ASH: Sustained Benefit Seen for Etranacogene Dezaparvovec in Hemophilia B

WEDNESDAY, Dec. 10, 2025 (HealthDay News) -- For men with hemophilia B, receipt of gene therapy comprising an infusion of etranacogene dezaparvovec results in sustained endogenous factor IX expression and low annualized bleeding rates over five years, according to a study published online Dec. 7 in the New England Journal of Medicine to coincide with the annual meeting of the American Society of Hematology, held from Dec. 6 to 9 in Orlando, Florida.Steven W. Pipe, M.D., from the University of Michigan in Ann Arbor, and colleagues conducted an open-label, phase 3 study involving men with hemophilia B who received a single infusion of etranacogene dezaparvovec after a lead-in period (at least six months) of factor IX prophylaxis.The researchers found that the adjusted annualized bleeding rate for all bleeding events was 4.16 and 1.52 during the lead-in period and months 7 though 60 after gene therapy, respectively, in the full analysis population (54 participants), a reduction of 63 percent. Endogenous factor IX expression remained stable during the five-year follow-up period; the mean factor IX activity level was 36.1 ± 15.7 IU/dL at five years, and the mean exogenous factor IX consumption for routine prophylaxis and treatment of bleeding events decreased by 96 percent from the lead-in period to months 7 through 60 after gene therapy. There was no substantial difference seen in efficacy for participants with and without adeno-associated virus serotype 5 neutralizing antibodies at baseline."For those who have relied on frequent prophylactic infusions, achieving lasting 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," Pipe said in a statement.Several authors disclosed ties to biopharmaceutical companies, including uniQure and CSL Behring, which funded the study. CSL Behring manufactures etranacogene dezaparvovec.Abstract/Full Text (subscription or payment may be required)More Information

ASH: Sustained Benefit Seen for Etranacogene Dezaparvovec in Hemophilia B

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