Real‐World Clinical Data and Thrombin Generation of Efanesoctocog Alfa Prophylaxis in Pediatric Patients With Haemophilia A

BACKGROUND: Clinical trials have shown efficacy and safety of efanesoctocog alfa prophylaxis in children and adults, however, real-world data on the efficacy and safety remains scarce. OBJECTIVES: To report real-world data on the effectiveness, immunogenicity, safety, pharmacokinetics and thrombin generation in pediatric persons with haemophilia A receiving efanesoctocog alfa. METHODS: We performed a retrospective chart review of pediatric males with haemophilia A on efanesoctocog alfa prophylaxis at Children's Health in Dallas, Texas. RESULTS/CONCLUSION: Twenty two pediatric patients with haemophilia A (mean age of 13 years old (4-17)) switched or started efanesoctocog alfa prophylaxis. Over a median (IQR) duration of 15.5 (10-26) months, two patients experienced minor side effects. No inhibitors were detected. The mean trough FVIII level was 15 IU/dL (7-29; SD 6) and FVIII peak 137 IU/dL (92-207; SD 28), mean trough ETP 396, SD 180 nanomolar-minutes (nM.min), and peak ETP 980, SD 219 nM.min, mean trough PT 38, SD 23 nM, and mean peak PT 161, SD 65. There were no spontaneous breakthrough bleeding events; six patients (5 played sports) developed a traumatic bleeding event. Our real-world data shows that efanesoctocog alfa was overall well tolerated, effective, and favourable immunogenicity in pediatric patients. Cohorts with longer follow-up, further measures of haemostasis, joint health surveillance with imaging and quality of life measurements should be included in future reports.