Allergy and inhibitors in hemophilia - a rare complication with potential novel solutions

Abstract Introduction Hemophilia is a rare bleeding disorder caused by a deficiency of the plasma coagulation factors VIII and IX (hemophilia A [HA] and hemophilia B [HB], respectively). Replacement therapy with clotting factorconcentrates is the mainstay of treatment. Unlike in patients with HB, anaphylaxisin patients with HA is extremely rare. Methods A retrospective study of prospectively collected data on patients with hemophilia who experienced anaphylaxiswas conducted in our center. Demographic and clinical data were collected, and laboratory workups that included thrombin generation were conducted. Results Our first patient underwent successful immune toleranceinduction ( ITI) following the administration of rituximab. The second patient was transitioned to emicizumab. The third patient receives recombinant activated VIIa (rFVIIa) on demand. Thrombin generation was performed following current medical management protocols for supporting hemostasis. Discussion Our case series illustrates the difficulty in managing patients with anaphylaxisto replacement therapy. In the era of novel therapies, such as emicizumab, the management of HA patients who experience anaphylaxisto replacement therapy is becoming easier and may obviate the need for ITI. Current treatment strategies for HB patients with such anaphylaxis, however, are limited to rFVIIa, and it continues to pose a challenge.