Stroke and Systemic Embolism Prevention in Adult Participants With Atrial Fibrillation for Whom Oral Anticoagulation is Unsuitable

NCT07430956 | Recruiting Phase 3 DMC FDA Drug

• 2 other identifiers: R9933-CVA-24952025-521618-25-00
• Study Type: interventional
• Target: 2,628
• Locations: 1 country
• Sites: 13

Brief Summary

This study is researching 2 different experimental drugs called REGN7508 and REGN9933 (called "study drugs"). The study is focused on people who have atrial fibrillation, which means that the heart beats too fast and unevenly. When this happens, blood cannot move smoothly through the heart; it can slow down or pool in one spot, which can lead to the formation of blood clots. REGN7508 and REGN9933 are designed to help stop blood clots forming in patients with atrial fibrillation. The aim of the study is to see how effective and safe REGN7508 and REGN9933, individually, are in preventing ischemic stroke or systemic embolism in people with atrial fibrillation who cannot or may choose to not take blood thinners. The study is looking at several other research questions, including:

• What side effects may happen from taking REGN7508 or REGN9933
• How well does REGN7508 or REGN9933 lower the risk of having an ischemic stroke and/or systemic embolism compared to the placebo
• How well does REGN7508 or REGN9933 lower the risk of having a major health problem affecting heart and blood circulation compared to placebo
• How well does REGN7508 or REGN9933 lower the risk of death compared to placebo
• How much REGN7508 or REGN9933 is in the blood at different times
• Whether the body makes antibodies against REGN7508 or REGN9933 (which could make the study drugs less effective or could lead to side effects)

Conditions

Atrial Fibrillation (AF)

Keywords

Blood clots; Ischemic stroke; Systemic embolism; Pulmonary embolism; Venous Thromboembolism (VTE)

Outcome Measures

Primary Outcomes (2)

• Time to first occurrence of ischemic stroke or systemic embolism

  Up to 36 months

• Time to first occurrence of International Society on Thrombosis and Haemostasis (ISTH) major bleeding

  Up to 36 months

Secondary Outcomes (15)

• Time to first occurrence of Major Adverse Cardiovascular Event (MACE)

  Up to 36 months

• Time to first occurrence of MACE, pulmonary embolism, or Venous Thromboembolism (VTE)

  Up to 36 months

• Time to first occurrence of ischemic stroke

  Up to 36 months

• Time to Cardiovascular (CV) death

  Up to 36 months

• Time to all-cause death

  Up to 36 months

Study Arms (3)

REGN7508

EXPERIMENTAL

Drug: REGN7508

REGN9933

EXPERIMENTAL

Drug: REGN9933

Placebo

PLACEBO COMPARATOR

Drug: Placebo

Interventions

REGN7508 DRUG

Administered per the protocol

Also known as: cenvacibart

REGN7508

REGN9933 DRUG

Administered per the protocol

Also known as: amrecibart

REGN9933

Placebo DRUG

Administered per the protocol

Placebo

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Has AF or flutter (paroxysmal or persistent), not considered to be secondary to a reversible cause
• At moderate to high risk for stroke defined as:
• CHA2DS2-VA \[C: Congestive heart failure; H: Hypertension; A2: Age ≥75 years (double points); D: Diabetes mellitus; S2: Stroke or TIA or Systemic embolism (double points); V: Vascular disease; A: Age 65-74 years\] score ≥4 OR
• CHA2DS2-VA score of 3 AND at least 1 enrichment criteria as described in the protocol
• Shared decision making between the participant and provider determining that the bleeding risk of Oral Anticoagulant (OAC) therapy outweighs the benefits, making the participant unsuitable for OAC therapy as described in the protocol

You may not qualify if:

• Had an ischemic stroke within 2 days prior to randomization
• Has persistent, uncontrolled hypertension (per investigator's discretion)
• Has a history of Central Nervous System (CNS) bleeding within 30 days prior to randomization
• Has a life expectancy less than 12 months
• Has participated in a prior Factor XI (FXI) inhibitor study

Sponsors & Collaborators

• Regeneron Pharmaceuticals: lead

Study Sites (13)

SEC Clinical Research

Dothan, Alabama, 36305, United States

RECRUITING

Mission Cardiovascular Research Institute

Fremont, California, 94538, United States

RECRUITING

National Institute of California Heart and Vein Specialists

Huntington Beach, California, 92648, United States

RECRUITING

Profound Research LLC at Southern California Heart Specialists

Pasadena, California, 91105, United States

RECRUITING

Cardiology Associates Medical Group

Ventura, California, 93003, United States

RECRUITING

Interventional Cardiology Medical Group

West Hills, California, 91307, United States

RECRUITING

South Florida Research Organization LLC

Medley, Florida, 33166, United States

RECRUITING

Clinical Site Partners, LLC DBA Flourish Research

Winter Park, Florida, 32789, United States

RECRUITING

NSC Research, Inc

Johns Creek, Georgia, 30024, United States

RECRUITING

Monroe Research, LLC

West Monroe, Louisiana, 71291, United States

RECRUITING

AA Medical Research Center (MRC)

Flint, Michigan, 48504, United States

RECRUITING

K&R Research LLC

Marion, Ohio, 43302, United States

RECRUITING

PharmaTex Research

Amarillo, Texas, 79106, United States

RECRUITING

MeSH Terms

Conditions

Atrial Fibrillation; Thrombosis; Ischemic Stroke; Pulmonary Embolism; Venous Thromboembolism

Condition Hierarchy (Ancestors)

Arrhythmias, Cardiac; Heart Diseases; Cardiovascular Diseases; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Embolism and Thrombosis; Vascular Diseases; Stroke; Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Lung Diseases; Respiratory Tract Diseases; Embolism; Thromboembolism

Study Officials

• Clinical Trial Management

  Regeneron Pharmaceuticals

  STUDY DIRECTOR

Central Study Contacts

Clinical Trials Administrator

CONTACT

844-734-6643; clinicaltrials@regeneron.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 18, 2026
• First Posted: February 24, 2026
• Study Start: April 3, 2026
• Primary Completion (Estimated): March 28, 2029
• Study Completion (Estimated): June 26, 2029
• Last Updated: May 29, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, CSR, 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

Locations

US (13)