We retrospectively analyzed the impact of conditioning intensity on transplant outcomes according to their cytogenetic/molecular risk in a cohort of 1823 patients with acute myeloid leukemia (AML) and intermediate- or adverse-risk cytogenetics in first complete remission (CR1). These patients received their first hematopoietic stem cell transplantation (HSCT) using post-transplant cyclophosphamide (PTCy). The intermediate-risk cytogenetic group included 1386 (76%) patients, and 608 (34%) had mutated FLT3-ITD. Myeloablative conditioning was used in 930 patients (51%), while 1130 (62%) received an intensified conditioning (score ≥2.5) based on the transplant conditioning intensity (TCI) score. Conditioning intensity using the myeloablative/reduced intensity stratification did not impact transplant outcomes across the entire cohort. However, a higher TCI score was associated with a lower risk of relapse, with no effect on survival. In specific cytogenetic risk groups, a higher TCI score did not influence outcomes in the adverse-risk group. In the intermediate-risk group, the impact varied with FLT3-ITD status. Patients with FLT3-ITD mutation who received a higher TCI showed a beneficial effect on relapse, leukemia-free survival (LFS), and overall survival. Conversely, in FLT3-ITD wild-type patients, more intense conditioning had a detrimental effect on graft-versus-host disease-free, and relapse-free survival with no effect on other outcomes. In conclusion, for AML patients in CR1 undergoing HSCT with PTCy, it is crucial to consider cytogenetic risk and molecular status when selecting the conditioning regimen. Intensive conditioning should be considered for patients with intermediate-risk cytogenetics and mutated FLT3-ITD but should probably be avoided for those with wild-type FLT3-ITD.

• MeSH
• Leukemia, Myeloid, Acute * therapy   genetics   mortality   MeSH
• Cyclophosphamide * therapeutic use   administration & dosage   pharmacology   MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Transplantation Conditioning * methods   MeSH
• Retrospective Studies MeSH
• Risk Factors MeSH
• Aged MeSH
• Hematopoietic Stem Cell Transplantation * methods   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cyclophosphamide * MeSH

We compared transplantation (HSCT) outcomes in AML patients undergoing HSCT with post-transplant cyclophosphamide (PTCy) in first complete remission from 1065 young (<35 years) haploidentical (Haplo) donors (yHaplo) vs. 147 old (≥35 years) mismatched unrelated donors (oMMUD) (first comparison) and from 271 young (<35 years) MMUD (yMMUD) vs. 1315 old (≥35 years) Haplo donors (oHaplo) (second comparison). Acute graft-versus-host disease (aGVHD) grades II-IV were significantly lower in the yHaplo vs. oMMUD group (HR = 0.62, p = 0.007). There were no significant differences in chronic GVHD, non-relapse mortality (NRM), relapse incidence, leukemia-free survival, overall survival, and GVHD-free and relapse-free survival. As for the second comparison, more patients in the oHaplo group had de novo AML, 86.6% vs. 81.9% in the yMMUD group (p = 0.044), while myeloablative conditioning was used more frequently in the yMMUD group, 53.3% vs. 46.8% in the oHaplo group (p = 0.049). aGVHD grades II-IV and NRM were significantly lower in the yMMUD vs. oHaplo group (HR = 0.69, p = 0.013 and HR = 0.60, p = 0.022). All other transplant outcomes did not differ. In conclusion, HSCT from young alternative donors (<35 years) results in a lower incidence of grades II-IV aGVHD. In addition, NRM is lower in HSCT from yMMUD compared to HSCT from oHaplo.

• MeSH
• Leukemia, Myeloid, Acute * therapy   mortality   MeSH
• Cyclophosphamide * therapeutic use   MeSH
• Child MeSH
• Adult MeSH
• Transplantation, Haploidentical methods   MeSH
• Transplantation, Homologous methods   MeSH
• Remission Induction MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Graft vs Host Disease MeSH
• Unrelated Donors * MeSH
• Disease-Free Survival MeSH
• Transplantation Conditioning methods   MeSH
• Hematopoietic Stem Cell Transplantation * methods   MeSH
• Age Factors MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Geographicals
• Europe MeSH
• Names of Substances
• Cyclophosphamide * MeSH