protocolSection identificationModule nctId: NCT06379789, orgStudyIdInfo id: R131L1265-HEMB-2318, secondaryIdInfos id: 2023-507260-40-00, type: REGISTRY, domain: EU CTR Number, briefTitle: A Trial to Learn if REGV131-LNP1265 is Safe and Works to Help the Body Make Clotting Factor in Pediatric, Adolescent and Adult Patients With Hemophilia B, acronym: BEYOND-9, statusModule overallStatus: NOT_YET_RECRUITING, startDateStruct date: 2024-07-25, primaryCompletionDateStruct date: 2032-07-03, completionDateStruct date: 2032-07-03, studyFirstPostDateStruct date: 2024-04-23, lastUpdatePostDateStruct date: 2024-04-23, sponsorCollaboratorsModule leadSponsor name: Regeneron Pharmaceuticals, class: INDUSTRY, collaborators name: Intellia Therapeutics, descriptionModule briefSummary: 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.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 quality of life is affected by hemophilia B and if it changes after taking study drug* How joint health is affected by hemophilia B and if it changes after taking study drug* How often visits are required for the emergency room, urgent care center, physician's office, hospital, telephone or online are required as a result of bleeding events, and if the frequency changes after taking study drug* 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, conditionsModule conditions: Hemophilia B, designModule studyType: INTERVENTIONAL, phases: PHASE1, phases: PHASE2, designInfo allocation: NON_RANDOMIZED, interventionModel: SEQUENTIAL, primaryPurpose: TREATMENT, maskingInfo masking: NONE, enrollmentInfo count: 130, type: ESTIMATED, armsInterventionsModule interventions name: REGV131, interventions name: LNP1265, outcomesModule primaryOutcomes measure: Incidence of treatment-emergent adverse events (TEAEs), primaryOutcomes measure: Severity of TEAEs, primaryOutcomes measure: Coagulation Factor IX (FIX) functional activity measured using the chromogenic substrate assay, primaryOutcomes measure: Change in FIX functional activity in plasma, measured using the chromogenic substrate assay, primaryOutcomes measure: Annualized bleeding rate (ABR) following sustained FIX functional activity among participants receiving the RDE, secondaryOutcomes measure: Change in FIX functional activity in plasma measured using the chromogenic substrate assay, secondaryOutcomes measure: ABR following sustained FIX functional activity among participants receiving the RDE, secondaryOutcomes measure: FIX functional activity in plasma over time during the study period using the chromogenic substrate assay, secondaryOutcomes measure: Annualized treated bleeding rate (tABR) following sustained FIX functional activity, among participants receiving the RDE, secondaryOutcomes measure: Annualized utilization (IU/kg/year) of FIX replacement therapy following sustained FIX functional activity among participants receiving the RDE, secondaryOutcomes measure: Remaining free of FIX replacement therapy among those receiving the RDE following sustained FIX expression, secondaryOutcomes measure: Remaining zero spontaneous bleeding events among those receiving the RDE over sustained FIX functional activity period, secondaryOutcomes measure: Concentrations of REGV131 components, secondaryOutcomes measure: Concentrations of LNP1265 components, secondaryOutcomes measure: Detection of antibodies to the F9 transgene product FIX protein, secondaryOutcomes measure: Detection of total binding antibodies (TAbs) to the adeno-associated virus 8 (AAV8) capsid proteins, secondaryOutcomes measure: Detection of neutralizing antibodies/transduction inhibitors (NAb/TI) to the adeno-associated virus 8 (AAV8) capsid proteins, secondaryOutcomes measure: Detection of antibodies to LNP1265, secondaryOutcomes measure: Detection of antibodies to CRISPR-associated protein 9 (Cas9) protein, secondaryOutcomes measure: Detection of vector DNA in blood, secondaryOutcomes measure: Detection of vector DNA in saliva, secondaryOutcomes measure: Detection of vector DNA in nasal secretions, secondaryOutcomes measure: Detection of vector DNA in semen, secondaryOutcomes measure: Detection of vector DNA in urine, secondaryOutcomes measure: Detection of vector DNA in feces, secondaryOutcomes measure: Incidence of TEAEs, secondaryOutcomes measure: Severity of TEAEs, secondaryOutcomes measure: Detection of vector DNA in relevant matrices based on data analysis of Part 1 Dose Confirmation Cohort, secondaryOutcomes measure: Detection of vector DNA in relevant matrices over time based on data analysis from adult cohorts over time, eligibilityModule sex: MALE, minimumAge: 18 Years, stdAges: ADULT, stdAges: OLDER_ADULT, contactsLocationsModule, hasResults: False