MHRA approves Pfizer's Hympavzi for haemophilia A and B treatment

Pfizer has achieved a significant milestone with the approval of its new drug Hympavzi (marstacimab) by the UK Medicines and Healthcare products Regulatory Agency (MHRA). This medication is designed to treat haemophilia A or B in both adult and pediatric patients. Specifically, it has been authorized to prevent or reduce bleeding episodes in individuals aged 12 years and older, who weigh at least 35 kilograms and suffer from severe haemophilia A without factor VIII inhibitors or severe haemophilia B without factor IX inhibitors.

In the UK, as of 2023/2024, more than 11,800 people are affected by haemophilia A or B, with approximately 2,700 individuals dealing with a severe form of the disorder. Haemophilia is a genetic blood condition that primarily affects males, stemming from a deficiency in clotting factors. Patients with haemophilia not only face excessive and prolonged bleeding episodes but can also experience spontaneous bleeding in their joints and muscles without incurring any injury. This can potentially lead to joint damage over time.

Hympavzi is administered as a once-weekly subcutaneous injection using a pre-filled pen. The drug functions by reducing the levels of tissue factor pathway inhibitor (TFPI), a naturally occurring protein that normally restrains excessive blood clotting. By lowering TFPI, Hympavzi facilitates the generation of thrombin, an enzyme that plays a crucial role in the blood clotting process.

The MHRA's approval of Hympavzi was based on findings from the late-stage BASIS trial. During this study, participants receiving routine factor-based prophylaxis had an annualized bleeding rate of 7.85 treated bleeds over a six-month observation period. In comparison, those on Hympavzi prophylaxis experienced a reduced rate of 5.08 treated bleeds over a 12-month active treatment period.

Seema Patel, the medical director of specialty care at Pfizer UK, emphasized the significance of this approval, stating it marks an important advancement in providing eligible patients with a novel treatment option. Currently, Hympavzi is under evaluation by the National Institute for Health and Care Excellence as well as the Scottish Medicines Consortium for potential inclusion in the NHS.

Patel expressed Pfizer's commitment to collaborating with reimbursement agencies across the UK with the goal of ensuring that Hympavzi becomes available through the NHS. Haemophilia represents a key therapeutic focus for Pfizer, and the company has established a robust presence in this area. In July of the previous year, Pfizer's haemophilia B gene therapy received conditional marketing authorization from the European Commission for treating adults with severe and moderately severe cases of the disease.

Moreover, during the same month, Pfizer announced encouraging top-line results from a late-stage study of its investigational haemophilia A gene therapy, giroctocogene fitelparvovec. This therapy is being co-developed with Sangamo Therapeutics under a collaborative agreement, reflecting Pfizer's ongoing commitment to advancing treatments for haemophilia and improving patient outcomes in this field.