NCT07213778From ClinicalTrials.govRecruiting

REGN7508 Versus Acetylsalicylic Acid (ASA) for Venous Thromboprophylaxis After Total Knee Arthroplasty in Adult Participants

A Phase 3, Multicenter, Double-Blinded, Randomized Study to Evaluate REGN7508, a Factor XI Monoclonal Antibody, Versus Acetylsalicylic Acid for Prophylaxis of Symptomatic Venous Thromboembolism After Elective Total Knee Arthroplasty (ROXI-ASPEN)

Symptomatic Venous Thromboembolism (VTE)

At a glance

Phase: Phase 3
Study type: Interventional
Sponsor: Regeneron Pharmaceuticals
Enrolment target: 2,000
Started: 24 November 2025
Main results due: 17 May 2027
Study sites: 46
Registry updated: 25 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. Is undergoing a primary elective unilateral TKA
2. Is in good health based on laboratory safety testing as described in the protocol

Key Exclusion Criteria:

1. Any condition that, as assessed by the investigator, may confound the results of the study or pose an additional risk to the participant by study participation
2. History of bleeding in the 6 months prior to randomization requiring hospitalization or transfusion; history of intracranial or intraocular bleeding, excessive operative or post-operative bleeding, and traumatic spinal or epidural anesthesia; history of bleeding diathesis (eg, hemophilia A or B, von Willebrand's Factor deficiency)
3. History of thromboembolic disease or thrombophilia
4. History of platelet dysfunction
5. Has received or plans to receive preoperative enoxaparin on the day prior to TKA surgery

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 an experimental drug called REGN7508 (called "study drug") and how it compares against another treatment called Acetylsalicylic Acid (ASA). The study is focused on adults undergoing elective, unilateral (one side) total knee replacement surgery.

The aim of the study is to see how effective the study drug is at preventing Venous Thromboembolism (VTE) and other related diseases after total knee replacement surgery compared to acetylsalicylic acid.

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

* What side effects may happen from taking the study drug * How much study drug is in the blood at different times * Whether the body makes antibodies against the study drug (which could make the study drug less effective or could lead to side effects)

Study sites(46)

Horizon Clinical Research
La Mesa, California, United States
Recruiting
Eisenhower Medical Center
Rancho Mirage, California, United States
Recruiting
CARI Clinical Trials
Riverside, California, United States
Recruiting
Sky Ridge Medical Center
Lone Tree, Colorado, United States
Recruiting
South Florida Joint Replacement Center
Deerfield Beach, Florida, United States
Recruiting
Delray Physician Care Center
Delray Beach, Florida, United States
Recruiting
Medical Research of Westchester - MPLUS Research Network
Miami, Florida, United States
Recruiting
Larkin Community Hospital South Miami
South Miami, Florida, United States
Recruiting
Phoenix Clinical Research
Tamarac, Florida, United States
Recruiting
Endeavor Health
Skokie, Illinois, United States
Recruiting
The Orthopaedic Research Foundation, Inc.
Indianapolis, Indiana, United States
Recruiting
NextStage Clinical Research, St. Francis Medical Park
Wichita, Kansas, United States
Recruiting
Velocity Clinical Research, Annapolis
Annapolis, Maryland, United States
Recruiting
Sinai Hospital of Baltimore, Inc.
Baltimore, Maryland, United States
Recruiting
Tufts Medical Center
Boston, Massachusetts, United States
Recruiting
Boston Medical Center
Boston, Massachusetts, United States
Recruiting
Holy Name Medical Center
Teaneck, New Jersey, United States
Recruiting
Northwell Orthopaedic Institute
New York, New York, United States
Recruiting
University of Rochester Medical Center
Rochester, New York, United States
Recruiting
UBMD Orthopaedics and Sports Medicine
Williamsville, New York, United States
Recruiting
Atrium Health Musculoskeletal Institute and Sports Medicine
Charlotte, North Carolina, United States
Recruiting
Duke University Health System (Duke Health), Duke University Hospital
Durham, North Carolina, United States
Recruiting
Eximia Equihealth Research-Raleigh. LLC
Raleigh, North Carolina, United States
Recruiting
The Vein and Vascular Center at Raleigh Radiology
Raleigh, North Carolina, United States
Recruiting
Coastal Vascular Institute, PA
Wilmington, North Carolina, United States
Recruiting
University of Cincinnati
Cincinnati, Ohio, United States
Recruiting
The Ohio State University Wexner Medical Center
Columbus, Ohio, United States
Recruiting
Ohio Clinical Trials
Columbus, Ohio, United States
Recruiting
Penn State Health Milton S. Hershey Medical Center
Hershey, Pennsylvania, United States
Recruiting
University of Pittsburgh
Pittsburgh, Pennsylvania, United States
Recruiting
HD Research - Memorial Hermann Village
Houston, Texas, United States
Completed
NextStage Clinical Research, All American Orthopedics and Sports Medicine
Houston, Texas, United States
Recruiting
Flourish Research - San Antonio (Formerly Clinical Trials of Texas)
San Antonio, Texas, United States
Recruiting
Endeavor Clinical Trials
San Antonio, Texas, United States
Withdrawn
Carilion Clinic
Roanoke, Virginia, United States
Recruiting
Spokane Joint Replacement Center
Spokane, Washington, United States
Recruiting
Henry Dunant Hospital Center
Athens, Attica, Greece
Recruiting
Sultan Abdul Halim Hospital
Sungai Petani, Kedah, Malaysia
Recruiting
Hospital Pakar Universiti Sains Malaysia
Kota Bharu, Kelantan, Malaysia
Recruiting
Hospital Tengku Ampuan Afzan (HTTA)
Kuantan, Pahang, Malaysia
Recruiting
Hospital Queen Elizabeth II
Kota Kinabalu, Sabah, Malaysia
Recruiting
PMSI Emergency Medicine Institute
Chisinau, Moldova
Recruiting
Hospital Universitario Costa del Sol
Marbella, Malaga, Spain
Recruiting
Hospital Clinic Barcelona
Barcelona, Spain
Recruiting
Hospital Universitario Infanta Leonor
Madrid, Spain
Recruiting
Hospital Clinico Universitario de Valencia
Valencia, Spain
Recruiting

Showing 46 of 46 sites. 44 of the 46 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 NCT07213778. 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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