Pfizer Announces First Participant Dosed Phase 3 Study of Marstacimab

Note: Marstacimab is a laboratory-engineered monoclonal antibody developed to treat hemophilia A and B patients, with or without inhibitors.

Pfizer recently announced that the first participant has been dosed in the phase 3 BASIS study of marstacimab, the company’s investigational hemophilia therapy that targets an anticoagulant protein known as tissue factor pathway inhibitor (TFPI).

Marstacimab is a laboratory-engineered monoclonal antibody developed to treat hemophilia A and B patients, with or without inhibitors. It works by blocking and effectively preventing TFPI from performing the anticoagulant function that it naturally carries out in the human body. This type therapy allows treaters to forgo the need for traditional factor replacement.

BASIS is a global study designed to evaluate annualized bleed rate through one year of treatment with marstacimab, via subcutaneous administration, in approximately 145 adolescent and adult participants between ages 12 to 75 years with severe hemophilia A or B, with or without inhibitors.

Investigators will compare the investigational therapy with a six month “run-in” observational period during which patients’ were prescribed factor replacement or bypass products. The subsequent active period of the study will encompass one year of prophylactic therapy with marstacimab. According to a Pfizer press release, the primary endpoint is its impact on annualized bleed rate, while incidence and severity of thrombotic events will also be examined.

“Our approach to hemophilia research includes the investigation of multiple mechanisms to help address the needs of all people with hemophilia, including those with hemophilia A or B, and with or without inhibitors, and targeting TFPI provides a novel approach to improve blood coagulation,” said Brenda Cooperstone, Chief Development Officer, Rare Disease, Pfizer Global Product Development. “Based on the Phase 2 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.”

Source: Pfizer press release dated November 23, 2020