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Safety and Pharmacodynamics of RBD4059 and Apixaban in Patients with Non‑Valvular Atrial Fibrillation: A Randomized Active‑Controlled Study

Fast replyRegistered drugNo placebo

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What is this trial about?

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

The study involves patients with non-valvular atrial fibrillation, a condition where the heart beats irregularly without problems in the heart valves. The investigational medication vortosiran is given as a small injection under the skin, while the standard blood‑thinner apixaban is taken as a tablet once daily. A matching placebo injection that looks the same as the active product is also used for comparison.

The purpose of the study is to assess how safe the new injection is and how it changes the activity of a clotting protein called factor XI (FXI) over a 16‑week period. Participants will be randomly assigned to receive one of two hidden doses of the injection or the placebo, and all will receive the open‑label tablet. Visits will include simple blood draws to measure FXI activity and routine safety checks such as checking for bleeding or other side effects.

Throughout the trial, researchers will watch for any bleeding events, record any adverse experiences, and perform standard laboratory tests and vital‑sign measurements. Blood samples will also be taken at several time points to see how the drug behaves in the body and whether the immune system produces any antibodies against it.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

Step 1
Baseline visit and start of treatment
After enrollment you will attend a baseline visit where a physical exam, vital‑sign check, and blood sample are taken to record your initial health status.
You will begin taking apixaban orally at a dose of 10 mg once each day.
You will also receive the first subcutaneous injection of vortosiran (or matching placebo) as directed by the study staff.
Step 2
Daily oral medication
Each day you will swallow one tablet of apixaban (10 mg).
The tablet should be taken at the same time each day, with or without food, and you should not miss any doses.
Step 3
Scheduled subcutaneous injections
You will receive additional subcutaneous injections of vortosiran (or placebo) according to the study schedule, typically every few weeks.
The injection is given under the skin by a trained professional; the exact dose is defined by the protocol and will not be changed by you.
Step 4
Regular clinic visits and assessments
You will return to the clinic for visits at weeks 4, 8, 12, and 16.
At each visit blood will be drawn to measure factor xi activity, a‑ptt, pt/inr, and to check for any antibodies against the study drug.
Vital signs and any side effects, including bleeding, will be recorded.
Step 5
Monitoring for bleeding and adverse events
Throughout the 16‑week treatment period you should watch for signs of bleeding, such as unusual bruising, nosebleeds, or blood in urine or stool, and report them to the study team promptly.
Any other symptoms or changes in health are also recorded as adverse events.
Step 6
Final evaluation at week 16
At the week‑16 visit a comprehensive assessment is performed, including the primary measurement of the percent change in factor xi activity from baseline.
The study medication is discontinued after this final evaluation unless the protocol specifies a longer follow‑up.

Who can join the trial?

4 criteria

You must be 45 years old or older.
You need a confirmed diagnosis of non-valvular atrial fibrillation (a type of irregular heartbeat not caused by a heart valve problem) that was made within the past 12 months, proven by an ECG (a test that records the heart’s electrical activity), and you must have been taking a blood‑thinning medicine called a DOAC (direct oral anticoagulant) continuously for stroke prevention for at least the last 3 months.
You must be able to understand the study information and sign a written informed consent form before any study procedures begin.
Both men and women are eligible to take part.

Who cannot join the trial?

4 criteria

Women who could become pregnant – this includes any woman who is not surgically sterile and who has not gone through menopause (no periods for more than 12 months).
Atrial fibrillation caused by a reversible condition – if the irregular heartbeat is due to something that can be fixed (such as heart surgery, a lung blood clot, untreated overactive thyroid, or heavy alcohol use), or if the person is already in a normal rhythm after a successful ablation (a procedure that destroys small areas of heart tissue) or plans to have a cardioversion (a procedure that restores normal rhythm) or another ablation during the study.
Bleeding inside the brain or eye within the last 3 months, or any past episode of a sudden brain bleed (called a spontaneous intracerebral haemorrhage) that happened without the use of blood‑thinning medicines.
Recent stroke or mini‑stroke – any stroke that occurred within 14 days before the start of the study, or a transient ischemic attack (a brief, temporary blockage of blood flow to the brain, often called a “mini‑stroke”) within 3 days before the start of the study.

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Verified sites

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

Verified
Akershus University Hospital
Lorenskog, Norway
Responsive
Soedersjukhuset AB
Stockholm, Sweden
Responsive
Sykehuset Oestfold HF Kalnes
Graalum, Norway

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Investigated drugs

Apixaban
is an oral medication that helps keep blood from clotting. In people with non‑valvular atrial fibrillation, it is used to reduce the risk of stroke and other clot‑related problems. In this study the drug is given as the standard treatment (comparator) so the researchers can see how the new therapy compares to a well‑known blood‑thinner.
RBD4059 injection
is an experimental medicine given by a subcutaneous (under‑the‑skin) injection. It works by lowering the activity of factor XI, a protein that helps blood form clots. The trial is testing this new drug (also called vortosiran) to see if it is safe and how well it changes clot‑forming activity in patients with non‑valvular atrial fibrillation.

What is already known about the treatment

Apixaban
This medication is taken as an oral tablet of 10 mg once daily. It is an approved drug that is widely used to lower the risk of stroke and blood clots in people with non‑valvular atrial fibrillation. Apixaban works by directly blocking a protein called factor Xa, which is needed for blood clot formation, and it belongs to the class of direct oral anticoagulants.
RBD4059
The test drug is given as a subcutaneous injection under the skin. It is an investigational compound that is still being studied and has not yet received marketing approval. RBD4059 is designed to reduce the activity of factor XI, a protein that helps blood clot, by using a small piece of genetic material to silence its production, placing it in the experimental RNA‑interference therapeutic class.

Investigated diseases

Non-valvular atrial fibrillation - Non-valvular atrial fibrillation is an irregular heart rhythm that occurs in the upper chambers of the heart without significant valve disease. The condition causes chaotic electrical signals, leading to a faster or irregular pulse. Over time, the atria may enlarge as they work harder to pump blood. The irregular rhythm can lead to periods where the heart beats very rapidly or very slowly. Episodes may become more frequent or last longer as the condition advances.