The rationale for conducting this open-label phase 4 study is to assess whether once-weekly prophylaxis with efanesoctocog alfa (50 IU/kg) improves the disease course of existing synovial hypertrophy and prevents the risk of joint bleeds in patients with moderate or severe haemophilia A. The use of imaging assessments will allow for objective detection and monitoring of synovial hypertrophy, and thus expand on the previous findings demonstrating positive effects of once-weekly prophylaxis with efanesoctocog alfa (50 IU/kg) on joint health.
Who can participate
Age range
12 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion criteria
. Capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in the protocol. Parents' or legally designated representatives' consent is required for patients who are \<18 years of age or unable to give consent, or as applicable per local laws. Patients who are \<18 years of age should provide assent in addition to the parents'/legally designated representatives' consent, if appropriate.
. Male or female patients who are ≥12 years of age and diagnosed with moderate or severe haemophilia A (defined as ≤5% of normal FVIII clotting activity) at the time of signing the ICF.
. A female patient is eligible to participate if she is not pregnant at enrolment and does not plan to become pregnant during the study. A woman of child-bearing potential (WOCBP) must have a negative highly sensitive serum pregnancy test at the Screening Visit.
. Must have received prophylactic treatment per local label with any marketed FVIII product or emicizumab for ≥12 months prior to the Baseline Visit.
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
Haemophilia Early Arthropathy Detection with Ultrasound (HEAD-US) synovial hypertrophy domain score decrease.
. Have at least one eligible index joint (ankle, elbow, knee).
. Have 12 months of documented pre-study treatment data on haemophilia prescriptions and on treated bleeding episodes prior to the Baseline Visit.
. Willingness and the ability of the patient or their legally designated representative to complete training in the use of the study patient diary and to complete the diary throughout the study.
Exclusion criteria
. Blood clotting disorders other than haemophilia A
. Already on efanesoctocog alfa treatment
. Positive inhibitor result (assessed by local laboratory) from the Screening Visit, defined as ≥0.6 Bethesda units (BU)/mL.
. History of inhibitors without successful immune tolerance induction (ITI)
. ITI performed within the last 2 years prior to the Baseline Visit.
. Currently receiving treatment with any of the prohibited concomitant medications, as specified by the protocol.
. Planned major orthopaedic procedure in any eligible index joint during the course of the study.
. Patients are not eligible for participation in the study if they cannot undergo MRI assessments at the Baseline Visit.