RT Journal Article T1 Post-Transplantation Cyclophosphamide for Graft-versus- Host Disease Prophylaxis in Multiple Myeloma Patients Who Underwent Allogeneic Hematopoietic Cell Transplantation: First Comparison by Donor Type. A Study from the Chronic Malignancies Working Party of the European Society for Blood and Marrow Transplantation A1 Sahebi, Firoozeh A1 Eikema, Dirk-Jan A1 Koster, Linda A1 Kroger, Nicolaus A1 Meijer, Ellen A1 van Doesum, Jaap A. A1 Rovira, Montserrat A1 Koc, Yener A1 Angelucci, Emanuele A1 Blaise, Didier A1 Sammassimo, Simona A1 McDonald, Andrew A1 Arroyo, Concepcion Herrera A1 Sanchez, James F. A1 Forcade, Edouard A1 Castagna, Luca A1 Stolzel, Friedrich A1 Sanz, Jaime A1 Tischer, Johanna A1 Ciceri, Fabio A1 Valcarcel, David A1 Proia, Anna A1 Hayden, Patrick J. A1 Beksac, Meral A1 Yakoub-Agha, Ibrahim A1 Schoenland, Stefan K1 multiple myeloma K1 transplantation K1 engraftment K1 hematology K1 clinical research K1 Bone-marrow K1 Autologous transplantation K1 Fludarabine K1 Tolerance K1 Busulfan K1 Outcomes AB Graft-versus-host disease (GVHD) remains among the major causes of treatment failure in patients with multiple myeloma (MM) undergoing allogeneic hematopoietic cell transplantation (allo-HCT). The use of post-transplantation cyclophosphamide (PT-Cy) is now a well-established and widely used method for GVHD prophylaxis after HLA haploidentical HCT. However, the rationale for using PT-Cy in the setting of matched donor transplantation is less apparent, given the lesser degree of bidirectional alloreactivity. In this retrospective study, we investigated the role of PT-Cy as GVHD prophylaxis in patients with multiple myeloma underoing allo-HCT, among different donor types, to determine cumulative incidence of acute and chronic GVHD and impact on engraftment, progression-free survival (PFS), GVHD-free/relapse- free survival (GRFS), overall survival (OS), and NRM A total of 295 patients with MM underwent allo-HCT using grafts from a matched related donor (MRD; n = 67), matched unrelated donor (MUD; n = 72), mismatched related or unrelated donor (MMRD/MMUD, 1 antigen; n = 27), or haploidentical donor (haplo; n = 129) using PT-Cy between 2012 and 2018. In addition to PT-Cy, agents used in GVHD prophylaxis included calcineurin inhibitors in 239 patients (81%), with mycophenolate mofetil in 184 of those 239 (77%). For grade II-IV acute GVHD, the cumulative incidence at day +100 was 30% (95% confidence interval [CI], 25% to 36%), 9% (95% CI, 5% to 12%) for grade III-IV acute GVHD, and 27% (95% CI, 21% to 32%) for chronic GVHD (limited, 21%; extensive, 6%), with no differences by donor type. The median time to neutrophil engraftment was 19d (95% CI, 18-19), with no significant difference by donor type. The median time to platelet engraftment was delayed in haploidentical donor graft recipients (27 days versus 21 days; P PB Elsevier science inc SN 2666-6375 YR 2021 FD 2021-12-08 LK https://hdl.handle.net/10668/25370 UL https://hdl.handle.net/10668/25370 LA en DS RISalud RD Apr 10, 2025