An increasing number of older patients with acute myeloid leukemia (AML) are offered an allogeneic hematopoietic stem cell transplantation (allo-HSCT). Normally, older patients have older matched related donors (MRD). Matched unrelated donors (MUD) are an important alternative, but it remains unclear whether a younger MUD is associated with better outcomes, especially in the context of post-transplant cyclophosphamide (PTCy). We compared outcomes of patients older than 50 years with AML in first complete remission (CR1) and receiving a first HSCT from a 10/10 MUD aged younger than 40 years to those receiving a graft from a MRD aged older than 50 years, using PTCy and with well-known transplant conditioning intensity (TCI) score. A total of 345 consecutive patients were included and classified according to TCI score as low, intermediate, or high. On multivariable analysis in the TCI-intermediate/high group, MUD was associated with better graft-versus-host disease-free, relapse-free survival, lower non-relapse mortality and lower relapse incidence. For patients receiving a TCI-low regimen, outcomes are independent on the type of donor. In patients with AML in CR1, older than 50 years and receiving a TCI-intermediate/high conditioning regimen using PTCy, a MUD younger than 40 years is preferable over a MRD older than 50 years.

BMT Unit Haematology Department Hospital Clinic IDIBAPS and Josep Carreras Foundation Barcelona Spain

Bone Marrow Transplantation and Institute of Cell Therapy University of Patras Patras Greece

Bone Marrow Transplantation Program Department of Internal Medicine American University of Beirut Medical Center Beirut Lebanon

Department of Haematology Oncology Vanderbilt University Medical Center Nashville TN USA

Department of Hematology Amsterdam UMC location VU Amsterdam The Netherlands

Department of Internal Medicine Division of Hematology GROW School for Oncology and Developmental Biology Maastricht University Medical Center Maastricht The Netherlands

Division of Hematology Sheba Medical Center Tel Hashomer Israel

EBMT Paris Office Hopital Saint Antoine Paris France

Erasmus MC Cancer Institute Rotterdam Rotterdam The Netherlands

Fondazione Policlinico Universitario A Gemelli IRCCS Roma Italy

Hematology and Bone Marrow Transplant Unit IRCCS San Raffaele Hospital Milan Italy

Hematology Hospital Regional de Málaga Malaga Spain

Hôpital Saint Antoine Sorbonne University INSERM UMRs 938 Paris France

Hospital Universitari i Politècnic La Fe Hematology Department Departament de Medicina Universitat de Valencia Valencia Spain

Institute of Hematology and Blood Transfusion Prague Prague Czech Republic

RM Gorbacheva Research Institute Pavlov University Saint Petersburg Saint Petersburg Russian Federation

Università Vita Salute San Raffaele Milan Italy

University Medical Center Groningen University of Groningen Groningen The Netherlands

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