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We investigated the impact of the number of induction/consolidation cycles on outcomes of 3113 adult AML patients who received allogeneic hematopoietic cell transplantation (allo-HCT) between 2008 and 2019. Patients received allo-HCT using myeloablative (MAC) or reduced-intensity (RIC) conditioning in first complete remission (CR) or with primary induction failure (PIF). Patients who received MAC allo-HCT in CR after 1 induction cycle had 1.3-fold better overall survival (OS) than 2 cycles to CR and 1.47-fold better than ≥3 cycles. OS after CR in 2 or ≥3 cycles was similar. Relapse risk was 1.65-fold greater in patients receiving ≥3 cycles to achieve CR. After RIC allo-HCT, the number of induction cycles to CR did not affect OS. Compared to CR in 1 cycle, relapse risk was 1.24-1.41-fold greater in patients receiving 2 or ≥3 cycles. For patients receiving only 1 cycle to CR, consolidation therapy prior to MAC allo-HCT was associated with improved OS vs. no consolidation therapy. Detectable MRD at the time of MAC allo-HCT did not impact outcomes while detectable MRD preceding RIC allo-HCT was associated with an increased risk of relapse. For allo-HCT in PIF, OS was significantly worse than allo-HCT in CR after 1-3 cycles.

Reduced-intensity conditioning (RIC) regimens developed to extend allogeneic stem cell transplantation (HSCT) to older patients have resulted in encouraging outcomes. We aimed to compare the two most commonly used RIC regimens, intravenous use of fludarabine with busulfan (FluBu) and fludarabine with melphalan (FluMel), in myelodysplastic syndrome (MDS). Through CIBMTR, we identified 1045 MDS patients aged ≥ 60 years who underwent first HSCT with a matched related or matched (8/8) unrelated donor using RIC. CIBMTR’s definition of RIC was used: a regimen that incorporated an intravenous busulfan total dose ≤ 7.2 mg/kg, or a low-dose melphalan total dose of ≤ 150 mg/m(2). The two groups, FluBu (n=697) and FluMel (n=448), were comparable for disease and transplant-related characteristics except for the more frequent use of anti-thymocyte globulin or alemtuzumab in the FluBu group (39% vs. 31%). The median age was 67 in both groups. FluMel was associated with a reduced relapse incidence (RI) compared with FluBu, with a 1-year adjusted incidence of 26% vs. 44% (p≤0.0001). Transplant-related mortality (TRM) was higher with FluMel compared with FluBu (26% vs. 16%, p≤0.0001). Since the magnitude of improvement with FluMel in RI was greater than the improvement in TRM with FluBu, disease-free survival (DFS) was improved at 1-year and beyond with FluMel compared with FluBu (48% vs. 40% at 1 year, p=0.02, and 35% vs. 27% at 3 years, p=0.01). Overall survival (OS) was comparable at 1 year (63% vs. 61%, p=0.4) but significantly improved with FluMel compared with FluBu at 3 years (46% vs. 39%, p=0.03). Our results suggest that FluMel is associated with superior DFS compared with FluBu due to reduced RI in older MDS patients.

Cytogenetic risk stratification at diagnosis has long been one of the most useful tools to assess prognosis in acute lymphoblastic leukemia (ALL). To examine the prognostic impact of cytogenetic abnormalities on outcomes after allogeneic hematopoietic cell transplantation, we studied 1731 adults with Philadelphia-negative ALL in complete remission who underwent myeloablative or reduced intensity/non-myeloablative conditioning transplant from unrelated or matched sibling donors reported to the Center for International Blood and Marrow Transplant Research. A total of 632 patients had abnormal conventional metaphase cytogenetics. The leukemia-free survival and overall survival rates at 5 years after transplantation in patients with abnormal cytogenetics were 40% and 42%, respectively, which were similar to those in patients with a normal karyotype. Of the previously established cytogenetic risk classifications, modified Medical Research Council-Eastern Cooperative Oncology Group score was the only independent prognosticator of leukemia-free survival (P=0.03). In the multivariable analysis, monosomy 7 predicted post-transplant relapse [hazard ratio (HR)=2.11; 95% confidence interval (95% CI): 1.04-4.27] and treatment failure (HR=1.97; 95% CI: 1.20-3.24). Complex karyotype was prognostic for relapse (HR=1.69; 95% CI: 1.06-2.69), whereas t(8;14) predicted treatment failure (HR=2.85; 95% CI: 1.35-6.02) and overall mortality (HR=3.03; 95% CI: 1.44-6.41). This large study suggested a novel transplant-specific cytogenetic scheme with adverse [monosomy 7, complex karyotype, del(7q), t(8;14), t(11;19), del(11q), tetraploidy/near triploidy], intermediate (normal karyotype and all other abnormalities), and favorable (high hyperdiploidy) risks to prognosticate leukemia-free survival (P=0.02). Although some previously established high-risk Philadelphia-negative cytogenetic abnormalities in ALL can be overcome by transplantation, monosomy 7, complex karyotype, and t(8;14) continue to pose significant risks and yield inferior outcomes.