Pfizer has announced results from its phase 3 BASIS study of Hympavzi (marstacimab), demonstrating its success in reducing bleeds in adults and adolescents living with haemophilia A or B with inhibitors.
Over 800,000 people worldwide live with haemophilia; of these, around 20% of people with haemophilia A and 3% of people with haemophilia B are unable to take factor replacement therapies due to developing inhibitors, or antibodies, that neutralise these therapies.
The BASIS study evaluated 48 adults and adolescents living with haemophilia A or B. Following a six-month observational period when they received on-demand (OD) intravenous treatments, the patients received HYMPAVZI once-weekly over a 12-month period.
The study found a 93% reduction in mean treated annualised bleeding rate (ABR) in patients treated with Hympavzi, demonstrating that it is more effective than OD treatment. This superiority was also demonstrated across secondary endpoints such as spontaneous bleeds, joint bleeds and total treated and untreated bleeds.
Hympavzi was generally well tolerated, and few serious adverse events were reported, with no deaths or thromboembolic events associated with treatment. One patient reported a serious skin rash emergent from treatment with HYMPAVZI, which led to study discontinuation and was resolved.
“In patients with inhibitors, this study demonstrates Hympavzis potential as a safe and efficacious treatment option that not only significantly reduced bleeding episodes via a once-weekly subcutaneous administration, but also demonstrated improvement in certain aspects of health-related quality of life,” said Davide Matino, BASIS principal investigator and associate professor of medicine at McMaster University.
Michael Vincent, chief inflammation and immunology officer at Pfizer, said: “It is encouraging that this data demonstrates the potential of Hympavzi to combine efficacy, safety and straightforward administration for adults and adolescents living with haemophilia A or B with inhibitors and address a significant patient need.”
The drug is already approved in more than 40 countries worldwide for the treatment of patients 12 years and older with haemophilia A without factor VIII inhibitors, or haemophilia B without factor IX inhibitors.