Advances in inhibitor knowledge and treatment

Written by Jeff Courtney, March 29, 2022

Inhibitors are a complication of haemophilia treatment, in which the patient’s body begins to produce antibodies to their factor replacement treatment. Inhibitors occur most frequently in children with haemophilia A, usually within their first 50 treatment days, but can also occur later in life and less frequently in people with haemophilia B.  Inhibitors can also occur very rarely in other bleeding disorders such as VWD.

At this year’s EAHAD Virtual Congress, Dr Rolf Ljung from Lund University in Sweden, presented the latest data and most up to date knowledge on inhibitor development in Europe. The ongoing PedNet research has shown that around 30% of people with severe haemophilia develop an inhibitor with around two thirds of those having a high titre inhibitor. Their data has not shown any statistically significant difference in the incidence of inhibitor development between people treated with plasma-derived or recombinant products but certain genetic mutations carry a much higher risk.

Another study, the SIPPET study, agreed that the inhibitor risk was around 30% in severe haemophilia A but also showed a statistically significant higher risk of inhibitor development in people treated with recombinant factor products.

Inhibitors also occur in mild and moderate haemophilia A but are less likely. The level of risk will depend on the genetic mutation that the person with haemophilia has and the intensity of treatment but is around 13% on average within the first 100 treatment days.

The incidence of inhibitors in severe haemophilia B is now thought to be higher than previously understood and is around 10% with half of those having a high titre inhibitors. Inhibitors in mild and moderate haemophilia B and in previously treated patients remain rare.

Treatments for people with haemophilia A in the UK who develop an inhibitor are very good. An inhibitor can often be successfully treated through a process called ITI and bleeding in people with an ongoing inhibitor can be controlled with Emicizumab (Hemlibra). Treatment of inhibitors in haemophilia B remains more complex but treatment options are available.

If you want to read more about inhibitors and their treatment, or if you need more information for you or your child visit our inhibitor information page or get in touch on [email protected]

Article written by Jeff Courtney, Public Affairs Advisor at the Haemophilia Society.