Background: Haemophilia is associated with significant treatment burden. Concizumab, an anti-tissue factor pathway inhibitor antibody in clinical development as a subcutaneous, prophylactic treatment, aims to improve patient experience by reducing treatment burden. explorer4 and explorer5 (NCT03196284/NCT03196297) investigated daily concizumab prophylaxis in patients with haemophilia A/B with inhibitors (HAwI/HBwI), and severe HA, respectively. Haemophilia Treatment Experience Measure (Hemo-TEM), a 26-item questionnaire with five domains developed to measure treatment burden in haemophilia patients, was used to investigate the value of subcutaneous prophylaxis with concizumab.

Aims: Assess impact of concizumab subcutaneous prophylaxis on treatment burden.

Methods: explorer4 and 5 comprised main (≤24 weeks) and extension parts (≤94 and ≤102 weeks, respectively). In explorer4, HAwI/HBwI patients were randomised 2:1 to concizumab prophylaxis or bypassing agent on-demand. On-demand patients switched to concizumab prophylaxis in the extension. In explorer5, all patients received concizumab. Hemo-TEM was completed at baseline, 24 and ≥76 weeks. Scores range from 0–100; lower scores indicate lower treatment burden. Individual domain and total scores are calculated. Hemo-TEM development and validation are presented separately.

Results: Twenty-five and 29 patients completed explorer4 and 5, respectively. In explorer4, mean baseline Hemo-TEM total scores were similar between concizumab (25.0) and on-demand arms (26.2). After 24 weeks of treatment, the concizumab arm demonstrated change from baseline in mean Hemo-TEM total score of -15.3, indicating lower treatment burden versus baseline, with no change in the on-demand arm (Table 1). Similarly, change in mean Hemo-TEM total score from baseline (21.9) was -12.8 for patients in explorer5 after 24 weeks (Table 2). Improved scores were observed for all Hemo-TEM domains, with sustained improvements at last observational visit in both trials (Table 1, 2).

Conclusion(s): Hemo-TEM scores improved after ≥24 weeks of concizumab subcutaneous prophylaxis during explorer4 and explorer5, in patients with and without inhibitors, illustrating the potential value of concizumab in reducing treatment burden.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/treatment-experience-in-hemophilia-patients-with-and-without-inhibitors-on-concizumab-prophylaxis-hemo-tem-results-from-the-phase-2-explorer4-5-studies/