A Trial to Learn How Well REGN9933 Works for Preventing Blood Clots After Knee Replacement Surgery in Adult Participants

A Phase 2, Multicenter, Randomized, Open-Label, Active-Control Study of REGN9933, a Factor XI Monoclonal Antibody, for Prevention of Venous Thromboembolism After Elective, Unilateral, Total Knee Arthroplasty

The primary objective of the study is to evaluate the efficacy of REGN9933 for the prevention of venous thromboembolism (VTE) after unilateral total knee arthroplasty (TKA), compared to enoxaparin

The secondary objectives of the study are:

• To evaluate the bleeding risk (ie, major and clinically relevant non-major [CRNM] bleeding) of REGN9933 after unilateral TKA through time of venography, compared to enoxaparin
• To assess overall safety and tolerability of REGN9933 in participants undergoing TKA
• To evaluate the efficacy of REGN9933 in prevention of clinically relevant VTE, compared to enoxaparin
• To evaluate the efficacy of REGN9933 in prevention of deep venous thrombosis (DVT) detected by venography, compared to enoxaparin
• To evaluate the pharmacokinetics (PK) of REGN9933 after single intravenous (IV) administration
• To assess pharmacodynamic (PD) effects of REGN9933 on intrinsic and extrinsic coagulation pathways
• To assess immunogenicity following a single dose of REGN9933 over time
• To compare the efficacy of enoxaparin and apixaban in prevention of VTE after unilateral TKA

Key Inclusion Criteria:

1. Undergoing elective unilateral TKA
2. Has a body weight ≤130 kg at screening visit
3. Is judged by the investigator to be in good health based on medical history, physical examination, vital sign measurements, and Electrocardiograms (ECG) performed at screening and/or prior to administration of initial dose of study drug
4. Is in good health based on laboratory safety testing obtained during the screening period as described in the protocol

Key Exclusion Criteria:

1. History of bleeding in the past 6 months 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.
2. History of thromboembolic disease or thrombophilia
3. History of major surgery, including brain, spinal, or ocular, within approximately the past 6 months.
4. History of major trauma within approximately the past 6 months.
5. Hospitalized (>24 hours) for any reason within 30 days of the screening visit
6. Using the Modification of Diet in Renal Disease equation, has an estimated glomerular filtration rate as described in the protocol

Note: Other protocol-defined Inclusion/ Exclusion Criteria apply