bleeds) and factor IX-treated bleeds, respectively, over months 7 to 18.

Additionally, 98% of patients treated with a full dose of etranacogene dezaparvovec discontinued use of prophylaxis. The treatment was found to be well tolerated with most adverse events considered to be of mild severity.

The FDA’s Priority Review accelerates the process of review for therapies that are considered to be significant improvements over current standards. “The acceptance of etranacogene dezaparvovec for review by the FDA brings us closer to our goal of delivering a life-changing treatment option for people with hemophilia B,” said Bill Mezzanotte, MD, MPH, Executive Vice President, Head of R&D and Chief Medical Officer for CSL. The Agency is expected to take action on the application in 6 months as compared with a 10-month standard review.


FDA accepts CSL Behring’s Biologics License Application for etranacogene dezaparvovec for Priority Review. News release. May 24, 2022.