Perioperative Management With Efanesoctocog Alfa in Patients With Haemophilia A in the Phase 3 XTEND‐1 and XTEND‐Kids Studies

ABSTRACT Introduction The Phase 3 studies, XTEND‐1 (NCT04161495) and XTEND‐Kids (NCT04759131), showed once‐weekly efanesoctocog alfa provided high‐sustained factor VIII (FVIII) activity levels that translated into highly effective bleed prevention in patients with severe haemophilia A. Aim This analysis evaluated the efficacy and safety of efanesoctocog alfa for perioperative management during XTEND‐1 and XTEND‐Kids. Methods Patients undergoing major or minor surgery were to receive a single preoperative 50 IU/kg dose, with additional 30 or 50 IU/kg doses every 2–3 days as needed following major surgery. Outcomes assessed included FVIII activity levels, number and dose of efanesoctocog alfa injections, surgeon's/investigator's assessment of haemostatic response, total factor consumption, estimated blood loss, number and type of blood transfusions, and safety. Results In XTEND‐1, 11 adults/adolescents underwent 12 evaluable major surgeries (6 orthopaedic). Eleven surgeries had one preoperative dose (median [range]: 49.9 [13–52] IU/kg); one had no preoperative dose. Median (range) total consumption from Day −1 to 14 was 163.3 (45–361) IU/kg. In XTEND‐Kids, two children underwent major surgery with a single preoperative loading dose (60.4 and 61.9 IU/kg). Across trials, 15 adults/adolescents underwent 18 minor surgeries and 8 children underwent 9 minor surgeries, with a single preoperative dose or no preoperative dose (5 surgeries in adults/adolescents). Haemostatic response was rated excellent for all surgeries. No surgeries required blood transfusion. No safety concerns or inhibitor development was reported. Conclusion Efanesoctocog alfa provided highly effective perioperative protection in patients with severe haemophilia A. Trial Registration : XTEND‐1: NCT04161495 https://clinicaltrials.gov/study/NCT04161495 ; XTEND‐Kids: NCT04759131 https://clinicaltrials.gov/study/NCT04759131