Emicizumab prophylaxis in haemophilia A with inhibitors: Three years follow‐up from the UK Haemophilia Centre Doctors’ Organisation (UKHCDO)

Abstract

AbstractIntroductionThe UK National Haemophilia Database (NHD) collects data from all UK persons with haemophilia A with inhibitors (PwHA‐I). It is well‐placed to investigate patient selection, clinical outcomes, drug safety and other issues not addressed in clinical trials of emicizumab.AimsTo determine safety, bleeding outcomes and early effects on joint health of emicizumab prophylaxis in a large, unselected cohort using national registry and patient reported Haemtrack (HT) data between 01 January 2018 and 30 September 2021.MethodsProspectively collected bleeding outcomes were analysed in people with ≥6 months emicizumab HT data and compared with previous treatment if available. Change in paired Haemophilia Joint Health Scores (HJHS) were analysed in a subgroup. Adverse events (AEs) reports were collected and adjudicated centrally.ResultsThis analysis includes 117 PwHA‐I. Mean annualised bleeding rate (ABR) was .32 (95% CI, .18; .39) over a median 42 months treatment with emicizumab. Within‐person comparison (n = 74) demonstrated an 89% reduction in ABR after switching to emicizumab and an increase in zero treated bleed rate from 45 to 88% (p < .01). In a subgroup of 37 people, total HJHS improved in 36%, remained stable in 46% and deteriorated in 18%, with a median (IQR) within‐person change of −2.0 (−9, 1.5) (p = .04). Three arterial thrombotic events were reported, two possibly drug related. Other AEs were generally non‐severe and usually limited to early treatment, included cutaneous reactions (3.6%), headaches (1.4%), nausea (2.8%) and arthralgia (1.4%).ConclusionsEmicizumab prophylaxis is associated with sustained low bleeding rates and was generally well‐tolerated in people with haemophilia A and inhibitors.