Emicizumab in children: bleeding episodes and outcome before and after transition to Emicizumab

Purpose Real-world data and study data regarding therapy with Emicizumab in pediatric cohorts with haemophilia A is scarce. Especially, data on previously untreated pediatric patients (PUPs) and minimally treated patients (MTPs) are missing. Methods Thirteen pediatric patients with haemophilia A and treatment with Emicizumab were retrospectively evaluated for Annual Bleeding Rates (ABR) pre-and post-Emicizumab treatment. Safety data and data on management of minor surgery as well as laboratory results were collected. Additionally, we describe the clinical features of two PUPs and one MTP that are included in our cohort. Results Median age at initiation of Emicizumab was 5.3 (range: 0.26-17.5) years, three patients were younger than one year at initiation of treatment with Emicizumab. Median follow-up time on Emicizumab was 23.8 (range: 0.7-40) months. Total ABR (p = 0.009) as well as spontaneous (p = 0.018), traumatic (p = 0.018), and joint (p = 0.027) ABR reduced significantly post-Emicizumab transition. Safety profile was favourable as only one local site reaction occurred; no cessation of treatment was necessary. Surgery was successfully performed in three patients receiving rFVlla pre- and post-surgery. Emicizumab trough levels showed a median of 43.2 [mu]g/ml (range: 23.9-56.8) after three doses of 3 mg/kg and 51.9 [mu]g/ml (range: 30.4-75) at first follow-up with 1.5 mg/kg. Conclusion Emicizumab is safe and efficient in pediatric patients with and without inhibitors. More data on larger multicenter cohorts and especially on PUPs/MTPs are still needed. Keywords: Emicizumab, Hemlibra, Children, Annual bleeding rate