Persistence of Minimal Residual Disease Assessed By Multi-Parameter Flow Cytometry (MFC) at 30 and 90 Days after Achieving Complete Remission Predicts Outcome in Patients with Acute Myeloid Leukemia

Abstract Purpose – To determine the value of Minimal Residual Disease (MRD) assessed by Multi-parameter Flow Cytometry (MFC) after achieving initial response to therapy, in predicting outcome in patients with acute myeloid leukemia (AML) Methods – We investigated the predictive value of MRD assessment by MFC in 191 patients with newly diagnosed AML treated between February 2010 and April 2014 at our institution who had available MRD assessment. MRD by MFC was assessed using an 8-color panel containing 19 distinct markers, on bone marrow specimens obtained at the time of achievement of CR and at approximately 30 days and 90 days after achieving CR. Residual leukemic blasts were identified based on phenotypic differences from normal myelomonocytic precursors. Sensitivity was estimated at 0.1% in most cases, with maximum achievable sensitivity of 0.01%, depending on the leukemic phenotype. Results – Of the 191 patients, 167 (87%) achieved complete remission (CR) or CR without platelet recovery (CRp). Their median age was 58 years (Range, 17-85). 84 (44%) were older than 60 years. Median WBC at presentation was 3.2 x 109/L(Range, 0.5-100.2 x 109/L) and median bone marrow blast percentage was 43% (Range, 11-96%). Cytogenetics was favorable risk in 4 (2%), intermediate risk in130 (68%) and adverse risk in 57 (30%). Treatment included cytarabine plus anthracycline in 170 (89%) and hypomethylating agents-based strategies in 21 (11%). 48 patients had available samples at 30 days post CR and 32 (67%) became MRD negative. Achieving MRD negative status was associated with a statistically significant improvement in CR duration (p=0.02) and overall survival (OS) (p=0.0005). 56 patients were evaluated for MRD status at 90 days and 45 (80%) were negative. Again, achieving MRD negative status was associated with a significant improvement in CR duration (p=0.002) and OS (p=0.0009). Conclusion – Achieving MRD negative status by MFC at 30 and 90 days post CR is associated with an improved outcome in patients with AML Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.