Catalyst Biosciences is a step closer to challenging Novo Nordisk’s NovoSeven in the haemophilia A and B market after reporting positive results in a phase 2 trial.

The US biotech’s marzeptacog alfa (MarzAA) met the primary endpoint of significantly reducing the annualized bleeding rate (ABR) in patients with haemophilia A or B with inhibitors – antibodies that bind to clotting factor replacement therapies and stop them working properly – when given as a once-daily prevention therapy.

The new results were presented at the International Society on Thrombosis and Haemostasis (ISTH) congress in Melbourne over the weekend, and also showed that Catalyst’s drug met secondary endpoints of safety, tolerability and lack of inhibitor formation.

MarzAA can be dosed subcutaneously while NovoSeven (eptacog alfa) is administered by intravenous infusion so is used to treat rather than prevent bleeding episodes. Novo Nordisk’s drug is the top-selling haemophilia drug in its portfolio with sales of more than $1.1 billion last year.

The big rival for Catalyst is not only NovoSeven but also Roche’s rapidly-growing antibody therapy Hemlibra (eculizumab), which has been approved as a prophylactic treatment for haemophilia A, with and without inhibitors, and is already starting to eat into NovoSeven sales.

Haemophilia A is the most common form of the bleeding disorder, occurring in around five times as many patients as haemophilia B, although Catalyst says there are no preventive therapies for patients with haemophilia B with inhibitors or those with haemophilia A and inhibitors who fail Hemlibra therapy.

Catalyst says it has orphan designations for MarzAA in both the US and Europe, and is now moving forward with phase 3 study planning as well as exploring the use of MarzAA in additional indications.

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