Highlights From the 34th Congress of the International Society on Thrombosis and Haemostasis
Durable efficacy and safety in responders: 5-year post hoc end-of-study analysis of etranacogene dezaparvovec in the phase 3 HOPE-B trial in patients with severe/moderately severe haemophilia B
Presenting Author: Cedric Hermans, MD, PhD, FCRP
Cedric Hermans1, Emily Symington2, Michael Recht3, Nigel Key4, Giancarlo Castaman5, Wolfgang Miesbach6, Sandra Le Quellec7, Nathalie Jansen7, Douglass Drelich7, Fei Wang7, Steven Pipe8
1 Division of Hematology, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium; 2 Haemophilia Centre, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom; 3 Yale School of Medicine, New Haven, CT, United States; 4 Department of Medicine and Blood Research Center, University of North Carolina, Chapel Hill, NC, United States; 5 Center for Bleeding Disorders and Coagulation, Department of Heart, Lungs, and Vessels, Careggi University Hospital, Florence, Italy; 6 University Hospital Frankfurt, Frankfurt, Germany; 7 CSL Behring, King of Prussia, PA, United States; 8 Departments of Pediatrics and Pathology, University of Michigan, Ann Arbor, MI, United States
At ISTH 2026, a 5-year post hoc analysis evaluated the safety and efficacy of etranacogene dezaparvovec in the Phase 3 HOPE-B clinical trial. HOPE-B was an international study conducted in adult men with severe/moderately severe haemophilia B (FIX ≤ 2 IU/dL). Etranacogene dezaparvovec produced a durable response in 96% of treated participants, with sustained near-normal FIX activity, significant reductions in annualized bleeding rates, and a 98% decrease in exogenous FIX use. Only 1 participant resumed continuous prophylaxis. Most treatment-related adverse events occurred within the first 6 months, with transient corticosteroid-treated liver enzyme elevations in a small proportion of patients and no treatment-related serious adverse events, inhibitors, thrombosis, late hepatotoxicity, or AAV-related oncogenic events. These results support etranacogene dezaparvovec as a durable, well-tolerated treatment option for eligible patients with haemophilia B while long-term follow-up continues through 15 years.
Adjusted ABRs during lead-in - versus months 7–60 (n = 52)
