A Phase 2 interventional study of REGN7508 and REGN9933 in Atrial Fibrillation (AF), sponsored by Regeneron Pharmaceuticals. Recruiting at 91 sites in 4 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-05.
Sponsored by Regeneron Pharmaceuticals · Phase 2, Interventional, and Prevention
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:
4,009 studies on the registry are indexed under Atrial Fibrillation; 961 are open to participants now.
This study's planned enrollment of 1,200 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:
Meets one of the following:
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.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
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.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Drug: REGN7508
Drug: REGN9933
Drug: Apixaban
Incidence of any bleeding
Defined as the composite of International Society on Thrombosis and Haemostasis (ISTH) major bleeding, ISTH Clinically Relevant Non-Major (CRNM) bleeding, or minor bleeding
Time frame: 12 weeks
Incidence of the composite of ISTH major bleeding or ISTH CRNM bleeding
Time frame: 12 weeks
Incidence of ISTH major bleeding
Time frame: 12 weeks
Incidence of ISTH CRNM bleeding
Time frame: 12 weeks
Incidence of minor bleeding
Time frame: 12 weeks
Number of ISTH major bleeding events
Time frame: 12 weeks
Number of ISTH CRNM bleeding events
Time frame: 12 weeks
Number of minor bleeding events
Time frame: 12 weeks
Incidence of Treatment-Emergent Adverse Events (TEAEs)
Time frame: Approximately 25 weeks
Severity of TEAEs
Time frame: Approximately 25 weeks
Incidence of the composite of stroke or systemic embolism
Time frame: Approximately 12 weeks
Incidence of Antidrug Antibodies (ADA) to REGN7508
Time frame: 12 weeks
Magnitude of ADA to REGN7508
Time frame: 12 weeks
Incidence of ADA to REGN9933
Time frame: 12 weeks
Magnitude of ADA to REGN9933
Time frame: 12 weeks
Concentrations of REGN7508
Time frame: Approximately 25 weeks
Concentrations of REGN9933
Time frame: Approximately 25 weeks
Change from baseline in activated Partial Thromboplastin Time (aPTT)
Time frame: Approximately 25 weeks
Change from baseline in Prothrombin Time (PT)
Time frame: Approximately 25 weeks
Not enrolling at this site — choose another above.
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 Oct 2025 (actual). Primary completion is estimated for Feb 2027, 15 months after the start.
Of 41 phase 2 interventional studies under Atrial Fibrillation, half reached primary completion within 32 months of starting (the median), counting those still running; a quarter within 18 and three quarters within 39. This study's planned 15 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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