FDA Accepts Priority Review BLA for Hemophilia B Gene Therapy

The U.S. Food and Drug Administration (FDA) has accepted CSL Behring’s Biologics License Application (BLA) for priority review of etranacogene dezaparvovec, an investigational gene therapy for hemophilia B.

Etranacogene dezaparvovec, also known as CSL222, consists of adeno-associated virus serotype 5 (AAV5), which function as a delivery vector carrying a gene cassette with the Padua variant of factor IX (FIX). AAV5 is a variant of the type of the adeno-associated virus vectors (AAVs) investigated in multiple ongoing gene therapy clinical trials.

The FDA accepted the BLA based on positive results of the HOPE-B Trial program, which has been investigating etranacogene dezaparvovec in patients with severe and moderately severe hemophilia B. According to a new company press release, trial participants demonstrated reduced adjusted annualized bleeding rate (ABR) by 64% and “superiority to prophylaxis treatment at 18 months post-treatment compared to a 6-month run in period.” Previously reported data from HOPE-B has also showed patients demonstrating significant and sustained increases in FIX activity at 18 months post-infusion.

The BLA’s priority review status is significant, as it allows the FDA to potentially act on the application in six months, in contrast to the 10 months allotted for a standard review.

“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. “Etranacogene dezaparvovec, potentially the first gene therapy approved for hemophilia B, further demonstrates CSL’s promise to relentlessly pursue innovative and disruptive technologies when it benefits rare and serious disease patients with unmet medical needs.”

Source: CSL Behring press release dated May 2022

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