PB0634 - The MAPTO survey, Mapping Approaches to Tolerance in PUP/MTP treatment around the world in the non-replacement era

Monday, June 24, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Lilianne van Stam, MSc

PhD Candidate Pediatric Hematology
Department of Pediatric Hematology, Emma Children’s Hospital, Amsterdam UMC location University of Amsterdam, Amsterdam, the Netherlands
Amsterdam, Noord-Holland, Netherlands

Co-Author(s)

Pantep Angchaisuksiri

Professor of Medicine and Chief of the Haemostasis and Thrombosis Unit
Department of Medicine, Ramathibodi Hospital, Mahidol University
Bangkok, Krung Thep, Thailand
Manuel Carcao

Professor
Department of Pediatrics, Division of Hematology/Oncology, Hospital for Sick Children, Toronto, Canada
Toronto, Ontario, Canada
GK

Gili Kenet

CONSULTANT PAEDIATRIC HAEMATOLOGIST
National Hemophilia Center Sheba Medical center, Tel Hashomer & Amalia Biron Research Institute of Thrombosis & Hemostasis, Tel Aviv University, Israel,
Tel Aviv, Tel Aviv, Israel
CK

Christoph Königs

MD, PhD
University Hospital Frankfurt, Goethe University, Department of Pediatrics and Adolescent Medicine, Clinical and Molecular Hemostasis, Frankfurt, Germany
Frankfurt, Hessen, Germany
Johnny Mahlangu, MBBCh, MMed

Head of Department and Principal Haematologist
Department of Molecular Medicine and Haematology, University of the Witwatersrand, National Health Laboratory Service, and Charlotte Maxeke Johannesburg Academic Hospital
Johannesburg, Gauteng, South Africa
Maria Elisa Mancuso, MD, PhD

Senior Consultant in Haematology
Centre for Thrombosis and Haemorrhagic Diseases, IRCCS Humanitas Research Hospital
Milan, Lombardia, Italy
Suely M. Rezende, MD, PhD

Professor of Internal Medicine
Universidade Federal de Minas Gerais
Belo Horizonte, Minas Gerais, Brazil
Robert F. Sidonio, Jr., MD, M.Sc.

Associate Professor of Pediatrics
Emory University
Decatur, Georgia, United States
Suthesh Sivapalaratnam, MD, PhD, FRCP, FRCPath

Clinical Senior Lecturer
QMUL/Barts Health NHS Trust
London, England, United Kingdom
Alok Srivastava

Professor of Medicine
Christian Medical College, Department of Haematology, Vellore, Tamil Nadu, India
Vellore, Tamil Nadu, India
Guy Young, MD

Director, Hemostasis and Thrombosis Program
Children's Hospital of Los Angeles, Los Angeles, USA
Los Angeles, California, United States
KF

Karin Fijnvandraat

Professor
Emma Kinderziekenhuis/AMC, University of Amsterdam, Netherlands
Amsterdam, Noord-Holland, Netherlands
SG

Samantha C. Gouw, MD PhD

Pediatric hematologist
Department of Pediatric Hematology, Emma Children’s Hospital, Amsterdam UMC location University of Amsterdam, Amsterdam, the Netherlands
Amsterdam, Noord-Holland, Netherlands

Background: Previously untreated patients (PUPs) and minimally treated patients (MTPs, i.e. < 5 exposure days to factor VIII) with severe hemophilia are at risk for inhibitor development during the first 50 exposure days (EDs) to factor VIII. Presently, many PUPs/MTPs receive prophylaxis with emicizumab instead of factor VIII (FVIII). As FVIII exposure for breakthrough bleeds is infrequent, it may take years to reach a total of 50 EDs. Earlier FVIII tolerance may be preferred to avoid unexpected inhibitor development and treatment failure during breakthrough bleeds or emergency surgery. Tolerance may be achieved by regular doses of FVIII alongside emicizumab. It is currently unknown whether regular doses of FVIII have a tolerizing effect and reduce inhibitor risk or whether it triggers inhibitor development. Anecdotal information demonstrates different strategies globally. We lack more precise information on this heterogeneity in treatment paradigms.

Aims: To describe current practices and perspectives of hemophilia treaters worldwide on obtaining FVIII tolerance/inhibitor unmasking for PUPs/MTPs with severe hemophilia A on emicizumab prophylaxis.

Methods: We are currently performing a global international survey among a total of > 500 hemophilia treaters from all continents addressing real world approaches to obtain FVIII tolerance/unmask inhibitors in PUPs/MTPs with severe hemophilia A on emicizumab prophylaxis and their experiences with the perspectives of parents on the use of concomitant FVIII.

Results: The results will be presented during the ISTH congress. We expect to reveal heterogeneous clinical practices, reflecting the uncertainty of clinicians on the best treatment for this vulnerable group of PUPs/MTPs with severe hemophilia A.

Conclusion(s): We will not only learn about the perspectives of hemophilia health care providers, but also whether parents and children are willing to undergo intravenous injections for tolerization purposes. This information will clarify a need for further research into FVIII tolerization with additional FVIII exposure, alongside emicizumab prophylaxis.