A Phase 3 interventional study of REGN7508 and REGN9933 in Atrial Fibrillation (AF), sponsored by Regeneron Pharmaceuticals. Recruiting at 45 sites in 2 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by Regeneron Pharmaceuticals · Phase 3, Interventional, and Prevention
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:
4,009 studies on the registry are indexed under Atrial Fibrillation; 961 are open to participants now.
This study's planned enrollment of 2,628 is above the median of 150 across 2,476 interventional studies indexed under Atrial Fibrillation.
Browse Atrial Fibrillation studies →Regeneron Pharmaceuticals is the lead sponsor of 411 studies on the registry; 90 are open to participants now.
Of its 125 completed or terminated interventional studies of FDA-regulated products, 79 (63%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
At moderate to high risk for stroke defined as:
Key Exclusion Criteria:
Note: Other protocol-defined Inclusion/ Exclusion criteria apply
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Drug: REGN7508
Drug: REGN9933
Drug: Placebo
Time to first occurrence of ischemic stroke or systemic embolism
Time frame: Up to 36 months
Time to first occurrence of International Society on Thrombosis and Haemostasis (ISTH) major bleeding
Time frame: Up to 36 months
Time to first occurrence of Major Adverse Cardiovascular Event (MACE)
Time frame: Up to 36 months
Time to first occurrence of MACE, pulmonary embolism, or Venous Thromboembolism (VTE)
Time frame: Up to 36 months
Time to first occurrence of ischemic stroke
Time frame: Up to 36 months
Time to Cardiovascular (CV) death
Time frame: Up to 36 months
Time to all-cause death
Time frame: Up to 36 months
Occurrence of Treatment-Emergent Adverse Events (TEAEs)
Time frame: Up to 39 months
Severity of TEAEs
Time frame: Up to 39 months
Concentrations of REGN7508 over time
Time frame: Up to 36 months
Concentrations of REGN9933 over time
Time frame: Up to 36 months
Change from baseline in activated Partial Thromboplastin Time (aPTT) over time
Time frame: Up to approximately 9 weeks
Change from baseline in Prothrombin time (PT)/International Normalized Ratio (INR) over time
Time frame: Up to approximately 9 weeks
Occurrence of Anti-Drug Antibody (ADA) to REGN7508 over time
Time frame: Up to 36 months
Magnitude of ADA to REGN7508 over time
Time frame: Up to 36 months
Occurrence of ADA to REGN9933 over time
Time frame: Up to 36 months
Magnitude of ADA to REGN9933 over time
Time frame: Up to 36 months
Plan to share: Yes — All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Clinical study report, 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
Data sharing details ↗ · vivli.org
No publications or documents are linked to this record.
Started Apr 2026 (actual). Primary completion is estimated for Mar 2029, 35 months after the start.
Of 83 phase 3 interventional studies under Atrial Fibrillation, half reached primary completion within 42 months of starting (the median), counting those still running; a quarter within 32 and three quarters within 63. This study's planned 35 months is below that.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
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