A Clinical Trial of Study Medicine (Marstacimab) in Pediatric Patients With Hemophilia A or Hemophilia B

NCT05611801 | Recruiting Phase 3 DMC FDA Drug

• 3 other identifiers: B7841008ANTI-TFPI PEDIATRIC STUDY2022-500495-65-00
• Study Type: interventional
• Target: 100
• Locations: 17 countries
• Sites: 33

Brief Summary

The purpose of this clinical trial is to learn about the safety and effects of the study medicine (called marstacimab) for the potential treatment of hemophilia in pediatric patients. This study will enroll pediatric participants from ages 1 to 17 years in a sequential manner. The study will open enrollment to adolescent participants aged 12 to 17 years first. Then children aged 6 to 11 years will be permitted to enroll. Lastly, children aged 1 to 5 years will be permitted to enroll. This study will enroll participants who:

• have severe Hemophilia A or moderately severe to severe Hemophilia B (with or without inhibitors)
• have accurate historical records documenting all factor VIII, factor IX, or bypass agent infusions and hemophilia bleed events for at least 1 year prior to entering the study
• if a non-inhibitor patient, must be on a stable routine prophylaxis regimen with factor VIII or factor IX replacement products for at least 12 months prior to study entry
• if an inhibitor patient, must be on an on-demand bypass treatment regimen during the 12 months prior to study entry All participants in this study will receive marstacimab to use prophylactically. Marstacimab will be given once a week as a subcutaneous (under the skin) shot. The first dose of marstacimab will be given at the study site by the study site staff. During the 12-month treatment period, weekly doses of marstacimab can be given at home, or if preferred, the doses may be given by the study site staff. To help us determine if the study medicine is safe and effective, we will compare participant experiences when they are taking the study medicine to a historical period when they were not. Researchers want to see if the study medicine works to prevent the bleeding episodes commonly experienced by patients with Hemophilia. Participants will be in this study for about 14 months (approximately 1 month in a Screening period, 12 months receiving treatment, and 1 month in a follow-up period) during which they will visit the study site at least 10 times. If preferred, and if local regulations allow it, 2 of the study visits can be completed at the participant's home instead of at the study site. There will also be 6 scheduled telephone calls approximately every 2 months.

Conditions

Hemophilia A; Hemophilia B

Keywords

Factor VIII Inhibitor; Factor IX Inhibitor; PF-06741086; Marstacimab; Anti-TFPI; Factor VIII; Factor IX; Inhibitors; Anti-Tissue Factor Pathway Inhibitor (TFPI); Subcutaneous (sc); Prophylaxis; On-Demand; BASIS KIDS; Inhibitor; SC; Subcutaneous; Injection; On demand; aTFPI; Severe hemophilia; Severe bleeding; Hemophilia

Outcome Measures

Primary Outcomes (8)

• Annualized bleeding rate (ABR) of treated bleeding events

  Derived for each subject for each period (historical and study treatment) by using the following formula: ABR = number of bleeds requiring treatments/ (days on treatment period / 365.25)

  Baseline to end of 12-month treatment period

• Incidence of adverse events and serious adverse events

  Screening through end of follow-up period (approximately 14 months)

• Incidence and severity of thrombotic events

  Baseline to end of 12-month treatment period

• Incidence and severity of thrombotic microangiopathy

  Baseline to end of 12-month treatment period

• Incidence and severity of disseminated intravascular coagulation/consumption coagulopathy events

  Baseline to end of 12-month treatment period

• Immunogenicity (incidence of ADA and clinically significant persistent NAb against marstacimab)

  Baseline to end of 12-month treatment period

• Incidence and severity of injection site reaction

  Baseline to end of 12-month treatment period

• Incidence of severe hypersensitivity and anaphylactic reactions

  Baseline to end of 12-month treatment period

Secondary Outcomes (10)

• Incidence of joint bleeds (treated)

  Baseline to end of 12-month treatment period

• Incidence of spontaneous bleeds (treated)

  Baseline to end of 12-month treatment period

• Incidence of target joint bleeds (treated)

  Baseline to end of 12-month treatment period

• Incidence of total bleeds (treated and untreated)

  Baseline to end of 12-month treatment period

• Number of target joints

  Baseline to end of 12-month treatment period

Study Arms (1)

marstacimab (PF-06741086)

EXPERIMENTAL

Weekly subcutaneous injections.

Drug: marstacimab

Interventions

marstacimab DRUG

marstacimab

Also known as: PF-06741086

marstacimab (PF-06741086)

Eligibility Criteria

• Age: 1 Year - 17 Years
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• Male participants of appropriate age and required minimum weight
• Participants aged 12 to 17 years must be at least 25 kgs at time of consent.
• Participants aged 6 to 11 years must be at least 19 kgs at time of consent.
• Minimum weight requirement for participants aged 1 to 5 years is to be determined.
• Participants with a diagnosis of severe hemophilia A or moderately severe to severe hemophilia B
• Participants must have at least 1 year of diary and/or medical records available in which exogenous FVIII or FIX replacement or bypass agent infusions and hemophilic bleeding episodes were consistently documented over the 12 months prior to the time of consent.
• Participants who are enrolled into the Non-Inhibitor Cohort must also meet the following criteria:
• No current detectable inhibitor and no documented history of inhibitors in the 5 years prior to consent
• Must have at least 50 exposure days to FVIII/FIX replacement products
• Must be at least 80% compliant with a stable and effective routine prophylaxis regimen with FVIII/FIX replacement products, for at least 12 months prior to consent
• Participants who are enrolled into the Inhibitor Cohort must also meet the following criteria:
• Documentation of current high titer inhibitor (≥5 BU/mL); or current low titer inhibitor (\<5 BU/mL) refractory to FVIII or FIX replacement and with FVIII or FIX recovery \<60% of expected within previous 12 months prior to the time of consent
• Participants who have documented inhibitors while on factor-replacement therapy but who do not meet the high quantitative inhibitor criteria described in the prior bullet at the time of screening (eg, participant with a previously documented high-titer inhibitor ≥5 BU/mL) and whose condition precludes re-challenge with FVIII or FIX replacement may be considered for eligibility on a case-by-case basis with discussion and agreement from the Pfizer medical monitor.
• Hemophilia A participants with on-demand treatment regimen with ≥12 bleeding episodes or hemophilia B participants with on-demand treatment regimen with ≥8 bleeding episodes (spontaneous or traumatic) necessitating treatment with bypass factor in the 12 months prior to informed consent
• Participants must be on an on-demand bypass treatment regimen during the 12 months prior to informed consent

You may not qualify if:

• Known coronary artery, thrombotic, or ischemic disease, or current evidence of congenital or acquired thrombophilic disease such as Anti-thrombin III deficiency, Factor V Leiden mutation, prothrombin 20210 mutation, protein C deficiency, protein S deficiency and antiphospholipid syndrome.
• Known planned surgical procedure during the planned study period
• Known hemostatic defect other than hemophilia A or B
• Abnormal hematology, renal or hepatic function laboratory results at screening
• Other acute or chronic medical or psychiatric condition that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results and, in the judgment of the investigator
• Individuals with known allergic reaction or hypersensitivity to hamster protein or other components of the study intervention
• Current routine prophylaxis with bypassing agent, non-coagulation non-factor replacement therapy (eg, emicizumab), or any previous treatment with a gene therapy product for treatment of hemophilia
• Participants with inhibitors who are being treated using a prophylaxis treatment regimen with a bypass agent, and, participants who have previously received non-factor-based hemophilia therapy (eg, fitusiran, concizumab, emicizumab) will be considered on a case-by-case basis, only after discussion and agreement between the investigator and the Pfizer medical monitor
• Regular use of immunomodulatory medications (eg, IVIG, routine systemic corticosteroids, rituximab)
• Use of systemic antifibrinolytics, medications that may increase the risk of bleeding, and certain non-steroidal anti-inflammatory drugs within 120 hours of first dose of study intervention and while on study
• Ongoing or planned use of ITI, or prophylaxis with FVIII or FIX replacement at any time after initiation of treatment with study intervention
• Participation in other studies involving investigational drug(s) or investigational vaccine(s) within 30 days (or as determined by local requirements) or 5 half-lives prior to study entry or during study participation
• Previous exposure to marstacimab during participation in other marstacimab clinical studies
• CD4 cell count ≤200/uL if HIV-positive
• Abnormal ECG of clinical relevance that may affect participant safety or interpretation of study results

Sponsors & Collaborators

• Pfizer: lead

Study Sites (34)

Arbesu Hematología

Mendoza, M5501, Argentina

RECRUITING

Murdoch Children's Research Institute

Parkville, 3052, Australia

RECRUITING

Medizinische Universität Wien

Vienna, State of Vienna, 1090, Austria

RECRUITING

Hamilton Health Sciences - McMaster University Medical Centre

Hamilton, Ontario/canada, L8N 3Z5, Canada

RECRUITING

Tongji Hospital of Tongji Medical College of Huazhong University of Science and Technology

Wuhan, Hubei, 430030, China

RECRUITING

Tongji Hospital of Tongji Medical College of HUST/Pediatric Hematology Department Pharmacy

Wuhan, Hubei, 430030, China

RECRUITING

Institute of hematology&blood disease hospital

Tianjin, Tianjin Municipality, China

RECRUITING

Detska nemocnice FN Brno

Brno, Brno-město, 613 00, Czechia

RECRUITING

Motol University Hospital

Prague, 150 06, Czechia

RECRUITING

Rigshospitalet

Copenhagen, Capital Region, 2100, Denmark

RECRUITING

Aarhus Universitetshospital, Skejby

Aarhus N, 8200, Denmark

RECRUITING

Charité Campus Virchow-Klinikum

Berlin, 13353, Germany

RECRUITING

Ospedale Pediatrico Bambino Gesù IRCCS

Rome, ROMA, 00165, Italy

RECRUITING

Azienda Ospedaliero Universitaria di Parma

Parma, 43126, Italy

RECRUITING

Azienda Ospedaliero-Universitaria Città della Salute e della Scienza di Torino

Torino, 10126, Italy

NOT YET RECRUITING

Hyogo prefectural Kobe Children's Hospital

Kobe, Hyōgo, 650-0047, Japan

RECRUITING

Saitama Prefectural Children's Medical Center

Saitama-shi, Saitama, 330-8777, Japan

RECRUITING

Saga University Hospital

Saga, 849-8501, Japan

RECRUITING

Arké SMO S.A de C.V

Veracruz, 91900, Mexico

NOT YET RECRUITING

King Fahad Specialist Hospital

Dammam, 32253, Saudi Arabia

RECRUITING

Detska fakultna nemocnica Kosice

Košice, 040 11, Slovakia

RECRUITING

Severance Hospital, Yonsei University Health System

Seoul, Seoul-teukbyeolsi [seoul], 03722, South Korea

RECRUITING

Kyung Hee University Hospital at Gangdong

Seoul, Seoul-teukbyeolsi [seoul], 05278, South Korea

RECRUITING

Hospital Universitario La Paz

Madrid, Madrid, Comunidad de, 28046, Spain

RECRUITING

Changhua Christian Hospital

Changhua County, Changhua, 50006, Taiwan

RECRUITING

Taichung Veterans General Hospital

Taichung, 407219, Taiwan

RECRUITING

National Taiwan University Hospital

Taipei, 100, Taiwan

RECRUITING

Gazi Universitesi Tip Fakultesi Hastanesi Cocuk Hematologi Bolumu

Ankara, 06560, Turkey (Türkiye)

RECRUITING

Ege University

Izmir, 35010, Turkey (Türkiye)

RECRUITING

Erciyes University Faculty of Medicine Pediatric

Kayseri, 38039, Turkey (Türkiye)

RECRUITING

Ondokuz Mayıs Universitesi

Samsun, 55200, Turkey (Türkiye)

RECRUITING

Royal Victoria Infirmary

Newcastle upon Tyne, England, NE1 4LP, United Kingdom

RECRUITING

Royal Manchester Children's Hospital

Manchester, M13 9WL, United Kingdom

RECRUITING

Freeman Hospital

Newcastle upon Tyne, NE7 7DN, United Kingdom

RECRUITING

Related Links

• To obtain contact information for a study center near you, click here.

MeSH Terms

Conditions

Hemophilia A; Hemophilia B; Hemorrhage

Interventions

marstacimab

Condition Hierarchy (Ancestors)

Blood Coagulation Disorders, Inherited; Blood Coagulation Disorders; Hematologic Diseases; Hemic and Lymphatic Diseases; Coagulation Protein Disorders; Hemorrhagic Disorders; Genetic Diseases, Inborn; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Genetic Diseases, X-Linked; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Study Officials

• Pfizer CT.gov Call Center

  Pfizer

  STUDY DIRECTOR

Central Study Contacts

Pfizer CT.gov Call Center

CONTACT

1-800-718-1021; ClinicalTrials.gov_Inquiries@pfizer.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: October 27, 2022
• First Posted: November 10, 2022
• Study Start: December 9, 2022
• Primary Completion (Estimated): September 10, 2028
• Study Completion (Estimated): September 10, 2028
• Last Updated: May 7, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share

Locations

ES (1); ME (1); AU (1); JP (3); SA (1); SL (1); DK (2); AR (1); DE (1); TU (4); GB (3); CA (1); CZ (2); IT (3); CN (3); TW (3); KR (2)