Comparative analysis of flow cytometry and polymerase chain reaction for the detection of minimal residual disease in childhood acute lymphoblastic leukemia

Abstract

Minimal residual disease (MRD) is an independent prognostic factor in childhood acute lymphoblastic leukemia (ALL). The most widely applied MRD assays in ALL are flow cytometric identification of leukemia immunophenotypes and polymerase chain reaction (PCR) amplification of antigen-receptor genes. We measured MRD by both assays in 227 patients with childhood B-lineage ALL. Of 1375 samples (736 bone marrow and 639 peripheral blood) examined, MRD was o0.01% in 1200, and X0.01% in 129 by both assays; MRD levels measured by the two methods correlated well. Of the remaining 46 samples, 28 had MRD X0.01% by flow cytometry but o0.01% by PCR. However, PCR (which had a consistent sensitivity of 0.001%) detected leukemic gene rearrangements in 26 of these 28 samples. Conversely, in 18 samples, MRD was X0.01% by PCR but o0.01% by flow cytometry. In nine of these samples, flow cytometry had a sensitivity of 0.001%, and detected aberrant immunophenotypes in eight samples. Therefore, the two most widely used methods for MRD detection in ALL yield concordant results in the vast majority of cases, although the estimated levels of MRD may vary in some. The use of the two methods in tandem ensures MRD monitoring in all patients.

Impact of pretransplant minimal residual disease after cord blood transplantation for childhood acute lymphoblastic leukemia in remission: an Eurocord, PDWP–EBMT analysis

“…Nonetheless, even if the techniques used to detect MRD may vary, some authors have shown that MFC-and PCR-based detection methods in ALL provides concordant results in the vast majority of cases. 32 In our analysis, we confirmed that the presence of detectable MRD assessed either by PCR (n ¼ 119) or by MFC (n ¼ 51) was statistically associated with LFS (PCR: P ¼ 0.02, MFC: P ¼ 0.05) and relapse (PCR: P ¼ 0.04, MFC: P ¼ 0.01).…”

Standardized MRD quantification in European ALL trials: Proceedings of the Second International Symposium on MRD assessment in Kiel, Germany, 18–20 September 2008

“…Sensitivity can be determined exactly for every junctional region target and currently tends to be 0.5-1.0 log higher than while using flow cytometric MRD assessment. [48][49][50] However, a main disadvantage of using Ig/TCR gene rearrangements as MRD targets in ALL is the occurrence of continuing rearrangements during the disease course, potentially leading to false-negative PCR results. 46,[51][52][53] Moreover, follow-up of subclones existing at initial diagnosis may lead to overestimation or underestimation of MRD values.…”

“…20,[48][49][50]57 Instead, FCM-based risk definition may be independently reliable and therefore has to be independently validated.…”

Clinical significance of minimal residual disease in childhood acute lymphoblastic leukemia after first relapse

“…Moreover, they published recently a large-scale comparative analysis on flow cytometry and PCR for the detection of MRD, showing good concordance and recommending a tandem application. 4 In Europe, molecular genetics is most widely used in a number of countries for MRDquantification in ALL, and a co-operative group has been established to set standards for quality control in the different laboratories. This is essential if a method is being applied in several institutions or reference laboratories in order to get reliable and comparable results.…”