CSL Behring (ASX: CSL, OTCQX: CSLLY) has released four-year data from its Phase 3 HOPE-B trial, demonstrating the long-term efficacy and safety of its gene therapy, HEMGENIX® (etranacogene dezaparvovec-drlb), for adults with hemophilia B. The data, presented at the European Association for Haemophilia and Allied Disorders (EAHAD) Congress, reinforces HEMGENIX’s potential as a transformative treatment option.
The HOPE-B trial involved 54 adult males with severe or moderately severe hemophilia B. The results showed that a single infusion of HEMGENIX led to sustained factor IX activity levels, with a mean of 37% at four years post-treatment. This level is considered near-normal, offering significant bleed protection.
A key benefit highlighted in the study is the reduction in bleeding episodes. The mean adjusted annualized bleeding rate (ABR) decreased by approximately 90% from the lead-in period to year four. Joint bleeds, a common and debilitating symptom of hemophilia B, also saw a significant reduction.
Importantly, 94% of patients remained free of continuous factor IX prophylaxis through the four-year follow-up, indicating a potential for long-term independence from regular infusions.
HEMGENIX was approved by the U.S. FDA in 2022 as the first gene therapy for adults with hemophilia B who require factor IX prophylaxis, have a history of life-threatening bleeds, or experience frequent spontaneous bleeding. It is also the only approved gene therapy for hemophilia B that can treat adult patients with and without AAV5 neutralizing antibodies.
The safety profile of HEMGENIX remains favorable. The most common adverse event was an increase in alanine transaminase (ALT), which was managed with corticosteroids. No serious treatment-related adverse events were reported.
HEMGENIX works by using an adeno-associated virus (AAV5) to deliver a gene variant of Factor IX (FIX-Padua) to liver cells, enabling the continuous production of factor IX, the deficient protein in hemophilia B.
CSL licensed global rights to commercialize HEMGENIX from uniQure (Nasdaq: QURE), who led the multi-year clinical development. CSL has also established a post-marketing registry to monitor the long-term safety and efficacy of the gene therapy. HEMGENIX has been granted conditional marketing authorization in several regions, including the European Union, the UK, Canada, Switzerland, and Australia.
These latest results position CSL as a leader in gene therapy for hemophilia B, offering a potentially life-changing treatment option for patients and reducing the burden of this chronic condition.
