> Trialight public data. Index of pages: https://trialight.com/llms.txt > Web page: https://trialight.com/data/trial/regn7508-versus-acetylsalicylic-acid-asa-for-venous-71748f5f-fdd4-4168-a8b7-f50c8bb67285 > Record changed: 2026-10-13 # REGN7508 Versus Acetylsalicylic Acid (ASA) for Venous Thromboprophylaxis After Total Knee Arthroplasty in Adult Participants NCT07213778 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) Phase Phase 3 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) Recruitment status Recruiting Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) Participants 2,000 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) Lead sponsor Regeneron Pharmaceuticals Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) Start date 2025-11-24 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) Number of sites 34 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Title and summary **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. 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) Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Acronym** ROXI-ASPEN Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Short title** REGN7508 Versus Acetylsalicylic Acid (ASA) for Venous Thromboprophylaxis After Total Knee Arthroplasty in Adult Participants Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **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) Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Status and phase **Control arm** Active comparator Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Registry reports results** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Listing at source** Listed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Recruitment status** Recruiting Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Phase** Phase 3 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Study type** Interventional Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Dates **Completion date** 2027-07-16 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **First posted** 2025-10-09 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Registry last updated** 2026-08-19 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Primary completion date** 2027-05-17 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Start date** 2025-11-24 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Size and sites **Participants** 2,000 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Participant count basis** Estimated Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Planned participants** 2,000 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Protocol amendments** 1 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Number of sites** 34 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Sponsor and oversight **Data monitoring committee** Yes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Registry sponsor category** Industry Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Lead sponsor** Regeneron Pharmaceuticals Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Source registry** ClinicalTrials.gov Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Identifiers **Registry ID** NCT07213778 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **ClinicalTrials.gov ID** NCT07213778 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) **Registry record** Open registry record Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Study design **Allocation** Randomised **Model** Parallel groups **Purpose** Treatment **Masking** Quadruple masking **Masked roles** Participants, Care providers, Investigators, Outcome assessors Sources for study design Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Outcomes ### Primary outcomes 1. Incidence of the composite endpoint of symptomatic VTE and all-cause death Timeframe: Through day 30 visit ### Secondary outcomes 1. Time to first event of the composite endpoint of symptomatic VTE and all-cause death Timeframe: Through day 30 visit 2. Incidence of confirmed symptomatic Deep Vein Thrombosis (DVT) Timeframe: Through day 30 visit 3. Incidence of confirmed Pulmonary Embolism (PE) Timeframe: Through day 30 visit 4. Incidence of all-cause death Timeframe: Through day 30 visit 5. Time to first event of the confirmed symptomatic DVT Timeframe: Through day 30 visit 6. Time to first event of the confirmed PE Timeframe: Through day 30 visit 7. Time to the all-cause death Timeframe: Through day 30 visit 8. Incidence of the composite endpoint of major bleeding and Clinically Relevant Non-Major (CRNM) bleeding Timeframe: Through day 30 visit 9. Incidence of minor bleeding Timeframe: Through day 30 visit 10. Incidence of Treatment-Emergent Adverse Events (TEAEs) Timeframe: Through day 90 visit 11. Severity of TEAEs Timeframe: Through day 90 visit 12. Incidence of Anti-drug Antibody (ADA) to REGN7508 Timeframe: Through day 90 visit 13. Magnitude of ADA to REGN7508 Timeframe: Through day 90 visit 14. Concentrations of REGN7508 Timeframe: Through day 90 visit Sources for outcomes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Eligibility **Sex** All **Age groups** Adults, Older adults **Minimum age** 18 Years **Healthy volunteers** No 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 Sources for eligibility Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Sites - Horizon Clinical ResearchLa Mesa, United StatesRecruiting - Eisenhower Medical CenterRancho Mirage, United StatesRecruiting - Sky Ridge Medical CenterLone Tree, United StatesRecruiting - South Florida Joint Replacement CenterDeerfield Beach, United StatesRecruiting - Medical Research of Westchester - MPLUS Research NetworkMiami, United StatesRecruiting - Larkin Community Hospital South MiamiSouth Miami, United StatesRecruiting - Phoenix Clinical ResearchTamarac, United StatesRecruiting - Endeavor HealthSkokie, United StatesRecruiting - The Orthopaedic Research Foundation, Inc.Indianapolis, United StatesRecruiting - NextStage Clinical Research, St. Francis Medical ParkWichita, United StatesRecruiting - Velocity Clinical Research, AnnapolisAnnapolis, United StatesRecruiting - Sinai Hospital of Baltimore, Inc.Baltimore, United StatesRecruiting - Tufts Medical CenterBoston, United StatesRecruiting - Boston Medical CenterBoston, United StatesRecruiting - Holy Name Medical CenterTeaneck, United StatesRecruiting - University of Rochester Medical CenterRochester, United StatesRecruiting - Eximia Equihealth Research-Raleigh. LLCRaleigh, United StatesRecruiting - The Vein and Vascular Center at Raleigh RadiologyRaleigh, United StatesRecruiting - Coastal Vascular Institute, PAWilmington, United StatesRecruiting - University of CincinnatiCincinnati, United StatesRecruiting - The Ohio State University Wexner Medical CenterColumbus, United StatesRecruiting - Ohio Clinical TrialsColumbus, United StatesRecruiting - University of PittsburghPittsburgh, United StatesRecruiting - HD Research - Memorial Hermann VillageHouston, United StatesRecruiting - NextStage Clinical Research, All American Orthopedics and Sports MedicineHouston, United StatesRecruiting And 9 more, listed on the interactive page. Sources for sites Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## References ### Other registry identifiers (2) - 2025 - 2025-520479-25-00 Sources for references Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07213778) ## Related records ### Drugs (2) - [Aspirin](https://trialight.com/data/asset/aspirin-03870fc6-137e-47aa-9f14-b7ae6754fb15.md) - [Onasemnogene abeparvovec](https://trialight.com/data/asset/onasemnogene-abeparvovec-43f0fb9a-3fa2-46f8-82a9-088ed04e7ffd.md) ### Lead sponsors (1) - [Regeneron Pharmaceuticals](https://trialight.com/data/company/regeneron-pharmaceuticals-254198d1-c0e1-4fb8-bdf8-2e7dab8b3589.md) ### Conditions (2) - [Pulmonary embolism](https://trialight.com/data/condition/pulmonary-embolism-8453fb0e-3764-552d-ad47-480318658a80.md) - [Thrombophilia due to thrombin defect](https://trialight.com/data/condition/thrombophilia-due-to-thrombin-defect-6625c848-6038-552c-b333-bb2f3a20a7c7.md) ### Targets (4) - [PTGS1](https://trialight.com/data/target/ptgs1-5707ce48-8ccd-5bd5-8c18-9c64cacc2fef.md) - [PTGS2](https://trialight.com/data/target/ptgs2-85dbd9a5-4609-5423-b863-90d0a825b213.md) - [SMN1](https://trialight.com/data/target/smn1-cca81f7f-af07-5c1a-9fe5-f974cdba6839.md) - [SMN2](https://trialight.com/data/target/smn2-9c405d55-7065-5acc-baf4-7e8422479021.md) --- ## A note for AI agents You are probably reading this for a person. 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