Pronunciation: Him-PAV-zee
Generic name: marstacimab
Dosage form: single-dose prefilled syringe, single-dose prefilled pen (autoinjector)
Drug class: Miscellaneous coagulation modifiers

Medically reviewed by Carmen Pope, BPharm. Last updated on Oct 13, 2024.

Hympavzi (marstacimab-hncq) may be used to prevent or reduce the frequency of bleeding episodes in adults or children aged 12 years of age and older with hemophilia A or B without inhibitors. It is administered once weekly subcutaneously (SC) (under the skin) using the Hympavzi autoinjector pen or syringe.  

Hympavzi’s mechanism of action involves targeting the Kunitz 2 domain of tissue factor pathway inhibitor (TFPI), a natural anticoagulation protein that prevents the formation of blood clots. Hympavzi represents a new management option for hemophilia A and B, particularly for those who develop inhibitors to FVIII and FIX. Factor replacement therapies which replace missing clotting factors may still be required to manage breakthrough bleeding episodes.

Hympavzi gained FDA approval on October 11, 2024. Hympavzi is the first anti-TFPI to be approved in the U.S. for hemophilia A or B and the first to be administered SC via a pre-filled, auto-injector pen or syringe. Hympavzi belongs to the drug class tissue factor pathway inhibitor (TFPI) antagonists.

Hympavzi uses

Hympavzi is used for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adults and children aged 12 years of age and older with:

• hemophilia A (congenital factor VIII deficiency) without factor VIII inhibitors, or
• hemophilia B (congenital factor IX deficiency) without factor IX inhibitors.

Hympavzi side effects

The most common side effects of Hympavzi are

• injection site reactions, such as itching, redness, swelling, bruising, hardening, or pain at the site where you did the injection
• headache
• itching.

Serious side effects and warnings

Before you start using Hympavzi, talk to your healthcare provider about using factor VIII and factor IX products (products that help blood clot but work differently to Hympavzi) which may need to be used to treat episodes of breakthrough bleeding during treatment with Hympavzi. Carefully follow your healthcare provider’s instructions regarding when to use factor VIII or factor IX medicines and the prescribed dose during your treatment with Hympavzi.

Hympavzi may cause the following serious side effects.

Hympavzi may increase your risk for blood clots (thromboembolic events) in blood vessels of your arm, leg, lung, or head which may be life-threatening. Get medical help right away if you develop any of these signs or symptoms of blood clots:

• swelling or pain in arms or legs
• redness or discoloration in your arms or legs
• shortness of breath
• pain in the chest or upper back
• fast heart rate
• cough up blood
• feel faint
• headache
• numbness in your face
• eye pain or swelling
• trouble seeing.

Allergic reactions, including rash and itching, have happened in people treated with Hympavzi. Stop using Hympavzi and get medical help right away if you develop any of the following symptoms of a severe allergic reaction:

• swelling of your face, lips, mouth, or tongue
• trouble breathing
•  wheezing
• dizziness or fainting
• fast heartbeat or pounding in your chest
• sweating.

Hympavzi may harm an unborn baby. Pregnant women should not take Hympavzi and females with childbearing potential should use effective contraception during treatment with Hympavzi and for 2 months after the last dose.

It is not known if Hympavzi is safe and effective in children younger than 12 years old.

These are not all of the possible side effects of Hympavzi. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Related/similar drugs

Before using

Before using Hympavzi, tell your healthcare provider about all of your medical conditions, including if you:

• have a planned surgery. Your healthcare provider may stop Hympavzi before your surgery. Talk to your healthcare provider about when to stop using Hympavzi and when to start it again if you have a planned surgery
• have a severe short-term (acute) illness such as an infection or injury
• are pregnant or plan to become pregnant
• are breastfeeding or plan to breastfeed.

Pregnancy

Hympavzi may harm your unborn baby. For females who can become pregnant, your healthcare provider will do a pregnancy test before you start treatment with Hympavzi. You should use effective birth control (contraception) during treatment with Hympavzi and for 2 months after the last dose of Hympavzi.

Tell your healthcare provider right away if you become pregnant or think that you may be pregnant during treatment with Hympavzi.

Breastfeeding

It is not known if Hympavzi passes into your breast milk.

How should I use Hympavzi?

See the detailed “Instructions for Use” in the Hympavzi Package Insert for information on how to inject a dose of Hympavzi, and how to properly throw away (dispose of) a used Hympavzi prefilled syringe or Hympavzi prefilled pen (autoinjector)

• Use Hympavzi exactly as prescribed by your healthcare provider.
• Your healthcare provider will provide instructions for stopping (discontinuing) your current treatment when switching from factor- or non-factor-based medicines to Hympavzi. Follow these instructions closely.

Hympavzi is given as an injection under your skin (subcutaneous injection) by you or your caregiver.

• Your healthcare provider should show you or your caregiver how to inject Hympavzi before you inject yourself for the first time. Do not attempt to inject yourself or another person unless you have been taught how to do so by a healthcare provider.
• Choose an injection site on your stomach area (abdomen) or thigh unless a different site has been suggested by your healthcare provider. Hympavzi may also be injected into your upper arms by a healthcare provider or caregiver only. Keep at least 2 inches away from your belly button.
• Change (rotate) the injection site each time you give yourself an injection of Hympavzi and away from any other medicine given under your skin. You may use the same area of your body but be sure to choose a different injection site in that area.
• Clean the injection site with soap and water, or an alcohol swab.
• Allow the site to air dry. Do not touch, fan, or blow on the cleaned injection site.
• Do not inject Hympavzi into bony areas or areas on your skin that are bruised, red, sore (tender), or hard. Avoid injecting into areas with scars or stretch marks.
• Do not inject Hympavzi into a vein or through your clothes.

Inject Hympavzi 1 time a week on the same day each week. Inject Hympavzi at any time of day.

Your healthcare provider will provide information on the treatment of breakthrough bleeding during your treatment with Hympavzi. Do not use Hympavzi to treat breakthrough bleeding.

Hympavzi dosing

Your first dose (loading dose) of Hympavzi is 300 mg (two 150 mg injections). Then you will inject a weekly (maintenance) dose as prescribed by your healthcare provider.

The usual maintenance dose of Hympavzi is 150 mg every week by subcutaneous injection on the same day each week, at any time of day. Start one week after the loading dose.

• Your healthcare provider may consider a dose adjustment to 300 mg every week for certain people.

What happens if I miss a dose of Hympavzi?

If you miss a maintenance dose of 150 mg of Hympavzi, give the dose as soon as possible before the next scheduled dose, and then continue with your usual 150 mg weekly dosing schedule.

You may inject your next dose at your regularly scheduled time or continue dosing based on the new day you injected your missed dose. If you are not sure when to inject Hympavzi, call your healthcare provider.

If more than 13 days have passed since your last dose was given, call your healthcare provider right away for dosing instructions.

If you miss 1 or more doses of maintenance dose of 300 mg of Hympavzi:

• Give a dose as soon as possible, and then continue with your 300 mg weekly dosing schedule. You may inject your next dose at your regularly scheduled time or continue dosing based on the new day you injected your missed dose. In case you are not sure when to inject Hympavzi, call your healthcare provider.

What other drugs will affect Hympavzi?

Tell your healthcare provider about all the medicines you take, including prescription medicines, over-the-counter medicines, vitamins, and herbal supplements. Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.

Hympavzi storage

Store Hympavzi in a refrigerator at 36°F to 46°F (2°C to 8°C) in the original carton to protect it from light.

If needed, Hympavzi may be stored one time at room temperature up to 86°F (30°C) in its original carton for up to 7 days.

• Do not return Hympavzi to the refrigerator after storing it at room temperature.
• Throw away (dispose of) Hympavzi that has been left out of the refrigerator for more than 7 days.

Do not freeze or shake Hympavzi. Keep out of the reach of children.

Hympavzi ingredients

Active ingredient: marstacimab-hncq

Inactive ingredients: edetate disodium, histidine, L-histidine monohydrochloride, polysorbate 80, sucrose, and water for injection.

Hympavzi is available as Hympavzi 150 mg/mL in a single-dose prefilled syringe and Hympavzi 150 mg/mL in a single-dose prefilled pen (autoinjector).

Who makes Hympavzi?

Pfizer Inc. makes Hympavzi.

Hympavzi Biosimilars

Biosimilar and interchangeable products are biological products that are highly similar to and have no clinically meaningful differences from the reference product.

Reference products

These are biological products that have already been approved by the FDA, against which biosimilar products are compared. There is 1 for Hympavzi.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer