Management of Breakthrough Bleeding During Emicizumab Prophylaxis in Acquired Haemophilia A: Data From the GTH‐AHA‐EMI Study

INTRODUCTION: The GTH-AHA-EMI study showed that emicizumab reduces bleeding in patients with acquired haemophilia A (AHA). However, 22 clinically relevant new bleeds (CRNB) occurred in 14 of the 47 study patients, most of which required haemostatic treatment. AIM: To describe characteristics, treatment, and outcome of CRNB that occurred during the 12 weeks of haemostatic prophylaxis with emicizumab. METHODS: Data were extracted from the GTH-AHA-EMI study data base. Further information was collected retrospectively using a standardized questionnaire answered by study investigators. RESULTS: Of the 22 CRNB, 9 and 13 were classified as major and non-major, respectively. 15 bleeds occurred spontaneously, and 20 bleed required treatment. Recombinant factor VIIa was used for treatment in 16 of 20 treated bleeds, recombinant porcine factor VIII was used in three events. Eight patients were admitted to the hospital because of CRNB; extension of hospitalization was reported in 13 patients; 9 were admitted to an intensive care unit; invasive interventions were required in nine patients. Most bleeds were treated successfully; permanent harm from bleeding was reported in two patients. No thromboembolic events or other adverse events were reported. CONCLUSION: Although emicizumab reduces bleeding in AHA, breakthrough bleeding can still occur, was often severe and required haemostatic treatment. Haemostatic treatment was safe and usually effective. TRIAL REGISTRATION: NCT04188639.