Pfizer rounds out haemophilia portfolio with FDA approval

Pfizer’s anti-TFPI antibody marstacimab has been approved by the FDA to treat haemophilia, becoming the pharma group’s second new therapy for the blood disorder this year.

Marstacimab will be launched as Hympavzi to treat haemophilia A without factor VIII inhibitors and haemophilia B without factor IX inhibitors in patients aged 12 and older and is the first drug in the anti-TFPI class to be approved in the US.

The once-weekly injectable joins one-shot haemophilia B gene therapy Beqvez (fidanacogene elaparvovec) in Pfizer’s portfolio, which was approved by the FDA in April, as well as its range of recombinant clotting factor replacement products.

Hympavzi is the first once-weekly subcutaneous treatment for people living with haemophilia B administered using a pen-injector and the first treatment administered as a flat dose – i.e., not determined by weight, which simplifies administration – for people living with either haemophilia A or B.

The new drug “aims to reduce the current treatment burden by meeting an important need for these patients, including many who have required frequent, time-consuming intravenous treatment infusion regimens,” remarked bleeding disorder specialist Suchitra Acharya, of Cohen Children’s Medical Center in New York.

It will compete in haemophilia A with Roche’s hugely successful Hemlibra (emicizumab), which has less frequent dosing, is approved for patients with and without inhibitors, and is approaching $5 billion in annual sales. Another rival is Sanofi’s long-acting FVIII replacement therapy Altuviiio (efanesoctocog alfa), which also offers once-weekly dosing.

Haemophilia B is likely to be the greatest opportunity for Hympavzi, as it will offer an advance over standard clotting factor replacement therapies, which have to be administered multiple times a week.

In the BASIS trial that underpinned the FDA approval, Pfizer’s antibody achieved a 35% reduction in patients’ annualised bleeding rate (ABR) compared to standard prophylaxis and a 92% reduction in ABR compared to on-demand treatment in haemophilia A and B patients with inhibitors.

Hympavzi has been given a list price of $795,600 per year before discounts and rebates, which Pfizer said was in line with other prophylactic treatments for haemophilia A or B currently available on the US market. The drug, which will launch later this quarter, has also been recommended for approval in the EU.

Its closest rival in the anti-TFPI class, Novo Nordisk’s concizumab, was turned down by the FDA last year due to manufacturing issues, but has been launched in Canada and some other markets, including Australia, as Alhemo. It requires once-daily dosing, however, which could put it at a competitive disadvantage to Pfizer’s drug.