Marstacimab at a glance
Medicine class
Human monoclonal antibody and anti-TFPI haemostatic treatment
Licensed role
Routine prevention of bleeding in severe haemophilia A or B without factor inhibitors
Who it is licensed for
People aged 12 years or older who weigh at least 35 kg and meet the haemophilia criteria
Administration
Injection under the skin using a pre-filled pen; self-injection is possible after training and approval by the haemophilia team
Breakthrough bleeding
Do not use extra marstacimab for an active bleed; follow the factor-treatment plan agreed with the haemophilia team
What is Marstacimab used for?
Marstacimab is licensed for routine prevention of bleeding episodes in:
Severe congenital haemophilia A without factor VIII inhibitors, in people aged 12 years or older weighing at least 35 kg.
Severe congenital haemophilia B without factor IX inhibitors, in people aged 12 years or older weighing at least 35 kg.
How does Marstacimab work?
TFPI normally restrains the pathway that generates factor Xa and thrombin. Marstacimab binds to TFPI, increasing thrombin generation and supporting clot formation despite deficient factor VIII or IX.
Marstacimab preparations and strengths
Injection
Route: Parenteral
Strengths: 150 mg
How to take Marstacimab
Use the pre-filled pen exactly as demonstrated by the haemophilia team and follow its instructions for use.
Inject under the skin only; do not inject into a vein or muscle.
Suitable areas include the abdomen or thigh. A caregiver or healthcare professional may use the buttock.
Rotate sites and avoid bruised, red, tender, hard, scarred or stretched skin.
Allow the pen to reach room temperature in its carton away from sunlight; do not use a heat source.
Do not shake. Check that the solution is clear and colourless to light yellow, without flakes or particles.
Use each pen once and place it in an approved sharps container.
Marstacimab side effects
Common or expected effects
- Injection-site reactions such as pain, redness, swelling, itching, bruising or hardening
- Headache
- High blood pressure
- Itching
Get urgent medical advice
- Blood clots
- Severe allergic reaction, including facial or throat swelling or difficulty breathing or swallowing
- Severe or widespread rash
Marstacimab in pregnancy
There are no clinical studies during pregnancy, and potential fetal effects are unknown. Use requires specialist assessment of maternal benefit and fetal risk, including the increased thrombosis risk during and after pregnancy. Effective contraception is advised during treatment and for at least one month after the final injection.
Marstacimab while breastfeeding
It is unknown whether marstacimab enters human milk. A risk to the infant cannot be excluded during the first days after birth; afterwards, use is allowed if clinically needed. Discuss the benefits and risks with the haemophilia and maternity or infant-care teams.
Marstacimab interactions
Formal interaction studies have not been conducted. Conventional metabolic interactions are considered unlikely because marstacimab is cleared mainly through protein catabolism.
Factor VIII or factor IX concentrates
These may be needed for breakthrough bleeding according to the individual haemophilia-team plan; do not substitute extra marstacimab.
Bypassing agents and other haemostatic treatments
Close exposure to additional haemostatic agents has been linked to thrombosis with other anti-TFPI products, so specialist coordination is required.
Other medicines injected under the skin
Use a different anatomical injection site where possible.
Common questions about Marstacimab
Answers are fully visible for fast scanning and source review.
What is marstacimab used for?
It prevents or reduces bleeding in eligible people with severe haemophilia A or B without inhibitors against factor VIII or IX.
Is marstacimab a clotting-factor replacement?
No. It blocks TFPI to increase thrombin generation rather than replacing factor VIII or IX.
Can marstacimab treat a breakthrough bleed?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.