The marketing authorization application of the experimental hemophilia B gene therapy etranacogene dezaparvovec (EtranaDez) is now being reviewed by the European Medicines Agency (EMA) under its accelerated assessment procedure, according to a press release by CSL Behring.

“The acceptance of etranacogene dezaparvovec for review by the EMA furthers our relentless pursuit to improve the lives and well-being of those living with hemophilia B and other rare and serious medical disorders,” said Bill Mezzanotte, executive vice president, head of research and development, and chief medical officer of CSL Behring.

The application is based on positive results from a pivotal, phase 3, open-label, multinational clinical trial that aimed to demonstrate the efficacy and further describe the safety of EtranaDez.

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The results showed that patients with hemophilia B with a severe bleeding phenotype treated with etranacogene dezaparvovec had a 64% reduction in adjusted annualized bleed rates. Moreover, EtranaDez was superior to prophylaxis treatment at 18 months post-treatment compared to a 6-month run-in period. Finally, there were stable and durable increases in the mean activity levels of factor IX.

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EtranaDez is a gene therapy that uses an adeno-associated virus serotype 5. The vector carries the Padua variant of factor IX. The factor IX protein that this gene encodes is 5 to 8 fold more active than normal factor IX.

“As the first gene therapy candidate for hemophilia B, this pivotal regulatory milestone brings CSL Behring one step closer to delivering on the promise of gene therapy for the bleeding disorders community,” said Emmanuelle Lecomte Brisset, head of Global Regulatory Affairs at CSL Behring.

“We look forward to working with regulatory authorities to bring the transformative potential of gene therapy to people living with this debilitating, life-long condition.” The accelerated assessment procedure potentially reduces the timeline once a marketing authorization application is accepted for review.


European Medicines Agency commences review of novel gene therapy candidate etranacogene dezaparvovec for people with hemophilia B. New release. CSL Behring; March 28, 2022.

HOPE-B: trial of AMT-061 in severe or moderately severe hemophilia B patients. US National Library of Medicine. Updated March 21, 2022. Accessed March 29, 2022.