The phase 3 HOPE-B clinical trial of etranacogene dezaparvovec achieved its primary endpoint for patients with hemophilia B, according to a new press release from uniQure and CSL Behring, the developers of the investigational gene therapy.

“We are very pleased with these top-line results from what is the largest and first pivotal trial of a gene therapy for patients with hemophilia B,” Ricardo Dolmetsch, PhD, president of research and development at uniQure said.

“These encouraging results illustrate the potential that gene therapy has to be a long-term treatment option for patients living with hemophilia B and we look forward to sharing more detailed data with the medical community in the near future,” Brahm Goldstein, MD, MCR, vice president of hematology research and development at CSL Behring added.

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The aim of the open-label, single-arm, multicenter, multinational trial was to demonstrate the efficacy of etranacogene dezaparvovec and to further describe its safety profile.

The primary endpoint of the trial was the annualized bleeding rate. Secondary endpoints were factor IX activity levels, the use of factor IX replacement therapy, and adverse events.

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A noninferiority in annualized bleeding rate 18 months after the administration of the treatment was achieved during the trial. This was compared to baseline factor IX prophylactic therapy.

The secondary endpoint of statistical superiority in reducing the annualized bleeding rate was also achieved compared to baseline factor IX prophylactic therapy. The treatment was generally well-tolerated with more than 80% of adverse events being mild. No factor IX inhibitors were reported.

Etranacogene dezaparvovec is an investigational gene therapy based on AAV5. It contains the Padua variant of a codon-optimized human factor IX cDNA under the control of a liver-specific promoter.

The companies expect to submit regulatory applications for marketing approval of the treatment in the US and Europe in the first half of 2022.


uniQure and CSL Behring announce primary endpoint achieved in HOPE-B pivotal trial of etranacogene dezaparvovec gene therapy in patients with hemophilia B. News release. CSL Behring; December 9, 2021.

HOPE-B: trial of AMT-061 in severe or moderately severe hemophilia B patients. US National Library of Medicine. Updated November 9, 2021. Accessed December 14, 2021.