Disease and treatment burden of patients with haemophilia entering the explorer6 non-interventional study

Objectives: We aimed to characterise baseline disease and treatment burden in a large population with haemophilia A/B, both with (HAwI/HBwI) and without (HA/HB) inhibitors. Methods: The prospective, non-interventional explorer6 study included patients ≥12 years old with severe HA, severe/moderate HB or HAwI/HBwI of any severity, treated according to local standard of care (excluding previous/current exposure to concizumab or emicizumab). Baseline characteristics and historical clinical data were collected and patient-reported outcomes, including treatment burden, were assessed. Results: The explorer6 study enrolled 231 patients with haemophilia (84 HAwI/HBwI) from 33 countries. At baseline, patients with HA/HB treated with prophylaxis had the lowest median annualised bleeding rates (ABRs; 2.0), irrespective of haemophilia type; of these patients, 27.5% (HA) and 31.4% (HB) had target joints. Patients with HAwI/HBwI treated episodically reported the highest treatment burden. Of these patients, 28.5% (HAwI) and 25.1% (HBwI) performed sports activities in the month before screening. Conclusion: Despite receiving routine clinical care, historical and baseline information from patients enrolled in explorer6 showed that patients with HA/HB treated episodically and patients with HAwI/HBwI had higher ABRs, higher treatment burden and participated in sports less than those with HA/HB treated with prophylaxis. Emerging treatments could be beneficial in addressing these unmet medical needs.