Despite the known haemostatic action of emicizumab (Hemlibra) in haemophilia A patients, its role in the prevention and control of bleeding in high-demand haemostatic situations, such as major surgery, remains to be determined. Patients receiving regular emicizumab prophylaxis often require concomitant factor VIII (FVIII) therapy during major surgery to prevent uncontrolled bleeding and to promote postoperative healing. However, there are limited prospective surgical data relating to concomitant FVIII and emicizumab use. Simoctocog alfa (Nuwiq) is a B-domain deleted recombinant FVIII produced in a human cell line without chemical modification or protein fusion with proven efficacy as surgical prophylaxis in adult and paediatric patients. The Nuwiq for Perioperative management Of patients With haemophilia A on Emicizumab Regular prophylaxis (NuPOWER) study aims to examine perioperative efficacy and safety of simoctocog alfa in haemophilia A patients on emicizumab prophylaxis undergoing major surgery.

NuPOWER is a prospective, open-label, single-arm, multicentre study that will be conducted at approximately 15 centres worldwide. Up to 28 male patients ≥12 years with severe haemophilia A and no FVIII inhibitors will be recruited. All patients must be receiving regular emicizumab prophylaxis and scheduled to undergo a major surgical procedure during which concomitant simoctocog alfa will be administered. The primary endpoint is the overall haemostatic efficacy of simoctocog alfa, adjudicated by an independent data monitoring committee using a pre-defined algorithm, and will consider intraoperative and postoperative efficacy assessments by the surgeon and investigator, respectively. Secondary endpoints include intraoperative haemostatic efficacy, postoperative haemostatic efficacy, number of allogeneic blood products transfused, perioperative FVIII plasma levels (as measured by FVIII activity) and thrombin generation, and safety parameters. In the era of non-factor therapy, NuPOWER will generate valuable prospective data on concomitant use of simoctocog alfa and emicizumab prophylaxis in patients with severe haemophilia A undergoing major surgery.

Ethical approval has been received from institutional review boards/independent ethics committees, and the study will be conducted in compliance with the Declaration of Helsinki. This work will be disseminated by publication of peer-reviewed manuscripts and presentations at scientific meetings.

CT EU 2022-502060-21-00; NCT05935358.