REGN7508 for Venous Thromboembolism

(ROXI-APEX Trial)

Recruiting at 12 trial locations

Overseen By Clinical Trials Administrator

Age: 18+

Sex: Any

Trial Phase: Phase 3

Sponsor: Regeneron Pharmaceuticals

Disqualifiers: Bleeding history, Thromboembolic disease, Major surgery, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Pivotal Trial (Near Approval) This treatment is in the last trial phase before FDA approval

Prior Safety Data This treatment has passed at least one previous human trial

Compensation: Varies

Number of Visits: Unknown

Duration: 6 weeks

2000 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests an experimental drug, REGN7508, to determine its effectiveness in preventing blood clots after knee replacement surgery. The study will also assess side effects, the drug's concentration in the blood, and any immune response. Participants will receive either the study drug or a placebo (inactive substance) alongside other standard treatments. The trial seeks healthy adults undergoing one-sided knee replacement surgery who have not recently experienced major surgeries or blood clots. As a Phase 3 trial, this study represents the final step before FDA approval, offering participants the opportunity to contribute to a potentially groundbreaking treatment.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. It's best to discuss this with the study team or your doctor.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Previous studies have tested REGN7508 for safety and effectiveness in preventing blood clots after knee surgery. Research has shown that both the intravenous (IV) and subcutaneous (SC) forms of REGN7508 are well-tolerated by participants. For instance, one study found that only 7% of patients experienced a blood clot with the SC version, which is relatively low.

Additionally, these studies did not identify any major safety issues or severe side effects, suggesting that REGN7508 might be safe for individuals undergoing knee replacement surgery. However, like any treatment, side effects may occur, and the current trial aims to better understand these. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

REGN7508 is unique because it offers a new approach to treating venous thromboembolism (VTE) by potentially targeting specific pathways involved in clot formation, setting it apart from standard anticoagulants like apixaban and enoxaparin. Unlike traditional treatments that broadly inhibit clotting factors, REGN7508 might work with more precision, potentially reducing the risk of bleeding complications. Researchers are excited about this treatment because it could provide an effective and safer alternative for patients who are at high risk of bleeding with current anticoagulants. Additionally, its innovative delivery method, available both intravenously and subcutaneously, offers flexibility in administration, which can enhance patient comfort and adherence to treatment.

What evidence suggests that REGN7508 might be an effective treatment for venous thromboembolism?

This trial will evaluate the effectiveness of REGN7508 in preventing venous thromboembolism (VTE). Studies have shown that REGN7508 effectively prevents blood clots in veins, a condition known as VTE, which often occurs after surgeries like knee replacements. In previous trials, patients taking REGN7508 had only a 7% chance of developing VTE, compared to 21% for those taking enoxaparin, a commonly used blood thinner. Another study found that REGN7508 was also more effective than apixaban, another blood thinner, which had a 12% rate of VTE. These findings suggest that REGN7508 may be more effective than some standard treatments at preventing blood clots after surgery. Participants in this trial will receive either REGN7508 or a placebo with standard treatments like enoxaparin or apixaban. ^{1 2 6 7 8}

Who Is on the Research Team?

Clinical Trial Management

Principal Investigator

Regeneron Pharmaceuticals

Are You a Good Fit for This Trial?

Adults scheduled for elective, one-sided total knee replacement surgery are eligible for this trial. Participants must be at risk of developing blood clots post-surgery. Those with conditions that increase bleeding risk, previous adverse reactions to the drugs being tested, or other health issues that could interfere with the study may not participate.

Inclusion Criteria

I am scheduled for a knee replacement surgery on one knee.

Is in good health based on laboratory safety testing as described in the protocol

My body weight is 130 kg or less.

Exclusion Criteria

I have a history of blood clots or clotting disorders.

Has an estimated Glomerular Filtration Rate (GFR) of <30 mL/min/1.73 m2 at the screening visit as described in the protocol

I haven't had major surgery or serious injury in the last 6 months.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive REGN7508 or comparator drugs for thromboprophylaxis after total knee arthroplasty

6 weeks

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• REGN7508

Trial Overview The trial is testing REGN7508 against Apixaban and Enoxaparin in preventing blood clots after knee surgery. It will also assess side effects, how much of the drug is present in the bloodstream over time, and if the body creates antibodies against REGN7508.

How Is the Trial Designed?

Group I: IV REGN7508 Experimental Treatment 1 Intervention

Group II: IV Placebo, SC REGN7508 Experimental Treatment 2 Interventions

Group III: IV Placebo, apixaban Active Control 2 Interventions

Group IV: IV Placebo, enoxaparin Active Control 2 Interventions

Who Is Running the Clinical Trial?

Regeneron Pharmaceuticals

Lead Sponsor

Trials

690

Recruited

948,000+

Founded

1988

Headquarters

Tarrytown, USA

Known For

Precision medicine

Top Products

Dupixent, EYLEA, Libtayo, Praluent

Leonard Schleifer

Regeneron Pharmaceuticals

Chief Executive Officer since 1988

MD and PhD in Medicine

George Yancopoulos

Regeneron Pharmaceuticals

Chief Medical Officer since 1997

MD from Harvard Medical School

Citations

1. investor.regeneron.com investor.regeneron.com/news-releases/news-release-details/phase-2-trials-demonstrating-antithrombotic-effect-two-novel

Phase 2 Trials Demonstrating Antithrombotic Effect of Two ... As published and presented, the results showed that both REGN7508Cat and REGN9933A2 demonstrated clear efficacy for VTE prevention following ...

2. thelancet.com thelancet.com/journals/lancet/article/PIIS0140-6736(25)02097-5/fulltext?rss=yes

Efficacy and safety of REGN9933 A2 and REGN7508 Cat ... REGN7508Cat was superior to enoxaparin for venous thromboembolism prevention; REGN9933A2 was not superior to enoxaparin. The findings with ...

3. clinicaltrials.gov clinicaltrials.gov/show/NCT07213778

NCT07213778 | REGN7508 Versus Acetylsalicylic Acid ... 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 ...

4. join.hcplive.com join.hcplive.com/view/regeneron-s-factor-xi-antibodies-prevent-thromboembolism-after-knee-replacement

Regeneron's Factor XI Antibodies Prevent ... REGN7508 and REGN9933 displayed their efficacy in reducing bleeding after knee replacement surgery in 2 phase 2 clinical trials.

5. prismmarketview.com prismmarketview.com/regeneron-advances-next-generation-anticoagulant-program-following-strong-phase-2-data/

Regeneron Advances Next-Generation Anticoagulant ... REGN7508 achieved a 7% incidence of venous thromboembolism (VTE), compared with 21% for enoxaparin and 12% for apixaban, demonstrating superior ...

6. clinicaltrials.gov clinicaltrials.gov/study/NCT07015905

Study Details | NCT07015905 | REGN7508 Versus ... 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 ...

7. globenewswire.com globenewswire.com/news-release/2025/11/08/3184069/0/en/Phase-2-Trials-Demonstrating-Antithrombotic-Effect-of-Two-Novel-Regeneron-Factor-XI-Antibodies-Presented-at-American-Heart-Association-Scientific-Sessions-and-Published-in-The-Lanc.html

Phase 2 Trials Demonstrating Antithrombotic Effect of Two The results include data from two open-label, active-controlled Phase 2 trials evaluating a single intravenous (IV) dose of REGN7508Cat and a ...

8. clinicaltrials.gov clinicaltrials.gov/study/NCT06454630

Study Details | NCT06454630 | A Trial to Learn How Well ... The aim of the study is to see how effective the study drug is at preventing venous thromboembolism (VTE) and other related diseases after unilateral total knee ...