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Recruiting

NCT Number: NCT07175428

Safety in Adult Participants With Atrial Fibrillation Who Are Treated With Anticoagulation

This study is researching experimental drugs called REGN7508 and REGN9933. The study is focused on participants who have atrial fibrillation, which means that the heart beats too fast and unevenly. 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 well REGN7508 and REGN9933 work in patients that get medicine for their atrial fibrillation. The bleeding effects of REGN7508 and REGN9933 will be compared to another medicine (apixaban), which is available on the market to treat and prevent formation of blood clots.

The study is looking at several other research questions, including:

* What side effects may happen from taking REGN7508 or REGN9933 * How well do the study drugs reduce the risk of having a stroke * How much of REGN7508 or REGN9933 is in the blood at different times * Whether the body makes antibodies against REGN7508 or REGN9933 (which could make the drugs less effective or could lead to side effects)

Recruiting

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Key information

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

Fundacion Estudios Clinicos - Cardiologia, Rosario, Santa Fe Province, Argentina

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Key Inclusion Criteria:

  • Has AF or flutter (paroxysmal or persistent), not felt to be secondary to a reversible cause, and an indication for indefinite anticoagulation treatment as described in the protocol
  • Meets one of the following:
  • CHA2DS2-VA [C: Congestive heart failure; H: Hypertension; A2: Age ≥75 years (double points); D: Diabetes mellitus; S2: Stroke or TIA or Thromboembolism (double points); V: Vascular disease; A: Age 65-74 years] score ≥2 and Oral Anticoagulant (OAC) naïve or
  • CHA2DS2-VA score ≥3 or
  • CHA2DS2-VA score of 2 and at least 1 enrichment criteria as described in the protocol
  • Must have an International Normalization Ratio (INR) <2.5 at the time of randomization if taking warfarin or another Vitamin K Antagonist (VKA)

Key Exclusion Criteria:

  • Has a mechanical heart valve prosthesis (Note: transcatheter aortic valve replacement is not an exclusion)
  • Has known moderate-to-severe mitral stenosis
  • Has had successful ablation therapy or Left Atrial Appendage (LAA) occlusion/exclusion, or planned ablation or LAA occlusion/exclusion as described in the protocol
  • Had an ischemic stroke within 2 days prior to randomization
  • Has estimated Glomerular Filtration Rate (eGFR) <15 mL/min/1.73m^2 within 30 days prior to randomization or on dialysis or expected to be started as described in the protocol
  • Has a history of central nervous system bleeding within 30 days prior to randomization

Note: Other protocol-defined Inclusion/ Exclusion criteria apply

Treatment and study plan

REGN7508

Drug

Administered per the protocol

Other names: cenvacibart

REGN9933

Drug

Administered per the protocol

Other names: amrecibart

Apixaban

Drug

Administered per the protocol

Other names: Eliquis

Primary outcomes

  1. Incidence of any bleeding

    Time frame: 12 weeks

    Defined as the composite of International Society on Thrombosis and Haemostasis (ISTH) major bleeding, ISTH Clinically Relevant Non-Major (CRNM) bleeding, or minor bleeding

Secondary outcomes

  1. Incidence of the composite of ISTH major bleeding or ISTH CRNM bleeding

    Time frame: 12 weeks

  2. Incidence of ISTH major bleeding

    Time frame: 12 weeks

  3. Incidence of ISTH CRNM bleeding

    Time frame: 12 weeks

  4. Incidence of minor bleeding

    Time frame: 12 weeks

  5. Number of ISTH major bleeding events

    Time frame: 12 weeks

  6. Number of ISTH CRNM bleeding events

    Time frame: 12 weeks

  7. Number of minor bleeding events

    Time frame: 12 weeks

  8. Incidence of Treatment-Emergent Adverse Events (TEAEs)

    Time frame: Approximately 25 weeks

  9. Severity of TEAEs

    Time frame: Approximately 25 weeks

  10. Incidence of the composite of stroke or systemic embolism

    Time frame: Approximately 12 weeks

  11. Incidence of Antidrug Antibodies (ADA) to REGN7508

    Time frame: 12 weeks

  12. Magnitude of ADA to REGN7508

    Time frame: 12 weeks

  13. Incidence of ADA to REGN9933

    Time frame: 12 weeks

  14. Magnitude of ADA to REGN9933

    Time frame: 12 weeks

  15. Concentrations of REGN7508

    Time frame: Approximately 25 weeks

  16. Concentrations of REGN9933

    Time frame: Approximately 25 weeks

  17. Change from baseline in activated Partial Thromboplastin Time (aPTT)

    Time frame: Approximately 25 weeks

  18. Change from baseline in Prothrombin Time (PT)

    Time frame: Approximately 25 weeks

Study contacts

Contact information is provided by the study sponsor or research team.

Clinical Trials Administrator

CONTACT

[email protected]

844-734-6643

Sponsors and collaborators

Lead sponsor

Regeneron Pharmaceuticals

Industry

Registry information

Official study title

A Phase 2, Randomized, Multicenter, Open-label, Blinded-endpoint Study to Evaluate the Safety of REGN7508 and REGN9933, Monoclonal Antibodies Against FXI, Versus Apixaban in Participants With Atrial Fibrillation (ROXI-ATLAS)

Acronym: ROXI-ATLAS

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Sep 16, 2025
Registry last updated
Jul 23, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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