Value of flow cytometry for MRD-based relapse prediction in B-cell precursor ALL in a multicenter setting

Abstract

PCR of TCR/Ig gene rearrangements is considered the method of choice for minimal residual disease (MRD) quantification in BCP-ALL, but flow cytometry analysis of leukemia-associated immunophenotypes (FCM-MRD) is faster and biologically more informative. FCM-MRD performed in 18 laboratories across seven countries was used for risk stratification of 1487 patients with BCP-ALL enrolled in the NOPHO ALL2008 protocol. When no informative FCM-marker was available, risk stratification was based on real-time quantitative PCR. An informative FCM-marker was found in 96.2% and only two patients (0.14%) had non-informative FCM and non-informative PCR-markers. The overall 5-year event-free survival was 86.1% with a cumulative incidence of relapse (CIR5y) of 9.5%. FCM-MRD levels on days 15 (HzR 4.0, p < 0.0001), 29 (HzR 2.7, p < 0.0001), and 79 (HzR 3.5, p < 0.0001) associated with hazard of relapse adjusted for age, cytogenetics, and WBC. The early (day 15) response associated with CIR5y adjusted for day 29 FCM-MRD, with higher levels in adults (median 2.4 × 10−2 versus 5.2 × 10−3, p < 0.0001). Undetectable FCM- and/or PCR-MRD on day 29 identified patients with a very good outcome (CIR5y = 3.2%). For patients who did not undergo transplantation, day 79 FCM-MRD > 10−4 associated with a CIR5y = 22.1%. In conclusion, FCM-MRD performed in a multicenter setting is a clinically useful method for MRD-based treatment stratification in BCP-ALL.

High CD34 surface expression in BCP‐ALL predicts poor induction therapy response and is associated with altered expression of genes related to cell migration and adhesion

“…At MRD timepoints, the first aspirate was used for FCM‐ and PCR‐MRD to avoid hemodilution and subsequent differences in assessment of blast concentration, and the bone marrow material was split equally for FCM‐ and PCR‐MRD. MRD was measured by flow cytometry using protocol‐defined six‐color panels for identification and monitoring of the LAIP according to the NOPHO ALL2008 guidelines [3,28]. At least 300 000 events, but preferably 1 million events, per antibody combination were analyzed when sufficient material was available, corresponding to a sensitivity of 1 × 10 −5 (sensitivity calculated as 10/live singlets, corresponding to the identification of ≥ 10 clustered leukemic events among all live singlets analyzed, as defined by the ALL2008 protocol [3]).…”

Minimal Residual Disease Prior to and After Haematopoietic Stem Cell Transplantation in Children and Adolescents With Acute Lymphoblastic Leukaemia: What Level of Negativity Is Relevant?

“…Today, MRD is routinely measured by two sensitive methods: MFC and quantitative PCR (qPCR)-based analysis. Both techniques have strengths and pitfalls and there is a growing recognition of the need for both methods because they supplement each other in the management of B-cell precursor (BCP)-ALL and T-cell ALL, especially when aiming for correct stratification of virtually all patients (10)(11)(12). Droplet digital PCR (ddPCR) and next generation sequencing (NGS), especially, are promising technologies for MRD detection and are potentially useful as future methods for MRD monitoring, providing even higher sensitivity and accuracy than MFC and qPCR.…”

“…MFC-MRD can be applied to most ALL patients (>90% of BCP-ALL cases have an informative LAIP), although it has been especially studied and implemented in BCP-ALL (11,28,29). MFC-MRD is also used successfully for treatment stratification in T-cell ALL (6,10,12,30).…”

Multiparametric Flow Cytometry for MRD Monitoring in Hematologic Malignancies: Clinical Applications and New Challenges

“…Originally, seminal studies in pediatric ALL have represented a leading clinical experience of MFC-MRD use in hematologic patients [ 39 , 40 , 41 , 42 , 43 ]. Today, although RQ-PCR of Ig/TCR gene rearrangements and other specific gene fusions constitutes the most validated method for MRD monitoring in ALL, LAIP detection by MFC is commonly suggested to complement the molecular approach, as MFC can provide faster accurate results and deeper biological information [ 36 , 37 , 44 , 45 , 46 , 47 ].…”