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Symptomatic Venous Thromboembolism (VTE)Phase 3ROXI-ASPENNCT07213778

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

A Phase 3 study testing REGN7508 and Acetylsalicylic Acid (ASA) in people with Symptomatic Venous Thromboembolism (VTE), run by Regeneron Pharmaceuticals at 51 sites in 5 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record

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Trial summary

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. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Symptomatic Venous Thromboembolism (VTE)
What is being tested?
REGN7508 and Acetylsalicylic Acid (ASA)
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
2,000 participants
Where
51 sitesin 5 countries
Study dates
24 Nov 2025to 16 Jul 2027
Phase
Phase 3

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Is undergoing a primary elective unilateral TKA
  • Is in good health based on laboratory safety testing as described in the protocol

Who cannot join

  • 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
  • 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)
  • History of thromboembolic disease or thrombophilia
  • History of platelet dysfunction
  • Has received or plans to receive preoperative enoxaparin on the day prior to TKA surgery
  • Note: Other protocol-defined Inclusion/ Exclusion criteria apply

Trial locations and contacts

51 sites in 5 countries. Contact the study team or a site near you to ask about taking part.

Clinical Trials Administrator contact

844-734-6643

clinicaltrials@regeneron.com

51 sites in 5 countries

United States38 sites, 36 recruiting

  • Velocity Clinical Research, Annapolis

    Annapolis, Maryland, 21401

    Recruiting

  • Sinai Hospital of Baltimore, Inc.

    Baltimore, Maryland, 21215

    Recruiting

  • Tufts Medical Center

    Boston, Massachusetts, 02111

    Recruiting

  • Boston Medical Center

    Boston, Massachusetts, 02118

    Recruiting

  • Atrium Health Musculoskeletal Institute and Sports Medicine

    Charlotte, North Carolina, 28211

    Recruiting

  • University of Cincinnati

    Cincinnati, Ohio, 45267

    Recruiting

  • The Ohio State University Wexner Medical Center

    Columbus, Ohio, 43210

    Recruiting

  • Ohio Clinical Trials

    Columbus, Ohio, 43212

    Recruiting

  • South Florida Joint Replacement Center

    Deerfield Beach, Florida, 33064

    Recruiting

  • Delray Physician Care Center

    Delray Beach, Florida, 33445

    Recruiting

  • Duke University Health System (Duke Health), Duke University Hospital

    Durham, North Carolina, 27710

    Recruiting

  • HCA HealthONE Centennial

    Englewood, Colorado, 80113

    Recruiting

  • Penn State Health Milton S. Hershey Medical Center

    Hershey, Pennsylvania, 17033

    Recruiting

  • HD Research - Memorial Hermann Village

    Houston, Texas, 77043

    Completed

  • NextStage Clinical Research, All American Orthopedics and Sports Medicine

    Houston, Texas, 77058

    Recruiting

  • The Orthopaedic Research Foundation, Inc.

    Indianapolis, Indiana, 46278

    Recruiting

  • Horizon Clinical Research

    La Mesa, California, 91942

    Recruiting

  • HCA HealthONE, HCA HealthONE Sky Ridge

    Lone Tree, Colorado, 80124

    Recruiting

  • Medical Research of Westchester - MPLUS Research Network

    Miami, Florida, 33165

    Recruiting

  • Northwell Orthopaedic Institute

    New York, New York, 10065

    Recruiting

  • University of Pittsburgh

    Pittsburgh, Pennsylvania, 15213-3108

    Recruiting

  • Eximia Equihealth Research-Raleigh. LLC

    Raleigh, North Carolina, 27612

    Recruiting

  • The Vein and Vascular Center at Raleigh Radiology

    Raleigh, North Carolina, 27612

    Recruiting

  • Eisenhower Medical Center

    Rancho Mirage, California, 92270

    Recruiting

  • CARI Clinical Trials

    Riverside, California, 92504

    Recruiting

  • Carilion Clinic

    Roanoke, Virginia, 24015

    Recruiting

  • University of Rochester Medical Center

    Rochester, New York, 14623-5863

    Recruiting

  • Flourish Research - San Antonio (Formerly Clinical Trials of Texas)

    San Antonio, Texas, 78229

    Recruiting

  • Endeavor Clinical Trials

    San Antonio, Texas, 78240

    Withdrawn

  • Endeavor Health

    Skokie, Illinois, 60076

    Recruiting

  • Larkin Community Hospital South Miami

    South Miami, Florida, 33143

    Recruiting

  • Spokane Joint Replacement Center

    Spokane, Washington, 99218

    Recruiting

  • DRx Clinical Research, LLC

    St. George, Utah, 84770

    Recruiting

  • Phoenix Clinical Research

    Tamarac, Florida, 33321

    Recruiting

  • Holy Name Medical Center

    Teaneck, New Jersey, 07666

    Recruiting

  • NextStage Clinical Research, St. Francis Medical Park

    Wichita, Kansas, 67214

    Recruiting

  • UBMD Orthopaedics and Sports Medicine

    Williamsville, New York, 14211

    Recruiting

  • Coastal Vascular Institute, PA

    Wilmington, North Carolina, 28401

    Recruiting

Other trials in United States

Spain6 sites, 6 recruiting

  • Hospital Clinic Barcelona

    Barcelona, 08036

    Recruiting

  • Hospital Universitario Infanta Leonor

    Madrid, 28031

    Recruiting

  • Hospital Universitario Costa del Sol

    Marbella, Malaga, 29603

    Recruiting

  • Clinica Universidad de Navarra

    Pamplona, Navarre, 31008

    Recruiting

  • Hospital Clinico Universitario de Valencia

    Valencia, 46010

    Recruiting

  • Hospital Miks Ospitalea

    Vitoria-Gasteiz, Araba/Alava, 01010

    Recruiting

Other trials in Spain

Malaysia4 sites, 4 recruiting

  • Hospital Pakar Universiti Sains Malaysia

    Kota Bharu, Kelantan, 16150

    Recruiting

  • Hospital Queen Elizabeth II

    Kota Kinabalu, Sabah, 88300

    Recruiting

  • Hospital Tengku Ampuan Afzan (HTTA)

    Kuantan, Pahang, 25100

    Recruiting

  • Sultan Abdul Halim Hospital

    Sungai Petani, Kedah, 08000

    Recruiting

Other trials in Malaysia

Greece2 sites, 2 recruiting

  • Henry Dunant Hospital Center

    Athens, Attica, 11526

    Recruiting

  • National and Kapodistrian University of Athens, General Hospital of Nea Ionia Konstantopouleio Patision

    Nea Ionia, Attica, 142 33

    Recruiting

Other trials in Greece

Moldova1 site, 1 recruiting

  • PMSI Emergency Medicine Institute

    Chisinau, MD-2004

    Recruiting

Other trials in Moldova

About this study

Official title: 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)

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.

Read more

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)
Being tested
REGN7508, Acetylsalicylic Acid (ASA), Placebo
Keywords
Total Knee Arthroplasty (TKA), Elective Unilateral TKA, Deep Vein Thrombosis (DVT), Pulmonary Embolism (PE)
Medical subject headings
Venous Thrombosis, Pulmonary Embolism

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • REGN7508Drug

    Also called cenvacibart

    Administered per the protocol

  • Acetylsalicylic Acid (ASA)Drug

    Administered per the protocol

  • PlaceboDrug

    Administered per the protocol

Study groups in NCT07213778
Study groupRoleWhat they receive
REGN7508 and PlaceboExperimentalNot described
Receives: Drug: REGN7508; Drug: Placebo
Placebo and ASAActive comparatorNot described
Receives: Drug: Acetylsalicylic Acid (ASA); Drug: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Incidence of the composite endpoint of symptomatic VTE and all-cause death

    Measured: Through day 30 visit

Secondary outcomes (14)

  1. Time to first event of the composite endpoint of symptomatic VTE and all-cause death

    Measured: Through day 30 visit

  2. Incidence of confirmed symptomatic Deep Vein Thrombosis (DVT)

    Measured: Through day 30 visit

  3. Incidence of confirmed Pulmonary Embolism (PE)

    Measured: Through day 30 visit

  4. Incidence of all-cause death

    Measured: Through day 30 visit

  5. Time to first event of the confirmed symptomatic DVT

    Measured: Through day 30 visit

  6. Time to first event of the confirmed PE

    Measured: Through day 30 visit

  7. Time to the all-cause death

    Measured: Through day 30 visit

  8. Incidence of the composite endpoint of major bleeding and Clinically Relevant Non-Major (CRNM) bleeding

    Measured: Through day 30 visit

  9. Incidence of minor bleeding

    Measured: Through day 30 visit

  10. Incidence of Treatment-Emergent Adverse Events (TEAEs)

    Measured: Through day 90 visit

  11. Severity of TEAEs

    Measured: Through day 90 visit

  12. Incidence of Anti-drug Antibody (ADA) to REGN7508

    Measured: Through day 90 visit

  13. Magnitude of ADA to REGN7508

    Measured: Through day 90 visit

  14. Concentrations of REGN7508

    Measured: Through day 90 visit

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted9 Oct 2025
  2. Study start24 Nov 2025
  3. Primary completion17 May 2027 (estimated)
  4. Study completion16 Jul 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
2,000 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07213778
Sponsor's protocol ID
R7508-DVT-24120
Other IDs
2025-520479-25-00, 2025
Acronym
ROXI-ASPEN
Status last verified
Oct 2026
First submitted
3 Oct 2025
Last updated
22 Oct 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing

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