Global biotechnology leader CSL announced the four-year results from the pivotal HOPE-B study confirming the long-term durability and safety of a one-time infusion of HEMGENIX^® (etranacogene dezaparvovec-drlb) for adults living with hemophilia B. In an oral presentation at the 18th Annual Congress of the European Association for Haemophilia and Allied Disorders (EAHAD), data showed that through four years, HEMGENIX continues to deliver elevated and sustained factor IX activity levels, can offer long-term and greater bleed protection compared to prophylactic treatment, can eliminate the need for routine factor IX prophylaxis, and maintains a favorable safety profile. Approved in 2022 by the U.S. Food and Drug Administration (FDA), HEMGENIX is the first gene therapy for the treatment of adults with hemophilia B who currently use factor IX prophylaxis therapy, or have current or historical life-threatening bleeding, or have repeated, serious spontaneous bleeding episodes. It is also the only approved gene therapy for hemophilia B that can treat adult patients with and without AAV5 neutralizing antibodies thereby providing the potential for a greater number of eligible patients to be treated.

"Hemophilia B can cause spontaneous bleeds into the joints, resulting in extreme pain and progressive, arthritis-like damage, which can lead to permanent physical debility," said Steven Pipe, MD, Professor of Pediatrics and Pathology, Laurence A. Boxer Research Professor of Pediatrics and Communicable Diseases, Pediatric Medical Director, Hemophilia and Coagulation Disorders Program Director, Special Coagulation Laboratory University of Michigan. "These results underscore the ability of HEMGENIX to offer long-term bleed protection with a one-time treatment, resulting in dramatic decreases in all annual bleed rates, including joint bleeds, and sustained independence from regular prophylactic infusions."

In the Phase III, open-label, single-dose, single-arm HOPE-B trial, 54 adult male participants with severe or moderately severe hemophilia B, with or without preexisting AAV5 neutralizing antibodies, were infused with a single dose of HEMGENIX. Of the 54 participants who received HEMGENIX, 51 completed four years of follow-up. HEMGENIX produced mean factor IX levels of 41.5 IU/dL (n=50) at year one, 36.7 IU/dL (n=50) at year two, 38.6 IU/dL (n=48) at year three and 37.4 IU/dL (n=47) at year four post-infusion. In addition, mean adjusted annualized bleeding rate (ABR) for all bleeds was reduced by approximately 90% from lead-in (4.16, n=54) as compared to year four (0.40, n=51). Furthermore, joint bleeds were reduced from a mean ABR of 2.34 at lead-in to 0.09 during year four. In year four, 94% of patients remained free of continuous prophylaxis treatment. No patients returned to continuous prophylaxis between year three and year four.

There were no serious adverse events related to treatment with HEMGENIX. HEMGENIX was generally well-tolerated, with a total of 96 treatment-related adverse events (AEs), 92 (96%) of which occurred in the first six months post-treatment. The most common adverse events were an increase in alanine transaminase (ALT), for which nine (16.7%) participants received supportive care with reactive corticosteroids for a mean duration of 81.4 days (standard deviation: 28.6; range: 51-130 days).

"These data continue to instill confidence in the clinical benefits of HEMGENIX, highlighting the remarkable impact of this one-time treatment to reduce the frequency of bleeds in people with hemophilia B and improve quality of life by alleviating the burden of ongoing factor IX prophylactic treatment," said Andres Brainsky, Vice President R&D Hematology at CSL. "CSL is committed to continuing to provide ongoing data analyses of HEMGENIX, ensuring that healthcare providers and patients have the necessary information to make informed decisions about treatment options. We are proud to continue to provide life-changing treatment options to the hemophilia community." 

The multi-year clinical development of HEMGENIX was led by uniQure (Nasdaq: QURE) and sponsorship of the clinical trials transitioned to CSL after it licensed global rights to commercialize the treatment. Additionally, CSL established a post-marketing registry, which will be informative to all stakeholders and will generate additional evidence on the long-term safety, efficacy, and durability of gene therapy. HEMGENIX has also been granted conditional marketing authorization by the European Commission (EC) for the European Union and European Economic Area, the UK's Medicines and Healthcare products Regulatory Agency (MHRA), as well as authorization by Health Canada, Switzerland's Swissmedic and provisional approval by Australia's Therapeutic Goods Administration (TGA).