A Study to Assess the Safety of Marstacimab and How Well it Works in People With Mild to Moderate Hemophilia A or B Without Inhibitors
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Official title
AN OPEN-LABEL STUDY TO EVALUATE THE EFFICACY AND SAFETY OF MARSTACIMAB PROPHYLAXIS IN ADOLESCENT AND ADULT PARTICIPANTS WITH MILD (FVIII OR FIX ACTIVITY >5% TO ≤15%) TO MODERATE (≥1% TO ≤5%) HEMOPHILIA A OR B WITHOUT INHIBITORS
Brief summary
Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.
This is an open-label, multicenter study evaluating the efficacy and safety of marstacimab prophylaxis in approximately 95 male and female adolescents and adults aged 12 to \<75 years with mild to moderate hemophilia A or B without inhibitors who have a severe bleeding phenotype. Eligible participants must have baseline factor VIII or factor IX activity levels \>1% to ≤15% and a history of clinically significant bleeding despite prior treatment with either on-demand factor replacement therapy or routine factor prophylaxis. The study will compare bleeding outcomes and other efficacy measures during a historical 12-month period of prescribed factor replacement therapy prior to study entry with outcomes observed during a 12-month treatment phase in which participants receive marstacimab 150 mg administered subcutaneously once weekly. Participants will be enrolled into 2 cohorts based on their treatment regimen before study entry: a prior on-demand treatment cohort and a prior routine prophylaxis treatment cohort. Female participants with severe hemophilia A or B without inhibitors may also be enrolled on a case-by-case basis. Data from these participants will contribute to safety assessments, and separate descriptive analyses of efficacy outcomes will be performed for all female participants. The study will also evaluate the long-term safety and efficacy of marstacimab during a long-term extension (LTE) treatment phase of up to 36 months. Participants who complete the 12-month treatment phase may continue into the LTE phase. Participants may be in the study for approximately 50 months, including a 12-month treatment phase and a long-term extension phase of up to 36 months.
Study identification
- NCT ID
- NCT07923981
- Recruitment status
- Recruiting
- Study type
- Interventional
- Phase
- Phase 3
- Enrollment
- 95 participants
Conditions and interventions
Conditions
Eligibility (public fields only)
- Age range
- 12 Years to 74 Years
- Sex
- All
- Healthy volunteers
- Healthy volunteers not accepted
This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.
Study timeline
- Start date
- Oct 23, 2026 (Estimated)
- Primary completion
- Jul 2, 2029 (Estimated)
- Completion
- Jun 16, 2032 (Estimated)
- Last update posted
- Nov 9, 2026
2026 – 2032
United States locations
- U.S. sites
- 1
- U.S. states
- 1
- U.S. cities
- 1
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| Southern Specialty Clinic | Flowood | Mississippi | 39232 | Recruiting |
Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT07923981, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
- What this page does not do
- No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
- Where the data comes from
- Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
- Last refresh
- Last update posted Nov 9, 2026 · Synced Nov 14, 2026
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