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Evaluating bleeding events in adult males with Hemophilia B receiving FIX therapy

A Prospective Study to Evaluate Disease Characteristics in Hemophilia B Participants Receiving Prophylaxis With Standard of Care FIX Replacement Therapy

Observational Regeneron Pharmaceuticals · NCT05568459

This study looks at how often adult men with Hemophilia B experience bleeding while they are receiving regular treatment with factor IX therapy.

Quick facts

Study typeObservational
Enrollment120 (estimated)
Ages16 Years and up
SexMale
SponsorRegeneron Pharmaceuticals Industry-sponsored
Locations20 sites (Los Angeles, California and 19 other locations)
Trial IDNCT05568459 on ClinicalTrials.gov

What this trial studies

This observational study focuses on adult males with Hemophilia B who are undergoing regular preventive treatment with factor IX (FIX) replacement therapy. Participants will provide data on their bleeding events over a period of at least six months while continuing their usual FIX therapy. The study aims to gather information on the frequency of FIX usage and the measurement of FIX activity to better understand individual disease characteristics. This study is part of a larger initiative to inform future experimental therapies for Hemophilia B.

Who should consider this trial

Good fit: Ideal candidates are adult males with Hemophilia B who have been on a stable FIX replacement therapy regimen for over two months.

Not a fit: Patients with other coagulation disorders or those who do not adhere to therapy documentation may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could enhance understanding of Hemophilia B management and inform future treatment strategies.

How similar studies have performed: Other studies have successfully gathered similar data on bleeding events in hemophilia patients, indicating that this approach is well-established.

Eligibility criteria

Show full inclusion / exclusion criteria 
Key Inclusion Criteria:

1. Previous experience with FIX therapy (≥50 documented exposure days to a FIX protein product such as recombinant, plasma-derived or extended half-life FIX product) with a current stable prophylaxis regimen for \>2 months prior to enrollment and intention to use FIX replacement therapy for the duration of the study
2. No known hypersensitivity to FIX replacement product
3. Willing to be contacted about a potential future clustered regularly interspaced short palindromic repeats (CRISPR)-based Factor 9 (F9) gene insertion clinical trial in which they may have the opportunity to screen for enrollment

Key Exclusion Criteria:

1. History of any coagulation disorder; requires anticoagulant therapy
2. Lack of adherence with documentation of bleeds and/or prophylaxis replacement therapy administration in the opinion of the investigator, based on medical history
3. History of FIX inhibitor (clinical or laboratory-based assessment) on 2 or more occasions, as defined in the protocol
4. Bethesda inhibitor titer greater than the upper limit of normal (ULN) at screening
5. Any detectable pre-existing antibodies to the Adeno-associated virus serotype 8 (AAV8) capsid; as measured by an assay at prescreening, as defined in the protocol
6. Is positive for hepatitis B or C at screening, as defined in protocol
7. If any of the following pre-existing diagnoses are documented:

   * Cholestatic liver disease
   * Liver cirrhosis
   * Portal hypertension; or
   * Splenomegaly; or
   * Hepatic encephalopathy
8. History of arterial or venous thrombo-embolic events, as defined in the protocol
9. History of clinically significant cardiovascular, respiratory, hepatic, renal (including nephrotic syndrome), gastrointestinal (including protein-losing enteropathy), endocrine, hematological (including thrombophilia), psychiatric, or neurological disease, as assessed by the investigator that may confound the results of the study or poses an additional risk to the participant by study participation
10. Previously received of any AAV-gene based therapy with a marketed gene therapy or in a clinical trial or intent to receive approved or investigational AAV-gene based therapy during the study period

NOTE: Other Inclusion/Exclusion Protocol Defined Criteria Apply

Where this trial is running

Los Angeles, California and 19 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Hemophilia BFIX replacement therapy
Last reviewed 2026-06-10 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.