Pfizer
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.
Inclusion Criteria * Male or female, 12 to less than 75 years of age and weighing at least 35 kg. * Moderate hemophilia A or B (factor VIII or factor IX activity ≥1% to ≤5%), or Mild hemophilia A or B (factor VIII or factor IX activity \>5% to ≤15%). * Females with severe hemophilia A or B may be eligible on a case-by-case basis following discussion with sponsor. * No history of factor VIII or factor IX inhibitors within the 5 years before screening. * At least 12 months of medical records and/or bleeding diary data documenting hemophilia-related bleeding episodes and factor VIII or factor IX…
* Participants with mild to moderate hemophilia will receive 150 mg subcutaneous (SC) injection once weekly. * Female participants with severe hemophilia will receive 300 mg SC loading dose followed by 150 mg SC once weekly. A dose of 300 mg administered SC once weekly may be prescribed for participants who meet the dose-escalation criteria.