Sahebi, FiroozehEikema, Dirk-JanKoster, LindaKroger, NicolausMeijer, Ellenvan Doesum, Jaap ARovira, MontserratKoc, YenerAngelucci, EmanueleBlaise, DidierSammassimo, SimonaMcDonald, AndrewArroyo, Concepcion HerreraSanchez, James FForcade, EdouardCastagna, LucaStölzel, FriedrichSanz, JaimeTischer, JohannaCiceri, FabioValcarcel, DavidProia, AnnaHayden, Patrick JBeksac, MeralYakoub-Agha, IbrahimSchönland, Stefan2025-01-072025-01-072021-09-17https://hdl.handle.net/10668/25369Graft-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; PenAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/clinical researchengraftmenthematologymultiple myelomatransplantationBone MarrowCyclophosphamideGraft vs Host DiseaseHematopoietic Stem Cell TransplantationHumansMultiple MyelomaNeoplasm Recurrence, LocalRetrospective StudiesUnited StatesUnrelated Donorsresearch article34543768open access10.1016/j.jtct.2021.09.0082666-6367https://doi.org/10.1016/j.jtct.2021.09.008