2025 Approvals

QFITLIA (fitusiran): A New Treatment for Hemophilia A and B Approved by the FDA on March 28, 2025

Jasmine C

30 Sep 2025 — 2 min read

What is it prescribed for?

QFITLIA is used for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adults and children aged 12 years and older with hemophilia A or B, with or without factor VIII or IX inhibitors.

What is the name of the drug and what does it do?

The brand name is QFITLIA (pronounced "kew-fit-lee-ah"), and the generic name is fitusiran. QFITLIA helps treat hemophilia A and B by reducing the number of bleeding episodes, even in patients who have developed inhibitors against standard clotting factor therapies.

How does it work?

QFITLIA works by targeting and lowering the levels of a protein called antithrombin in the blood. By reducing antithrombin, QFITLIA helps the blood form clots more effectively, decreasing the risk of bleeding episodes in people with hemophilia.

What did the research discover?

In clinical research studies, patients treated with QFITLIA experienced significantly fewer bleeding episodes compared to those receiving on-demand clotting factor or bypassing agents.

In patients with inhibitors, QFITLIA reduced bleeding episodes by 73% compared to traditional treatments.
In patients without inhibitors, QFITLIA reduced bleeding episodes by 71%.
These improvements were measured by looking at the annualized bleed rate (ABR) for treated, spontaneous, and joint bleeds during the study periods.

What are some of the side effects?

QFITLIA can lead to several serious side effects, including:

Abnormal Blood Clotting (Thrombotic Events)

- QFITLIA may cause blood clots in various blood vessels, including those in the arms, legs, lungs, heart, brain, and eyes.

- The risk of blood clots increases if antithrombin (AT) blood levels are persistently below 15% or if certain other conditions are present.

- Seek immediate medical attention if you experience symptoms such as:

- Swelling, pain, or redness in arms or legs

- Coughing up blood

- Shortness of breath

- Severe chest pain or tightness

- Fast heart rate

- Fainting or feeling faint

- Severe or persistent headache

- Difficulty speaking or understanding language

- Confusion

- Numbness or weakness in the face, arms, or legs

- Sudden vision changes, eye pain, or swelling

Gallbladder Disease

- QFITLIA can lead to gallstones and inflammation of the gallbladder, potentially requiring surgical removal.

- Inform your healthcare provider if you experience abdominal pain, indigestion, nausea, or vomiting, as treatment may need to be adjusted.

Liver Problems

- The medication can cause elevated liver enzymes, necessitating regular blood tests to monitor liver function before and during treatment.

Patients should be vigilant for these side effects and communicate any concerning symptoms to their healthcare provider promptly.

Common side effects (more than 10% of patients):

Viral infections
Nasopharyngitis (common cold symptoms)
Bacterial infections

What are the dosage recommendations and how is it prescribed?

QFITLIA is given by subcutaneous injection (under the skin).

The starting dose is 50 mg once every two months.
Dosage may be adjusted to maintain antithrombin activity between 15–35%.
Monitoring antithrombin levels is required before starting and during treatment.
Patients must stop using regular clotting factor concentrates or bypassing agents within 7 days after starting QFITLIA.