FDA Approves Fitusiran With or Without Inhibitors for Bleeding Prophylaxis in Hemophilia A, B

The FDA has approved fitusiran for bleeding management in hemophilia A or B in patients aged 12 years and older, with or without factor VIII or IX inhibitors. Sanofi, which markets fitusiran as Qfitlia, announced the FDA’s approval in a press release.

“Qfitlia has the potential to meaningfully change the hemophilia landscape through effective bleed protection, infrequent dosing, and simplified administration,” Brian Foard, executive vice president and head of Specialty Care at Sanofi, commented in the press release.

Fitusiran is approved for routine prophylaxis to prevent or reduce bleeding episodes in hemophilia. It is a small interference RNA agent that applies the ESC-GalNAc conjugate platform from Alnylam Pharmaceutical Inc and is administered subcutaneously as either a 50-mg dose in a prefilled pen or by vial and syringe.¹

“Unlike therapies that replace missing blood factors, Qfitlia lowers antithrombin to promote thrombin generation, restoring hemostasis and reducing bleeding episodes,” explained Sanjay Ahuja, MD, chief medical and informatics officer at Innovative Hematology and the Indiana Hemophilia and Thrombosis Center, in remarks forwarded to Heme Today.

The FDA approval was based on data from the ATLAS clinical development program, which is composed of several phase 3 studies evaluating the efficacy and safety of fitusiran in hemophilia. Performance data for the agent include, as measured by estimated annualized bleeding rates, that among patients who did not receive inhibitors, those treated with fitusiran prophylaxis had 71% reduced bleeding as compared with those treated with on-demand clotting factor concentrate. Among patients who received inhibitors, those treated with fitusiran had 73% reduced bleeding as compared with those given an on-demand bypassing agent.¹

“Potential significant adverse reactions include thrombotic events, gallbladder disease, and hepatotoxicity, and common reactions include viral infection, nasopharyngitis, and bacterial infection,” noted Dr. Ahuja who is a researcher in the ATLAS clinical program.

The FDA has also cleared the Siemens Healthineers’ INNOVANCE Antithrombin assay for diagnostic use in conjunction with fitusiran. Regarding other regulatory approvals for fitusiran globally, a submission for the agent to treat hemophilia A or B in adult and adolescent patients, with or without inhibitors, is currently under review in Brazil, and in China, a regulatory decision is planned for the second half of 2025.¹

Reference

1. Sanofi. Accessed April 29, 2025. https://www.sanofi.com/en/media-room/press-releases/2025/2025-03-28-20-07-38-3051637