Study of REGN7508 versus apixaban for treating and preventing cancer-associated blood clots in adults with solid or blood cancers

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What is this study about?

The study focuses on patients with cancer who develop blood clots in veins, known as Cancer Associated Thrombosis, a type of Venous Thromboembolism. The clotting problem can appear as deep vein thrombosis in the legs or as pulmonary embolism in the lungs. The experimental medicine being tested is REGN7508, a monoclonal antibody that blocks a protein called Factor XI. The standard treatment used for comparison is the oral anticoagulant apixaban.

The study aims to assess whether the new medicine is safe and works better than the standard drug in preventing new clots and serious bleeding. Participants are first observed for safety after receiving the test drug, and later are randomly assigned to receive either the test drug or the standard drug for several months while doctors watch for any new clot events or bleeding problems.

During the trial, participants will take the assigned medication by injection or by mouth according to a schedule set by the study team, and they will attend regular clinic visits where simple blood tests and scans may be performed to check how well the blood is clotting and to look for any side effects. All health information is recorded, and any problems are treated promptly.

1 baseline assessment

after joining the study, a series of baseline measurements are performed. these include a review of medical history, physical examination, blood tests, and imaging to confirm the presence of deep vein thrombosis or pulmonary embolism.

the information collected serves as a reference point for later comparisons.

2 randomization and start of part 1

the participant is assigned to receive the test medication regn7508. the medication is given by intravenous, subcutaneous, or intramuscular injection. the exact dose is not specified in the provided information.

the purpose of part 1 is to evaluate safety and tolerability of regn7508 in participants with deep vein thrombosis.

3 monitoring during part 1

regular clinic visits are scheduled to check for any treatment‑emergent adverse events (side effects that appear after the medication is started).

blood samples are taken to measure inhibition of factor xi activity, activated partial thromboplastin time (a test that shows how long it takes blood to clot), concentration of regn7508, and factor xi levels.

the monitoring period continues for the duration defined by the study protocol, which is not detailed in the source data.

4 transition to part 2

after completing part 1, the participant enters part 2, which compares the test medication regn7508 with the standard anticoagulant apixaban (brand name eliquis).

participants continue to receive the medication they were assigned during randomization.

5 administration of regn7508 in part 2 (if assigned)

the same injection route as in part 1 is used. the dose and frequency are not specified in the source information.

the medication is taken for the period required to assess prevention of recurrent venous thromboembolism and related outcomes.

6 administration of apixaban in part 2 (if assigned)

the participant takes oral tablets of apixaban. two tablet strengths are listed: 2.5 mg and 5 mg. the usual regimen for venous thromboembolism prevention is one tablet taken twice daily, but the exact dose and schedule are not provided in the source data.

treatment continues for the duration defined by the study protocol.

7 ongoing safety and efficacy assessments in part 2

periodic visits are made to evaluate the occurrence of recurrent venous thromboembolism (deep vein thrombosis or pulmonary embolism) and any bleeding events.

blood tests are performed to detect anti‑drug antibodies against regn7508 and to monitor other laboratory parameters.

adverse events are recorded and graded for severity.

8 final study visit

at the end of the study period, a final assessment is performed. this includes a summary of all safety data, efficacy outcomes, and laboratory results.

the participant is informed that the study has concluded.

Who Can Join the Study?

Must have an ECOG Performance Status of 0 to 2, which means you are able to take care of yourself and move around with little or no limitation.
Must have a histologically confirmed (tissue‑under‑microscope) diagnosis of a malignant solid tumor or certain blood cancers, but not just a basal‑cell or squamous‑cell skin cancer alone.
Must be an adult (male or female) who meets the study’s age requirements.
Part 1 specific: Must have a newly diagnosed blood clot in the lower leg (deep‑vein thrombosis, or DVT) that is either causing symptoms or was found by a scan, located in the popliteal or femoral vein, and diagnosed within 5 days before randomization, confirmed by imaging such as an ultrasound.
Part 1 specific: Must be planned to take a therapeutic dose of a Direct Oral Anticoagulant (DOAC)—a type of blood‑thinning pill—for at least 3 months for the newly diagnosed DVT.
Part 2 specific: Must have a newly diagnosed venous thromboembolism (VTE)—which includes a deep‑vein clot or a lung clot—identified within 5 days before randomization and confirmed by imaging.
Part 2 specific: Must be planned to take a therapeutic dose of a Direct Oral Anticoagulant (DOAC) for at least 6 months for the newly diagnosed VTE.
Other protocol‑defined inclusion criteria may also apply as required by the study.

Who Cannot Join the Study?

Being judged by the doctor to have a high chance of bleeding inside the skull (intracranial bleeding).
Having a known bleeding disorder such as Hemophilia A or B or von Willebrand’s disease, having a tumor that is bleeding, or having liver disease that makes clotting difficult (hepatic disease with coagulopathy).
Having a doctor‑determined reason not to take blood‑thinning medication (contraindication to anticoagulation).
Having an expected life span of less than six months (life expectancy < 6 months).
Having acute leukemia or myelodysplastic syndrome, which are cancers of the blood‑forming tissue (acute leukemia or myelodysplastic syndrome).
Having a cancer that started in the brain (primary brain tumor).
Having cancer that has spread to the brain (brain metastases).
For Part 1 only: having a blood clot in the lungs that causes symptoms (symptomatic pulmonary embolism).
For Part 1 only: having an incidentally discovered clot in a larger lung artery (a clot in a segmental or larger pulmonary artery) that does not cause symptoms (asymptomatic pulmonary embolism).
For Part 2 only: having a lung clot that leads to unstable blood pressure or heart function (pulmonary embolism leading to hemodynamic instability).
Any other reasons listed in the study’s protocol (protocol‑defined exclusion criteria).

Where you can join this trial?

Verified and Recommended Sites

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Verified Sites

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Other Sites

Site Name	City	Country
Multispecialty hospital for active treatment Sveta Sofia EOOD	Sofia	Bulgaria
Institute Of Oncology Prof. Dr. Ion Chiricuta Cluj-Napoca	Cluj Napoca	Romania
Institutul Oncologic Prof. Dr. Alexandru Trestioreanu Bucuresti	Bucharest	Romania

Trial status

Country	Status	Recruitment Start
Bulgaria	Not yet recruiting	07.04.2026
Romania	Not yet recruiting	07.04.2026

Trial locations

Investigated drugs:

apixaban is an oral blood‑thinner that helps prevent clots from forming or getting bigger. In this study it is used as the standard‑of‑care treatment to compare against the new drug. Participants take the tablets by mouth, and the researchers look at how well it works to stop new episodes of venous thromboembolism (VTE) and to see how safe it is, especially regarding bleeding.

REGN7508 is an experimental monoclonal antibody that targets a protein called Factor XI, which plays a role in blood clot formation. It is given by injection (intravenous, subcutaneous, or intramuscular) and is being tested to see if it can treat existing deep‑vein thrombosis (DVT) and prevent future clot events in people with cancer. The trial evaluates its safety, how well patients tolerate it, and whether it reduces the risk of recurrent VTE and related deaths compared with the standard oral blood‑thinner.

Deep vein thrombosis – A condition where a blood clot forms in a deep vein, most often in the leg. The clot can cause swelling, warmth, and sometimes pain in the affected area. Over time the clot may grow larger or break loose and travel through the bloodstream.

Pulmonary embolism – Occurs when a clot travels to the lungs and blocks a pulmonary artery. This blockage can cause sudden shortness of breath and chest discomfort. The clot may increase in size or affect additional vessels in the lungs.

Venous thromboembolism – Refers to the combined occurrence of deep vein thrombosis and pulmonary embolism. It starts with clot formation in a vein and may progress if the clot moves toward the lungs. The condition can involve multiple clot events over time.

Cancer-associated thrombosis – Describes clot formation that happens in people who have cancer. Tumor-related changes in the blood can promote clot development in veins. These clots can appear in various locations and may increase in size or spread.

Arterial thromboembolism – Involves a clot forming in an artery and blocking blood flow to an organ or limb. The blockage can cause sudden pain, loss of function, or other symptoms in the affected area. The clot may enlarge or break into smaller pieces that travel to other arterial sites.

Trial ID:

2024-519299-16-00

Protocol code:

R7508-CAT-2396

Trial Phase:

Therapeutic confirmatory (Phase III)

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Study of REGN7508 versus apixaban for treating and preventing cancer-associated blood clots in adults with solid or blood cancers

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?