Hemophilia B is a bleeding disorder caused by missing or low levels of clotting factor IX. It affects about 1 in 25,000 male births. Treatment traditionally meant regular infusions of factor IX concentrate to prevent bleeding, but gene therapy approved in 2022 and newer long-acting products are changing what's possible.
What's actually going on in research
Trials are testing gene therapies that enable the body to produce its own factor IX, newer factor IX products that last longer between doses, and drugs that rebalance clotting without needing factor replacement. Several gene therapy approaches are in late-stage testing, aiming to reduce or eliminate the need for regular infusions.
Gene therapy
Etranacogene dezaparvovec was FDA-approved in 2022 as the first gene therapy for hemophilia B. Additional gene therapy candidates are in trials, testing whether one-time treatment can maintain protective factor IX levels for years.
Extended half-life products
Newer factor IX products stay active in the body longer, allowing people to infuse once weekly or less instead of multiple times per week. These products make prophylaxis more practical for many people.
Non-replacement therapies
Drugs like emicizumab and fitusiran work by different mechanisms than factor replacement. They're being tested in hemophilia B to see if they can prevent bleeding without needing factor IX infusions.
What to know before you search
Eligibility typically depends on baseline factor IX level, presence of inhibitors (antibodies against factor IX), age, liver health, and prior treatments.
What types of trials are currently open
- Gene therapy trials — Testing one-time treatments that give the body instructions to produce factor IX on its own, potentially reducing or eliminating the need for regular infusions.
- Extended half-life trials — Testing factor IX products engineered to last longer in the body, allowing less frequent dosing while maintaining protection.
- Non-replacement trials — Testing drugs that prevent bleeding through mechanisms other than replacing factor IX, such as rebalancing the clotting system.
- Pediatric studies — Testing treatments specifically in children with hemophilia B, including safety and dosing of gene therapy and long-acting products.
- Registry studies — Following people with hemophilia B over time to track bleeding patterns, joint health, treatment responses, and long-term outcomes with different therapies.
Recently added Hemophilia B trials
A Study to Assess the Safety of Marstacimab and How Well it Works in People With Mild to Moderate Hemophilia A or B Without Inhibitors
This is an open-label, multicenter study evaluating the efficacy and safety of marstacimab prophylaxis in approximately 95 male and female adolescents and adults aged 12 to \<75 years with mild to moderate hemophilia A or B without inhibitors who have a severe bleeding phenotype. Eligible participants must have baseline factor VIII or factor IX activity levels \>1% to ≤15% and a history of clinically significant bleeding despite prior treatment with either on-demand factor replacement therapy or routine factor prophylaxis. The study will compare bleeding outcomes and other efficacy measures during a historical 12-month period of prescribed factor replacement therapy prior to study entry with outcomes observed during a 12-month treatment phase in which participants receive marstacimab 150 mg administered subcutaneously once weekly. Participants will be enrolled into 2 cohorts based on their treatment regimen before study entry: a prior on-demand treatment cohort and a prior routine prophylaxis treatment cohort. Female participants with severe hemophilia A or B without inhibitors may also be enrolled on a case-by-case basis. Data from these participants will contribute to safety assessments, and separate descriptive analyses of efficacy outcomes will be performed for all female participants. The study will also evaluate the long-term safety and efficacy of marstacimab during a long-term extension (LTE) treatment phase of up to 36 months. Participants who complete the 12-month treatment phase may continue into the LTE phase. Participants may be in the study for approximately 50 months, including a 12-month treatment phase and a long-term extension phase of up to 36 months.
Donate blood and tissue samples to identify hemophilia arthritis markers
Chronic arthropathy is one of the most common complications of haemophilia, affecting up to 90 per cent of patients aged 4 and over in at least one joint. the study aims to assess gene expression in biological samples collected via synovectomy and joint replacement surgery, as well as in peripheral blood, in patients with severe haemophilia A or B; to compare these data with those from patients with osteoarthritis and rheumatoid arthritis; and to correlate the gene expression data with information relating to the clinical and laboratory phenotype, the history of inhibitors, and ultrasound and histological findings.
Find Hemophilia B trials matched specifically to you
Answer 3 quick questions and we'll show you trials that fit your situation.