NCT05145127 · Pfizer
Open-Label Extension Study of Marstacimab in Hemophilia Participants With or Without Inhibitors
What this study is about
Study B7841007 is an where both patients and doctors know the treatment given extension study to assess the long-term safety, tolerability, and effectiveness of prophylaxis treatment with marstacimab in participants who did not require "Early Termination" from the Phase 3 Study B7841005 and from the Phase 3 Study B7841008.
View original scientific description
Study B7841007 is an open-label extension study to assess the long-term safety, tolerability, and efficacy of prophylaxis treatment with marstacimab in participants who did not require "Early Termination" from the Phase 3 Study B7841005 and from the Phase 3 Study B7841008.
Interventions
DRUG
PF-06741086
For participants aged ≥12 years 300 milligrams(mg) subcutaneous (sc) loading dose followed by 150 mg sq once weekly (qw). 300 mg sc qw is prescribed for participants who meet dose escalation criteria. For participants aged ≥6 to \<12 years is marstacimab 150 mg SC for initial loading dose followed by 75 mg SC QW. 150 mg sc qw is prescribed for participants who meet dose escalation criteria.
Primary outcome measures
Number of subject reporting Adverse Events
Time frame: Baseline up to 7 years
Number of subjects reporting Serious Adverse Events
Time frame: Baseline up to 7 years
Incidence and severity of thrombotic events
Time frame: Baseline up to 7 years
Incidence and severity of thrombotic microangiopathy
Time frame: Baseline up to 7 years
Number of subjects reporting Disseminated intravascular coagulalopathy/consumption coagulopathy
Time frame: Baseline up to 7 years
Incidence of clinically significant persistent NAb against marstacimab
Time frame: Baseline up to 7 years
Incidence and severity of injection site reaction
Time frame: Baseline up to 7 years
Clinically significant changes in vital signs from baseline
Time frame: Baseline up to 7 years
Incidence of clinically significant laboratory value abnormalities
Time frame: Baseline up to 7 years
Incidence of severe hypersensitivity and anaphylactic reactions
Time frame: Baseline up to 7 years
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- All participants will have a minimum body weight as defined by parent studies
- Participants who are willing and able to comply with all scheduled visits, treatment plan, laboratory tests, and other study procedures.
- Participants have successfully completed participation in parent studies, defined as did not require "Early Termination"
Exclusion criteria
- Previous or current treatment for or history of coronary artery disease, venous or arterial thrombosis (CTCAE Grade \>3), or ischemic disease (except catheter-associated thrombosis)
- Abnormal renal function as defined by eGFR \<30 mL.min/1.73 m(2)
- Known planned surgical procedure during the planned study period
- Unstable hepatic function as determined by the Investigator clinical assessment and review of the participant's most recent laboratory results, which would make the participant inappropriate for the study
- For participants known to be HIV+, worsening disease status as determined by the Investi
Where
- Iowa City, Iowa
- New Hyde Park, New York
- Philadelphia, Pennsylvania
- Seattle, Washington
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jul 1, 2026 · Source of record for eligibility and locations