RECRUITING Phase 1 / Phase 2 ClinicalTrials.gov

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

Sponsor: Regeneron Pharmaceuticals • ClinicalTrials.gov ID: NCT06379789

Registry updated: 2026-10-21

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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. 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

Interventions

REGV131 (Drug)
Administered per the protocol before LNP1265
LNP1265 (Drug)
Administered per the protocol following REGV131

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 Upper Limit of Normal (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 hypersensitivity to corticosteroids or known medical condition that requires chronic administration of corticosteroids 9. Previously received any AAV gene-based therapy or intends to receive approved or investigational AAV-based gene therapy other than REGV131-LNP1265 during the study period NOTE: Other Inclusion/Exclusion Protocol Defined Criteria Apply

Conditions

Hemophilia B

Locations

Phoenix Children's Hospital — Phoenix, Arizona, United States
Orthopaedic Hemophilia Treatment Center — Los Angeles, California, United States
David Geffen School of Medicine at UCLA — Los Angeles, California, United States
Children's Hospital Los Angeles — Los Angeles, California, United States
University of California Davis — Sacramento, California, United States
University California San Francisco — San Francisco, California, United States
University of Colorado Hemophilia and Thrombosis Center — Aurora, Colorado, United States
Yale HTC — New Haven, Connecticut, United States
University of Florida — Gainesville, Florida, United States
Indiana Hemophilia and Thrombosis Center — Indianapolis, Indiana, United States
Tulane University School of Medicine, Louisiana Center for Bleeding and Clotting Disorders — New Orleans, Louisiana, United States
University of Michigan — Ann Arbor, Michigan, United States
Nationwide Children's Hospital — Columbus, Ohio, United States
Children's Hospital of Philadelphia (CHOP) — Philadelphia, Pennsylvania, United States
Vanderbilt University Medical Center — Nashville, Tennessee, United States
Children's Medical Center Dallas — Dallas, Texas, United States
University of Texas Health Science Center at Houston — Houston, Texas, United States
Royal Prince Alfred Hospital, Haemophilia Treatment Centre — Camperdown, New South Wales, Australia
Royal Brisbane and Women's Hospital — Herston, Queensland, Australia
Royal Adelaide Hospital — Adelaide, South Australia, Australia
Alfred Hospital — Melbourne, Victoria, Australia
Centro Estadual de Hemoterapia e Hematologia Marcos Daniel Santos — Vitória, Espírito Santo, Brazil
Hemocentro Unicamp — Campinas, São Paulo, Brazil
Hemorio — Rio de Janeiro, Brazil
University of Alberta Hospital — Edmonton, Alberta, Canada
McMaster University Medical Centre - Hamilton Health Sciences — Hamilton, Ontario, Canada
McGill University Health Center (MUHC) — Montreal, Quebec, Canada
Hospices Civils de Lyon — Bron, Lyon, France
Hemostase Clinique, Institut Coeur Poumon — Lille, Nord, France
Hopital Necker — Paris, Île-de-France Region, France
University Hospital Frankfurt — Frankfurt am Main, Hesse, Germany
University Hospital Hamburg Eppendorf — Hamburg, Germany
Careggi University Hospital — Florence, Firenze, Italy
Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ca Granda Ospedale Maggiore Policlinico — Milan, Lombardy, Italy
Irccs Humanitas Research Hospital — Rozzano, Lombardy, Italy
Ospedale san Bortolo — Vicenza, Italy
Hospital Universitario Virgen del Rocio — Seville, Andalusia, Spain
Complejo Hospitalario Universitario de A Coruña (Edificio Teresa Herrera-Materno Infantil) — A Coruña, Galicia, Spain
Hospital Clinico Universitario Virgen De La Arrixaca — El Palmar, Murcia, Spain
Hospital Universitario Central de Asturias — Oviedo, Principality of Asturias, Spain
Hospital Universitario Vall d'Hebron — Barcelona, Spain
Hospital Universitario La Paz — Madrid, Spain
Haemostasis and Thrombosis Unit, Hospital La Fe — Valencia, Spain
Hospital Universitario Miguel Servet — Zaragoza, Spain
Oxford Haemophilia and Thrombosis Centre (OHTC) — Oxford, Oxfordshire, United Kingdom
Glasgow Royal Infirmary - Clinical Research Facility — Glasgow, Scotland, United Kingdom
Queen Elizabeth Hospital Birmingham — Birmingham, West Midlands, United Kingdom
Addenbrooke's Hospital, Cambridge University Hospitals NHS FT — Cambridge, United Kingdom
Pathology and Pharmacy Building, The Royal London Hospital — London, United Kingdom
Royal Free London NHS Foundation Trust — London, United Kingdom
St. Thomas' Hospital — London, United Kingdom
Hammersmith Hospital Comprehensive Care Centre — London, United Kingdom

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Official Source

Data sourced from ClinicalTrials.gov, a service of the U.S. National Institutes of Health.

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