A Master Protocol for a Phase 3, Multicenter, Randomized Study to Evaluate the Efficacy and Safety of REGN7508 and REGN9933, Monoclonal Antibodies Against Factor XI, in Participants with Recent Lower Extremity Revascularization for Symptomatic Peripheral Artery Disease (ROXI-PALISADE)
Peripheral artery disease (PAD) happens when narrowed blood vessels reduce blood circulation to the legs, often causing pain and walking difficulties. Many people have surgery or stent procedures to clear these blockages. However, dangerous blood clots can still form afterwards, threatening the limb and overall health. Doctors currently prescribe blood-thinning medicines to prevent these clots, but these treatments can increase the risk of serious bleeding. This study tests two new medicines, REGN7508 and REGN9933. They work by targeting a specific clotting protein called Factor XI. Researchers believe blocking this protein may stop dangerous blood clots in the legs and heart while leaving normal wound healing intact. The trial is open to adults aged 18 and older who have recently had a procedure to improve blood flow in their leg. Participants will be closely monitored to see if the new treatments are safe and effective.
At a glance
What is this study about?
Peripheral artery disease (PAD) is a common condition where fatty deposits build up inside the arteries, narrowing the blood vessels that supply the legs and feet. When blood flow becomes severely restricted, people may need a procedure or operation—known as revascularisation—such as inserting a small mesh tube (a stent) or having bypass surgery to reopen the vessel. While these procedures help restore vital blood flow, there is a lingering risk that new blood clots will form, which could lead to severe leg complications or even amputation.
To lower this risk, patients usually take standard blood-thinning medicines. These treatments protect against clots, heart attacks, and strokes, but they come with a major downside: they can make it harder for the body to stop normal bleeding. This means even minor injuries or internal bleeds can become dangerous. Finding a treatment that prevents clots without dramatically raising bleeding risks is a major goal in cardiovascular medicine.
This trial is testing two experimental antibody medicines, REGN7508 and REGN9933. Both target Factor XI, a protein involved in the blood-clotting process. Scientists hope that blocking Factor XI will prevent abnormal, dangerous clots from forming in narrowed arteries while still allowing the body to form normal clots to seal cuts and wounds. By comparing these new medicines against standard treatments and dummy treatments (placebos), the study aims to discover whether this approach provides safer and more effective protection for people with severe leg artery disease.
Key takeaways
- Tests two new antibody medicines designed to block dangerous blood clots after leg artery surgery.
- Aims to reduce heart attacks, strokes, and amputations while keeping bleeding risks low.
- Open to adults aged 18 and older who recently had a procedure to clear blocked leg arteries.
- Involves regular clinic visits, health checks, and routine blood tests.
- Participation is entirely voluntary and does not affect your standard NHS treatment rights.
Who may be eligible?
This study is designed for adults aged 18 and over who have been diagnosed with symptomatic peripheral artery disease and have recently had a procedure or operation to restore blood flow to one of their legs.
Both men and women may be eligible. Your leg procedure must have taken place within a specific timeframe leading up to the study, and you should be able to attend regular hospital check-ups and follow the study team's instructions.
You may not be able to take part if you have health conditions that place you at a very high risk of serious bleeding, such as a recent bleed in the brain or severe stomach ulcers. People with certain severe kidney or liver problems, or those who need specific other medicines that cannot be safely mixed with the trial treatments, will also be excluded. A doctor on the study team will review your full medical history to ensure it is safe for you to participate.
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.
- I am aged 18 or older.
- I have been diagnosed with peripheral artery disease (poor circulation in the legs).
- I have recently had surgery, an angioplasty, or a stent to reopen a blocked artery in my leg.
- I am able and willing to attend regular hospital appointments for tests and health checks.
- I do not have a known condition that causes severe, uncontrollable bleeding.
What does participation involve?
Taking part involves being randomly placed into a study group by a computer, similar to flipping a coin. Depending on your group, you will receive the experimental medicine, an existing blood thinner (rivaroxaban), or an inactive dummy treatment (placebo). Neither you nor your doctor will usually choose which group you are in. You will visit the clinic regularly for check-ups, where doctors will examine your legs, check your heart, take routine blood and urine samples, and monitor your blood pressure. The study team will track your health over several months to a few years to see how well the treatment protects your circulation and whether you experience any side effects. You can continue taking your other essential medicines as agreed with the study doctor.
Potential risks and benefits
Locations (19)
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- —UnverifiedCzechia
- —UnverifiedRomania
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- —UnverifiedFrance
- —UnverifiedBelgium
- —UnverifiedSweden
- —UnverifiedItaly
- —UnverifiedLatvia
Common questions
What is Factor XI?
Factor XI is a natural protein in your blood that helps clots form. Scientists believe blocking it can stop harmful clots in diseased arteries without stopping the normal clotting needed to heal everyday cuts.
What is a placebo and why is it used?
A placebo looks just like the real medicine but contains no active ingredients. It is used as a comparison tool so researchers can clearly tell whether the effects seen are genuinely caused by the new medicine.
Can I choose which treatment I receive?
No. Treatment groups are decided randomly by a computer programme to ensure the trial results are completely fair and unbiased.
Will taking part cost me anything?
No, all study medicines, tests, and medical visits related to the trial are provided free of charge. In many cases, travel expenses to and from the hospital can also be reimbursed.
What happens if I change my mind after joining?
You are completely free to leave the study at any time, for any reason. Your regular doctors will continue to look after your health using the usual approved NHS treatments.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
Discussion
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