Global pharma powerhouse Pfizer has won a major European approval for its hemophilia drug HYMPAVZI, opening the door for a new group of hard-to-treat patients who have run out of reliable treatment options.

 

The European Commission has approved HYMPAVZI (marstacimab) for adults and adolescents aged 12 and older with hemophilia A or B who have developed inhibitors — dangerous antibodies that can neutralize standard clotting-factor therapies and leave patients vulnerable to uncontrolled bleeding.

 

The decision marks a significant expansion for Pfizer’s once-weekly injectable therapy, which the company says is now the only subcutaneous treatment approved in the EU for both hemophilia A and B patients, with or without inhibitors.

 

For patients battling inhibitors, the stakes are high. Roughly 20% of people with hemophilia A and 3% with hemophilia B develop these antibodies, often rendering traditional replacement therapies ineffective and sharply increasing the risk of severe bleeding episodes, joint damage and hospitalization.

 

“Inhibitors present a substantial challenge for people living with hemophilia as they neutralize traditional factor replacement therapies, in turn limiting treatment options and leaving patients vulnerable to uncontrolled bleeding episodes,” said Laurent Frenzel, Head of the Hemophilia Treatment and Research Center at the Necker-Enfants malades Hospital (Paris Cité). 

 

“The approval of HYMPAVZI offers adults and adolescents in the EU a once-weekly subcutaneous option that has demonstrated the ability to reduce bleeding episodes and maintain bleed reduction based on observation to date in a long-term extension study.”

 

Pfizer said the approval was driven by late-stage clinical trial data showing HYMPAVZI slashed treated bleeding rates by 93% compared with on-demand therapies. Patients in the study recorded an average annualized bleeding rate of 1.39, down from nearly 20 bleeds per year under standard treatment.

 

The company also said the benefit held up over time, with patients maintaining low bleeding rates after as long as 53 months on the therapy in an ongoing extension study.

 

“For people living with hemophilia with inhibitors, recurring bleeding episodes can lead to damaged joints and introduce real limitations and disruptions to everyday life,” said Alexandre de Germay, Chief International Commercial Officer and Executive Vice President, Pfizer. 

 

“This approval brings a once-weekly medicine to the EU that meets a critical need for patients who face a treatment journey that can be complex and challenging with limited options available today, representing the latest step in Pfizer’s more than 40-year commitment to advancing care for people living with hemophilia. We look forward to working with regulators globally to continue bringing HYMPAVZI to those who can benefit from it.”

 

HYMPAVZI works differently from traditional clotting-factor replacement drugs. Instead of replacing missing clotting factors, the therapy targets tissue factor pathway inhibitor (TFPI), a natural protein that slows blood clotting. 

 

Pfizer says the approach is designed to restore balance between bleeding and clot formation while reducing the burden of frequent intravenous infusions.

 

Despite the breakthrough, safety concerns remain under close watch. Pfizer said the most serious adverse event linked to HYMPAVZI in clinical trials was thrombosis, or dangerous blood clots. Common side effects included injection-site reactions, headache, itching, hypertension and rash.