Minimal Residual Disease Assessment by Flow Cytometry in B-lineage Acute Lymphoblastic Leukemia to Assess Response to Treatment and Impact on Outcome

Abstract

Abstract The prognostic value of minimal residual disease (MRD) assessed by multi-parameter flow cytometry (MFC) was investigated among 56 adult patients with B-cell acute lymphoblastic leukaemia (B-ALL) treated between 2014 and 2018 using regimens including the Dana Farber and Hoelzer protocols. In this study, 44 (78.6%) achieved complete remission (CR) with a relapse rate of 38.6% (17 cases out of 44 cases) after a median follow up of 15 months. median age was 29.5 years (range18 to 60). Median white blood cell count (WBC) was17.75 x 103 (range, 0.38-340 x103/µl). MRD by MFC was assessed with a sensitivity of 0.01%, using a 7 marker, 4-colour panel on bone marrow specimens obtained at D14, D28 and post consolidation. MRD ≤0.01 at D14 was associated with improved disease-free survival (DFS) and overall survival (OS) (P <0.001and P <0.001 respectively). Similarly MRD ≤0.01 at D28 and undetectable levels post consolidation was associated with improved DFS (P <0.001and P <0.001 respectively) and OS (P <0.001and P <0.001 respectively). Multivariate analysis including age, WBC at presentation, IPT, cytogenetics, treatment protocol and MRD status at D14, D28 and post consolidation, indicated that MRD negative status was an independent predictor of DFS. Achievement of an MRD negative state assessed by MFC is an important predictor of DFS and OS in adult patients with ALL.