Marstacimab

Marstacimab – Description

• Marstacimab is an anti-tissue pathway factor inhibitor indicated for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in individuals 12 years and older with hemophilia A without factor VIII inhibitors or hemophilia B without factor IX inhibitors.
• Factor VIII and factor IX products can be administered for the treatment of breakthrough bleeding in individuals receiving marstacimab.
• Marstacimab may increase the risk of thromboembolic events.
• Marstacimab was FDA-approved in October 2024.

Indications & Dosage

•  bleeding prophylaxis
•  hemophilia A
•  hemophilia B

NOTE: Marstacimab is designated as an orphan drug by the FDA for this indication.

Subcutaneous dosage

Adults weighing 50 kg or more:

300 mg subcutaneously as a single dose, then 150 mg subcutaneously once weekly starting 1 week after the loading dose. Consider increasing the dose to 300 mg subcutaneously once weekly when control of bleeding events is determined to be inadequate.⁷¹⁴⁰⁶

Adults weighing less than 50 kg:

300 mg subcutaneously as a single dose, then 150 mg subcutaneously once weekly starting 1 week after the loading dose.⁷¹⁴⁰⁶

Children and Adolescents 12 to 17 years weighing 50 kg or more:

300 mg subcutaneously as a single dose, then 150 mg subcutaneously once weekly starting 1 week after the loading dose. Consider increasing the dose to 300 mg subcutaneously once weekly when control of bleeding events is determined to be inadequate.⁷¹⁴⁰⁶

Children and Adolescents 12 to 17 years weighing less than 50 kg:

300 mg subcutaneously as a single dose, then 150 mg subcutaneously once weekly starting 1 week after the loading dose.⁷¹⁴⁰⁶

Maximum Dosage Limits:

•Adults

Weighing 50 kg or more: 300 mg/week subcutaneously.

Weighing less than 50 kg: 300 mg loading dose and 150 mg/week subcutaneously.

•Geriatric

Weighing 50 kg or more: 300 mg/week subcutaneously.

Weighing less than 50 kg: 300 mg loading dose and 150 mg/week subcutaneously.

•Adolescents

Weighing 50 kg or more: 300 mg/week subcutaneously.

Weighing less than 50 kg: 300 mg loading dose and 150 mg/week subcutaneously.

•Children

12 years weighing 50 kg or more: 300 mg/week subcutaneously.

12 years weighing less than 50 kg: 300 mg loading dose and 150 mg/week subcutaneously.

1 to 11 years: Safety and efficacy have not been established.

•Infants

Safety and efficacy have not been established.

•Neonates

Safety and efficacy have not been established.

Patients with Hepatic Impairment Dosing

Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.

Patients with Renal Impairment Dosing

Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.

Precautions

•  breast-feeding
•  people who may become pregnant
•  planned procedure
•  pregnancy
•  reproductive risk
•  sepsis
•  trauma

Pregnancy

Based on its mechanism of action, marstacimab may cause fetal harm when administered during pregnancy. There are no available data on marstacimab use during pregnancy to evaluate for a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. Female animal reproduction studies have not been conducted with marstacimab. Although there are no data on marstacimab, monoclonal antibodies can be actively transported across the placenta and marstacimab may cause fetal harm.⁷¹⁴⁰⁶

Lactation

Use marstacimab with caution during breast-feeding. There are no data on the presence of marstacimab in human milk, its effects on the breast-fed child, or its effects on milk production. Consider the benefits of breast-feeding, the patient’s clinical need for treatment, and any potential adverse effects on the breast-fed child from the medication or from the underlying maternal medical condition. Endogenous maternal immunoglobulin G (IgG) and monoclonal antibodies are known to be present in human milk. The effects of local gastrointestinal exposure and limited systemic exposure in the breast-fed child to marstacimab are unknown.⁷¹⁴⁰⁶

Interactions

There are no drug interactions associated with Marstacimab products.

Adverse Reactions

•  antibody formation
•  headache
•  injection site reaction
•  pruritus
•  thromboembolism
•  urticaria

Monitoring Parameters

•  clotting inhibitor titers

Classifications

• Blood and Blood Forming Organs
  • Antihemorrhagics
    • Hemostatics
      • Monoclonal Antibodies for Bleeding Disorders
        •  Monoclonal Antibodies Targeting Tissue Factor Pathway Inhibitor (TFPI)

References

71406.Hympavzi (marstacimab-hncq) injection package insert. New York, NY: Pfizer Inc.; 2024 Oct.