NCT07213778

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)

• Status: Recruiting
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 2,000 (estimated)
• Sponsor: Regeneron Pharmaceuticals · Industry
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

This study is researching an experimental drug called REGN7508 versus Acetylsalicylic Acid (ASA) (each called "study drug"). 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)

Conditions

• Symptomatic Venous Thromboembolism (VTE)

Interventions

Type	Name	Description
DRUG	REGN7508	Administered per the protocol
DRUG	Acetylsalicylic Acid (ASA)	Administered per the protocol
DRUG	Placebo	Administered per the protocol

Timeline

• Start date: 2025-11-24
• Primary completion: 2027-05-17
• Completion: 2027-07-16
• First posted: 2025-10-09
• Last updated: 2026-04-09

Locations

13 sites across 1 country: United States

Regulatory

• FDA-regulated drug study