Five-year study confirms durable efficacy of etranacogene dezaparvovec

CSL has announced five-year results from the pivotal phase 3 HOPE-B study, presented at the American Society of Hematology Annual Meeting.The data confirm the durability and safety of a single infusion of etranacogene dezaparvovec in adults with moderate to severe haemophilia B, reinforcing its position as the only commercially available gene therapy for this condition.The trial involved 54 adult male participants, of whom 50 completed five years of follow-up. Results showed that 94% of patients remained free from continuous prophylaxis treatment, with mean factor IX activity levels sustained at 36.1% at year five. Bleed protection was maintained, with the mean annualised bleeding rate reduced by around 90% compared to lead-in, joint bleeds reduced by 93% and spontaneous bleeds reduced by 94%. Safety findings were favourable, with no serious adverse events related to treatment and only five treatment-related adverse events reported between years four and five.Steven Pipe, Professor of Pediatrics and Pathology at the University of Michigan, explained: “The five-year HOPE-B results mark a pivotal milestone for gene therapy, providing clear, five-year data of the ability of etranacogene dezaparvovec to potentially reshape care for adults with haemophilia B. For those who have relied on frequent prophylactic infusions, achieving years of bleed control from a single treatment offers the potential for greater day-to-day freedom and a life less burdened by the demands of ongoing therapy.”Deborah Long, Senior Vice President and Head of Medical Affairs at CSL, said: “We are incredibly proud to share the five-year results from the HOPE-B study, which reinforce the impact of etranacogene dezaparvovec as a one-time treatment option for adults with haemophilia B over this period. These results highlight the meaningful difference etranacogene dezaparvovec could make—helping people experience fewer bleeds compared to prophylaxis treatment and freeing them from the burden of regular ongoing treatment.”Participants will continue to be monitored in the IX-TEND extended follow-up study for up to 15 years. To date, more than 75 individuals across eight countries have received etranacogene dezaparvovec in real-world settings, reflecting growing global adoption.