On March 31, 2025, the FDA approved Qfitlia™ (fitusiran), the first and only siRNA (RNAi) therapeutic for hemophilia A or B, with or without inhibitors. Discovered by Alnylam Pharmaceuticals and licensed to Sanofi, Qfitlia works by lowering antithrombin (AT) to restore thrombin generation, reducing annual bleeding rates by up to 90% in trials. It is administered as a subcutaneous injection once every two months and is indicated for patients aged 12 and older.

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