A Study to Learn About How Changing Therapy From Emicizumab to Marstacimab Affects People With the Severe Hemophilia A.

NCT06703606 | Recruiting Phase 1 DMC FDA Drug

• 2 other identifiers: B7841014NCT06703606
• Study Type: interventional
• Target: 15
• Locations: 3 countries
• Sites: 4

Brief Summary

The purpose of the study is to learn about safety, how the body processes marstacimab and how it works in patients with severe hemophilia A without inhibitors. Hemophilia A is rare bleeding disorder where the blood doesn't clot normally. This causes a person to bleed a lot, even from a small cut. These patients who are on emicizumab medicine for routine prophylaxis for at least 6 months, and desire to switch to marstacimab medicine. Inhibitors are antibodies that the immune system develops because it sees the infused clotting factor as a foreign substance that needs to be destroyed. Antibodies are proteins that eat up the activated factor before it has time to stop the bleeding. Prophylaxis are preventive medicines. This study is seeking for participants:

• with severe Hemophilia A withouth inhibitors who are on emicizumab treatment for at least 6 months.
• must be 12 to less than 75 years old
• must have a body weight of at least 35 kilograms. The results from this study will serve as a guide to doctors and their hemophilia A patients who will change their medicines in the real-world clinical setting. Patients who can take part in the study will receive marstacimab medicine as weekly injections under the skin of 150 milligrams for 4 months. Study treatment with marstacimab will be initiated no earlier than 14 days after last dose of emicizumab. The study can last up to 6 months. The sponsor will provide marstacimab. Patients will continue their usual treatment with the infused clotting factor for their bleeds when taking part in the study. Roll-over into an optional study treatment extension period will be available to participants who wish to continue prophylaxis with marstacimab in countries where it is not commercially available.

Conditions

Severe Hemophilia A

Keywords

Hemophilia A; Severe Hemophilia A; Severe Hemophilia A Without Inhibitors

Outcome Measures

Primary Outcomes (2)

• Incidence of marstacimab-related adverse events (AEs)

  Approximately 178 days: from the time the participant provides informed consent, through and including a minimum of 28 calendar days after last dose of study treatment

• Incidence of marstacimab-related serious AEs (SAEs)

  Approximately 178 days: from the time the participant provides informed consent, through and including a minimum of 28 calendar days after last dose of study treatment

Secondary Outcomes (10)

• Plasma Concentration Versus Time of Marstacimab (Listings)

  Day 1 up to day 135

• Maximum Observed Plasma Concentration (Cmax) of Marstacimab

  Day 1 up to day 135

• Average Plasma Concentration (Cavg) of Marstacimab

  Day 1 up to day 135

• Minimum Observed Plasma Concentration (Cmin)

  Day 1 up to day 135

• Change from baseline in tissue factor pathway inhibitor (TFPI).

  Baseline, Day 1 up to day 135

Study Arms (1)

MARSTACIMAB

EXPERIMENTAL

Marstacimab 150 mg subcutaneous (SC) once weekly (QW)

Drug: MARSTACIMAB

Interventions

MARSTACIMAB DRUG

Marstacimab 150 mg administered subcutaneous (SC) once weekly (QW)

Also known as: PF-06741086

MARSTACIMAB

Eligibility Criteria

• Age: 12 Years - 74 Years
• Gender Eligibility Details: Adolescent and adult male patients
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• Male and 12 to \<75 years of age with a minimum body weight of 35 kg at the time of signing the informed consent.
• Diagnosis of severe hemophilia A (FVIII activity \<1%) without inhibitors.
• On emicizumab therapy at a standard clinical dose for ≥6 months.

You may not qualify if:

• Previous or current treatment for or history of coronary artery diseases, venous or arterial thrombosis, or ischemic disease.
• Any medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.
• Known hemostatic defect other than hemophilia A.
• Current use of any prohibited concomitant medication(s) or unwillingness or inability to use a required concomitant medication(s).
• Previous administration of an investigational product (drug or vaccine) within 30 days or 5 half-lives preceding the first dose of study intervention used in this study (whichever is longer). Participation in studies of other investigational products (drug or vaccine) at any time during participation in this study.
• Platelet count \<100,000/μl or hemoglobin \<10 g/dL.
• Clinically significant renal or hepatic function abnormality based on laboratory results at screening, or known kidney or liver disease.
• CD4 cell count ≤200/μl if HIV positive.
• Screening 12-lead ECG that demonstrates clinically significant abnormalities that, in the opinion of the investigator, may affect participant safety or interpretation of study results.
• Known planned surgical procedure.
• Hypersensitivity or allergic reaction to hamster protein or other components of the study intervention.
• Investigator site staff directly involved in the conduct of the study and their family members, site staff otherwise supervised by the investigator, and sponsor and sponsor-delegate employees directly involved in the conduct of the study and their family members.

Sponsors & Collaborators

• Pfizer: lead

Study Sites (4)

Orthopaedic Institute for Children/Orthopaedic Hemophilia Treatment Center

Los Angeles, California, 90007, United States

RECRUITING

Nirmal Hospital Pvt Ltd.

Surat, Gujarat, 395002, India

RECRUITING

K J Somaiya Hospital & Research Centre

Mumbai, Maharashtra, 400022, India

RECRUITING

Ege University Faculty of Medicine Dean's Office

Bornova, İzmir, 35100, Turkey (Türkiye)

RECRUITING

Related Links

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

MeSH Terms

Conditions

Hemophilia A

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

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 1
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: November 21, 2024
• First Posted: November 25, 2024
• Study Start: May 13, 2025
• Primary Completion (Estimated): May 5, 2027
• Study Completion (Estimated): May 5, 2027
• Last Updated: March 30, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

US (1); TU (1); IN (2)