TREATMENT BURDEN AND PATIENT PREFERENCE IN PATIENTS WITH HEMOPHILIA A OR B WITH INHIBITORS ON CONCIZUMAB PROPHYLAXIS: RESULTS FROM THE PHASE 3 EXPLORER7 STUDY

Concizumab is a humanised, recombinant monoclonal antibody administered to patients with haemophilia A/B with inhibitors (HAwI/HBwI) as a once-daily prophylaxis (PPX) in the phase 3 explorer7 study (NCT04083781). In the primary analysis, concizumab PPX reduced the annualised bleeding rate for patients with HAwI/HBwI. Subcutaneous (SC) administration of concizumab may contribute to a lower treatment burden compared to intravenous factor replacement therapy. Here, we present data from explorer7 on patient-reported treatment burden and patient preference. Methods: A total of 133 patients aged ≥12 years were either randomised 2:1 to concizumab PPX (arm 2; n = 33) or no PPX (arm 1; n = 19) or assigned to non-randomised concizumab PPX (arms 3 or 4; n = 81). Patients could complete the Hemophilia Treatment Experience Measure (Hemo-TEM) questionnaire at baseline (Week 0) and Week 24 and the Haemophilia Patient Preference Questionnaire (H-PPQ) at Week 24. Analysis of covariance was applied to estimate mean change in Hemo-TEM domain and total scores from baseline to Week 24. The H-PPQ results were analysed descriptively. The Hemo-TEM total score improved with concizumab PPX (n = 19) from baseline to Week 24 (mean estimate -17.0 points [95% CI: -23.7; -10.3]), but not in patients with no PPX (n = 6, mean estimate 3.0 points [95% CI: -9.4; 15.3]). The estimated treatment difference in Hemo-TEM total score between both arms was statistically significant (-19.9 points [95% CI: -34.3; -5.6]; p = 0.009). Significant improvements in arm 2 were observed in the domains "injection difficulties", "interference", and "emotional impact". In the H-PPQ questionnaire; 77/99 patients (78%) preferred concizumab over their previous treatment, while only one patient (1%) preferred their previous treatment (16 patients did not respond, and 5 patients had no preference). Of all responding patients, 93% preferred concizumab with the 3 main reasons being "fewer bleeds"(75%), "require less time"(43%), and "less painful to inject"(33%). Discussion/Conclusion: A lower treatment burden was observed for daily concizumab PPX with better Hemo-TEM domain and total scores. Lower treatment burden due to SC administration combined with reduced bleeding (especially in HBwI) resulted in a clear patient preference in favour of concizumab over their previous treatment.