Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Not yet recruiting

A study to compare REGN7508 and acetylsalicylic acid for preventing blood clots in adults undergoing elective total knee replacement.

Fast replyRegistered drugNo placebo
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

A plain-language summary of the goals, design and what participants do

This study aims to evaluate the effectiveness of a new medication for preventing blood clots following a planned Total Knee Arthroplasty, which is a surgical procedure to replace a damaged knee joint with an artificial one. The condition being studied is Venous Thromboembolism, a term used to describe blood clots that form in the veins. This condition can include Deep Vein Thrombosis, which is a clot typically located in the deep veins of the leg, or a Pulmonary Embolism, which occurs when a blood clot travels to the lungs.

Participants in the study will be assigned to receive either the study drug REGN7508, which is a Factor XI monoclonal antibody delivered through an intravenous injection, or acetylsalicylic acid, also known as aspirin. Some participants may also receive a placebo. The study is designed so that neither the researchers nor the participants know which treatment is being administered during the process.

The research process

The trial runs in 3 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Study participation and treatment assignment

    Upon joining the study, an assignment is made to receive one of two different treatments to prevent symptomatic venous thromboembolism, which is a condition involving blood clots in the veins, following total knee arthroplasty, also known as a total knee replacement surgery.

    The assignment is determined by a process called randomization, meaning the specific treatment is chosen by chance, and it is double-blinded, which means neither the participant nor the medical staff knows which treatment is being administered during the study.

  2. Step 2

    Administration of treatment

    One group of participants receives regn7508, which is administered as an intravenous injection, meaning it is delivered directly into a vein through a solution.

    Another group receives acetylsalicylic acid, which is taken by oral administration, meaning it is swallowed as a pill.

    Some participants may receive a placebo, which is an inactive substance that looks like the medication, either instead of regn7508 or instead of acetylsalicylic acid, to ensure the study results are accurate.

  3. Step 3

    Monitoring and observation

    During the study, observations are made regarding the occurrence of symptomatic venous thromboembolism, which includes deep vein thrombosis (blood clots in the deep veins, usually in the legs) and pulmonary embolism (blood clots that travel to the lungs).

    The occurrence of any bleeding, ranging from minor to major, is recorded.

    Any adverse events, which are unexpected medical problems or side effects, are monitored and documented.

Who can join the trial?

5 criteria

  • You must be scheduled for a primary elective unilateral TKA, which means a planned, non-emergency surgery to replace one knee joint.
  • You must be in good health, as confirmed by laboratory safety testing, which are medical tests performed on your blood or other samples to ensure your body is healthy enough for the study.
  • You must meet any other specific medical requirements defined by the study rules.
  • You must be either male or female.
  • You must fall within the specific age range required for this study.

Who cannot join the trial?

10 criteria

  • You have any medical condition that the doctor believes could confuse the results of the study or increase your safety risks while participating.
  • You have a history of bleeding in the 6 months before starting the study that required you to stay in the hospital or receive a blood transfusion (a procedure where blood is put into your body).
  • You have a history of bleeding inside the brain (intracranial) or inside the eye (intraocular).
  • You have a history of heavy bleeding during or after a surgical operation.
  • You have experienced injury or bleeding related to spinal anesthesia or epidural anesthesia (numbing medicine injected into the back).
  • You have a history of a bleeding disorder, which is a condition where your blood does not clot normally, such as hemophilia or von Willebrand’s Factor deficiency.
  • You have a history of thromboembolic disease, which means blood clots that have traveled through your blood vessels, or thrombophilia, which is a condition that makes your blood more likely to clot.
  • You have a history of platelet dysfunction, meaning the tiny cells in your blood that help stop bleeding (platelets) are not working correctly.
  • You have taken or plan to take enoxaparin (a blood-thinning medicine) the day before your TKA (total knee replacement surgery).
  • You meet any other reasons for being left out of the study as defined by the specific rules of this research.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Not yet recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

  • REGN7508

    is a medication given through an injection into a vein. It is being tested to see if it can help prevent the formation of dangerous blood clots in patients after they have undergone elective total knee replacement surgery.

  • Aspirin

    is a medication taken by mouth. In this study, it is being used as a comparison to see how well it prevents blood clots in patients after they have undergone elective total knee replacement surgery.

What is already known about the treatment

  • Acetylsalicylic acid

    This medication is taken orally as a pill and is widely used and well-known in medicine to prevent blood clots and reduce pain. It belongs to a group of drugs called nonsteroidal anti-inflammatory drugs. It works by blocking specific enzymes in the body that help blood cells stick together, thereby making the blood less likely to clot.

  • Regn7508

    This is an experimental medication administered through an intravenous injection as a liquid solution. It is currently being studied in clinical trials to determine its effectiveness in preventing blood clots. As a monoclonal antibody, it works by targeting and blocking a specific protein called Factor XI in the blood, which helps prevent dangerous clot formation without significantly increasing the risk of bleeding.

Investigated diseases

Venous thromboembolism - This condition occurs when a blood clot forms in one or more of the veins in the body. It often begins as a deep vein thrombosis, where a clot develops in a deep vein, most commonly in the legs. If the clot breaks loose, it can travel through the bloodstream to the lungs, causing a pulmonary embolism. The progression depends on the size and location of the clot within the circulatory system. This process can involve various parts of the venous network.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-520479-25-00Protocol codeR7508-DVT-24120Estimated enrolment2 050 patientsSponsorRegeneron Pharmaceuticals Inc.

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

ClinicalTrials.eu

Every clinical trial in Europe, in plain language.

Explore the full ecosystem of clinical research in Europe.

Search trials

Legal notice · Published by CTIN POLAND sp. z o.o., ul. rtm. Witolda Pileckiego 67/109, 02-781 Warsaw, Poland · KRS 0001111334 · REGON 528919042 · NIP 9512598637

© 2026 Clinical Trials EU – European Clinical Trials Information Network

GDPR compliance, ISO 9001 and ISO 27001 certified (LL-C Certification)

On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).