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

• Status: Recruiting
• Trial end date: 2030-07-31
• Target enrollment: 0
• Participant gender: Male

Summary

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. 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 this study during which they will receive prophylaxis (defined as treatment by SC injection of marstacimab). The dosing regimen of marstacimab is 150 mg SC once weekly.

All participants will be provided the PFP for administration of marstacimab in the study. Use of the PFS will be permitted at the investigator's discretion for those participants who have difficulty with administration of the PFP. Additionally, participants will be provided the PFS for use in this study in countries where the PFS is anticipated to be the only presentation available commercially. In addition, an optional, open-label, single arm, substudy using the PFP will be administered to the first approximately 20 participants rolling over from Study B7841005 who agree to participate in the substudy.

• Phase: Phase 3
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Pfizer

Criteria

Inclusion Criteria:

• All participants will have a minimum body weight of 35 kg

• Participants have successfully completed participation in study B7841005, defined as did not require "Early Termination" from study B7841005

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 Investigator clinical assessment and review of participant's most recent laboratory results, to include recent locally available CD4 count (if available), which would make the participant inappropriate for the study

• Regular, concomitant therapy with immunomodulatory drugs (eg, IVIG, and routine systemic corticosteroids, rituximab)

• Ongoing or planned use of immune tolerance induction or prophylaxis with FVIII or FIX replacement during the study

• Participation in other study involving investigational drug(s) or investigational vaccine(s) within 30 days or 5 half-lives prior to or during study participation, with the exception of participation in study B7841005

• 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