AMT-060 Gene Therapy in Adults With Severe or Moderate-Severe Hemophilia B Confirm Stable FIX Expression and Durable Reductions in Bleeding and Factor IX Consumption for Up to 5 Years
Highlights From the 14th Annual Congress of EAHAD

AMT-060 Gene Therapy in Adults With Severe or Moderate-Severe Hemophilia B Confirm Stable FIX Expression and Durable Reductions in Bleeding and Factor IX Consumption for Up to 5 Years

Frank W.G. Leebeek, MD, PhD1, Karina Meijer, MD, PhD2, Michiel Coppens, MD, PhD3, Peter Kampmann, MD4, Robert Klamroth, MD5, Roger Schutgens, MD, PhD, MSc6, Giancarlo Castaman, MD7, Erhard Seifried, MD, PhD8, Joachim Schwaeble, MD9, Halvard Bönig, MD1,10, Eileen K. Sawyer, PhD11, and Wolfgang Miesbach, MD, PhD12

1Erasmus University Medical Center, Rotterdam, Netherlands

2University Medical Center Groningen, Groningen, Netherlands

3Amsterdam University Medical Center, Amsterdam, Netherlands

4Rigshospitalet, Copenhagen, Denmark

5Vivantes Klinikum, Berlin, Germany

6Van Creveldkliniek, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands

7Azienda Ospedaliera Universitaria Careggi, Florence, Italy

8Institute Frankfurt, German Red Cross Blood Service Baden Wurttemberg-Hessen, Frankfurt, Germany

9Institute Frankfurt, German Red Cross Blood Service Baden Wurttemberg-Hessen, Frankfurt, Germany

10University of Washington, Seattle, WA

11uniQure Inc., Lexington, MA

12University Hospital Frankfurt, Frankfurt, Germany

Key Data Points

FIX Activity Sustained Over 4.5–5 Years in 2 Dose Cohorts
AMT-060 was administered at doses of 5x1012 gc/kg (cohort 1, N = 5) and 2x1013 gc/kg (cohort 2, n = 5). During 5 years (cohort 1) and 4.5 years (cohort 2) of follow-up, mean endogenous FIX activity was 5.2% (95% CI 2.0–8.4) in cohort 1 and 7.4% (95% CI 4.2–10.6) in cohort 2. FIX activity was dose dependent and stable during the follow-up period for both cohorts. Values in parentheses represent mean FIX activity over time. Only values at least 10 days after last FIX concentrate administration are included.
Sustained Reductions in Bleeds and Estimated FIX Use

*Prophylaxis was tapered and discontinued by 12 weeks if FIX activity was maintained at ≥ 2%; * Cohort 2 data for year 5 represents 6 months. FIX, factor IX

In both dose cohorts, mean ABR and FIX replacement therapy dropped sharply during the first year after infusion and remained low for subsequent years. In cohort 1, FIX usage was reduced by 84% and ABR by 55% at 5 years relative to pretreatment levels. For cohort 2, FIX usage and ABR were both reduced by ~ 100% at 4.5 years after infusion.

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