NCT07175428From ClinicalTrials.govRecruiting

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

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)

Atrial Fibrillation (AF)

At a glance

Phase: Phase 2
Study type: Interventional
Sponsor: Regeneron Pharmaceuticals
Enrolment target: 1,200
Started: 20 October 2025
Main results due: 9 February 2027
Study sites: 84
Registry updated: 28 September 2026

Can you take part?

Aged 18 years and over.
Open to any sex.
You need the condition being studied — healthy volunteers are not accepted.

These are the headline rules only. Every study has a longer list, and whether you are eligible is decided by the research team at the site — never by this page.

Read the full eligibility criteria

Key Inclusion Criteria:

1. 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
2. Meets one of the following:

   1. 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
   2. CHA2DS2-VA score ≥3 or
   3. CHA2DS2-VA score of 2 and at least 1 enrichment criteria as described in the protocol
3. 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:

1. Has a mechanical heart valve prosthesis (Note: transcatheter aortic valve replacement is not an exclusion)
2. Has known moderate-to-severe mitral stenosis
3. Has had successful ablation therapy or Left Atrial Appendage (LAA) occlusion/exclusion, or planned ablation or LAA occlusion/exclusion as described in the protocol
4. Had an ischemic stroke within 2 days prior to randomization
5. 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
6. Has a history of central nervous system bleeding within 30 days prior to randomization

Note: Other protocol-defined Inclusion/ Exclusion criteria apply

What this study is about

In the sponsor’s own words, from the registry.

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)

Study sites(84)

SEC Clinical Research
Dothan, Alabama, United States
Recruiting
Eastern Shore Research Institute
Fairhope, Alabama, United States
Recruiting
Valley Clinical Trials, Inc
Covina, California, United States
Recruiting
North Coast Cardiology
Encinitas, California, United States
Recruiting
Mission Cardiovascular Research Institute
Fremont, California, United States
Recruiting
National Institute of California Heart and Vein Specialists
Huntington Beach, California, United States
Recruiting
Profound Research LLC at Southern California Heart Specialists
Pasadena, California, United States
Recruiting
Empire Clinical Research
Pomona, California, United States
Recruiting
The Cardiovascular Center
Redding, California, United States
Recruiting
Northbay Clinical Research Center
Santa Rosa, California, United States
Recruiting
Cardiology Associates Medical Group
Ventura, California, United States
Recruiting
Interventional Cardiology Medical Group
West Hills, California, United States
Recruiting
Nouvelle Clinical Research LLC
Cutler Bay, Florida, United States
Recruiting
South Florida Research Organization LLC
Medley, Florida, United States
Recruiting
Inpatient Research Clinic LLC
Miami Lakes, Florida, United States
Recruiting
Cardiovascular Center of Sarasota Foundation for Research and Education
Sarasota, Florida, United States
Recruiting
Clinical Site Partners, LLC DBA Flourish Research
Winter Park, Florida, United States
Recruiting
Grady Health System
Atlanta, Georgia, United States
Recruiting
Health Sciences Research Building II
Atlanta, Georgia, United States
Withdrawn
NSC Research, Inc
Johns Creek, Georgia, United States
Recruiting
Indiana University
Indianapolis, Indiana, United States
Recruiting
Blue Coast Research Center, LLC
Indianapolis, Indiana, United States
Recruiting
Franciscan Physician Network, Indiana Heart Physicians
Indianapolis, Indiana, United States
Recruiting
Indiana Medical Research
Merrillville, Indiana, United States
Recruiting
Reid Physician Associates
Richmond, Indiana, United States
Recruiting
Monroe Research, LLC
West Monroe, Louisiana, United States
Recruiting
Anderson Medical Research
Ft. Washington, Maryland, United States
Recruiting
Beth Israel Lahey Health, Beth Israel Deaconess Medical Center (BIDMC)
Boston, Massachusetts, United States
Recruiting
Profound Research, Millennium Cardiology
Farmington Hills, Michigan, United States
Recruiting
AA Medical Research Center (MRC)
Flint, Michigan, United States
Recruiting
Fairview Health Services
Maplewood, Minnesota, United States
Recruiting
Moses Cone Hospital Operating Corporation dba Cone Health, Lebauer-Brodie Center for Cardiovascular Research
Greensboro, North Carolina, United States
Recruiting
K&R Research LLC
Marion, Ohio, United States
Recruiting
Advanced Medical Research
Maumee, Ohio, United States
Recruiting
Monument Health Clinical Research
Rapid City, South Dakota, United States
Recruiting
East Coast Institute for Research, Jefferson City
Jefferson City, Tennessee, United States
Recruiting
PharmaTex Research
Amarillo, Texas, United States
Recruiting
Complete Heart Care P.A.
McKinney, Texas, United States
Recruiting
Texas Institute of Cardiology PA
McKinney, Texas, United States
Recruiting
Synergy Group Medical, LLC
Missouri City, Texas, United States
Recruiting
Permian Research Foundation
Odessa, Texas, United States
Recruiting
Tyler Cardiovascular Consultants
Tyler, Texas, United States
Recruiting
Alpine Research TC
Clinton, Utah, United States
Recruiting
Centro de Investigacion Clinica
Ciudad Autonoma de Buenos Aires, Buenos Aires, Argentina
Recruiting
Fundacion Estudios Clinicos
Rosario, Santa Fe Province, Argentina
Recruiting
STAT Research Argentina
Buenos Aires, Argentina
Recruiting
Sanatorio Duarte Quiros
Córdoba, Argentina
Recruiting
Centro de Investigaciones Clinicas del Litoral
Santa Fe, Argentina
Recruiting
Via Medica Research Center
Goiânia, Goiás, Brazil
Recruiting
Hospital Ruy Azeredo
Goiânia, Goiás, Brazil
Recruiting
Hospital das Clinicas da Universidade Federal de Goias
Goiânia, Goiás, Brazil
Recruiting
Cardiologia Assistencial e de Pesquisa Ltda (Cardresearch)
Belo Horizonte, Minas Gerais, Brazil
Recruiting
Nucleo de Pesquisa do Hospital Cardiologico Costantini (NUPEC)
Belo Horizonte, Minas Gerais, Brazil
Recruiting
Hospital Maternidade e Pronto Socorro Santa Lucia
Poços de Caldas, Minas Gerais, Brazil
Recruiting
Eurolatino Medical Research
Uberlândia, Minas Gerais, Brazil
Recruiting
Sociedade Hospitalar Angelina Caron
Campina Grande do Sul, Paraná, Brazil
Recruiting
Quanta Diagnostico por Imagem
Curitiba, Paraná, Brazil
Recruiting
Pontificia Universidade Catolica do Paraná (PUC) Trials
Curitiba, Paraná, Brazil
Recruiting
Nucleo de Pesquisa Clínica SS
Curitiba, Paraná, Brazil
Recruiting
Hospital Ernesto Dornelles
Porto Alegre, Rio Grande do Sul, Brazil
Recruiting

Showing 60 of 84 sites — filter to narrow it down. 83 of the 84 sites on this study are recruiting right now — a site can stop enrolling while the study as a whole is still open.

Source: ClinicalTrials.gov record NCT07175428. Trialion does not run this study, is not paid to refer anyone to it, and cannot enrol you. Eligibility is always decided by the research team at the site.

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