The FDA has approved Qfitlia (fitusiran), the first antithrombin-lowering (AT) therapy for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adult and pediatric patients (aged 12 or older) with hemophilia A or B with or without factor VIII or IX inhibitors. The approval is based on data from the ATLAS phase 3 studies that demonstrated clinically meaningful bleed protection as measured by annualized bleeding rates (ABR) across hemophilia patients with or without inhibitors.
By lowering AT, a protein that inhibits blood clotting, Qfitlia helps increase thrombin generation to restore hemostasis in people with hemophilia. Qfitlia uses small-interfering RNA technology, which enables low treatment frequency, subcutaneous dosing, and low volume injections.
In the ATLAS clinical development program, Qfitlia demonstrated low bleed rates across subgroups with as few as six injections a year. Key results include:
- Significant bleed reduction by 71% in ABR for patients without inhibitors treated with Qfitlia prophylaxis compared to clotting factor concentrate on-demand (estimated mean: ABR 9.0 vs. 31.4, respectively; p<0.0001) and by 73% in ABR compared to bypassing agent on-demand for patients with inhibitors (estimated mean: ABR 5.1 vs. 19.1, respectively; p=0.0006)
- Median observed ABR during the open-label extension study was 3.8 (IQR: 0.0–11.2) in patients without inhibitors and 1.9 (IQR: 0.0–5.6) in patients with inhibitors
- Median observed annualized spontaneous bleeding rate during the open-label extension study was 1.9 (interquartile range (IQR): 0.0-7.5) in patients without inhibitors and 1.9 (IQR: 0.0-3.7) in patients with inhibitors
- Nearly half of patients in the open-label extension study experienced one or fewer bleeds (31% 0 bleeds and 47% 0-1 bleeds)
There is also the potential for significant adverse reactions, including thrombotic events, acute and recurrent gallbladder disease, and hepatotoxicity. The most common adverse reactions (incidence >10%) are viral infection, nasopharyngitis, and bacterial infection.
In conjunction with the Qfitlia approval, the FDA also cleared the Siemens Healthineers’ INNOVANCE® Antithrombin assay as a companion diagnostic for Qfitlia to measure AT levels. Through the Qfitlia Testing Program with Labcorp, the FDA-cleared companion diagnostic will be available to patients prescribed Qfitlia to measure AT levels at no cost.
Qfitlia can offer the fewest doses of all prophylactic therapies, and it will have a comparable price to other prophylactic hemophilia treatments. HemAssist is launching alongside Qfitlia to provide comprehensive patient support services, including insurance and financial assistance as well as educational resources. This program is for patients prescribed Qfitlia or other hemophilia treatments from Sanofi’s portfolio.
The FDA granted Qfitlia Orphan Drug Designation for hemophilia A and B, Fast Track Designation for hemophilia A and B with and without factor VIII or IX inhibitors, and Breakthrough Therapy Designation for hemophilia B with factor IX inhibitors. A regulatory submission for Qfitlia for the treatment of hemophilia A or B in adults and adolescents with or without inhibitors is under review in Brazil. A regulatory decision is expected in China in the second half of 2025.
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