Pre-transplant MRD predicts outcome following reduced-intensity and myeloablative allogeneic hemopoietic SCT in AML

The presence of minimal residual disease (MRD) by multiparametric flow cytometry (MFC) has been associated with adverse outcomes in AML patients treated with chemotherapy alone, but its impact in the setting of allogeneic hematopoietic SCT (HSCT) is less clear. We studied 88 patients who underwent myeloablative (MA) or reduced-intensity conditioned allogeneic HSCT for AML in first or subsequent remission at our center. MRD status was determined using three-color MFC on pre-HSCT BM aspirates, and patients were stratified by MRD status into MRD-negative, low-level MRD-positive (<1%) or high-level MRD-positive groups (1-4.9%). Two-year survival estimates in these groups were 66.8%, 51% and 30%, respectively (P=0.012), and 2-year estimates of relapse were 7.6, 37 and 70% (P<0.001). Pre-HSCT MRD was related to disease characteristics including secondary AML (P=0.002) and primary induction failure (P=0.005), but, despite these strong correlations, MRD remained independently associated with poorer survival in multivariate analysis (hazard ratio, 1.92; P=0.014). Pre-HSCT MRD is associated with adverse clinical outcomes in AML patients undergoing reduced-intensity or MA HSCT in first or subsequent remission and should be integrated into transplant strategies for patients with AML.