How much does gene therapy reduce bleeding rates for adults with severe Hemophilia A?

Gene therapy is a one-time treatment designed to lower bleeding rates in adults with severe Hemophilia A. Research shows it significantly reduces the need for regular infusions and improves quality of life. However, the reduction in bleeding is not permanent for everyone, as some patients eventually return to standard treatment.

What the research says

A systematic review found that gene therapy lowered annualized bleeding rates compared to standard factor VIII prophylaxis. The analysis of four studies showed a standardized mean difference of -0.72, indicating a strong reduction in bleeding frequency ². This reduction was consistent across different gene therapy products tested, including valoctocogene roxaparvovec and giroctocogene fitelparvovec ².

The therapy works by raising factor VIII activity levels. In the first year, activity levels ranged from 8.3 to 67.5 IU/dL. While these levels eventually declined over time, the reduction in bleeding remained significant for many patients ². Because the effect can fade, some patients eventually needed to return to regular factor infusions, with return rates ranging from 0% to 33% depending on the study ².

Other treatments like concizumab also reduce bleeding but work differently. In a separate study, concizumab lowered the median annualized bleeding rate to 0.8 at 56 weeks in patients with inhibitors ³. This highlights that while gene therapy offers a one-time fix, other non-clotting factor therapies provide ongoing protection with different mechanisms ¹³.

What to ask your doctor

• What are the chances I might need to return to regular factor infusions after gene therapy?
• How will my doctor monitor my factor VIII levels if they decline over time?
• What are the specific risks of liver enzyme elevations associated with gene therapy?
• How does gene therapy compare to other options like concizumab for my specific case?