FDA
FDA greenlights novel treatment for hemophilia A or B
Brand name: Qfitlia
Generic name: fitusiran
Manufacturer: Sanofi
Approval date: March 28, 2025
FDA approved Qfitlia (fitusiran) for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adult and pediatric patients ≥12 years of age with hemophilia A or hemophilia B, with or without factor VIII or IX inhibitors.
Qfitlia is administered SC q2mo initially. Dose and frequency of injections are adjusted using the FDA-cleared INNOVANCE Antithrombin companion diagnostic test. This companion diagnostic is intended to monitor and—by informing dosing and frequency of injections—achieve antithrombin activity in the target range to reduce the risk of bleeding and to reduce the risk of excessive clotting. FDA granted clearance of the INNOVANCE Antithrombin test to Siemens Healthcare Diagnostics GmbH.
Efficacy
Efficacy and safety were assessed in two multicenter, randomized trials that enrolled a total of 177 adult and pediatric male patients with either hemophilia A or hemophilia B. In ATLAS-INH (NCT03417102), participants had factor FVIII or FIX inhibitors and previously received on-demand treatment with bypassing agents (BPAs). In ATLAS-A/B (NCT03417245), participants didn’t have FVIII or FIX inhibitors and previously received on-demand treatment with clotting factor concentrates. In the two trials, participants received either a fixed dose of Qfitlia monthly or their usual on-demand treatment (BPAs or clotting factor concentrates) as needed for nine months. The fixed dose of Qfitlia is not approved because it led to excessive clotting in some patients.
Participants subsequently entered a long-term extension study (ATLAS-OLE; NCT03754790) in which they received an adjustable dose of Qfitlia based on periodic measurements of antithrombin activity. This antithrombin-based dosing regimen is the approved dosage regimen. Efficacy of Qfitlia using the antithrombin-based dosing regimen was established by comparing patients on this dosing regimen of Qfitlia during the long-term extension study to the on-demand control data from the two randomized trials.
The primary measure of efficacy of Qfitlia was the estimated annualized bleeding rate of treated bleeds. In participants with inhibitors who received the antithrombin-based dosing regimen of Qfitlia, there was a 73% reduction in estimated annualized bleeding rate compared with those who received on-demand treatment with BPAs. In participants without inhibitors who received the antithrombin-based dosing regimen of Qfitlia, there was a 71% reduction in estimated annualized bleeding rate compared with those who received on-demand treatment with clotting factor concentrates.
Safety
The most common side effects of Qfitlia are viral infection, nasopharyngitis, and bacterial infection.
Qfitlia has a boxed warning for thrombotic events and gallbladder disease, with some patients requiring cholecystectomy. Qfitlia also has a warning about liver toxicity and the need to monitor LFTs at baseline and then monthly for at least six months after initiating treatment or after a dose increase.
Sources:
FDA approves novel treatment for hemophilia A or B, with or without factor inhibitors. [News release]. 2025. https://www.fda.gov/news-events/press-announcements/fda-approves-novel-treatment-hemophilia-or-b-or-without-factor-inhibitors
Qfitlia (fitusiran) [package insert]. U.S. Food and Drug Administration. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/219019s000lbl.pdf Revised March 2025. Accessed April 1, 2025.