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Study identifier: NCT05145127 Synced from ClinicalTrials.gov · July 28, 2026
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Open-Label Extension Study of Marstacimab in Hemophilia Participants With or Without Inhibitors

Condition: Hemophilia A · Hemophilia B  ·  Sponsor: Pfizer

PhasePhase 3
Planned participants245
Who can joinMale, 1 Year to 74 Years
Healthy volunteersNo

About this study

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. Study B7841005: approximately 145 adolescent and adult participants 12 to \<75 years of age with severe hemophilia A or moderately severe to severe hemophilia B (defined as FVIII activity \<1% or FIX activity ≤2%, respectively) with or without inhibitors are expected to be enrolled in Study B7841005 during which they will receive prophylaxis (defined as treatment by SC injection of marstacimab). Study B7841008: this is an ongoing Phase 3, open-label study in pediatric participants \<18 years of age with severe hemophilia A (FVIII Coagulation Factor Activity \<1%) or moderately severe to severe hemophilia B (FIX Coagulation Factor Activity ≤2%). A sequential approach will be used in enrolling at least 100 pediatric participants, at least 20 of which will be aged ≥12 to \<18 years and at least 80 participants will be aged ≥1 to \<12 years. At the start of study B7841008, the dosing and data available in adolescent and adult participants in Study B7841005 supported the initiation of B7841008 study in participants aged ≥12 to \<18 years. Subsequently, additional safety and efficacy data from adolescent participants in Study B7841005 became available for benefit/risk assessment in support of dosing participant…

This description comes directly from the study's public registry record.

Talk to the study team

Pfizer CT.gov Call Center  ·  1-800-718-1021  ·  ClinicalTrials.gov_Inquiries@pfizer.com

Always discuss trial participation with your own doctor first.

Locations (75)

University of IowaIowa City, Iowa, United StatesActive Not Recruiting
Northwell Health HTCNew Hyde Park, New York, United StatesRecruiting
The Feinstein Institutes for Medical ResearchPhiladelphia, Pennsylvania, United StatesRecruiting
Washington Institute for Coagulation d/b/a WACBDSeattle, Washington, United StatesRecruiting
Arbesu HematologíaMendoza, ArgentinaRecruiting
Royal Children's HospitalMelbourne, Victoria, AustraliaRecruiting
HEMOESVitória, Espírito Santo, BrazilRecruiting
Stollery Children's HospitalEdmonton, Alberta, CanadaRecruiting
Hamilton Health Sciences - McMaster University Medical CentreHamilton, Ontario, CanadaRecruiting
Hamilton Health Sciences - McMaster University Medical CentreHamilton, Ontario, CanadaRecruiting
Nanfang Hospital, Southern Medical UniversityGuangzhou, Guangdong, ChinaRecruiting
The Affiliated Hospital of Guizhou Medical UniversityGuiyang, Guizhou, ChinaRecruiting

+ 63 more locations — full list on the registry record.

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Source record: clinicaltrials.gov/study/NCT05145127