Hemophilia B treatment typically involves regular factor IX infusions. The latest research includes two gene therapy drugs that may reduce the need for these infusions.

Though research is still ongoing, recent research in gene therapy has led to potentially life-altering treatment for hemophilia B.

Other research has improved IX factor products that allow people with hemophilia B to increase the time between infusions.

Keep reading to learn about new research, including clinical trials, for improving treatment for hemophilia B.

Hemophilia B is caused by genetic mutations in the F9 gene, which provides the body instructions for producing factor IX. If you have hemophilia B, your body does not produce enough factor IX, which slows the rate at which blood clots.

Treatment for hemophilia B usually involves factor IX replacement therapy. This includes:

  • high doses of factor IX concentrate to stop bleeding episodes when they occur
  • Factor IX prophylactic therapy, which involves regular doses of factor IX concentrate to help prevent bleeds

Factor IX prophylactic therapy can be inconvenient, especially if you need multiple infusions per week to prevent bleeds. Some people with hemophilia B also develop neutralizing antibodies, or inhibitors, that block the action of factor IX and make this therapy less effective.

To improve treatment options, researchers have been developing new factor IX products and other therapies.

Gene therapy corrects genetic mutations that cause certain diseases.

In this treatment approach, a doctor uses a modified virus to deliver nonfaulty genes into your body’s cells. They may also remove or inactivate faulty genes.

Successful gene therapy for hemophilia B can provide long-term or potentially permanent benefits by replacing your faulty F9 gene with a nonfaulty gene. This would allow your body to produce enough factor IX on its own, with fewer or no infusions of factor IX.

Scientists have been studying multiple gene therapy approaches for treating hemophilia B. The FDA has approved the following gene therapies for hemophilia B:

  • fidanacogene elaparvovec-dzkt (Beqvez)
  • etranacogene dezaparvovec-drlb (Hemgenix)

However, some people may not be eligible for gene therapy, including people with anti-adeno-associated virus (AAV) neutralizing antibodies.

The tissue factor pathway inhibitor (TFPI) is another protein that limits the action of clotting factor Xa. Blocking TFPI allows your body to produce more Xa, which helps your blood clot even without factor IX.

This new type of drug reduces the amount of the anti-clotting protein called tissue factor pathway inhibitor. This increases the amount of the enzyme thrombin, which helps improve blood clotting. It may reduce or prevent bleeding episodes.

The FDA approved two of these drugs in 2024 for routine prophylaxis to people ages 12 and older. These include:

  • The FDA approved marstacimab-hncq (Hympavzi), a TFPI antagonist, to treat both hemophilia A and B. This drug is administered weekly by subcutaneous injection (between the skin and muscle).
  • The agency also approved concizumab-mtci (Alhemo), a once-daily TFPI antagonist, for people with factor IX inhibitors. This drug is administered daily by subcutaneous injection.

Researchers are also investigating another new drug, MG1113, for the treatment of hemophilia B.

The earliest factor IX products were derived directly from human blood or plasma. Later, scientists developed recombinant factor IX (rFIX) products, which are genetically engineered in a lab.

The Food and Drug Administration (FDA) approved the first rFIX product in the 1990s.

Recently, scientists have modified rFIX to create products with an extended half-life. These products last longer in your body than rFIX products with a standard half-life. This means you need less frequent doses.

The FDA has approved multiple rFIX products with an extended half-life, including:

  • eftrenonacog alfa (Alprolix; rFIX-Fc), approved in 2014
  • albutrepenonacog alfa (Idelvion; rFIX-FP), approved in 2016
  • nonacog beta pegol (Rebinyn; N9-GP), approved in 2017

All these products are infused into a vein through an intravenous (IV) line.

Researchers are continuing to study the long-term effects of these products, according to a 2021 review.

Scientists are also developing and testing other rFIX products with an extended half-life, including dalcinonacog alfa (DalcA), which is injected under the skin.

A small 2021 phase 1/2a clinical trial found that daily injections of DalcA were safe and effective for increasing factor IX in people with hemophilia B. A small 2b clinical trial is ongoing with promising results so far.

Factor IX isn’t the only protein that helps your blood to clot. Some treatments for hemophilia B increase the availability or action of other clotting factors to help stop bleeding without factor IX.

These include recombinant factor VIIa (rFVIIa). Your doctor may prescribe rFVIIa to treat and prevent bleeding episodes if you have factor IX inhibitors.

The FDA has approved two rFVIIa products to treat hemophilia B:

  • NovoSeven RT, approved in 1999
  • eptacog beta (SEVENFACT), approved in 2020

SEVENFACT is currently approved only for adults and adolescents ages 12 years and older, but recent research suggests it may also be safe and effective for younger people.

In a phase 3 clinical trial, 25 children with hemophilia A or B under age 12 received SEVENFACT to treat a mild to moderate bleeding episode. The treatment was successful within 24 hours for at least 97% of children who received it. No participants experienced serious side effects.

Researchers are also developing rFVIIa products with an extended half-life that lasts longer in your body than NonoSeven RT or SEVENFACT. These products include MOD-5014 and marzeptacog alfa.

Research on these products is ongoing.

Antithrombin is a protein that blocks the action of factor Xa and factor IXa.

A antithombin, Fitusiran, is also being reviewed by the FDA. Fitusiran is an experimental drug that lowers levels of antithrombin. This promotes blood clotting and limits bleeding.

The results of two phase 3 clinical trials on fitusiran suggest that among trial participants, monthly doses of fitusiran were linked to fewer bleeding episodes in people with hemophilia A or B. Those who took fitusirin also required fewer doses of clotting factor to treat bleeds.

Studies have shown that fitusirin works in people with factor IX inhibitors and those without.

The FDA has not yet approved fitusirin for treating hemophilia A or B.

Researchers are continuing to study it to learn more about its efficacy, safety, and suitable dosing.

Treatment for hemophilia B can help prevent and manage bleeding episodes, lower your risk of complications, and improve your quality of life.

Factor IX replacement and prophylactic therapy are the main treatments for this condition. Some people develop inhibitors that make these treatments less effective.

New and experimental therapies may help improve treatment options, including for people with and without inhibitors.

Talk with your doctor to learn more about current and emerging treatment options. In some cases, they might encourage you to participate in a clinical trial to receive an experimental treatment that has not yet been approved.

Your doctor can help you learn more about the potential benefits and risks of different treatments for hemophilia B, including experimental treatments.