Pfizer's Hympavzi (marstacimab) has received approval from the European Commission as the first once-weekly subcutaneous treatment for individuals with severe hemophilia B. This approval extends to adults and adolescents aged 12 and older who do not have inhibitors. Hympavzi distinguishes itself as the first in its class in Europe, offering a novel approach to managing this challenging condition. The drug's approval follows its recent green light in the United States.
Clinical Significance
According to Dr. Laurent Frenzel, a hemophilia specialist at the Necker-Enfants Malades Hospital in Paris, "There is a considerable treatment burden associated with the standard-of-care options for hemophilia A and B, including time-consuming preparation and administration of infusions and injections potentially causing missed doses and an increased risk of bleeding." Hympavzi addresses this burden by offering a convenient, once-weekly subcutaneous administration via a pre-filled pen, potentially improving patient adherence and quality of life.
BASIS Phase 3 Trial Results
The approval is supported by data from the Phase 3 BASIS study, which demonstrated a significant reduction in the annualized bleeding rate (ABR) with Hympavzi. Specifically, the study showed a 35% reduction in ABR for treated bleeds over a 12-month treatment period compared to routine injections of recombinant clotting factors. The most common side effects, affecting less than 3% of patients, included injection site reactions, headache, and itching.
Mechanism of Action and Dosing
Hympavzi functions as an anti-TFPI antibody. Notably, the drug can be administered as a flat dose, independent of the patient's weight, which simplifies the administration process.
Competitive Landscape
Hympavzi enters a competitive market that includes Roche's Hemlibra (emicizumab) for hemophilia A, which boasts less frequent dosing and approval for patients with and without inhibitors. Sanofi's Altuviiio (efanesoctocog alfa), a long-acting Factor VIII replacement therapy with once-weekly dosing, is another competitor. However, analysts suggest that Hympavzi's greatest opportunity lies in hemophilia B, where it offers a significant advancement over standard clotting factor replacement therapies that require multiple weekly administrations.
Novo Nordisk's concizumab, a similar TFPI inhibitor, faced rejection by the FDA due to manufacturing issues but has been launched in Canada, Japan, Australia, and Switzerland as Alhemo. It received a positive recommendation for EU approval from the EMA. Alhemo is indicated for hemophilia A and B patients with inhibitors, differentiating it from Hympavzi's current indication.
