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Wolfgang Miesbach on Landmark 5-Year Haemophilia B Gene Therapy Results
Dec 8, 2025, 06:22

Wolfgang Miesbach on Landmark 5-Year Haemophilia B Gene Therapy Results

Wolfgang Miesbach, Professor of Medicine at Frankfurt University Hospital, shared on LinkedIn:

”Visualizing 5-year outcomes of haemophilia B gene therapy. Following up on yesterday’s post about the 5-year HOPE-B results in the New England Journal of Medicine and Steve Pipe’s ASH presentation, here are three key slides that really bring the data to life:

Durable, therapeutic FIX levels at 5 years
Most participants maintained FIX levels in the mild or near-normal range, with >90% between 5–100 IU/dL. The remarkable consistency across the cohort demonstrates sustained gene expression.

Similar FIX expression regardless of pre-existing AAV5 neutralizing antibodies
The boxplots illustrate a pivotal finding: no substantial difference in endogenous FIX activity over time, even in those with pre-existing AAV5 antibodies. This is a game-changer for expanding eligibility in real-world practice – many patients previously thought “ineligible” can now benefit.

Stable FIX activity over the full 5-year follow-up
Mean FIX levels peaked early and then stabilized, remaining in the therapeutic range (mean FIX activity: 39 % and no supraphysiological levels) through Year 5.

  • What else the full presentation reveal:
  • Hepatic safety: Early ALT elevation managed successfully without loss of therapeutic response
  • 94% freedom from FIX prophylaxis – transforming daily management into treatment-free living
  • 85% reduction in annualized joint bleeding rate – from 2.34 to 0.35
  • Zero FIX inhibitors | Zero thrombotic events

Deep gratitude to Steve Pipe, the HOPE-B investigators, CSL, and above all, the 54 participants whose courage and commitment made these landmark 5-year data possible.”

Haemophilia B

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