Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Not yet recruiting

Prevention of Stroke and Systemic Embolism in Atrial Fibrillation Patients Treated with REGN7508 (cenvacibart) versus Apixaban

Fast replyRegistered drug
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on people with Atrial Fibrillation, a heart rhythm problem that raises the chance of a stroke or systemic embolism. The investigational medicine is REGN7508, a monoclonal antibody designed to block Factor XI, a protein involved in blood clotting. It is compared with the approved blood‑thinner apixaban, taken as a tablet, and with matching placebo treatments.

The aim is to see whether the new injection can lower the risk of stroke or systemic embolism and reduce serious bleeding compared with the tablet. This protein is designed to target a specific part of the clotting system, while Factor XI is one of the factors that helps blood form clots; blocking it may prevent harmful clots without causing too much bleeding.

Participants are randomly assigned in a double‑blind fashion to receive either the injection, the tablets, or the corresponding inactive treatments, and they return for regular check‑ups where doctors look for any signs of clotting problems, bleeding, or other side effects. The study continues for several months, with each visit involving simple health questions and brief examinations.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment completed

    After you sign the consent form, the study staff confirm that you meet the criteria for atrial fibrillation. you then move to the next step.

  2. Step 2

    Randomization

    You will be assigned by a computer to receive either the investigational drug regn7508, the active drug apixaban, or a matching placebo. the assignment is double‑blind, so neither you nor the study staff know which product you receive.

  3. Step 3

    Start of study medication

    If you are assigned to regn7508, you will receive an injection of a solution for injection in a pre‑filled syringe administered by a health professional according to the trial protocol.

    If you are assigned to apixaban, you will take oral film‑coated tablets (either 5 mg or 2.5 mg) as directed. the exact dose, frequency, and duration are defined by the study protocol.

  4. Step 4

    Regular dosing

    You will continue to receive the assigned medication for the duration of the study, which may last until the final study date of 2029‑12‑10. you follow the dosing schedule specified in the protocol and do not change the dose without study approval.

  5. Step 5

    Follow‑up assessments

    At each scheduled visit, the study team checks for signs of stroke, systemic embolism, and bleeding. they also record any adverse events and may perform laboratory tests. visits occur according to the study schedule.

  6. Step 6

    Study completion

    The trial ends for you when the study reaches its final date or if you withdraw earlier. at that time, the study medication is stopped and a final assessment is performed.

Who can join the trial?

6 criteria

  • Must have Atrial Fibrillation (an irregular heartbeat) or atrial flutter that is not caused by a temporary problem, and need ongoing blood‑thinner (anticoagulant) medication.
  • Must meet one of the following CHA2DS2‑VA score requirements (a score that estimates stroke risk based on conditions such as heart failure, high blood pressure, age, diabetes, prior stroke, and other vascular disease):
    • Score ≥ 2 and have never taken a blood thinner before, or
    • Score ≥ 3, or
    • Score = 2 plus at least one additional risk factor as defined in the study.
    • If currently using warfarin or another Vitamin K Antagonist (a type of blood thinner), the International Normalized Ratio (INR) must be less than 2.5 at the time of randomization.
    • Can be male or female and must fall within the age range specified by the study protocol.

Who cannot join the trial?

6 criteria

  • Having a mechanical heart valve prosthesis (a man‑made valve that replaces a heart valve). Transcatheter aortic valve replacement does not count as an exclusion.
  • Having moderate‑to‑severe mitral stenosis (narrowing of the valve between the left atrium and left ventricle).
  • Having had a successful ablation therapy (a procedure that destroys small areas of heart tissue to control rhythm) and no repeat atrial fibrillation, or planning to have an ablation or left atrial appendage (LAA) occlusion (closing a small pouch in the heart) within 6 months after randomization.
  • Having an ischemic stroke (a stroke caused by a blocked blood vessel) within 2 days before randomization.
  • Having persistent, uncontrolled high blood pressure (hypertension) as judged by the doctor.
  • Having an estimated Glomerular Filtration Rate (eGFR) less than 15 mL/min/1.73 m² (a measure of kidney function) within 30 days before randomization, being on dialysis (a machine that cleans the blood), or expected to start dialysis within the next 6 months.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Not yet recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

  • REGN7508

    is an experimental medicine that is given by injection. It is a special type of protein called a monoclonal antibody that is designed to block a clotting factor in the blood called Factor XI. By blocking this factor, the drug aims to lower the chance of blood clots that can cause strokes or other serious problems. In the study, REGN7508 is the new treatment being tested to see if it works better or safer than the standard medicine.

  • Apixaban

    is an oral tablet that people take by mouth. It is a blood‑thinner that works by stopping the clotting process, helping to prevent strokes and other clot‑related events in people with irregular heart rhythm (atrial fibrillation). In this trial, apixaban is the standard medication used for comparison, so researchers can see how the new injection (REGN7508) measures up against it.

What is already known about the treatment

  • REGN7508

    REGN7508 is given as a sterile solution for injection in a pre‑filled syringe that is administered into a vein. It is an experimental drug currently being studied in Phase 3 clinical trials for its ability to prevent stroke and blood clots in people with atrial fibrillation. The medicine works by using a monoclonal antibody called Cenvacibart to attach to factor XI, a protein that helps start the clotting process, thereby slowing clot formation. It is classified as a factor XI‑targeting anticoagulant and a monoclonal antibody therapy.

  • Apixaban (Eliquis)

    Apixaban is taken as a film‑coated tablet taken by mouth, available in 2.5 mg and 5 mg strengths. It is an approved medication widely used to lower the risk of stroke, systemic embolism, and other clot‑related events in patients with atrial fibrillation and to treat or prevent deep‑vein thrombosis and pulmonary embolism. The drug works by directly blocking factor Xa, an enzyme that converts blood‑clotting proteins into their active form, thus reducing clot formation. It belongs to the class of oral direct factor Xa inhibitors, a type of anticoagulant.

Investigated diseases

Atrial fibrillation - Atrial fibrillation is an irregular heart rhythm that causes the upper chambers of the heart to beat fast and out of sync with the lower chambers. It often begins with brief episodes that stop on their own, but over time the episodes can become more frequent and last longer. The irregular beats reduce the efficiency of blood pumping, leading to a gradual decline in heart function. Triggers such as stress, high blood pressure, or other heart problems can cause the rhythm to persist or become permanent.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-521617-97-00Protocol codeR7508-CVA-24114Estimated enrolment15 335 patientsSponsorRegeneron Pharmaceuticals Inc.

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.