NCT06379789 · Regeneron Pharmaceuticals
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
(BEYOND-9)
What this study is about
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".
View original scientific description
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.
Interventions
DRUG
REGV131
Administered per the protocol before LNP1265
DRUG
LNP1265
Administered per the protocol following REGV131
Primary outcome measures
Occurrence of Treatment-Emergent Adverse Events (TEAEs)
Time frame: Up to 2 Years
Part 1, 2B, and 2C
Severity of TEAEs
Time frame: Up to 2 Years
Part 1, 2B, and 2C
Coagulation Factor IX (FIX) functional activity measured using the chromogenic substrate assay
Time frame: Up to 2 Years
Part 1
Change in FIX functional activity in plasma, measured using the chromogenic substrate assay
Time frame: Up to 2 Years
Part 2A, 2B, and 2C
Annualized Bleeding Rate (ABR) following sustained FIX functional activity among participants receiving the RDE
Time frame: Up to 2 Years
Part 2A, 2B, and 2C
Occurrence of Serious Adverse Events (SAEs)
Time frame: Through Long Term Follow Up (LTFU), Up to 15 Years
LTFU Period for Part 1, 2A, 2B, and 2C
Severity of SAEs
Time frame: Through LTFU, Up to 15 Years
LTFU Period for Part 1, 2A, 2B, and 2C
Occurrence of Adverse Event of Special Interests (AESIs)
Time frame: Through LTFU, Up to 15 Years
LTFU Period for Part 1, 2A, 2B, and 2C
Severity of AESIs
Time frame: Through LTFU, Up to 15 Years
LTFU Period for Part 1, 2A, 2B, and 2C
Occurrence of clinically meaningful Adverse Events (AEs)
Time frame: Through LTFU, Up to 15 Years
LTFU Period for Part 1, 2A, 2B, and 2C
Severity of clinically meaningful AEs
Time frame: Through LTFU, Up to 15 Years
LTFU Period for Part 1, 2A, 2B, and 2C
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- 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
- History of FIX inhibitor (clinical or laboratory-based assessment) on 2 or more occasions 2. Bethesda inhibitor titer greater than the upper limit of normal (ULN) at screening 3. Detectable pre-existing antibodies to the adeno-associated virus serotype 8 (AAV8) capsid; as measured by enzyme-linked immunosorbent assay (ELISA) at prescreening (or final lead-in visit, if applicable). 4. Any significant underlying liver di
Where
- Los Angeles, California
- Sacramento, California
- San Francisco, California
- Aurora, Colorado
- New Haven, Connecticut
- Gainesville, Florida
- Indianapolis, Indiana
- New Orleans, Louisiana
- Ann Arbor, Michigan
- Columbus, Ohio
- Philadelphia, Pennsylvania
- Nashville, Tennessee
Collaborators
Intellia Therapeutics
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jul 8, 2026 · Source of record for eligibility and locations