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Etranacogene Dezaparvovec for Hemophilia B

A clinical trial of etranacogene dezaparvovec gene therapy demonstrates its superiority over prophylactic factor IX with respect to annualized bleeding rate, researchers report, with a favorable safety profile. “Our findings suggest that gene therapy may reduce the burden of care and improve quality of life in patients with hemophilia B,” the authors conclude.

After a 6-month or longer lead-in period of factor IX prophylaxis, 54 men with hemophilia B (factor IX activity ≤2% of the normal value) received a single infusion of infusion of adeno-associated virus 5 (AAV5) vector expressing the Padua factor IX variant (etranacogene dezaparvovec; 2×1013 genome copies per kilogram of body weight). Based on a primary endpoint of the annualized bleeding rate, the study showed: “The annualized bleeding rate decreased from 4.19 (95% confidence interval [CI], 3.22 to 5.45) during the lead-in period to 1.51 (95% CI, 0.81 to 2.82) during months 7 through 18 after treatment, for a rate ratio of 0.36 (95% Wald CI, 0.20 to 0.64; P <0.001), demonstrating noninferiority and superiority of etranacogene dezaparvovec as compared with factor IX prophylaxis. Factor IX activity had increased from baseline by a least-squares mean of 36.2 percentage points (95% CI, 31.4 to 41.0) at 6 months and 34.3 percentage points (95% CI, 29.5 to 39.1) at 18 months after treatment, and usage of factor IX concentrate decreased by a mean of 248,825 IU per year per participant in the post-treatment period (P <0.001 for all three comparisons). Benefits and safety were observed in participants with predose AAV5 neutralizing antibody titers of less than 700. No treatment-related serious adverse events occurred.”

Source: New England Journal of Medicine