Pfizer has dosed the first participant in the Phase III BASIS study of the investigational therapy, marstacimab (PF-06741086), for treating people with severe haemophilia A or B, with or without inhibitors.

Marstacimab is a novel anti-tissue factor pathway inhibitor (anti-TFPI).

It secured fast track status from the US Food and Drug Administration (FDA) for use in combination with inhibitors as a potential treatment for haemophilia A and B.

A rare genetic haematological disease, haemophilia results in a deficiency of a protein needed for normal blood clotting, clotting factor VIII in haemophilia A and clotting factor IX in haemophilia B.

The global, open-label, multi-centre study will be conducted on about 145 adolescent and adult participants aged 12 and over.

It will analyse annualised bleed rate (ABR) for 12 months on prophylaxis treatment with the subcutaneous therapy option, marstacimab, versus run-in period on replacement therapy with FVIII or FIX clotting factor, respectively, or bypass therapy.

The study’s primary endpoint will be the impact on ABR through 12 months following prophylaxis treatment with marstacimab.

In addition, the incidence and severity of thrombotic events will be assessed.

According to the completed Phase II study results, treatment with marstacimab showed significant reductions in ABR for all participants in the study population.

Pfizer Global Product Development Rare Disease chief development officer Brenda Cooperstone said: “Our approach to haemophilia research includes the investigation of multiple mechanisms to help address the needs of all people with haemophilia, including those with haemophilia A or B, and with or without inhibitors, and targeting TFPI provides a novel approach to improve blood coagulation.

“Based on the Phase II study findings to date, marstacimab may have the potential to offer improved bleed control via subcutaneous injection and potentially eliminate the need for prophylactic factor replacement, providing an enhanced treatment option compared to factor replacement therapy.”