Inhibitors

Inhibitory antibodies are a serious complication of the treatment of haemophilia

Treating haemophilia A patients with FVIII concentrates has long been known to carry the risk of inducing an immune response against the perceived foreign protein FVIII. The development of antibodies with neutralising properties, known as FVIII inhibitors, is considered to be a serious complication of repeated FVIII administration in patients with haemophilia A. These inhibitors remain a challenging problem since they may preclude the use of FVIII concentrates as replacement therapy. Bleeding episodes are difficult to treat and must usually be managed with Factor VIII bypassing agents (such as activated prothrombin complex concentrates or recombinant FVIIa).

Despite the identification of some factors that may predispose a person with haemophilia A to inhibitor formation, it is not currently possible to prospectively identify patients who will form inhibitors.  

What factors influence the risk of inhibitor development?

Some haemophilia patients have a greater risk than others of inhibitor development following treatment with FVIII replacement:

  • Patients with FVIII mutations such as Intron 22 inversion or large deletions 1
  • Patients of African descent 8
  • Patients with severe haemophilia 9
  • Patients under the age of five years 9
  • Patients with a family history of inhibitors 1
  • The majority of patients who develop inhibitors do so early - within the first 10-20 exposure days 10

How common is inhibitor formation?

Studies have shown that:

  • Incidences of inhibitors in severe, previously untreated patients (PUPs) range from 15% to 52% (in non-comparative data) 1,9

PTPs - Inhibitor incidences from prospective studies of previously treated patients (PTPs) with haemophilia APUPs - KOGENATE® Bayer – the evidence on inhibitor formation

KOGENATE® Bayer

KOGENATE® Bayer inhibitor formation in PUPs is the lowest published rate. No comparative studies exist

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References

1. Kreuz W et al Thromb Haemost 2005;93:457-467
8. Viel K et al N Engl J Med 2009;360:1618-1627
9. Ehrenforth S et al Lancet 1992;339:594-598
10. World Federation of Hemophilia, Guidelines for the Management of Hemophilia, 2005

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Date of preparation: December 2010 UK.PH.HN.KOG.2010.250.17.4