Conditioning intensity and post-transplant outcomes in acute myeloid leukemia: A real-world analysis.

Abstract

e18573 Background: The choice of conditioning intensity for patients with acute myeloid leukemia (AML) undergoing allogeneic hematopoietic cell transplantation (allo-HCT) is influenced by multiple factors, including disease risk, remission status, patient fitness, and center-specific practice patterns. While myeloablative (MAC) and reduced-intensity conditioning (RIC) regimens have been extensively compared, less is known about their real-world effectiveness when accounting for contemporary patient selection and disease risk. Methods: We performed a retrospective analysis of adult patients with AML who underwent allo-HCT at the University of Kentucky between Jan 2015 and Jan 2025. Baseline demographics, disease characteristics, ELN risk classification, conditioning intensity, and transplant outcomes were collected. Overall survival (OS) was calculated from the time of transplant, and relapse outcomes were assessed longitudinally. Results: A total of 147 patients were included. Median age was 57 years (IQR 43–64), and 53% were male. Median follow-up from diagnosis was 59 months (IQR 47.7–77), with a median OS from transplant of 66 months (IQR 43.3–NR). ELN risk was favorable in 22%, intermediate in 28%, and unfavorable in 50%. Transplant occurred in first complete remission (CR1) in 61% and in second complete remission CR2 in 22% of patients. Conditioning regimens included RIC in 53% (FluBu2 45%, FluMel 49%, FluTreosulfan 6%), MAC in 32% (FluBu4 78%, TBI/etoposide 9%, other TBI-based regimens 13%), and non-myeloablative regimens in 5.4%. Post-transplant relapse occurred in 32% of patients. ELN risk distribution was similar between MAC and RIC groups (unfavorable risk: 53% vs 48%, p=0.2). Patients receiving MAC were younger than those receiving RIC (median age 48 vs 60 years, p<0.01). Median time to relapse was not reached in either group (MAC 95% CI 13–NR vs RIC 95% CI 34–NR; p=0.6). Conclusions: In this real-world cohort, conditioning intensity was not associated with differences in relapse timing despite clear differences in patient age and selection. These findings suggest that reduced-intensity conditioning provides comparable disease control to myeloablative approaches in appropriately selected patients with AML, supporting risk-adapted conditioning strategies in contemporary practice.