Rare & Genetic · Clinical trials
Haemophilia B Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About haemophilia b — and why its trials are hard
Haemophilia B, also called Christmas disease, is an X-linked recessive bleeding disorder caused by deficiency or dysfunction of coagulation factor IX. Like haemophilia A, severity is defined by residual factor activity and manifests as spontaneous joint and soft-tissue bleeding, with the risk of chronic arthropathy. Historical management uses intravenous factor IX replacement, plasma-derived or recombinant, given on-demand or as prophylaxis; extended half-life factor IX products (including fusion and pegylated molecules) allow less frequent infusions. Inhibitor formation is less common than in haemophilia A but can occur. The field has advanced with AAV-based gene therapies delivering a factor IX transgene—often the hyperactive Padua variant—to enable durable endogenous factor IX production from a single infusion. Etranacogene dezaparvovec (Hemgenix) and fidanacogene elaparvovec (Beqvez) are the approved one-time gene therapies. Non-factor rebalancing agents that lower natural anticoagulants are also expanding options across haemophilia A and B. The annualised bleeding rate (ABR) remains the pivotal efficacy endpoint, alongside factor IX activity and reduced infusion requirements.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Etranacogene dezaparvovec (Hemgenix) | 2022 | One-time gene therapy for adults with haemophilia B on prophylaxis or with severe/recurrent bleeding | HOPE-B (phase 3, NEJM) | Annualised bleeding rate after gene therapy vs lead-in factor IX prophylaxis (non-inferiority/superiority) | ~64% reduction in ABR vs lead-in period; most patients stopped routine factor IX prophylaxis |
| Fidanacogene elaparvovec (Beqvez) | 2024 | One-time gene therapy for adults with moderately severe to severe haemophilia B (AAV-negative) | BENEGENE-2 (phase 3) | Annualised bleeding rate after infusion vs prior factor IX prophylaxis (non-inferiority) | Met non-inferiority with reduced ABR vs the prophylaxis lead-in period; durable FIX expression |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in haemophilia b development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| BAX 335 (fidanacogene predecessor, Baxalta AAV8-FIX Padua) — Phase 1/2 haemophilia B gene therapy | Did not advance; factor IX expression declined over time in some participants | AAV capsid-directed immune responses/transaminitis and waning transgene expression; the program was not continued to registration in this form |
Choosing the right endpoint
Primary endpoints that matter in haemophilia b trials
- Annualised bleeding rate (ABR) — Primary efficacy endpoint; often compared against a factor IX prophylaxis lead-in period in gene-therapy trials
- Factor IX activity — Circulating FIX level after treatment; central pharmacodynamic measure of gene-therapy expression and durability
- Factor IX consumption — Reduction or cessation of exogenous factor IX infusions following gene therapy
- AAV neutralising antibodies — Pre-existing anti-AAV immunity affects eligibility and response to AAV gene therapies
How iNGENū runs haemophilia b trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
Request a fixed-milestone proposal and a tailored endpoint & feasibility summary for this indication.
Frequently asked questions
Haemophilia B clinical trials — FAQs
What is the difference between haemophilia A and B?
How do haemophilia B gene therapies work?
Who is eligible for gene therapy?
Ready to discuss your haemophilia b trial?
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