Last reviewed 2026-04-20 · How we verify

Qfitlia (FITUSIRAN)

Qfitlia works by using small RNA molecules to block the production of antithrombin, a protein that can interfere with blood clotting.

Qfitlia (fitusiran) is an Antithrombin-directed RNA Interaction, a type of siRNA modality developed by Genzyme Corp. It is approved to treat Hemophilia A, Hemophilia B, Factor VIII inhibitors, and Factor IX inhibitors. Qfitlia works by targeting and reducing the production of antithrombin, a protein that can interfere with blood clotting. The drug is patented and has not yet reached generic status. Qfitlia was FDA-approved in 2025.

At a glance

Mechanism of action

QFITLIA is a double-stranded siRNA that causes degradation of AT messenger RNA (mRNA) through RNA interference, reducing plasma AT levels.

Approved indications

• Hemophilia A
• Hemophilia B
• Factor VIII inhibitors
• Factor IX inhibitors

Boxed warnings

• WARNING: THROMBOTIC EVENTS AND ACUTE AND RECURRENT GALLBLADDER DISEASE WARNING: THROMBOTIC EVENTS and ACUTE AND RECURRENT GALLBLADDER DISEASE See full prescribing information for complete boxed warning. Thrombotic Events Serious thrombotic events have occurred in QFITLIA-treated patients with risk factors including persistent antithrombin (AT) activity less than 15%, QFITLIA 80 mg once monthly dosing, an indwelling venous catheter, and the post-operative setting when bleed management guidelines were not followed. Interrupt QFITLIA in patients with a thrombotic event and manage as clinically indicated. ( 5.1 ) Acute and Recurrent Gallbladder Disease Gallbladder disease has occurred in QFITLIA-treated patients, some requiring cholecystectomy or developing complications (e.g., pancreatitis). Monitor for signs and symptoms of gallbladder disease. Consider interruption or discontinuation of QFITLIA if gallbladder disease occurs. Consider alternative treatment for hemophilia if history of symptomatic gallbladder disease. ( 5.2 ) Thrombotic Events Serious thrombotic events have occurred in QFITLIA-treated patients with risk factors for thromboembolism including persistent antithrombin (AT) activity less than 15%, use of QFITLIA 80 mg once monthly, presence of indwelling venous catheters, and in the post-operative setting when bleed management guidelines were not followed. Monitor AT activity using an FDA-cleared test and target AT activity 15–35% to reduce the risk of thrombosis. Monitor patients for signs and symptoms of thrombotic events. Interrupt QFITLIA in patients with a thrombotic event and manage as clinically indicated. (5.1) Acute and Recurrent Gallbladder Disease Acute and recurrent gallbladder disease, including cholelithiasis and cholecystitis have occurred in QFITLIA-treated patients, some of whom required cholecystectomy or had complications (e.g., pancreatitis) related to gallbladder disease. Monitor patients for signs and symptoms of acute and recurrent gallbladder disease. Consider interruption or discontinuation of QFITLIA if gallbladder disease occurs. Consider alternative treatment for hemophilia in patients with a history of symptomatic gallbladder disease. (5.2)

Common side effects

• Viral infection
• Nasopharyngitis
• Bacterial infection
• Hepatic Injury
• Arthralgia
• Prothrombin fragment 1.2 increased
• Injection site reaction
• Headache
• Cough
• Dyspepsia
• Abdominal pain

Drug interactions

• QFITLIA

Key clinical trials

• A Study to Investigate the Efficacy and Safety of Fitusiran Prophylaxis in Male Participants Aged 1 to Less Than 12 Years With Hemophilia A or B (PHASE3)
• A Study to Test a Medicine (Fitusiran) Injected Under the Skin for Preventing Bleeding Episodes in Male Adolescent or Adult Participants With Severe Hemophilia (PHASE3)
• Long-term Safety and Efficacy Study of Fitusiran in Patients With Hemophilia A or B, With or Without Inhibitory Antibodies to Factor VIII or IX (PHASE3)
• A Study to Test a Medicine (Fitusiran) for Preventing Bleeds in People With Severe Hemophilia Who Previously Received Preventive Treatment With Emicizumab (PHASE4)
• Fitusiran Prophylaxis in Male Pediatric Subjects Aged 1 to Less Than 12 Years With Hemophilia A or B (PHASE3)
• An Open-label Extension Study of an Investigational Drug, Fitusiran, in Patients With Moderate or Severe Hemophilia A or B (PHASE1,PHASE2)
• A Study of Fitusiran in Severe Hemophilia A and B Patients Previously Receiving Factor or Bypassing Agent Prophylaxis (PHASE3)
• A Study of Fitusiran (ALN-AT3SC) in Severe Hemophilia A and B Patients Without Inhibitors (PHASE3)

Patents

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Qfitlia CI brief — competitive landscape report
• Qfitlia updates RSS · CI watch RSS
• Genzyme Corp portfolio CI