Busulfan/Melphalan/Fludarabine (Bu/Mel/Flu) Conditioning Versus Total Body Irradiation/Thiotepa/Cyclophosphamide (HFTBI/Thio/Cy) Based Conditioning in Patients with Acute Myeloid Leukemia (AML) or Myelodysplastic Syndrome (MDS) Undergoing CD34-Selected T-Cell Depleted Allogeneic Stem Cell Transplantation (alloSCT)

Abstract

Introduction In patients with poor risk AML or MDS in first complete remission (CR1), alloSCT can be potentially curative. Comparison of the non-hematologic toxicities between total body irradiation (TBI)-based conditioning versus chemotherapy alone prior to CD34-selected alloSCT requires further validation. Objective The primary objective of this analysis is to review the incidence of grade 3 or 4 non-hematologic toxicities at day 100 and 365. Methods Patients with AML or MDS in CR1 who underwent their first CD34-selected alloSCT were identified from our institutional database. Transplant outcomes and toxicity rates were assessed using cox proportional hazards regression. Toxicities were graded according to the NCI Common Technology Criteria for Adverse Effects v4.03. Baseline characteristics were assessed using the Wilcoxon rank-sum test, Fisher's exact test, and the chi-squared test. The cumulative incidence method was used to control for competing risks. Results 221 patients underwent CD34-selected alloSCT from Jan 2010-Dec 2016. 48 (22%) received HFTBI/Thio/Cy and 173 (78%) Bu/Mel/Flu. A statistically significant difference was noted in age, disease state, and Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI) score as summarized in Table 1. The cumulative incidence of non-hematologic toxicities most frequently reported at 12mo were infections (87.8%, 95% CI: 82.6-91.5), oral/GI (72.4%, 95% CI: 66-77.8) and metabolic (69.2%, 95% CI: 62.7-74.9). Incidence of gr 3/4 cardiovascular (43.4% vs. 18.8%, P = 0.002) at 12mo were significantly higher in the Bu/Mel/Flu arm. Incidence of gr 3/4 oral/GI toxicities (93.8% vs. 66.5%, P Conclusion Amongst adults with AML or MDS undergoing CD34-selected alloSCT, chemotherapy-based and TBI-based conditioning regimens appear to be associated with similar toxicity profiles. Most differences observed in the incidence of toxicities between the 2 groups can be attributed to the known side effects of the individual conditioning agents, however, we cannot determine impact of age on the toxicities due to the significant difference in age distribution between the 2 groups.