Pfizer has secured an expanded indication approval from the US Food and Drug Administration (FDA) for Hympavzi (marstacimab-hncq), broadening its use in the treatment of haemophilia A or B. The updated approval extends coverage to patients aged 12 years and older who have inhibitors, and also to children between six and 11 years of age, both with and without inhibitors.
With this development, Hympavzi now stands approved in the United States for routine prophylaxis aimed at preventing or reducing bleeding episodes in adults and children aged six years and above who have congenital factor VIII or IX deficiency, regardless of whether inhibitors are present. The therapy is administered as a once-weekly subcutaneous injection and does not require ongoing treatment-related laboratory monitoring, a feature that sets it apart from many existing treatment protocols.
The Hympavzi haemophilia approval in adults and adolescents with inhibitors was backed by results from the Phase III BASIS trial, which reported a 93% reduction in mean treated annualised bleeding rate when compared to on-demand intravenous agents. Supporting data for the younger paediatric population came from interim results of the Phase III BASIS KIDS trial, conducted in children aged six to 17 years, which demonstrated improved bleeding outcomes versus historical controls.
Haemophilia, a condition that commonly manifests in early childhood, is defined by impaired blood clotting, which elevates the risk of painful bleeding episodes — particularly in the joints — and can result in joint damage and long-term scarring.
Reported adverse reactions from clinical studies included injection site reactions, headache, fever, joint pain, diarrhoea, itching, and rash. Two thromboembolic events were observed among 259 patients participating in an open-label extension. The US prescribing label carries warnings regarding thromboembolic events, hypersensitivity, embryofetal toxicity, and laboratory anomalies in its Warnings and Precautions section.
Hympavzi’s application was granted FDA priority review and received breakthrough therapy designation specifically for younger paediatric patients with haemophilia B, which helped expedite the overall review process.
Aamir Malik, Chief Commercial Officer and Executive Vice President of Pfizer’s US commercial division, commented on the development: “With this expanded approval, we believe Hympavzi can become a transformative option and meet a significant medical need for people living with haemophilia A or B with or without inhibitors aged six years and older. Particularly for children ages six to 11 with haemophilia B who will now, for the first time, have a subcutaneous non-factor treatment available.”
Malik further added: “This milestone represents the latest step in Pfizer’s more than 40-year commitment to advancing care and quality of life for people living with haemophilia, which began with the introduction of recombinant therapies and has evolved with the introduction of this once-weekly subcutaneous treatment.”
The expanded FDA approval marks a continuation of Pfizer’s longstanding efforts in haemophilia care, bringing marstacimab-hncq — marketed as Hympavzi — to a wider patient population that previously had limited subcutaneous treatment options available.
