OC 30.1 - Emicizumab prophylaxis in people with severe haemophilia A without inhibitors: outcomes from the UK Haemophilia Centre Doctors' Organisation

Monday, July 11, 2022

10:45 AM – 11:00 AM

Location: ExCel Center, ICC Auditorium

Presentation Format: In-Person

Presenting Author(s)

CW

Caroline Wall, MBChB

Haematology Consultant
Manchester Royal Infirmary
Manchester, England, United Kingdom

Co-Author(s)

HX

Hua Xiang

Statistician
National Haemophilia Database
Manchester, England, United Kingdom
BP

Ben P. Palmer

Statistician
National Haemophilia Database
Manchester, England, United Kingdom
Pratima Chowdary, MD

Consultant Haematologist
Katharine Dormandy Haemophilia and Thrombosis Centre, Royal Free London NHS Foundation Trust, London, United Kingdom
London, England, United Kingdom
Peter W. Collins, MD

Professor of Haematology
Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University Hospital, Cardiff, United Kingdom
Cardiff, Wales, United Kingdom
Georgina W. Hall, MBBS, PhD

Consultant Paediatric Haematologist
Oxford Haemophilia and Thrombosis Centre
Oxford, England, United Kingdom
MM

Mary Mathias

Haemophilia Centre Director
Great Ormond Street Hospital for Children, NHS Foundation Trust
London, England, United Kingdom
CP

Charles Percy

Consultant Haematologist
University Hospitals Birmingham NHS Foundation Trust
Birmingham, England, United Kingdom
PS

Paul Sartain

Patient Representative
National Haemophilia Database
Manchester, England, United Kingdom
Susan Shapiro, MD, PhD

Consultant Hematologist
Oxford University Hospitals National Health Service Foundation Trust, Oxford, UK
Oxford, England, United Kingdom
DS

David Stephensen

physiotherapist, Visiting Reader in Physiotherapy
East Kent Hospitals University NHS Trust, Faculty of Health and Wellbeing, Canterbury Christ Church University
Canterbury, England, United Kingdom
KT

Kate Talks

Consultant in Haemostasis and Thrombosis
Newcastle Haemophilia Comprehensive Care Centre, Royal Victoria Infirmary
Newcastle upon Tyne, England, United Kingdom
CH

Charles R. Hay

Consultant in Haemostasis and Thrombosis
Manchester Royal Infirmary
Manchester, England, United Kingdom

Background: The uptake of emicizumab in persons with severe haemophilia A (pSHA) without inhibitors is heterogeneous. We present UK outcomes since its introduction in 2019.

Aims: To determine bleeding outcomes in pSHA treated with emicizumab in UK clinical practice

Methods: An observational study was conducted of 673 pSHA who switched from FVIII prophylaxis to emicizumab between 01/08/19 and 30/09/21. A within-person comparison of annualised bleed (ABR) and joint-bleed rate (AJBR) with prior FVIII prophylaxis was conducted in people with ≥6 months pre and post-switch Haemtrack home-therapy data using Wilcoxon signed rank test. Change in proportion reporting zero-treated bleeds was analysed using the McNemar test.

Results: Emicizumab was prescribed to 673 non-inhibitor pSHA, 36.9% of the UK-registered cohort, including 85 (12.6%) with an inhibitor history. A within-person comparison with previous FVIII prophylaxis was conducted in 401 pSHA broken down by age (table 1). A within-person sub-analysis of 144 people reporting bleeding (table 2) showed that 73% (105/144) had a reduced bleeding after switching (p < 0.001). Relatively few subjects had target joints using ISTH criteria; 35 switchers had 51 target joints and 45 non-switchers had 69 target joints. After a median 21 months follow-up, 74% of emicizumab switchers experienced fewer and 6% more target joints versus 42% fewer and 33% more target joints in non-switchers (p = 0.004). Recurrent FVIII inhibitors were reported in 4/85 (4.7%) people at risk. One person (0.15%) developed a low level anti-drug antibody (ADA).

Conclusion(s): Switching to emicizumab resulted in significantly improved bleed control in all age groups (p < 0.001) and in 65-80% no treated bleeds were reported. In subjects who reported bleeding, clinically and statistically significant reductions in ABR were observed. Target joints resolved more frequently than in people who continued FVIII prophylaxis. ADAs were uncommon and recurrent FVIII inhibitors occurred in ~5% of those at risk.