An Observational Cohort Study to Characterize the Effectiveness and Safety of HEMGENIX® in Patients With Hemophilia B (IX-TEND 4001)

An Observational Post-authorization Long-term Follow-up Study to Characterize the Effectiveness and Safety of HEMGENIX® (Etranacogene Dezaparvovec) in Patients With Hemophilia B

This observational, post-authorization, long-term follow-up study aims to investigate the short and long-term effectiveness and safety of HEMGENIX in patients with hemophilia B. The study will also include a cohort of patients with hemophilia B treated with FIX prophylaxis to enable interpretation of relevant efficacy and safety findings of HEMGENIX.

Study Overview

• Status: Recruiting
• Conditions: Hemophilia B
• Intervention / Treatment: Genetic: HEMGENIX; Biological: Factor IX (FIX)

• Study Type: Observational
• Enrollment (Estimated): 500

Contacts and Locations

• Study Contact: Name: Trial Registration Coordinator; Phone Number: +1 610-878-4697; Email: clinicaltrials@cslbehring.com

Study Locations

• Austria
  • Vienna, Austria
    • Recruiting
    • Medical University Vienna
• Denmark
  • Århus N, Denmark
    • Recruiting
    • Aarhus Universitetshospital
• France
  • Brest, France
    • Recruiting
    • Centre Hospitalier Universitaire de Brest / CHU Morvan
  • Nantes, France
    • Recruiting
    • Centre Régional de Traitement de l'hémophilie
  • Vandœuvre-lès-Nancy, France
    • Recruiting
    • CHU Nancy - Hôpital Brabois
• Germany
  • Berlin, Germany
    • Recruiting
    • Klinik für Angiologie/ Hämostaseologie
  • Bonn, Germany
    • Recruiting
    • University of Clinic Bonn
  • Frankfurt, Germany
    • Recruiting
    • Klinikum der Johann-Wolfgang Goethe Universitaet
  • Hanover, Germany
    • Recruiting
    • Hannover Medical School
• Spain
  • Vigo, Spain
    • Recruiting
    • Hospital Alvaro Cunqueiro Dr. Manuel Rodriquez-Lopez
• Switzerland
  • Bern, Switzerland
    • Recruiting
    • University Hospital Bern Inselspital
• United States
  • New York
    • Rochester, New York, United States, 14604
      • Recruiting
      • American Thrombosis and Hemostasis Network
      • Contact: Use Central Contact

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients with hemophilia B who have been treated with HEMGENIX and are enrolled in either the sponsor's study or the ATHN Transcends study NCT04398628 (Hemophilia Cohort, Gene Therapy Outcomes Arm), and patients who receive routine prophylaxis treatment with FIX replacement therapy that are enrolled in the ATHN Transcends study (Hemophilia Cohort, Natural History Arm), or a similar registry. All patients will provide signed informed consent required for participation.

Description

Inclusion Criteria:

• HEMGENIX Cohort:
• - Treatment with commercial HEMGENIX.
• - Have provided signed written informed consent within 3 months before or within 6 months after HEMGENIX treatment, or within 6 months of when the study is initiated at the participating site.
• FIX Prophylaxis Cohort:
• - Adult patients (≥ 18 years) with hemophilia B who have consented and enrolled in ATHN Transcends Hemophilia Cohort (or a similar registry) and are receiving FIX prophylaxis therapy.

Exclusion Criteria:

• HEMGENIX Cohort:
• - The patient population that will be observed in this study must not have been treated with etranacogene dezaparvovec in a clinical trial.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
HEMGENIX; Patients with hemophilia B treated with HEMGENIX in countries where HEMGENIX is approved for commercial use.	Genetic: HEMGENIX; HEMGENIX is a gene therapy medicinal product that aims to deliver a factor IX (FIX) gene expression cassette to the liver of patients with hemophilia B.; Other Names: Etranacogene dezaparvovec
FIX Prophylaxis; Patients with hemophilia B on FIX prophylaxis and enrolled in American Thrombosis and Hemostasis Network (ATHN) Transcends (A Natural History Cohort Study of the Safety, Effectiveness, and Practice of Treatment in People with Non-Neoplastic Hematologic Disorders) Hemophilia Cohort, or a similar registry.	Biological: Factor IX (FIX); FIX prophylaxis therapy

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Bleeding Rate (all bleeds) - HEMGENIX Cohort	Annualised Bleeding Rate (ABR) for all bleeds	During the 52 weeks following stable FIX expression (6 to 18 months) in the follow-up period and at Months 6 to: 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180 after HEMGENIX treatment.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Bleeding Rate (specified bleed types) - HEMGENIX Cohort	ABR for spontaneous, FIX-treated, traumatic, and joint bleeds	During follow-up period (52 weeks following stable FIX expression [6 to 18 months]), and at Months 6 to: 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180 after HEMGENIX treatment.
Zero bleeds - HEMGENIX Cohort	Number of patients with zero bleeds	During follow-up after HEMGENIX treatment, up to 180 months
Correlation analysis - HEMGENIX Cohort	Correlation analysis of ABR as a function of mean FIX activity.	Over the 6 to: 18, 24, 36, 48, 60, 72, 96, 108, 120, 132, 144, 156, 168, and 180 months after HEMGENIX treatment.
Bleeding Rate - FIX Prophylaxis Cohort	ABR (total, spontaneous, FIX-treated, traumatic, and joint bleeds)	In the period Months 0 to: 12, 18, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180 Months.
FIX activity - HEMGENIX Cohort	Mean uncontaminated endogenous FIX activity (%)	Day 1, Week 6, and Months 6, 12, 18, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180 after HEMGENIX treatment.
Annualized consumption of FIX replacement therapy - HEMGENIX Cohort	Mean annualized consumption (IU/kg/Yr) of FIX replacement therapy (including FIX replacement for various clinical scenarios eg, prophylaxis, spontaneous bleeding events, medical procedures, surgery, and trauma).	During the follow-up periods (52 weeks following stable FIX expression [6 to 18 months], & at Months 0 to: 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180), & at yearly intervals (ie, at 0 to 1 yr, 1 to 2 yrs, etc, up to 14 to 15 yrs).
Annualized consumption of FIX replacement therapy - FIX Prophylaxis Cohort	Mean annualized consumption (IU/kg/Yr) of FIX replacement therapy (including FIX replacement for various clinical scenarios eg, prophylaxis, spontaneous bleeding events, medical procedures, surgery, and trauma).	At Months 0 to: 12, 18, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180.
Number of patients remaining free of previous continuous routine prophylaxis - HEMGENIX Cohort	Number and proportion of patients remaining free of previous continuous routine prophylaxis (FIX replacement therapy)	At Months 6 to: 18, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180 after HEMGENIX treatment.
Target joints occurrence - HEMGENIX Cohort	The annualized occurrence of target joints (defined as 3 or more spontaneous bleeding events into a single joint within a consecutive 6-month period).	After HEMGENIX treatment, during the follow-up periods (52 weeks following stable FIX expression [6 to 18 months], and at Months 6 to: 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180).
Target joints resolution - HEMGENIX Cohort	The percentage of resolution of target joints (target resolution is defined as a recorded target joint with 2 or fewer spontaneous bleeding events within a consecutive 12-month period).	During the follow-up period, up to 180 months
Target joints - FIX Prophylaxis Cohort	The annualized occurrence of target joints	From Months 0 to 12, 18, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, and 180.
Related Serious Adverse Events (SAEs) - number	Incidence (number) of related SAEs	During 15 years of follow-up
Related SAEs - percent	Incidence (percent) of related SAEs	During 15 years of follow-up
Adverse Events of Special Interest (AESIs) - number	Incidence (number) of AESIs	During 15 years of follow-up
AESIs - percent	Incidence (percent) of AESIs	During 15 years of follow-up

Collaborators and Investigators

• Sponsor: CSL Behring
• Investigators: Study Director: Global Program Director, CSL Behring

Study record dates

Study Major Dates

• Study Start (Actual): June 15, 2023
• Primary Completion (Estimated): August 1, 2043
• Study Completion (Estimated): August 1, 2043

Study Registration Dates

• First Submitted: August 15, 2023
• First Submitted That Met QC Criteria: August 23, 2023
• First Posted (Actual): August 24, 2023

Study Record Updates

• Last Update Posted (Actual): February 19, 2026
• Last Update Submitted That Met QC Criteria: February 18, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Hemophilia B; HEMGENIX
• Additional Relevant MeSH Terms: Genetic Diseases, Inborn; Hematologic Diseases; Blood Coagulation Disorders; Hemorrhagic Disorders; Genetic Diseases, X-Linked; Blood Coagulation Disorders, Inherited; Coagulation Protein Disorders; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Hemic and Lymphatic Diseases; Hemophilia B; Amino Acids, Peptides, and Proteins; Proteins; Biological Factors; Enzymes and Coenzymes; Blood Proteins; Blood Coagulation Factors; Enzyme Precursors; Protein Precursors; Factor IX
• Other Study ID Numbers: CSL222_4001; EUPAS106066 (Registry Identifier: EU PAS (ENCePP))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

CSL will consider requests to share Individual Patient Data (IPD) from systematic review groups or bona-fide researchers. For information on the process and requirements for submitting a voluntary data sharing request for IPD, please contact CSL at clinicaltrials@cslbehring.com.

Applicable country specific privacy and other laws and regulations will be considered and may prevent sharing of IPD.

If the request is approved and the researcher has executed an appropriate data sharing agreement, IPD that has been appropriately anonymized will be available.

• IPD Sharing Time Frame: IPD requests may be submitted to CSL no earlier than 12 months after publication of the results of this study via an article made available on a public website.

IPD Sharing Access Criteria

Requests may only be made by systematic review groups or bona-fide researchers whose proposed use of the IPD is non-commercial in nature and has been approved by an internal review committee.

An IPD request will not be considered by CSL unless the proposed research question seeks to answer a significant and unknown medical science or patient care question as determined by CSL's internal review committee.

The requesting party must execute an appropriate data sharing agreement before IPD will be made available.

• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP