Comparative effectiveness of busulfan/cyclophosphamide versus busulfan/fludarabine myeloablative conditioning for allogeneic hematopoietic cell transplantation in acute myeloid leukemia and myelodysplastic syndrome.

Objective/background: Busulfan/cyclophosphamide (Bu/Cy) and busulfan/fludarabine (Bu/Flu) are both standard myeloablative conditioning (MAC) regimens for allogeneic hematopoietic cell transplantation (alloHCT). We compared the effectiveness of these regimens with a focus on quality of life (QOL).

Methods: This was a single center, retrospective analysis of adult acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients who underwent a first T-cell replete HLA-8/8 matched related or unrelated donor alloHCT. Patients received a myeloablative regimen of either parenteral Bu/Cy or Bu/Flu. Outcomes assessed included infections, graft-versus-host-disease (GVHD), relapse, relapse mortality (RM), relapse-free survival (RFS), nonrelapse mortality (NRM), overall survival (OS), and QOL.

Results: From 2008 to 2017, 126 AML and 84 MDS adult patients age ≥18 years were identified meeting inclusion criteria. In terms of QOL, there were no significant differences between Bu/Cy and Bu/Flu cohorts in the Functional Assessment of Cancer Therapy-Bone Marrow Transplant Scale (FACT-BMT) scores or mucositis severity for either AML or MDS patients. Amongst AML patients, those receiving Bu/Flu had more rapid neutrophil and platelet recovery and a shorter length of hospital stay (LOS); there were no differences in the other posttransplant outcomes. Similarly, amongst MDS patients, those receiving Bu/Flu had more rapid platelet recovery and a shorter LOS as well as more CMV infections, but less NRM and no differences in other outcomes.

Conclusion: We confirmed that myeloablative Bu/Flu conditioning has comparable clinical and QOL outcomes to Bu/Cy.