Updated May 2026 · ClinicalTrials.gov

RECRUITINGPhase 4INTERVENTIONAL

Efanesoctocog Alfa Prophylaxis in Patients With Hemophilia A With Synovial Hypertrophy

Q: What is the NCT06941870 clinical trial studying?

The objective of the study is to assess the improvement of synovial hypertrophy during the 12 months of efanesoctocog alfa prophylaxis once per week (QW) in joints with existing evidence of synovial hypertrophy in participants with hemophilia A. The study duration for each participant is approximately 12 months. The full protocol is registered on ClinicalTrials.gov and includes the primary outcome measures, eligibility criteria, and study endpoints.

Q: Who can participate in NCT06941870?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

Q: How do I contact the trial site for NCT06941870?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Q: Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Q: Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

Prospective Interventional Study of Effectiveness of Efanesoctocog Alfa Prophylaxis on Synovial Hypertrophy in Patients With Hemophilia A

Efanesoctocog Alfa Prophylaxis in Patients With Hemophilia A With Synovial Hypertrophy (NCT06941870) is a Phase 4 interventional studying Factor VIII Deficiency, sponsored by Sanofi. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

About This Trial

What Stage of Research Is This?

Phase 4 studies happen after a treatment has been approved by the FDA. They monitor long-term safety, real-world effectiveness, and any rare side effects that only emerge in larger populations over longer periods. Phase 4 results sometimes lead to label changes, additional warnings, or — rarely — withdrawal of approval.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

With a target enrollment of 35 participants, this is a small study — typical of early-phase research, rare-disease trials, or pilot studies designed to generate preliminary signal before a larger study is launched.

Who May Be Eligible (Plain English)

Who May Qualify: Participant is diagnosed with moderate to severe hemophilia A (defined as less than or equal to (≤)5 percent (%) of endogenous FVIII clotting activity) at the time of consent/assent. Participant is more than or equal to (≥)12 years old at the time of consent/assent. Participant has existing synovial hypertrophy, defined as at least 1 eligible\* joint by the HEAD-US score (Synovitis score: 1 or 2) at the time of consent/assent. Participant has at least 1 eligible\* joint without planned future major orthopedic procedures (example, arthroscopic synovectomy, radioisotopic or chemical synoviorthesis), or major orthopedic procedures in the past 3 months prior to the screening visit (Visit 1). \*An eligible joint is a joint with existing synovial hypertrophy, as defined by a HEAD-US synovitis score of 1 or 2, considering hypertrophic synovium as an indication of the presence of synovitis Participant has received prophylactic treatment with hemophilia prophylaxis prescriptions in the last 12 months prior to the baseline visit (Visit 2). Participant is capable of understanding the written willing to sign a consent form Form (ICF)/assent form, provides a signed and witnessed written ICF/assent form, and agrees to comply with the protocol requirements. If male, no contraceptive measures are required for this study. If female, is not pregnant or breastfeeding, and one of the following conditions applies: Is a women of nonchildbearing potential (WONCBP) Is a women of childbearing potential (WOCBP) and agrees to use a highly effective contraceptive method, with a failure rate of less than (\<)1 percent during the study treatment period (at least until the Week 52/ End of Treatment \[EoT\] visit). A WOCBP must have a negative serum pregnancy test at the screening visit (Visit 1) Who Should NOT Join This Trial: Participants are excluded from the study if any of the following criteria apply: ...See full criteria on ClinicalTrials.gov Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language

Inclusion Criteria: Participant is diagnosed with moderate to severe hemophilia A (defined as less than or equal to (≤)5 percent (%) of endogenous FVIII clotting activity) at the time of consent/assent. Participant is more than or equal to (≥)12 years old at the time of consent/assent. Participant has existing synovial hypertrophy, defined as at least 1 eligible\* joint by the HEAD-US score (Synovitis score: 1 or 2) at the time of consent/assent. Participant has at least 1 eligible\* joint without planned future major orthopedic procedures (example, arthroscopic synovectomy, radioisotopic or chemical synoviorthesis), or major orthopedic procedures in the past 3 months prior to the screening visit (Visit 1). \*An eligible joint is a joint with existing synovial hypertrophy, as defined by a HEAD-US synovitis score of 1 or 2, considering hypertrophic synovium as an indication of the presence of synovitis Participant has received prophylactic treatment with hemophilia prophylaxis prescriptions in the last 12 months prior to the baseline visit (Visit 2). Participant is capable of understanding the written Informed Consent Form (ICF)/assent form, provides a signed and witnessed written ICF/assent form, and agrees to comply with the protocol requirements. If male, no contraceptive measures are required for this study. If female, is not pregnant or breastfeeding, and one of the following conditions applies: Is a women of nonchildbearing potential (WONCBP) Is a women of childbearing potential (WOCBP) and agrees to use a highly effective contraceptive method, with a failure rate of less than (\<)1 percent during the study treatment period (at least until the Week 52/ End of Treatment \[EoT\] visit). A WOCBP must have a negative serum pregnancy test at the screening visit (Visit 1) Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: Has other associated clotting disorders at the time of consent/assent. Is already under efanesoctocog alfa treatment. Has a current diagnosis of an factor VIII (FVIII) inhibitor, defined as inhibitor titer ≥0.60 BU/mL. Has ITI within the last 2 years prior to the baseline visit (Visit 2). Has been enrolled in a concurrent clinical interventional study or exposed to other investigational drug(s) within 3 months prior to screening for this study. Is currently in an institution because of regulatory or legal order (that is, is a prisoner or a patient who is legally institutionalized). Is not suitable for participation, whatever the reason, as judged by the investigator, including medical or clinical conditions, or patients potentially at risk of noncompliance to study procedures. Is an employee or family member of the investigator or site personnel. Is involved in a specific situation during study implementation or the course of the study that may raise ethics considerations. Has hypersensitivity to efanesoctocog alfa or its components or any of its excipients that, in the opinion of the investigator, contraindicates participation in the study.

Treatments Being Tested

DRUG

Efanesoctocog alfa

Pharmaceutical form:Lyophilized powder in a sterile vial that requires reconstitution with sterile water for injection (diluent)-Route of administration:Intravenous

Locations (13)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

Orthopedic Institute for Children- Site Number : 8400009

Los Angeles, California, United States

Innovative Hematology, Inc.- Site Number : 8400006

Indianapolis, Indiana, United States

University of Iowa- Site Number : 8400004

Iowa City, Iowa, United States

Ohio State University Hospital East- Site Number : 8400001

Columbus, Ohio, United States

Investigational Site Number : 1240003

Hamilton, Ontario, Canada

Investigational Site Number : 1240004

Hamilton, Ontario, Canada

Investigational Site Number : 3920003

Kawasaki, Kanagawa, Japan

Investigational Site Number : 3920002

Hiroshima, Japan

Investigational Site Number : 3920001

Saitama, Japan

Investigational Site Number : 3920004

Tokyo, Japan

Investigational Site Number : 1580003

Kaohsiung City, Taiwan

Investigational Site Number : 1580001

Taichung, Taiwan

Investigational Site Number : 1580002

Taipei, Taiwan

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT06941870), the sponsor (Sanofi), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT06941870 clinical trial studying?

The objective of the study is to assess the improvement of synovial hypertrophy during the 12 months of efanesoctocog alfa prophylaxis once per week (QW) in joints with existing evidence of synovial hypertrophy in participants with hemophilia A. The study duration for each participant is approximately 12 months. The full protocol is registered on ClinicalTrials.gov and includes the primary outcome measures, eligibility criteria, and study endpoints.

Who can participate in NCT06941870?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT06941870?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

Source: ClinicalTrials.gov API v2 record for NCT06941870. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT06941870. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-05-08 · Data from ClinicalTrials.gov.