Concizumab is a humanised, monoclonal anti-tissue factor pathway inhibitor antibody. In explorer7, a phase 3 study (NCT04083781), patients with haemophilia A or B with inhibitors (HAwI/HBwI) received once-daily subcutaneous prophylactic treatment with concizumab for prevention of bleeding episodes. Here, we present data on patient-reported health-related quality of life (HRQoL) after concizumab treatment for 24 weeks in explorer7. Methods: Male patients aged ≥12 years (n = 133) were randomised to no prophylaxis (arm 1) or concizumab (arm 2) or assigned to non-randomised concizumab arms (arms 3 or 4). All patients could complete the 36-item Short Form Health Survey (SF-36v2) and patients ≥17 years could complete the Haemophilia Quality of Life Questionnaire for Adults (Haem-A-QoL) at Weeks 0, 4, 8, 16 and 24. SF-36v2 health scales “bodily pain” (BP) and “physical functioning”(PF) were analysed as key secondary endpoints. Several patient-reported outcomes recordings were not collected due to technical reasons. Therefore, a post-hoc mixed model for repeated measures (MMRM) was used for analysis. The MMRM analysis included patients from arms 1 and 2 completing the questionnaire at baseline and at least once on the new dosing regimen.

The estimated treatment difference (ETD) on the SF-36v2 BP scale between arm 1 (n = 9) and arm 2 (concizumab, n = 23) from baseline to Week 24 was 7.0 points (95% CI: -1.6; 15.6). On the PF scale, the ETD was 3.3 points (95% CI: -3.8; 10.4). While BP and PF scores were not significantly different between both arms, the scales “general health”, “mental health”, “role-emotional”and “vitality”showed statistically significant differences in favour of concizumab. The total Haem-A-QoL score was significantly improved in arm 2 (n = 13) compared to arm 1 (n = 4, ETD: -22.6 points [95% CI: -42.5; -2.7]). Significant differences were observed for the domains “feeling”, “treatment”, “view of yourself”, and “sport and leisure”. Discussion/Conclusion: Patients on daily subcutaneous concizumab prophylaxis reported better scores on generic (SF-36v2) and disease-specific (Haem-A-QoL) questionnaires compared to patients treated on-demand. The largest ETDs were related to mental and general health. This reflects the potential of concizumab prophylaxis to improve HRQoL in patients with HAwI/HBwI.