AuthorisedTherapeutic confirmatory (Phase III)Interventional

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)

This research study is look into a new medicine called REGN7508. We want to see if it can prevent blood clots effectively after patients have elective total knee replacement surgery. We'll be comparing it against acetylsalicylic acid, which is a type of aspirin often used for this purpose. Blood clots, or Venous Thromboembolism (VTE), can be a serious risk after surgery, so finding the best way to prevent them is very important. This study is in its final main stage (Phase 3), meaning it's been tested before and now we're carefully checking its safety and how well it works on a larger group of people. Participants will receive either the new medicine, aspirin, or a dummy medicine (placebo) to ensure we get clear results.

At a glance

Status

Authorised

Phase

Therapeutic confirmatory (Phase III)

Sponsor

Regeneron Pharmaceuticals Inc.

Enrolment target

Start

01 Apr 2026

Symptomatic Venous Thromboembolism (VTE)

What is this study about?

This important research is looking into how we can best prevent a serious problem called Venous Thromboembolism, or VTE, after major surgery. VTE is when blood clots form, usually in the leg (Deep Vein Thrombosis or DVT), and can sometimes travel to the lungs (Pulmonary Embolism or PE), which can be very dangerous. After an operation like a total knee replacement, there's a higher chance of these clots forming, so doctors often give medicine to prevent them.

Currently, aspirin (acetylsalicylic acid) is often used to help prevent these clots. This study aims to find out if a new medicine, called REGN7508, is better or at least as good as aspirin at preventing VTE. REGN7508 works in a different way, targeting a specific part of the blood clotting process.

We’re trying to understand if this new medicine can significantly reduce the number of patients who get these clots or even die because of them. We'll also be looking closely at any side effects both medicines might cause. This is a "Phase 3" study, which means it's one of the final steps before a new medicine might become widely available, if it proves to be safe and effective. It's a big step towards potentially improving treatment for people undergoing knee replacement surgery.

Key takeaways

Compares a new medicine (REGN7508) to aspirin for preventing blood clots after knee surgery.
Aims to reduce serious blood clots (VTE) and related complications.
Study is in its final testing stage (Phase 3).
Participants will receive one of four possible treatments: the new medicine, aspirin, or a dummy version of either.
Close monitoring of health and potential side effects is a key part of participating.
This research could lead to improved prevention methods for patients undergoing knee replacement.

Who may be eligible?

To join this study, you would need to be an adult, 18 years old or older, and have no upper age limit. Both men and women are welcome to participate. The study is specifically designed for people who are planning to have a total knee replacement operation.

There will also be other specific health requirements that your study doctor will check. These are in place to make sure the study is safe for you and that the results from the research are clear and accurate. For example, some existing health conditions or medicines you are already taking might mean this study isn't right for you.

It's important to discuss everything with the study team to see if you are a good fit. They will go through a full list of things that would allow you to join or prevent you from joining, to make sure it's the safest and most suitable option for your unique situation.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you 18 years old or older?
Are you planning to have an elective total knee replacement surgery?
Are you willing to potentially receive either the new medicine, regular aspirin, or a dummy medicine?
Are you able to attend several appointments and follow study instructions carefully?

Answer every question to see your result.

What does participation involve?

If you decide to take part in this study, you will likely be asked to attend several appointments at the study clinic or hospital before, during, and after your knee replacement surgery. You will be given either the new study medicine (REGN7508), aspirin, a dummy version of REGN7508, or a dummy version of aspirin. This choice is made by chance, like flipping a coin, and neither you nor your study doctor will know which one you are receiving (this is called 'double-blinded').

You'll need to take the study medication as instructed for a certain period after your surgery. The study team will monitor your health closely and regularly. This will involve physical examinations, blood tests, and perhaps imaging scans to check for blood clots and to see how your body is reacting to the treatment. You will also be asked to report any new symptoms or side effects you experience. The total duration of your participation in the study, from first visit to final follow-up, will be explained in detail by the study team.

Potential risks and benefits

Participating in this study might offer potential benefits, such as receiving a new treatment that could be more effective at preventing blood clots, or you might simply contribute to valuable medical knowledge that helps future patients. However, there are also potential risks, including side effects from the study medications – these will be carefully explained to you. As with any medical procedure, there's no guarantee of personal benefit. You will be fully informed about all known risks and benefits before deciding to join, and importantly, you have the right to withdraw from the study at any time, for any reason, without it affecting your usual medical care.

Locations (2)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Greece
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Unverified
Italy

Common questions

What is VTE?

VTE stands for Venous Thromboembolism. It's a medical term for when blood clots form, usually in your legs (DVT) or travel to your lungs (PE), which can be serious.

Why is this study 'double-blinded'?

Double-blinded means neither you nor your doctor will know if you're getting the new medicine, aspirin, or a dummy treatment. This helps make sure the results are fair and not influenced by anyone's expectations.

What is a 'Phase 3' study?

A Phase 3 study is one of the final stages of testing a new medicine. It means the medicine has already been studied for safety and basic effectiveness, and now it's being tested on a larger group of people to confirm its benefits and risks.

Will I definitely get the new medicine?

No, you might receive the new medicine, aspirin, or a 'placebo' (a dummy medicine with no active ingredients). Which one you get is decided by chance.

What if I experience side effects?

The study team will monitor you very closely. You should report any new symptoms or side effects immediately so they can be assessed and managed appropriately.