Open-Label Extension Study of Marstacimab in Hemophilia Participants With or Without Inhibitors

Prior treatment

• 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).
• Known planned surgical procedure during the planned study period. Potential participants who have a surgical procedure planned during the study period may be eligible for participation on a case-by-case basis, only after consultation between the investigator and the Pfizer medical monitor
• Regular, concomitant therapy with immunomodulatory drugs (eg, IVIG, and routine systemic corticosteroids, rituximab).
• 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, with the exception of participation in Studies B7841005 and B7841008.

Lab values

• Abnormal renal function as defined by eGFR <30 mL/min/1.73 m2 (see Section 10.2.1 of the protocol for formulas used in eGFR calculation). Prior determinations of eGFR up to 90 days prior to TPY1 Day 1 visit may be used to determine eligibility
• Other 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 judgement, make the participant inappropriate for the study. 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 investigator clinical assessment and review of the participant’s most recent laboratory results, to include recent locally available CD4 count (if available), which would make the participant inappropriate for the study.

Other

• Ongoing or planned use of immune tolerance induction or prophylaxis with FVIII or FIX replacement during the study.
• Investigator site staff or Pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

• Participants continuing from Study B7841005 and from Study B7841008 have met age criteria in their respective studies.
• Participants who are willing and able to comply with all scheduled visits, treatment plan, laboratory tests, and other study procedures
• All participants continuing from Study B7841005 and from Study B7841008 will have met minimum weight criteria in their respective study.
• The investigator, or a person designated by the investigator, will obtain written/electronically signed informed consent and assent from each study participant or participant’s legal guardian//legally designated representative and the participant’s assent, when applicable, before any study-specific activity is performed. All legal guardians/legally designated representative should be fully informed, and participants should be informed to the fullest extent possible, about the study in language and terms they are able to understand. The investigator will retain the original copy of each participant's signed consent/assent document.
• Participants who successfully completed participation in Studies B7841005 or B7841008, defined as did not require “Early Termination” from Studies or B7841008, respectively.