Bleeding control improves after switching to emicizumab: Real‐world experience of 177 children in the PedNet registry

Abstract Introduction Despite the rapid uptake of emicizumab in the paediatric haemophilia A (HA) population, real‐world data on the safety and efficacy is limited. Aim To report on bleeding and safety in paediatric patients receiving emicizumab prophylaxis. Methods Data were extracted from the multicentre prospective observational PedNet Registry (NCT02979119). Children with haemophilia A, and ≥50 FVIII exposures or inhibitors present receiving emicizumab maintenance therapy were analysed. Data were summarized as medians with interquartile range (IQR, P25–P75). Mean (95% confidence interval (CI)), annualized (joint) bleeding rate (A(J)BR) during emicizumab and ≤2 years before emicizumab prophylaxis were modelled and compared using negative binomial regression. Results Total of 177 patients started emicizumab at median 8.6 years (IQR 4.8–13.1), most had no FVIII inhibitors (64%). Follow up before emicizumab was median: 1.68 years (IQR: 1.24–1.90) and during emicizumab: 1.32 years (IQR: .94–2.11). In patients without inhibitors, mean ABR reduced after starting emicizumab from 2.41 (CI 1.98–2.95) to 1.11 (CI .90–1.36, p < .001), while AJBR reduced from.74 (CI .56–.98) to.31 (CI .21–.46, p < .001). Concordantly, in patients with inhibitors, mean ABR reduced from 5.08 (CI 4.08–6.38) to .75 (CI .56–1.01, p < .001), while AJBR reduced from 1.90 (CI 1.42–2.58) to .34 (CI .21–.56, p < .001). Five emicizumab‐related adverse events were reported (3% of the cohort), including one patient with antidrug antibodies. Conclusion This study showed improved bleeding control compared to previous treatment and a favourable safety profile during emicizumab therapy in paediatric haemophilia A patients.