NICE Recommends First Subcutaneous Option for Haemophilia B

The National Institute for Health and Care Excellence (NICE) has recommended marstacimab (Hympavzi, Pfizer) for treating severe haemophilia B.

The treatment is advised for patients aged 12 years and over who weigh at least 35 kg and do not have factor IX inhibitors. 

It is the first subcutaneous injection for this condition.

The treatment was approved by the Medicines and Healthcare products Regulatory Agency last month.

How Marstacimab Works

Marstacimab is administered weekly.

It works by targeting tissue factor pathway inhibitor (TFPI), a protein that prevents blood from clotting. By reducing TFPI levels, marstacimab promotes the formation of thrombin, helping to increase clotting and stop bleeding. 

About 255 people in England live with severe haemophilia B, defined by a factor IX activity level below 1%.

NICE estimates that around 205 patients will be eligible for marstacimab.

People with haemophilia B currently receive factor IX replacement therapy by infusion, sometimes every 2-3 days. Gene therapy is also available, following approval by NICE last year.

The final draft guidance is based on results from the BASIS study, a phase 3 trial that evaluated marstacimab in 116 adults and adolescents aged 12 years and older with severe haemophilia A or B without inhibitors. 

Marstacimab significantly reduced the annualised bleeding rate for treated bleeds during the 12-month active treatment period. It demonstrated both noninferiority and statistical superiority compared with routine factor-based prophylaxis.

Not Recommended for Haemophilia A

While marstacimab can also treat haemophilia A, NICE found it was not cost-effective for this group. It is therefore not recommended for NHS use in these patients.

Current treatment options for haemophilia A include factor VIII, emicizumab, and efanesoctocog alfa. 

“Marstacimab’s clinical and cost-effectiveness compared with current treatment, together with its once-weekly dosing by injection under the skin, means it has the potential to significantly improve the quality of life of people with severe haemophilia B,” said Helen Knight, director of medicines evaluation at NICE.

Conan McIlwrath, chair of the Haemophilia Society, welcomed the move. “This will hopefully help people move towards more individualised treatment plans, based on what best supports the life they choose to live,” he said.

Once the final NICE guideline is published, marstacimab could be available to eligible patients as early as this autumn. 

Dr Rob Hicks is a retired NHS doctor. A well-known TV and radio broadcaster, he has written several books and has regularly contributed to national newspapers, magazines, and online. He is based in the UK.