Minimal Residual Disease in Pediatric Acute Lymphoblastic Leukemia

Minimal Residual Disease following Allogeneic Hematopoietic Stem Cell Transplantation

Relevance and Clinical Implications of Tumor Cell Mobilization in the Autologous Transplant Setting

Analysis of Early Disease Response in Childhood ALL: Can Peripheral Blood Replace Bone Marrow Analysis?.

Minimal Residual Disease Levels At Time Of CR1 and Transplant Predict Outcome In Philadelphia Chromosome-Negative Adult ALL

Improved Concordance of Minimal Residual Disease Measurements By Quantitative PCR and 10-Color Flow Cytometry in Pediatric Acute Lymphoblastic Leukemia

8544 Background: MRD is an important prognostic factor for children with ALL and it provides crucial information on the response to treatment and risk of relapse. However, the frequency which MRD can be monitored is limited due the discomfort and practical difficulties posed by BM aspiration. Since there are few reported studies on the value of MRD in PB, we conducted a prospective study to evaluate and to compare FC MRD measurements in BM with PB and correlate with BM morphology in children with ALL. Methods: 76 BM aspirates and 64 PB samples obtained from 40 Brazilian children with ALL were analysed during days 14(D14) and 28(D28) of remission induction therapy with a three-color FC assay. Data acquisition and analysis were performed using BD-FACSCalibur flow cytometer with Cell-Quest and Paint-a-gate softwares, respectively. Detectable MRD was defined as ≥ 0,01% cells expressing an aberrant immunophenotype(detected at diagnosis) among total events in the sample. BM morphology was analysed at the same time points. Results: in 20/36 (55,6%) BM samples, MRD was detected at D14 and in 18/40 (45%) at D28. MRD was detected in PB in 12/28(42,9%) at D14 and in 11/36(30,6%) at D28. The concordance between MRD in BM and PB was 85,7%(P<.001) at D14 and a significant level of agreement was found in 71% of samples(P<.001) at D28,although MRD levels may differ. In patients in complete morphological remission,44% had detectable MRD at D14 and 38,9% at D28. MRD was not signicantly related to sex,age,WBC count or cell lineage. Conclusions: FC is a sensitive,fast and reproducible technique for detection of MRD in children with ALL. Our findings suggest that PB could be useful in monitoring MRD,particularly in T-lineage. This study reinforces the discrepancy between traditional morphology and MRD,reaffirming its prognostic importance in childhood ALL. No significant financial relationships to disclose.

Most current treatment protocols for acute lymphoblastic leukemia (ALL) include minimal residual disease (MRD) diagnostics, generally based on PCR analysis of rearranged antigen receptor genes. Although flow cytometry (FCM) can be used for MRD detection as well, discordant FCM and PCR results are obtained in 5-20% of samples. We evaluated whether 6-color FCM, including additional markers and new marker combinations, improved the results. Bone marrow samples were obtained from 363 ALL patients at day 15, 33 and 78 and MRD was analyzed using 6-color (218 patients) or 4-color (145 patients) FCM in parallel to routine PCR-based MRD diagnostics. Compared with 4-color FCM, 6-color FCM significantly improved the concordance with PCR-based MRD data (88% versus 96%); particularly the specificity of the MRD analysis improved. However, PCR remained more sensitive at levels <0.01%. MRD-based risk groups were similar between 6-color FCM and PCR in 68% of patients, most discrepancies being medium risk by PCR and standard risk by FCM. Alternative interpretation of the PCR data, aimed at prevention of false-positive MRD results, changed the risk group to standard risk in half (52%) of these discordant cases. In conclusion, 6-color FCM significantly improves MRD analysis in ALL but remains less sensitive than PCR-based MRD-diagnostics.

Comparison of High-Throughput Sequencing and Flow Cytometry for Measuring Minimal Residual Disease in Pediatric Acute Lymphoblastic Leukemia: A Children's Oncology Group Cohort

Improved Post-Induction Chemotherapy Does Not Abrogate Prognostic Significance of Minimal Residual Disease (MRD) for Children and Young Adults with High Risk Acute Lymphoblastic Leukemia (ALL). A Report From Children's Oncology Group (COG) Study AALL0232

BACKGROUND:Detection of minimal residual disease (MRD) in the early phase of therapy is the most powerful predictor of relapse risk in children with acute lymphoblastic leukaemia (ALL).AIM:We aimed to determine the significance of MRD at the end of remission induction therapy in the prediction of treatment outcome in children with ALL.METHODS:Sixty-four consecutive patients aged 1-14 years with newly diagnosed ALL were enrolled in this study from January 2010 to October 2017. All patients were treated according to the ALL IC BFM 2002 protocol. MRD was detected at the end of remission induction therapy (day 33) by multiparameter 6-colour flow cytometry performed on bone marrow specimens with a sensitivity of 0.01%.RESULTS:Overall, 42.2% of patients had detectable MRD on day 33 of therapy. MRD measurements were not significantly related to presenting characteristics but were associated with a poorer blast clearance on day 8 and 15 of remission induction therapy. Patients with negative MRD status on day 33 had a 5-year event-free survival of 94.6% compared with 76.1% for those with positive MRD status (P = 0.044).CONCLUSION:MRD levels at the end of remission induction therapy measured by multiparameter flow cytometry have clinical significance in childhood ALL. High levels of MRD are strongly related to poor treatment outcome.

Minimal Residual Disease Detected Prior to Transplantation Is Associated with Adverse Outcome in Pediatric Acute Lymphoblastic Leukemia.

Analysis of early disease response in childhood acute lymphoblastic leukaemia: can peripheral blood replace bone marrow analysis?

Clinical utility of sequential minimal residual disease measurements in the context of risk-based therapy in childhood acute lymphoblastic leukaemia: a prospective study

Background Acute lymphoblastic leukemia (ALL) is a biologically heterogeneous disorder. Clinical parameters, immunophenotype, cytogenetic factors, and minimal residual disease (MRD) are among currently used factors in risk stratification and therapy determination of ALL patients. MRD is gaining importance nowadays for therapy efficacy, follow-up, and relapse risk estimation. Recent studies have highlighted potential markers that may improve the sensitivity of MRD detection by flow cytometry. Cluster of differentiation (CD) 97 is one of the markers that show overexpression in pediatric ALL. In this study, we aimed to assess the value of CD97 as a biomarker for MRD detection in pediatric ALL. Patients and methods This cohort study was conducted on 30 newly diagnosed patients with B-ALL. There were 16 male and 14 female patients with a mean age of 8.38±4.21. Twenty patients were in the low-risk group and 10 patients were in the high-risk group and were treated according to modified CCG 1991. A panel of monoclonal antibodies was used, with special emphasis on CD10, CD19, CD34, and CD97 at diagnosis and at day 14 postinduction of chemotherapy for MRD detection. Results The percentage of CD19/CD97, CD34/CD97, and CD10/CD97 at day 0 was 57.15±21.74, 57.73±21.20, and 57.87±20.77, whereas at day 14 it was 6.09±2.50, 10.67±8.89, and 5.97±2.44, respectively (P<0.001). CD97 was expressed in 81.5% of patients at diagnosis and was not detected at day 14 (P<0.001). One patient had blast counts more than 5% by light microscopy, whereas 29 patients had MRD more than 0.1 by flow cytometry at day 14 (P<0.001). Conclusion CD97 can be used for MRD tracing in pediatric ALL.

Minimal (i.e. submicroscopic) residual disease (MRD) predicts outcome in childhood acute lymphoblastic leukaemia (ALL). To be used clinically, MRD assays must be reliable and accurate. Two well-established techniques, flow cytometry (FC) and polymerase chain reaction (PCR), can detect leukaemic cells with a sensitivity of 0.01% (10(-4)). We analysed diagnostic samples of 45 ALL-patients (37 B-lineage ALL, eight T-lineage ALL) by four-colour FC and real-time PCR. Leukaemia-associated immunophenotypes, at a sensitivity of MRD detection by FC at the 0.01% level, were identified in 41 cases (91%); antigen-receptor gene rearrangements suitable for MRD detection with a sensitivity of 0.01% or better by PCR were identified in 38 cases (84%). The combined use of FC and PCR allowed MRD monitoring in all 45 patients. In 105 follow-up samples, MRD estimates by both methods were highly concordant, with a deviation factor of <5 by Bland-Altman analysis. Importantly, the concordance between FC and PCR was also observed in regenerating bone marrow samples containing high proportions of CD19(+) cells, and in samples studied 24 h after collection. We conclude that both MRD assays yield generally concordant results. Their combined use should enable MRD monitoring in virtually all patients and prevent false-negative results due to clonal evolution or phenotypic shifts.