Pfizer Inc. recently announced that the U.S. Food and Drug Administration (FDA) has accepted a Biologics License Application (BLA) for marstacimab, its 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 of prophylactic therapy, which is administered subcutaneously once per week, would allow treaters to forgo the regular need for traditional factor replacement.

The BLA submission is supported by positive safety and efficacy data from an ongoing global phase 3 clinical trial known as BASIS. Investigators are looking at annual bleed rate (ABR) through 12 months of treatment with marstacimab in approximately 145 adolescent and adult participants between ages 12 to 75 years with severe hemophilia A or B, with or without inhibitors.

BASIS data reported by Pfizer in late May, included 116 participants who had been treated with marstacimab during a 12-month period versus a prophylaxis and on-demand intravenous regimen with FVIII or FIX replacement therapy administered as part of routine care in a six-month lead-in period. In the group of patients treated with on-demand factor replacement intravenous therapy in the lead-in period, marstacimab demonstrated superiority with a 92% reduction in bleeds. The results also showed superiority  with marstacimab compared to prophylaxis, with a 35% reduction in ABR

The Pfizer updates were presented during the 65th American Society of Hematology (ASH) Annual Meeting and Exposition, which was held December 8-12, in San Diego, CA. The therapy is also being reviewed by the European Medicines Agency (EMA).

“Marstacimab has demonstrated that it may be an efficacious treatment option with once-weekly, subcutaneous flat-dose administration via an auto-injector pen, for appropriate patients, if approved. This is critical as intravenous infusions are typically required for people living with these diseases today,” said James Rusnak, MD, PhD, Senior Vice President, Chief Development Officer, Internal Medicine and Infectious Diseases, Research and Development, Pfizer. “We look forward to progressing the review of this novel therapy with the FDA, EMA, and global regulatory authorities to bring this important medicine to patients globally.”

Source: Pfizer press release dated December 11, 2023