March 31, 2025 – The FDA has approved a new drug as a preventive treatment to reduce bleeding episodes in people with certain types of hemophilia. This first-of-its-kind injectable drug offers a treatment option requiring the fewest doses per year for adults and children age 12 or older.
Hemophilia is a rare blood clotting disorder that happens when the body lacks enough blood clotting proteins or factors, leading to prolonged bleeding after an injury or surgery, as well as spontaneous bleeding in the muscles, joints, or organs. The two main types, hemophilia A and hemophilia B, differ in terms of missing a specific clotting factor and are usually treated by replacing it. But some patients develop inhibitors – antibodies that block these factors – requiring alternative treatments. Since current medications are either IV infusions or under-the-skin injections, fewer doses can make the treatment simpler and easier to follow.
Sold as Qfitlia, the drug works by lowering the amount of a protein called antithrombin (AT); this helps increase the amount of thrombin, an enzyme essential for blood clotting. Qfitlia contains fitusiran, which uses RNA interference (RNAi) to block the production of AT, providing effective treatment for hemophilia, even in patients with inhibitors. It is given as a shot under the skin once every two months, with its dose and schedule adjusted based on a specific FDA-approved test that checks AT levels.
"Today’s approval of Qfitlia is significant for patients with hemophilia because it can be administered less frequently than other existing options," said Tanya Wroblewski, deputy director of the Division of Non-Malignant Hematology in the FDA’s Center for Drug Evaluation and Research.
The FDA approval is based on two clinical trials involving 177 men and boys with hemophilia A or hemophilia B, with or without inhibitors. Patients received either once-monthly Qfitlia or standard treatments for nine months, followed by a long-term study in which Qfitlia dosage was adjusted based on individual AT levels. Results showed that Qfitlia reduced annual bleeding episodes by 73% in people with inhibitors and by 71% in people without inhibitors, compared with standard treatments. Patients needed as few as six shots a year to see benefits, according to a news release by Sanofi, the drug’s maker. Qfitlia’s price will be comparable with that of other preventive hemophilia treatments, the company said.
The most common side effects of Qfitlia are viral and bacterial infections and common cold symptoms. The FDA has added a warning for possible blood clots and liver and gallbladder problems, with some patients needing gallbladder removal. They recommend getting blood tests for liver function done before and after starting Qfitlia, once a month for six months and after increasing the dose.