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RecruitingNCT06379789BEYOND-9Updated Oct 21, 2026

A Study to Investigate the Safety and Effectiveness of a Coagulation Factor IX Gene Insertion Therapy (REGV131-LNP1265) in Pediatric, Adolescent and Adult Participants With Hemophilia B

A Phase 1/2 interventional study of REGV131 and LNP1265 in Hemophilia B, sponsored by Regeneron Pharmaceuticals. Recruiting at 52 sites in 9 countries. Open to male participants aged 2 Years and older. Per ClinicalTrials.gov, last updated 2026-10-21.

Sponsored by Regeneron Pharmaceuticals · Phase 1/2, Interventional, and Treatment

From the registry’s dates

  • Started Sep 2024; still recruiting 2 years 2 months later.
Updated Oct 21, 20263 sites addedGo to Updates ↓
Phase
Phase 1/2
Study type
Interventional
Enrollment
130
Allocation
Non-randomized
Ages
2 Years and older
Sex
Male
01

Study summary

Participants in this study have a genetic mutation, specifically in the coagulation (blood clotting) Factor 9 gene that causes severe or moderately severe hemophilia B. This study is researching an experimental gene insertion therapy (the adding of a gene into your DNA) called REGV131-LNP1265, also called the "study drug". Gene insertion therapy aims to teach the body how to produce clotting factor long-term, without the need for factor replacement therapy.

The main aim of this study is to find a safe and well-tolerated dose of the study drug by checking the side effects that may happen from taking it, both in the near term and over time.

The study is looking at several other research questions including:

  • How much study drug is in the blood at different times
  • Whether the body makes antibodies against parts of the study drug, which could make the drug less effective or could lead to side effects. Antibodies are proteins produced by the body's immune system in response to a foreign substance
  • Whether the body makes antibodies against the clotting factor replacement therapy
  • How often factor replacement therapy is needed, both on a regular basis for prevention of bleeding, and as needed to treat bleeding events (and it if changes after taking study drug)
  • Whether there is a difference in 2 different methods for measuring Factor 9 activity in the blood
Read the detailed description

The study will be conducted with a 2-part adaptive design, with enrollment of patients into sequential parts of the study.

Part 1: Dose Escalation and Dose Confirmation in adult patients ≥18 years of age

  • Dose Escalation Cohorts to determine the Recommended Dose for Expansion (RDE) of REGV131-LNP1265
  • Dose Confirmation Cohort to gain further confidence in safety, tolerability, and Coagulation Factor IX (FIX) functional activity data at the RDE

Part 2: Dose Expansion at the RDE

  • Part 2A: Adult patients ≥18 years of age: RDE of REGV131-LNP1265, as determined in Part 1
  • Part 2B: Adolescent patients ≥12 to \<18 years of age will be administered weight-adjusted RDE
  • Part 2C: Adolescent and Pediatric patients ≥2 to \<12 years may be enrolled in an age staggered sequential manner; first participants aged ≥6 to \<12 years and then participants ≥2 to \<6 years of age and will receive a weight-adjusted RDE
02

Conditions studied

  • Hemophilia B

Browse trials for

Keywords

  • Severe and moderately severe congenital hemophilia B
  • FIX functional activity
03

In context

Hemophilia B

292 studies on the registry are indexed under Hemophilia B; 51 are open to participants now.

This study's planned enrollment of 130 is above the median of 26 across 171 interventional studies indexed under Hemophilia B.

Browse Hemophilia B studies →

Lead sponsor

Regeneron Pharmaceuticals is the lead sponsor of 411 studies on the registry; 90 are open to participants now.

Of its 125 completed or terminated interventional studies of FDA-regulated products, 79 (63%) have results posted.

Browse Regeneron Pharmaceuticals studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
2 Years and older
Sexes eligible
Male
Accepts healthy volunteers
No

Eligibility criteria

Key Inclusion Criteria:

  1. Confirmed diagnosis of severe or moderately severe hemophilia B with medical history of FIX functional activity (≤2% or \<0.02 IU/mL) or documented genotype known to produce severe hemophilia B
  2. Currently taking FIX prophylaxis and previous experience with FIX therapy, as defined in the protocol
  3. Participation in the lead-in period of this interventional study OR a separate lead-in study (R0000-HEMB-2187 [NCT05568459]) for at least 6 months for ABR data while taking FIX prophylaxis, as defined in the protocol

Key Exclusion Criteria:

  1. History of FIX inhibitor (clinical or laboratory-based assessment) on 2 or more occasions
  2. Bethesda inhibitor titer greater than the (ULN) at screening
  3. Detectable pre-existing antibodies to the AAV8 capsid; as measured by Enzyme-Linked ImmunoSorbent Assay (ELISA) at prescreening (or final lead-in visit, if applicable)
  4. Any significant underlying liver disease such as: cholestatic liver disease, liver cirrhosis, portal hypertension, splenomegaly, hepatic encephalopathy
  5. Evidence of advanced liver fibrosis or significant fatty liver, as defined in the protocol
  6. Evidence of cirrhosis and/or portal hypertension as assessed by abdominal ultrasound at screening or measured within 6 months prior to the screening visit
  7. History of arterial or venous thrombo-embolic events, as defined in the protocol
  8. History of to or known medical condition that requires chronic administration of corticosteroids
  9. Previously received any AAV gene-based therapy or intends to receive approved or AAV-based gene therapy other than REGV131-LNP1265 during the study period

NOTE: Other Inclusion/Exclusion Protocol Defined Criteria Apply

Terms in these criteria, in plain language(4)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

ULN (upper limit of normal)

The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.

“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

05

Study design

Phase
Phase 1 / Phase 2
Primary purpose
Treatment
Allocation
Non-randomized
Intervention model
Sequential assignment
Masking
None (open label)
Enrollment
130 participants (estimated)

Study arms

  • Experimental
    Part 1: Cohort 1 Dose Escalation for RDE

    Starting dose to determine the RDE of REGV131-LNP1265 and further assess the safety, tolerability, and FIX functional activity data at the RDE

    Drug: REGV131 · Drug: LNP1265

  • Experimental
    Part 1: Cohort 2 Dose Escalation for RDE

    Dose 2 of ascending dose level cohorts to determine the RDE of REGV131-LNP1265 and further assess the safety, tolerability, and FIX functional activity data at the RDE

    Drug: REGV131 · Drug: LNP1265

  • Experimental
    Part 1: Cohort 3 Dose Escalation for RDE

    Dose 3 of ascending dose level cohorts to determine the RDE of REGV131-LNP1265 and further assess the safety, tolerability, and FIX functional activity data at the RDE

    Drug: REGV131 · Drug: LNP1265

  • Experimental
    Part 1: Cohort 4 Dose Escalation for RDE

    Dose 4 of ascending dose level cohorts to determine the RDE of REGV131-LNP1265 and further assess the safety, tolerability, and FIX functional activity data at the RDE

    Drug: REGV131 · Drug: LNP1265

  • Experimental
    Part 2: Dose Expansion A

    Participants ≥18 Years of Age will receive the RDE of REGV131-LNP1265 determined by Part 1

    Drug: REGV131 · Drug: LNP1265

  • Experimental
    Part 2: Dose Expansion B

    Participants ≥12 to \<18 Years of Age will receive the administered weight-adjusted RDE of REGV131-LNP1265 determined by Part 1

    Drug: REGV131 · Drug: LNP1265

  • Experimental
    Part 2: Dose Expansion C

    Participants ≥2 to \<12 Years of Age will receive the administered weight-adjusted RDE of REGV131-LNP1265 determined by Part 1

    Drug: REGV131 · Drug: LNP1265

Interventions

  • DrugREGV131

    Administered per the protocol before LNP1265

  • DrugLNP1265

    Administered per the protocol following REGV131

06

What researchers measure

Primary outcomes

  1. Occurrence of Treatment-Emergent Adverse Events (TEAEs)

    Part 1, 2B, and 2C

    Time frame: Up to 2 Years

  2. Severity of TEAEs

    Part 1, 2B, and 2C

    Time frame: Up to 2 Years

  3. Coagulation Factor IX (FIX) functional activity measured using the chromogenic substrate assay

    Part 1

    Time frame: Up to 2 Years

  4. Change in FIX functional activity in plasma, measured using the chromogenic substrate assay

    Part 2A, 2B, and 2C

    Time frame: Up to 2 Years

  5. Annualized Bleeding Rate (ABR) following sustained FIX functional activity among participants receiving the RDE

    Part 2A, 2B, and 2C

    Time frame: Up to 2 Years

  6. Occurrence of Serious Adverse Events (SAEs)

    LTFU Period for Part 1, 2A, 2B, and 2C

    Time frame: Through Long Term Follow Up (LTFU), Up to 15 Years

  7. Severity of SAEs

    LTFU Period for Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 Years

  8. Occurrence of Adverse Event of Special Interests (AESIs)

    LTFU Period for Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 Years

  9. Severity of AESIs

    LTFU Period for Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 Years

  10. Occurrence of clinically meaningful Adverse Events (AEs)

    LTFU Period for Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 Years

  11. Severity of clinically meaningful AEs

    LTFU Period for Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 Years

Secondary outcomes

  1. Change in FIX functional activity in plasma measured using the chromogenic substrate assay

    Part 1

    Time frame: Up to 2 Years

  2. ABR following sustained FIX functional activity among participants receiving the RDE

    LTFU Period for Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 Years

  3. FIX functional activity in plasma over time during the study period using the chromogenic substrate assay

    LTFU Period for Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 10 Years

  4. Annualized treated Bleeding Rate (tABR) following sustained FIX functional activity, among participants receiving the RDE

    Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 years

  5. Annualized utilization (IU/kg/year) of FIX replacement therapy following sustained FIX functional activity among participants receiving the RDE

    Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 Years

  6. Remaining free of FIX replacement therapy among those receiving the RDE following sustained FIX expression

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  7. Remaining zero spontaneous bleeding events among those receiving the RDE over sustained FIX functional activity period

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  8. Concentrations of REGV131 components

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  9. Concentrations of LNP1265 components

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  10. Detection of antibodies to the Coagulation Factor IX gene (F9) transgene product FIX protein

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  11. Detection of Total binding Antibodies (TAbs) to the Adeno-Associated Virus 8 (AAV8) capsid proteins

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  12. Detection of Neutralizing Antibodies/Transduction Inhibitors (NAb/TI) to the AAV8 capsid proteins

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  13. Detection of antibodies to LNP1265

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  14. Detection of antibodies to CRISPR-associated protein 9 (Cas9) protein

    Part 1, 2A, 2B, and 2C

    Time frame: Up to 2 Years

  15. Detection of vector DeoxyriboNucleic Acid (DNA) in blood

    Part 1

    Time frame: Up to 2 Years

  16. Detection of vector DNA in saliva

    Part 1

    Time frame: Up to 2 Years

  17. Detection of vector DNA in nasal secretions

    Part 1

    Time frame: Up to 2 Years

  18. Detection of vector DNA in semen

    Part 1

    Time frame: Up to 2 Years

  19. Detection of vector DNA in urine

    Part 1

    Time frame: Up to 2 Years

  20. Detection of vector DNA in feces

    Part 1

    Time frame: Up to 2 Years

  21. Occurrence of TEAEs

    Part 2A

    Time frame: Up to 2 Years

  22. Severity of TEAEs

    Part 2A

    Time frame: Up to 2 Years

  23. Detection of vector DNA in relevant matrices based on data analysis of Part 1 Dose Confirmation Cohort

    Part 2A, 2B, and 2C

    Time frame: Up to 2 Years

  24. Detection of vector DNA in relevant matrices over time based on data analysis from adult cohorts over time

    Part 2B and 2C

    Time frame: Up to 2 Years

  25. Proportion of participants with zero spontaneous bleeding events following sustained FIX functional activity among those receiving RDE

    Part 1, 2A, 2B, and 2C

    Time frame: Through LTFU, Up to 15 Years

  26. Proportion of participants not requiring FIX replacement therapy following sustained FIX functional activity among those receiving RDE

    Part 1, 2A, 2B, and 2C

    Time frame: Throught LTFU, Up to 15 Years

07

Study locations

52 of 52 sites recruiting
08

References and documents

Individual participant data

Plan to share: Yes — All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.

Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Clinical study report, Analytic code

Time frame: When Regeneron has: received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry) the legal authority to share the data, and ensured the ability to protect participant privacy

Access criteria: Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf

Data sharing details ↗ · vivli.org

09

Updates

2 registry updates since Sep 25, 2026
Sites
3 sites added
Show 3 added (2 United States, 1 United Kingdom)
  • Phoenix Children's Hospital · Phoenix, United States
  • Children's Medical Center Dallas · Dallas, United States
  • Oxford Haemophilia and Thrombosis Centre (OHTC) · Oxford, United Kingdom
across 2 updates, Oct 8, 2026 – Oct 21, 2026
Show all 2 updates
  1. Oct 21, 2026
    2 sites added
    Show 2 added (1 United States, 1 United Kingdom)
    • Children's Medical Center Dallas · Dallas, United States
    • Oxford Haemophilia and Thrombosis Centre (OHTC) · Oxford, United Kingdom
  2. Oct 8, 2026
    1 site added
    Show site
    • Phoenix Children's Hospital · Phoenix, United States
    + 1 other change: verification date

From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗

10

Registry details

Key details

Study ID
NCT06379789
Lead sponsor
Regeneron Pharmaceuticals
Collaborators
Intellia Therapeutics
Responsible party
Sponsor
First posted
Apr 23, 2024
Start date
Sep 11, 2024
Primary completion
Aug 14, 2034 (estimated)
Completion
Aug 14, 2047 (estimated)
Last update
Oct 21, 2026

Study contacts

Clinical Trials Administrator
Contact
clinicaltrials@regeneron.com
844-734-6643
Clinical Trial Management
study director · Regeneron Pharmaceuticals

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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