Home › Trials › NCT07015905

REGN7508 versus apixaban and enoxaparin for preventing blood clots after total knee replacement

A Phase 3, Multicenter, Randomized, Open-Label, Study to Evaluate REGN7508, A Factor XI Monoclonal Antibody, Versus Apixaban and Enoxaparin for Prophylaxis of Venous Thromboembolism After Elective Total Knee Arthroplasty (ROXI-APEX)

PHASE3 · Regeneron Pharmaceuticals · NCT07015905

This trial will test whether REGN7508 prevents blood clots after elective one-sided total knee replacement in adults compared with apixaban, enoxaparin, or placebo.

Quick facts

PhasePHASE3
Study typeInterventional
Enrollment2000 (estimated)
Ages18 Years and up
SexAll
SponsorRegeneron Pharmaceuticals (industry)
Locations44 sites (Sheffield, Alabama and 43 other locations)
Trial IDNCT07015905 on ClinicalTrials.gov

What this trial studies

This Phase 3 randomized trial compares REGN7508, an investigational Factor XI–targeting drug, with standard anticoagulants apixaban and enoxaparin (and placebo) for preventing venous thromboembolism after elective unilateral total knee arthroplasty. Adults who meet weight, renal, and lab safety criteria and are undergoing primary unilateral TKA are randomized to a treatment arm and followed for post-operative VTE events, bleeding, drug levels, and anti-drug antibodies. Key exclusions include recent major surgery or trauma, recent significant bleeding, prior thromboembolic disease or known thrombophilia, and severe renal impairment. Multiple U.S. orthopedic clinical sites are enrolling participants and collecting safety and efficacy data.

Who should consider this trial

Good fit: Adults undergoing elective primary unilateral total knee replacement who meet protocol safety criteria (including weight ≤130 kg and acceptable kidney function) and have no recent bleeding or thromboembolic history are ideal candidates.

Not a fit: People with a history of thromboembolic disease or thrombophilia, recent major surgery or bleeding, or severe kidney impairment (eGFR <30 mL/min/1.73 m2) are unlikely to be eligible or to benefit from participation.

Why it matters

Potential benefit: If successful, REGN7508 could offer an effective option to prevent post-knee-replacement blood clots with a different bleeding-risk profile than current anticoagulants.

How similar studies have performed: Other Factor XI–targeting agents have shown promising phase 2 signals of VTE prevention with potentially less bleeding, but confirmatory phase 3 evidence is limited.

Eligibility criteria

Show full inclusion / exclusion 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
3. Body weight ≤130 kg at screening visit 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 as described in the protocol
3. History of thromboembolic disease or thrombophilia
4. History of major surgery, including brain, spinal, or ocular, or major trauma within approximately the past 6 months prior to randomization
5. Has an estimated Glomerular Filtration Rate (GFR) of \<30 mL/min/1.73 m2 at the screening visit as described in the protocol

Note: Other protocol-defined Inclusion/ Exclusion Criteria apply

Where this trial is running

Sheffield, Alabama and 43 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Venous Thromboembolism, Unilateral Total Knee Arthroplasty, Factor XI

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.