A study to investigate the efficacy and safety of fitusiran prophylaxis in male participants aged 1 to less than 12 years with hemophilia A or B.

Overview

Sponsor-declared trial summary

Key facts

Sponsor

Sanofi-Aventis Recherche & Developpement

Participant type

Pediatric, Patients

Age range

0-17 years

Gender

Male

Therapeutic area

Diseases [C] - Hemic and Lymphatic Diseases [C15]

Trial duration

16 Mar 2026 → ongoing

Decision date (initial)

2026-01-15

Transition trial

No

Low-intervention

No

Rare-disease indication

Yes

Vulnerable population

Yes

Funding sources

Sanofi-Aventis Research & Development

External identifiers

EU CT number

2025-521858-42-00

WHO UTN

U1111-1280-7028

Trial design

CTIS Part I — objectives, methods, condition coding

Main objective

Scope: Efficacy, Pharmacokinetic, Pharmacodynamic, Dose response, Prophylaxis, Safety

To evaluate treatment efficacy during fitusiran prophylaxis and SOC periods in the fitusiran-
naïve arm.

Secondary objectives 5

1. To characterize the following during the fitusiran prophylaxis and SOC periods in the fitusiran- naïve arm: - the frequency of treated spontaneous bleeding episodes - the frequency of treated joint bleeding episodes
2. To characterize the frequency of treated bleeding episodes during the fitusiran treatment period in both arms
3. To characterize the effect of fitusiran prophylaxis on health-related quality of life (HRQoL) outcomes in the fitusiran-naïve arm
4. To characterize the safety of fitusiran in both arms
5. To characterize the effect of fitusiran prophylaxis on joint health outcomes in the fitusiran-naïve arm

Conditions and MedDRA coding

Hemophilia

Regulatory references

Scientific advice from competent authorities

European Medicines Agency

EMA paediatric investigation plan (PIP)

EMEA-001855-PIP01-15

Plan to share IPD

Yes

IPD plan description

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of the trial participants. Further details on Sanofi´s data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org.

Eligibility criteria

Principal inclusion / exclusion criteria as submitted by sponsor

Inclusion criteria 6

1. Participant must be 1 to <12 years of age at the time of enrollment
2. Participants must have severe hemophilia A or B (FVIII <1% or FIX ≤2%) as evidenced by a central laboratory measurement at screening or documented medical record evidence.
3. -Participants must meet inhibitor or non-inhibitor status as defined below: Inhibitor: Requiring use of BPA for prophylaxis or BPA as on-demand therapy for any bleeding episodes for at least the last 3 months prior to screening, and meet one of the following Nijmegen-modified Bethesda assay results criteria: . Inhibitor titer of ≥0.6 BU/mL at screening, OR . Inhibitor titer of <0.6 BU/mL at screening with medical record evidence of 2 consecutive titers ≥0.6 BU/mL, OR . Inhibitor titer of <0.6 BU/mL at screening with medical record evidence of 1 inhibitor titer ≥0.6 BU/mL and a history of anamnestic response, or severe allergic reaction (eg, anaphylaxis) or nephrotic syndrome Non-inhibitor: Requiring use of clotting factor concentrates (CFCs) for prophylaxis or CFCs as on- demand therapy for any bleeding episodes for at least the last 3 months prior to screening, and meet each of the following criterion: . Nijmegen-modified Bethesda assay inhibitor titer of <0.6 BU/mL at screening, AND . No use of BPA to treat bleeding episodes for at least the last 3 months prior to screening
4. -Participants must have adequate peripheral venous access, as determined by the Investigator, to allow the blood draws required by the study protocol.
5. -Male: There are no contraceptive requirements for this study except where required by local regulations.
6. -Capable of giving signed informed consent/assent. A signed written informed consent must be obtained from parent(s)/legal guardian (hereafter referred to as the “parent”), as well as a written or oral assent obtained from participant, per local and national requirements.

Exclusion criteria 23

1. Known co-existing bleeding disorders other than hemophilia A or B.
2. Presence of clinically significant liver disease.
3. History of antiphospholipid antibody syndrome.
4. History of arterial or venous thromboembolism, unrelated to an indwelling venous access.
5. -Any condition (eg, medical concern), which in the opinion of the Investigator, would make the participant unsuitable for dosing or which could interfere with the study compliance, the participant's safety and/or the participant's participation in the completion of the treatment period of the study.
6. History of multiple drug allergies or history of allergic reaction to an oligonucleotide or GalNAc.
7. -Subjects with a central or peripheral indwelling catheter, with a history of venous access complications (such as infections, thrombosis) leading to hospitalization and/or systemic anticoagulation therapy in the last 12 months.
8. At screening, anticipated need of surgery during the study or planned surgery scheduled to occur during the study.
9. -Completion of a surgical procedure within 14 days prior to screening, or currently receiving additional BPA infusion for postoperative hemostasis.
10. History of intolerance to SC injection(s).
11. Current participation in ITI therapy.
12. -The use of emicizumab (Hemlibra®) or any non-factor bleed management treatment within 6 months prior to screening
13. Prior gene therapy
14. Current or future participation in another clinical study, scheduled to occur during this study, involving an investigational product other than fitusiran or an investigational device.
15. AT activity <60% at screening, as determined by central laboratory analysis.
16. Co-existing thrombophilic disorder.
17. -Presence of an active Hepatitis C virus infection
18. Presence of acute hepatitis A or Hepatitis E virus infection.
19. Presence of acute or chronic hepatitis B virus infection.
20. Platelet count ≤100 000/μL.
21. Presence of acute infection at screening.
22. Human immunodeficiency virus (HIV) positive with a CD4 count of <400 cells/μL.
23. Estimated glomerular filtration rate ≤45 mL/min/1.73 m2 (using the Schwartz formula).

Endpoints

Primary and secondary outcome measures (English text)

Primary endpoints 1

1. Annualized treated bleeding rate (ABR) in the fitusiran primary efficacy period and in the SOC period.

Secondary endpoints 10

1. Annualized spontaneous bleeding rate (AsBR) in the fitusiran primary efficacy period and in the SOC period.
2. Annualized joint bleeding rate (AjBR) in the fitusiran primary efficacy period and in the SOC period
3. ABR in the fitusiran treatment period (160 weeks) for fitusiran-naïve participants.
4. ABR in the fitusiran treatment period (60 weeks) for rolled-over participants
5. Change in physical activity
6. Change in pain intensity
7. Change in HRQoL
8. Incidence, severity, seriousness, and relatedness of adverse events (AEs)
9. Change in total score and domain scores
10. Target joints resolution

Investigational products

Investigational medicinal products (IMPs), comparators, placebo, auxiliary

Test 2

Sponsors and contacts

Sponsor organisations, regulatory contacts, third parties

Sanofi-Aventis Recherche & Developpement

Sponsor organisation

Sanofi-Aventis Recherche & Developpement

Address

82 Avenue Raspail

City

Gentilly

Postcode

94250

Country

France

Scientific contact point

Organisation

Sanofi-Aventis Recherche & Developpement

Contact name

Clinical Sciences and Operations

Public contact point

Organisation

Sanofi-Aventis Recherche & Developpement

Contact name

Clinical Sciences and Operations

Third parties 4

Locations

7 EU/EEA countries · 17 investigational sites

By country

Investigational sites

Country notifications

Trial-start, recruitment-start, end and early-termination notifications submitted per Member State

Results and documents

Annex IV summary of results, Annex V layperson summary, and all documents registered in CTIS for this trial

Documents 102 files

Public protocol annexes, IB summaries, regulatory submissions and post-authorisation documents registered in CTIS.

Application history

6 submissions — initial application plus substantial / non-substantial modifications