A Phase 4 interventional study of Efanesoctocog alfa in Haemophilia A (Moderate or Severe), Hemophilia, Classic and Haemophilia, sponsored by Swedish Orphan Biovitrum. Active, not recruiting at 10 sites in 4 countries. Open to participants aged 12 Years and older. Per ClinicalTrials.gov, last updated 2026-04-30.
Sponsored by Swedish Orphan Biovitrum · Phase 4, Interventional, and Treatment
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.
This is a 12-month, multicentre, open-label, non-randomized, interventional single-arm study to assess the course of synovial hypertrophy in previously treated patients ≥12 years of age with moderate or severe haemophilia A achieving high sustained FVIII levels provided by weekly efanesoctocog alfa prophylaxis. To be eligible to enroll in the study, patients must have existing synovial hypertrophy in at least one of the 6 index joints (ankles, elbows, and knees) as assessed by the HEAD-US scoring system. A retrospective data collection on patients' haemophilia, medical, and surgical history will be performed, including a 12-month history of previous treatment and treated bleeding episodes.
The study will start with the Screening Visit, which can be conducted up to 45 days prior to the Baseline Visit (Day 1), to check whether the patient fulfils all the inclusion criteria and none of the exclusion criteria. Patients will have an ultrasound examination of all non-prosthetic index joints at screening. The ultrasound images will be sent for central reading assessment using the HEAD-US scoring system to determine whether the patient has at least one eligible joint required for study inclusion. Once it is confirmed that a patient is eligible for inclusion, he/she will be enrolled in the study and attend a mix of on-site visits and phone call visits. The results from central reading assessment will be sent to the study sites and included in the baseline characteristics of the patients. MRI examinations can be conducted at the Baseline Visit or up to 28 days afterwards. Images from MRI will also be sent for central reading assessment using the International Prophylaxis Study Group (IPSG) MRI scale. The central reading assessment will be sent to the study sites and included in the patient data. Patients will be treated with once-weekly efanesoctocog alfa (50 IU/kg) prophylaxis and will complete the patient diary with their dosing and bleeding information. Assessments will be conducted during the on-site visits, which will occur every 6 months, and during phone call visits, which will occur halfway between these visits. A Safety Follow-up Call will be conducted 14 (+7) days after the End of Treatment (EoT) Visit. Ultrasound and MRI will be used to detect changes in synovial hypertrophy in index joints of patients. The primary endpoint of improvement in existing synovial hypertrophy from baseline to Month 12 as well as the key secondary endpoint of detection of new synovial hypertrophy and change in joint health status from baseline to Month 6 or Month 12 will be assessed using ultrasound and the HEAD-US scoring system.
To obtain 100 eligible index joints, the target is to enroll approximately 35 patients.
844 studies on the registry are indexed under Hemophilia A; 138 are open to participants now.
This study's enrollment of 37 is above the median of 30 across 499 interventional studies indexed under Hemophilia A.
Browse Hemophilia A studies →Swedish Orphan Biovitrum is the lead sponsor of 82 studies on the registry; 6 are open to participants now.
Of its 17 completed or terminated interventional studies of FDA-regulated products, 15 (88%) have results posted.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
History of inhibitors without successful immune tolerance induction (ITI)
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Drug: Efanesoctocog alfa
50 IU/kg once weekly, Intravenous injection
Haemophilia Early Arthropathy Detection with Ultrasound (HEAD-US) synovial hypertrophy domain score decrease.
At least 1 point decrease in HEAD-US synovial hypertrophy domain score at Month 12 (for joints with a domain score of 1 or 2 at baseline).
Time frame: Baseline to 12 months
Haemophilia Early Arthropathy Detection with Ultrasound (HEAD-US) synovial hypertrophy domain score increase.
At least 1 point increase in HEAD-US synovial hypertrophy domain score at Month 6 or Month 12 for joints with no synovial hypertrophy at baseline (domain score of 0).
Time frame: Baseline to 6 or 12 months
International Prophylaxis Study Group (IPSG) magnetic resonance imaging (MRI)
Change from baseline in total/domain scores of International Prophylaxis Study Group (IPSG) MRI per patient and per joint at Month 12.
Time frame: Baseline to 12 months
Haemophilia Joint Health Score (HJHS)
Change from baseline in total/domain scores of HJHS per patient and per joint at Month 12.
Time frame: Baseline to 12 months
Patient Reported Outcome (PRO) of Pain Intensity
Use of PROMIS SF v2.0 to measure change in patient-reported pain intensity from baseline.
Time frame: Baseline to 6 month and 12 months
Patient Reported Outcome of Pain Interference
Use of PROMIS SF v2.0 to measure change in patient-reported pain interference from baseline.
Time frame: Baseline to 6 month and 12 months
Patient Reported Outcome of Physical Function
Use of PROMIS SF v2.0 to measure change in patient-reported physical function from baseline.
Time frame: Baseline to 6 month and 12 months
Patient Reported Outcome of 5-level EuroQol-5 dimensions [EQ-5D-5L] score
Changes from baseline of patient self-care, usual activities, pain/discomfort, anxiety/depression.
Time frame: Baseline to 6 month and 12 months
Hemo-FAST scoring
Assess functional mobility in PWH. The Hemo-Fast tool is comprised of the Patient-reported outcome part and a Clinician-reported outcome (ClinRO) part, with a score of 0 to 100, with zero being the best possible joint health status. The change from baseline to month 12 will be evaluated.
Time frame: Baseline to 12 months
Change in annualized bleeding rate (ABR) and annualized joint bleeding rate (AjBR) (spontaneous, traumatic).
Time frame: 12 months prior to on-study period (retrospective) to 12 months after start of study intervention (prospective)
The occurrence of treatment-emergent adverse events (TEAEs) leading to treatment discontinuation, serious TEAEs, and adverse events of special interest (AESIs).
Time frame: 12 months, +14 (+7days) after the last IMP dose
Patient-Reported Treatment Preference Questionnaire
A 2-item treatment survey developed to evaluate perceived impact of treatment.
Time frame: 12 month
Qualitative Exit Interview
60-minute Telephone Interview patient reported preference for treatment.
Time frame: Within 14 days after EoT Visit
Plan to share: Yes — Qualified researchers may request access to patient level data and related study documents. Patient level data will be anonymized and study documents, if applicable will be redacted to protect the privacy of trial participants.
Data sharing details ↗ · www.sobi.com
No publications or documents are linked to this record.
This study is active, not recruiting, as verified in Apr 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Efanesoctocog alfa