Treatment and Secondary Prevention of Venous Thromboembolism (VTE) in Adult Participants With Solid and Hematologic Cancers (ROXI-CAT-II)

A 2-Part, Phase 3, Multicenter, Randomized, Open-Label, Active-Controlled Study to Assess Efficacy and Safety of REGN7508, a Monoclonal Antibody Against Factor XI, for the Treatment and Secondary Prevention of Venous Thromboembolism in Participants With Solid and Hematologic Cancers (ROXI-CAT-II)

This study is researching an experimental drug called REGN7508 (called "study drug") and will consist of 2 parts: Part 1 and Part 2. The study is focused on participants with or without cancer who develop blood clots in certain veins (called Deep Vein Thrombosis [DVT]) that block blood flow (Part 1) or focused on participants with cancer who develop blood clots in certain veins (DVT) or the lungs (also called Pulmonary Embolism [PE]) (Part 2).

The aim of the study is to see how safe and effective the study drug is at treating and preventing further blood clots in participants with or without cancer (Part 1) or in participants with cancer (Part 2) compared with another treatment (apixaban).

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 drug less effective or could lead to side effects)

Study Overview

• Status: Recruiting
• Conditions: Venous Thromboembolism (VTE)
• Intervention / Treatment: Drug: REGN7508; Drug: Apixaban

• Study Type: Interventional
• Enrollment (Estimated): 1600
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Clinical Trials Administrator; Phone Number: 844-734-6643; Email: clinicaltrials@regeneron.com

Study Locations

• United States
  • Florida
    • Hialeah, Florida, United States, 33013
      • Recruiting
      • Bioresearch Partner- Hialeah Hospital
  • Texas
    • El Paso, Texas, United States, 79902
      • Recruiting
      • El Paso Medical Research Institute (Medresearch Inc)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Key Inclusion Criteria:

1. Has an Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 to 2 at the time of screening and day 1 prior to first dose of study intervention
2. In Part 1 participants with cancer and Part 2 participants: Histologically confirmed diagnosis of malignant solid or select hematologic tumor (other than basal-cell or squamous-cell carcinoma of the skin alone) as described in the protocol

3. Part 1 additional criteria:

   1. Has newly diagnosed symptomatic lower extremity DVT or incidentally-detected proximal lower extremity DVT (eg, popliteal or femoral) within 5 days (120 hours) of randomization (with imaging confirmation)
   2. Anticoagulation therapy with a therapeutic dose of a Direct Oral Anticoagulant (DOAC) for at least 3 months is indicated for the newly diagnosed proximal lower extremity DVT

4. Part 2 additional criteria:

   1. Newly diagnosed VTE within 5 days (120 hours) of randomization (with imaging confirmation) as described in the protocol
   2. Anticoagulation therapy with a therapeutic dose of a DOAC for at least 6 months is indicated for newly diagnosed VTE

Key Exclusion Criteria:

1. Is at high risk of intracranial bleeding in the opinion of the investigator
2. Known bleeding conditions (eg, Hemophilia A or B, von Willebrand's disease), hemorrhagic tumor sites, or other conditions with a high risk for bleeding (eg, hepatic disease associated with coagulopathy)
3. Contraindication to anticoagulation in the opinion of the investigator
4. Life expectancy of < 6 months

5. Part 1 participants with cancer and Part 2 additional exclusion criteria:

   1. Has acute leukemia or myelodysplastic syndrome
   2. Has primary brain tumor
   3. Has brain metastases as described in the protocol

6. Part 1 additional exclusion criteria:

   1. Has a symptomatic PE
   2. Has an asymptomatic (incidentally-diagnosed) PE in a segmental or larger pulmonary artery
7. Part 2 additional exclusion criteria: PE leading to hemodynamic instability as described in the protocol

Note: Other Protocol Defined Inclusion/ Exclusion Criteria Apply

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Apixaban	Drug: Apixaban; Administered per the protocol
Experimental: REGN7508	Drug: REGN7508; Administered per the protocol; Other Names: cenvacibart

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Occurrence of Treatment-Emergent Adverse Events (TEAEs)	Part 1	Approximately 6 months
Severity of TEAEs	Part 1	Approximately 6 months
Time-to-first event of centrally adjudicated recurrent VTE [DVT (symptomatic or asymptomatic [proximal] or Non-fatal PE (symptomatic or asymptomatic [in a segmental or larger pulmonary artery] )or VTE-related death)]	Part 2	Up to approximately 3.5 years
Time-to-first event of centrally adjudicated International Society of Thrombosis and Hemostasis (ISTH)-defined major bleeding or Clinically Relevant Non-Major (CRNM) bleeding	Part 2	Up to approximately 3.5 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percent inhibition of Factor XI functional Coagulant activity (FXI:C)	Part 1	Approximately 3 months
Fold change from baseline in activated Partial Thromboplastin Time (aPTT)	Part 1	Approximately 3 months
Functional REGN7508 concentration	Part 1	Approximately 3 months
Factor XI (FXI) concentration	Part 1	Approximately 3 months
Occurrence of Anti-Drug Antibody (ADA) to REGN7508	Part 1 and Part 2	Up to approximately 3.5 years
Magnitude of ADA to REGN7508	Part 1 and Part 2	Up to approximately 3.5 years
Time-to-first centrally adjudicated event of DVT (symptomatic or asymptomatic [proximal])	Part 2	Up to approximately 3.5 years
Time-to-first centrally adjudicated event of Non-fatal PE (symptomatic or asymptomatic [in a segmental or larger pulmonary artery])	Part 2	Up to approximately 3.5 years
Time-to-first centrally adjudicated event of VTE-related death	Part 2	Up to approximately 3.5 years
Time-to-first event of centrally adjudicated venous thromboembolic events other than DVT and PE	Part 2	Up to approximately 3.5 years
Time-to-first event of centrally adjudicated Arterial Thromboembolism (ATE)	Part 2	Up to approximately 3.5 years
Time-to-first event of centrally adjudicated recurrent VTE and bleeding events [DVT (symptomatic or asymptomatic [proximal] or Non-fatal PE (symptomatic or asymptomatic) or VTE-related death) or bleeding (ISTH-defined major bleeding or CRNM bleeding)]	Part 2	Up to approximately 3.5 years
Occurrence of TEAEs	Part 2	Up to approximately 3.5 years
Severity of TEAEs	Part 2	Up to 3.5 approximately years

Collaborators and Investigators

• Sponsor: Regeneron Pharmaceuticals
• Investigators: Study Director: Clinical Trial Management, Regeneron Pharmaceuticals

Study record dates

Study Major Dates

• Study Start (Estimated): June 30, 2026
• Primary Completion (Estimated): July 8, 2031
• Study Completion (Estimated): July 8, 2031

Study Registration Dates

• First Submitted: March 5, 2026
• First Submitted That Met QC Criteria: March 19, 2026
• First Posted (Actual): March 25, 2026

Study Record Updates

• Last Update Posted (Actual): May 29, 2026
• Last Update Submitted That Met QC Criteria: May 26, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Cancer; Deep Vein Thrombosis (DVT); Pulmonary Embolism (PE); Cancer-Associated Thrombosis (CAT)
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Respiratory Tract Diseases; Lung Diseases; Embolism and Thrombosis; Embolism; Thromboembolism; Thrombosis; Neoplasms; Pulmonary Embolism; Venous Thrombosis; Venous Thromboembolism; apixaban
• Other Study ID Numbers: R7508-CAT-2396; 2024-519299-16-00 (Ctis)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.

IPD Sharing Time Frame

When Regeneron has:

• received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development
• made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry)
• the legal authority to share the data, and
• ensured the ability to protect participant privacy

• IPD Sharing Access Criteria: Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No