Background: Emicizumab is a recombinant, humanized, bispecific monoclonal antibody that bridges factor (F)IXa and FX to restore the function of missing activity FVIII to promote hemostasis in patients with hemophilia A (PHA). Clinical trials have shown the efficacy and safety of emicizumab in PHA with and without inhibitors, however, real-world data on the hemostatic efficacy, especially in a racially diverse, pediatric population is lacking.

Aims: To report real-world data of efficacy and safety in a diverse pediatric population with hemophilia A on emicizumab prophylaxis by retrospective chart review.

Methods: We reviewed medical records of PHA receiving emicizumab prophylaxis at The Bleeding Disorders and Thrombosis Program at the University of Texas Southwestern, Dallas and collected demographic and clinical information.

Results: We identified 30 patients with severe hemophilia A on emicizumab prophylaxis with a median age of 11.2 (range: 1-17) years without inhibitor (54%), and 47% with inhibitor. Fifty percent were Caucasians; the rest included Hispanics (26.7%), Blacks (13.3%) and Asian (10%). All patients received 4 weekly induction doses of emicizumab (3 mg/kg) followed by weekly maintenance dosing (1.5 mg/kg) in 22 patients and biweekly dosing (3 mg/kg) in 8 patients. Eight (26.7%) patients, whom 50% were Caucasians experienced bleeding while on emicizumab prophylaxis. Five (16.7%), whom four (80%) had history of inhibitor, experienced a breakthrough bleed while on emicizumab prophylaxis. Three (60%) were joint bleeds, one was an iliopsoas bleed, and one was a soft tissue bleed. All were on weekly maintenance dose except one on biweekly dosing. Four underwent surgical procedure, all with a history of inhibitor. Three (60%) developed post-operative bleeding. There were no reported side effects.

Conclusions: We report the largest real-world data of a racially diverse pediatric population of PHA with and without inhibitors receiving emizicumab prophylaxis. Breakthrough and post-operative bleeding occur in PHA on emicizumab prophylaxis similarly in different racial backgrounds.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/emicizumab-prophylaxis-in-a-racially-diverse-pediatric-population-with-hemophilia-a-with-and-without-inhibitors/