NICE recommends Pfizer’s new once-weekly treatment for haemophilia B on NHS

21 May 2025 -- Surrey, UK -- Pfizer Ltd announced today that the National Institute for Health and Care Excellence (NICE) has published final draft guidance which recommends Hympavzi (marstacimab) as an option for preventing bleeding episodes in people 12 years of age and older, weighing at least 35 kg, with severe haemophilia B (congenital factor IX deficiency, factor 9 activity less than 1%), without factor 9 inhibitors (anti-factor antibodies).

Discovered and developed by Pfizer scientists, marstacimab is the first once-weekly subcutaneous treatment administered via a pre-filled pen for severe haemophilia B to be routinely available on the NHS. It targets the Kunitz 2 domain of tissue factor pathway inhibitor (TFPI), which is a protein that can prevent blood clot formation. By inhibiting TFPI, the medicine can help to restore the body’s ability to stop bleeding.

In the UK, there were more than 2,150 people living with haemophilia B in 2023/2024. Of these, over 380 had severe haemophilia. The condition is usually inherited and predominantly affects men, although women can also have haemophilia.

People with haemophilia lack certain proteins needed for blood clotting, meaning it can take longer than normal for bleeding to stop. They may also experience spontaneous bleeding in joints and muscles without having had an injury, which could lead to joint damage.

Conan McIlwrath, Chair of the Haemophilia Society said: “A subcutaneous treatment option for severe haemophilia B is a positive development which will open up some much-needed choice for people living with the condition. This may hopefully help people move towards more individualised treatment plans, based on what best supports the life they choose to live.”

Eleanor Shelley, Head of Specialty Care, Pfizer UK said: “We have remained committed to researching and developing new treatment options for people living with haemophilia and are pleased that eligible people with severe haemophilia B will now have access to this treatment on the NHS.”

The medicine will be available in England from the end of June via interim funding through the Innovative Medicines Fund (IMF), until it becomes routinely available on the NHS.

The medicine has not been recommended by NICE for the treatment of haemophilia A, however Pfizer remains committed to working to make it available in the future. It is also currently under consideration by the Scottish Medicines Consortium (SMC) for use on the NHS in Scotland.

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