Minor Surgeries Outcomes with Efanesoctocog Alfa: 4 Years’ Experience in the XTEND Clinical Program

Introduction Efanesoctocog alfa is a first-in-class high sustained factor VIII replacement therapy that overcomes the von Willebrand factor-imposed half-life ceiling. In XTEND-1 (NCT04161495) and XTEND-Kids (NCT04759131), once-weekly efanesoctocog alfa was well tolerated and highly efficacious for perioperative management of bleeding in patients with severe hemophilia A. Participants completing these studies could continue weekly efanesoctocog alfa prophylaxis (50 IU/kg) in XTEND-ed (NCT04644575) Arm A. Here, we report data on perioperative use of efanesoctocog alfa during minor surgeries from parent studies’ baselines through the second interim analysis of XTEND-ed (datacut: 22 February 2024). Method Participants provided informed consent; the study was approved by applicable review boards. Participants entering XTEND-ed Arm A from XTEND-1/XTEND-Kids and those newly initiating prophylaxis (Arms B [China] and C [planned surgery]) were included. Participants received a single dose of 50 IU/kg per protocol on the day of surgery. This interim analysis included vascular access procedures, endoscopic procedures, ophthalmology procedures, and other minor surgeries; dental surgeries were excluded.Number and dose of injections to maintain hemostasis, total consumption, investigator assessment of hemostatic response, blood loss/transfusions, and safety are described. Results Twenty-nine males (mean [SD] age at enrollment: 32.4 [25.3] years) underwent 33 minor surgeries. Hemostasis during surgery was maintained with a single preoperative injection in all cases. The total dose to maintain hemostasis ranged from 50.0 to 52.1 IU/kg across different minor surgeries. Perioperative consumption (Day -1 to 7) was low for all surgeries and comparable to routine prophylaxis ([ Fig. 1 ]). Hemostatic response was rated excellent in all reported cases. No transfusions were required; no treatment-related adverse events were reported. Fig. 1