Successful treatment by switching from activated prothrombin complex concentrate to emicizumab therapy in a hemophilia A patient with inhibitors

Abstract

A 7-month-old male infant with severe hemophilia A who received on-demand therapy with recombinant factor VIII (rFVIII) vomited because of acute intracranial bleeding. With rFVIII treatment for suppressing bleeding, there was development of high-titer (≤673 BU/ml) inhibitors. The patient was administered bypassing agents followed by immune tolerance induction therapy (ITI) with 50 U/kg of FVIII thrice weekly. In addition, he was treated with weekly and thrice weekly prophylaxis with 50 U/kg of activated prothrombin complex concentrate (aPCC). Despite ITI and aPCC prophylaxis treatments, it was difficult to control the hemorrhage, and the annualized bleeding ratio (ABR) remained high (5-13 bleeding episodes per year). We started emicizumab 2 weeks after completing the administration of aPCC. Weekly subdermal injections of 1.5 mg/kg emicizumab after loading dramatically decreased ABR (one bleeding episode per year), although biweekly injections of 3 mg/kg emicizumab for several months were associated with one joint hemorrhage. Compared to regular aPCC administration, our observations suggest that weekly emicizumab treatments can improve the ABR in a hemophilia patient with inhibitors and improve the quality of life of patient without limitations in terms of school events.