Early chemosensitivity of normal hematopoietic cells and malignant lymphoblasts predicts relapse in childhood acute lymphoblastic leukemia

For the last 30 years, numerous clinical and biological pretreatment risk factors have been utilized for risk-based treatment assignment in childhood acute lymphoblastic leukemia (ALL). However, with improved chemotherapy regimens, many of these traditional prognostic factors have lost clinical significance. We aimed to improve relapse prediction in children with ALL through evaluation of the early chemosensitivity of normal and malignant cells and to determine the relationship between such chemosensitivity and risk of relapse. We retrospectively analyzed a cohort of 60 children with newly diagnosed ALL of whom 40 patients were in complete remission for at least 4 years and 20 patients relapsed during or following treatment. Time to peripheral blood blast clearance (PBBC) was used as a measure of chemosensitivity of malignant lymphoblasts while end-of-induction complete blood count (CBC) parameters were used as a measure of chemosensitivity of normal hematopoietic cells. Our results showed that longer time to PBBC and lower end-of-induction total leukocyte count (TLC) and absolute neutrophil count (ANC) were significantly associated with increased risk of relapse. In conclusion, time to PBBC and end-of-induction TLC and ANC are important predictors of relapse and should be used to modify the intensity of chemotherapy at earlier time points during the course of treatment. A wider prospective, randomized, controlled trial is required to confirm our results.     

Minimal residual disease detection in childhood precursor-B-cell acute lymphoblastic leukemia: relation to other risk factors. A Children's Oncology Group study.

Minimal residual disease (MRD) can be detected in the marrows of children undergoing chemotherapy either by flow cytometry or polymerase chain reaction. In this study, we used four-color flow cytometry to detect MRD in 1016 children undergoing therapy on Children's Oncology Group therapeutic protocols for precursor-B-cell ALL. Compliance was excellent, with follow-up samples received at the end of induction on nearly 95% of cases; sensitivity of detection at this time point was at least 1/10,000 in more than 90% of cases. Overall, 28.6% of patients had detectable MRD at the end of induction. Patients with M3 marrows at day 8 were much more likely to be MRD positive (MRD+) than those with M2 or M1 marrows. Different genetically defined groups of patients varied in their prevalence of MRD. Specifically, almost all patients with BCR-ABL had high levels of end-of-induction MRD. Only 8.4% of patients with TEL-AML1 were MRD+>0.01% compared with 20.3% of patients with trisomies of chromosomes 4 and 10. Our results show that MRD correlates with conventional measures of slow early response. However, the high frequency of MRD positivity in favorable trisomy patients suggests that the clinical significance of MRD positivity at the end of induction may not be the same in all patient groups.     

Importance of minimal residual disease testing during the second year of therapy for children with acute lymphoblastic leukemia.

PURPOSE: A high level of minimal residual disease (MRD) after induction chemotherapy in children with acute lymphoblastic leukemia (ALL) is an indicator of relative chemotherapy resistance and a risk factor for relapse. However, the significance of MRD in the second year of therapy is unclear. Moreover, it is unknown whether treatment intervention can alter outcome in patients with detectable MRD. PATIENTS AND METHODS: We assessed the prognostic value of MRD testing in bone marrow samples from 85 children at 1, 12, and 24 months from diagnosis using clone-specific polymerase chain reaction primers designed to detect clonal antigen receptor gene rearrangements. These children were part of a multicenter, randomized clinical trial, which, in the second year of treatment, compared a 2-month reinduction-reintensification followed by maintenance chemotherapy with standard maintenance chemotherapy alone. RESULTS: MRD was detected in 69% of patients at 1 month, 25% at 12 months, and 28% at 24 months from diagnosis. By univariate analysis, high levels of MRD at 1 month, or the presence of any detectable MRD at 12 or 24 months from diagnosis, were highly predictive of relapse. Multivariate analysis showed that MRD testing at 1 and 24 months each had independent prognostic significance. Intensified therapy at 12 months from diagnosis did not improve prognosis in those patients who were MRD positive at 12 months from diagnosis. CONCLUSION: Clinical outcome in childhood ALL can be predicted with high accuracy by combining the results of MRD testing at 1 and 24 months from diagnosis.     

Expression of TEL-AML1 fusion transcripts and response to induction therapy in standard risk acute lymphoblastic leukemia.

We prospectively examined the frequency of the t(12;21)TEL-AML1 fusion in 504 children with newly diagnosed standard risk ALL using RT-PCR assays. Cells from 95 patients (18.8%) were TEL-AML1+. There was a significantly higher frequency of pseudodiploidy among the TEL-AML1+ cases (39.4% versus 14.1%, P = 0.001), primarily because structural abnormalities involving 12p and del(6q) occurred more frequently in the TEL-AML1+ group. TEL-AML1+ ALL was more sensitive to the induction chemotherapy than TEL-AML1- ALL. The percentage of "rapid early responders", i.e., patients who achieved an M1 (< 5% blasts) or M2 (5-25% blasts) marrow status on day 7 of induction chemotherapy, was significantly higher among TEL-AML1+ cases. The quality of remission of RT-PCR positive cases was excellent, as evidenced by the very low to absent MRD burden of their end-of-induction bone marrow specimens. TEL-AML1+ patients also had an excellent early EFS outcome. The probability of EFS at 30 months from study entry were 98.9 +/- 1.0% for the TEL-AML1+ group and 92.1 +/- 1.5% for the TEL-AML1- group (P = 0.0001). This prospective study significantly expands the knowledge gained from previous studies regarding the prognostic significance of t(12;21)TEL-AML1 fusion in pediatric ALL.     

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

Using flow cytometric techniques capable of detecting 0.01% leukemic cells, we prospectively studied minimal residual disease (MRD) in patients with acute lymphoblastic leukemia (ALL) after first relapse. At the end of remission reinduction, 41 patients had a bone marrow sample adequate for MRD studies; 35 of these were in morphologic remission. Of the 35 patients, 19 (54%) had MRD >/=0.01%, a finding that was associated with subsequent leukemia relapse. The 2-year cumulative incidence of second leukemia relapse was 70.2+/-12.3% for the 19 MRD-positive patients and 27.9+/-12.4% for the 16 MRD-negative patients (P=0.008). Among patients with a first relapse off therapy, 2-year second relapse rates were 49.1+/-17.8% in the 12 MRD-positive and 0% in the 11 MRD-negative patients (P=0.014); among those who received only chemotherapy after first relapse, the 2-year second relapse rates were 81.5+/-14.4% (n=12) and 25.0+/-13.1% (n=13), respectively (P=0.004). Time of first relapse and MRD were the only two significant predictors of outcome in a multivariate analysis. We conclude that MRD assays should be used to guide the selection of postremission therapy in patients with ALL in first relapse.     

Minimal residual disease tests provide an independent predictor of clinical outcome in adult acute lymphoblastic leukemia.

PURPOSE: Investigation of minimal residual disease (MRD) in childhood acute lymphoblastic leukemia (ALL) using molecular markers has proven superior to other standard criteria (age, sex, and WBC) in distinguishing patients at high, intermediate, and low risk of relapse. The aim of our study was to determine whether MRD investigation is valuable in predicting outcome in Philadelphia-negative adult patients with ALL. PATIENTS AND METHODS: MRD was assessed in 85 adult patients with B-lineage ALL by semiquantitative immunoglobulin H gene analysis on bone marrow samples collected during four time bands in the first 24 months of treatment. Fifty patients received chemotherapy only and 35 patients received allogeneic (n = 19) or autologous (n = 16) bone marrow transplantation (BMT) in first clinical remission. The relationship between MRD status and clinical outcome was investigated and compared with age, sex, immunophenotype, and presenting WBC count. RESULTS: Fisher's exact test established a statistically significant concordance between MRD results and clinical outcome at all times. Disease-free survival (DFS) rates for MRD-positive and -negative patients and log-rank testing established that MRD positivity was associated with increased relapse rates at all times (P <.05) but was most significant at 3 to 5 months after induction and beyond. MRD status after allogeneic BMT rather than before was found to be an important predictor of outcome in 19 adult patients with ALL tested. In patients receiving autologous BMT (n = 16), the MRD status before BMT was more significant (P =.005). CONCLUSION: The association of MRD test results and DFS was independent of and greater than other standard predictors of outcome and is therefore important in determining treatment for individual patients.     

Flow cytometry and allele-specific oligonucleotide PCR are equally effective in detection of minimal residual disease in ALL.

The analysis of minimal residual disease (MRD) has assumed a growing role in the follow-up of patients with acute lymphoblastic leukemia (ALL). We have applied multiparameter flow cytometry (FC) with 'live-gate' analysis and allele-specific oligonucleotide (ASO)-PCR detecting leukemia-specific T cell receptor gamma and delta gene rearrangements for MRD follow-up in 30 ALL patients. The comparison of results obtained in 89 follow-up samples from 23 patients showed significantly consistent results in 70 samples (78%); (P < 0.001). Bone marrow samples taken during the first phase of treatment (during or immediately after induction) showed a lower level of consistency when compared to samples taken during later phases of treatment (69% vs 85% consistent results, respectively). Some of the discrepant results were due to low cellularity of the samples obtained for FC and some due to the presence of PCR inhibitors. Of 29 patients evaluated at the end of the induction treatment, 18 (62%) had detectable levels of MRD and six of these patients suffered relapse. In all these patients MRD levels by FC increased preceding relapse. Our results suggest that FC offers a MRD detection tool that can be easily applied in clinical practice and is as informative as molecular methods.     

Pretransplant minimal residual disease level predicts clinical outcome in patients with acute myeloid leukemia receiving high-dose chemotherapy and autologous stem cell transplantation.

A total of 31 adult patients with AML entered in the EORTC/GIMEMA AML-10 trial, who received autologous stem cell transplantation (ASCT) after induction and consolidation chemotherapy, were prospectively evaluated for minimal residual disease (MRD) by multidimensional flow cytometry (MFC). Using a cutoff level of 3.5 x 10(-4) leukemic cells pre-ASCT, 12 patients (39%) were stratified to MRD high-risk group and 19 (61%) into MRD low-risk group. During follow-up, all patients who were in the high-risk group relapsed at a median time of 7 months; in the low-risk group, five patients relapsed at a median time of 11 months and 14 remained in remission for 56 (range 7-80) months (P=0.00004). Longitudinal MFC determinations post-ASCT showed increased MRD levels in three of the five patients who underwent subsequent relapse, while disease recurrence was unpredicted in the remaining two cases. The pre-ASCT MRD status was the factor most strongly associated with relapse risk in the multivariate analysis (P=0.0014). We conclude that: (1) pre-ASCT MRD status predicts successful outcome in patients receiving ASCT; (2) high-dose chemotherapy conditioning regimen followed by ASCT has no impact on the unfavorable prognostic value of high pre-ASCT MRD level; and (3) sequential MRD monitoring post-ASCT may allow the prediction of impending relapse.     

Minimal residual disease in early phase of chemotherapy reflects poor outcome in children with acute lymphoblastic leukemia--a retrospective study by the Children's Cancer and Leukemia Study Group in Japan

We analyzed the minimal residual disease (MRD) in 50 children with acute lymphoblastic leukemia (ALL) by amplifying the clonally rearranged T-cell receptor (TCR) gamma/delta chain and/or immunoglobulin (Ig) kappa chain gene using the allele-specific-PCR method. All children were treated according to the protocols of the Children's Cancer and Leukemia Study Group of Japan (CCLSG). The patients were stratified into four risk-groups according to the leukocyte count and age at diagnosis. We prospectively sampled the patients' bone marrow at 1 month (point 1) and 3 months (point 2) after the initiation of chemotherapy and quantitated the MRD retrospectively. The results of MRD were closely related with the clinical outcome. The relapse rate of the patients MRD-positive at points 1 and 2 was 46% (6/13) and 86% (6/7), respectively, whereas those MRD-negative results at point 1 and 2 were 13% (3/13) and 3% (3/30), respectively. We found significant differences in the event-free survival between MRD-positive children and MRD-negative children like the reports, which have been made by BFM and EORTC groups. We conclude that MRD in an early phase of chemotherapy can be a good predictor of the prognosis of childhood ALL regardless of the protocol of chemotherapy or race.     

Minimal Residual Disease in Adult Acute Lymphoblastic Leukemia: Egyptian Experience

Background: Acute lymphoblastic leukemia (ALL) is a clonal disease that affects early lymphoid progenitors in the bone marrow. Minimal residual disease (MRD) is assessed by different methods to monitor disease kinetics after treatment. Aim: to Assess MRD post-induction, at 6 and 12 months after intensive chemotherapy in adult patients with ALL. Patients and Methods:  Seventy adult newly diagnosed acute lymphoblastic leukaemia patients were enrolled between July 2018 and July 2019 at the Clinical Hematology Unit, Ain Shams University hospitals, Egypt. MRD was assessed on the bone marrow samples using multi-parameter four color flow cytometry with 0.01% cut-off; below which cases are deemed MRD negative. Results: After the end of induction period, 13 out of 46 patients (28%) had positive MRD. However, MRD positivity is demonstrable in 14/32(43.8%), and 10/28(35.7%) patients at 6 and 12 months; respectively. MRD positivity was significantly associated with older age group (more than 39 years) and high NCCN risk stratum with p-values <0.05. Moreover, most of MRD positive patients at 12 months of therapy were of T-ALL immunophenotype (P value 0.002).  Patients with complete remission and negative MRD exhibited significantly higher overall survival when compared to patients having MRD positivity (P value 0.027). Conclusion: MRD is a powerful predictor of outcome in ALL and its positivity at different time points is associated with poor prognostic factors as well as survival outcomes.     

Quantification of minimal residual disease in children with oligoclonal B-precursor acute lymphoblastic leukemia indicates that the clones that grow out during relapse already have the slowest rate of reduction during induction therapy.

Antigen receptor gene rearrangements are applied for the PCR-based minimal residual disease (MRD) detection in acute lymphoblastic leukemia (ALL). It is known that ongoing rearrangements result in subclone formation, and that the relapsing subclone(s) can contain antigen receptor rearrangement(s) that differ from the rearrangements found in the major clone(s) at diagnosis. However, the mechanism leading to this so-called clonal evolution is not known, particularly at which time point in the disease the relapsing subclone obtains its (relative) therapy resistance. To obtain insight in clonal evolution, we followed the kinetics of several subclones in three oligoclonal ALL patients during induction therapy. Clone-specific nested PCR for immunoglobulin heavy chain or T cell receptor delta gene rearrangements were performed in limiting dilution assays on bone marrow samples taken at diagnosis, at the end of induction therapy and at possible relapse in three children with oligoclonal B-precursor ALL. We demonstrated that in all three patients the subclones were behaving differently in response to therapy. Moreover, in the two patients who relapsed, the clones that grew out during relapse showed the slowest regression or even evoluated during induction therapy and the clones that were not present at relapse showed good response to induction therapy. These results support the hypothesis that at least in some patients already at diagnosis or in the very first weeks, subclones have important differences in respect to resistance. Hence, these data give experimental evidence for the need to develop, during the first months after diagnosis, quantitative PCR assays for at least two different Ig/TCR gene rearrangement targets for every ALL patient.     

Prediction of immunophenotype, treatment response, and relapse in childhood acute lymphoblastic leukemia using DNA microarrays.

Gene expression profiling is a promising tool for classification of pediatric acute lymphoblastic leukemia (ALL). We analyzed the gene expression at the time of diagnosis for 45 Danish children with ALL. The prediction of 5-year event-free survival or relapse after treatment by NOPHO-ALL92 or 2000 protocols resulted in a classification accuracy of 78% and a Matthew's correlation coefficient of 0.59 independently of immunophenotypes. The sensitivity and specificity for prediction of relapse were 87% and 69% respectively. Prediction of high vs low levels of the minimal residual disease (MRD) on day 29 (>/=0.1% or 相似文献   

Molecular detection of minimal residual disease is a strong predictive factor of relapse in childhood B-lineage acute lymphoblastic leukemia with medium risk features. A case control study of the International BFM study group.

The medium-risk B cell precursor acute lymphoblastic leukemia (ALL) accounts for 50-60% of total childhood ALL and comprises the largest number of relapses still unpredictable with diagnostic criteria. To evaluate the prognostic impact of minimal residual disease (MRD) in this specific group, a case control study was performed in patients classified and treated as medium (or intermediate)-risk according to the criteria of national studies (ALL-BFM 90, DCLSG protocol ALL-8, AIEOP-ALL 91), which includes a good day 7 treatment response. Standardized polymerase chain reaction (PCR) analysis of patient-specific immunoglobulin and T cell receptor gene (TCR) rearrangements were used as targets for semi-quantitative estimation of MRD levels: > or =10(-2), 10(-3), < or =10(-4). Twenty-nine relapsing ALL patients were matched with the same number of controls by using white blood cell count (WBC), age, sex, and time in first complete remission, as matching factors. MRD was evaluated at time-point 1 (end of protocol Ia of induction treatment, ie 6 weeks from diagnosis) and time-point 2 (before consolidation treatment, ie 3 months from diagnosis). MRD-based high risk patients (> or =10(-3) at both time-points) were more frequently present in the relapsed cases than in controls (14 vs 2), while MRD-based low risk patients (MRD negative at both time-points) (1 vs 18) showed the opposite distribution. MRD-based high risk cases experienced a significantly higher relapse rate than all other patients, according to the estimated seven-fold increase in the odds of failure, and a much higher rate than MRD-based low risk patients (OR = 35.7; P= 0.003). Using the Cox model, the prediction of the relapse-free interval at 4 years was 44.7%, 76.4% and 97.7% according to the different MRD categories. MRD-based risk group classification demonstrate their clinical relevance within the medium-risk B cell precursor ALL which account for the largest number of unpredictable relapses, despite the current knowledge about clinical and biological characteristics at diagnosis. Therefore, MRD detection during the first 3 months of follow-up can provide the tools to target more intensive therapy to those patients at true risk of relapse.     

Measurable Residual Disease Assessment and Allogeneic Transplantation as Consolidation Therapy in Adult Acute Lymphoblastic Leukemia in Colombia

IntroductionDetectable minimal residual disease (MRD) after therapy for acute lymphoblastic leukemia (ALL) is the strongest predictor of hematologic relapse. The objective of the study was to assess disease-free survival (DFS) and overall survival (OS) of patients with ALL according with MRD status at the end of induction therapy in a Colombian population.Patients and MethodsWe assessed a retrospective cohort to compare DFS and OS in adults with de novo ALL according to MRD status at the end of induction chemotherapy, and the type of postinduction consolidation strategy used.ResultsA total of 165 adults with ALL were included in the MRD part of the study, 73 patients in the MRD-negative group and 92 in the MRD-positive group. Median DFS for the MRD-positive group was 11 months (95% confidence interval, 11.7-22.2) and was not reached for the MRD-negative group (P < .001). At 3 years, DFS was 18% and 55%, respectively (P < .001). The median OS for MRD-positive patients was 16 months (95% confidence interval, 8.8-23.15) and was not reached in the MRD-negative group. At 3 years, OS was 26% and 51% for the former and latter group, respectively. Among subjects who did not receive a transplant, median DFS was 21 months for MRD-negative patients and 9 months for MRD-positive patients (P < .001). The median DFS was not reached in either group, whereas 3-year DFS was 64% for MRD-negative and 70% for MRD-positive patients who underwent transplantation in first remission (P = .861).ConclusionMRD status at the end of induction is an independent prognostic factor for DFS and OS in adult ALL. Allogeneic transplantation in first remission could overcome the adverse prognostic impact of MRD.     

Phase II study of topotecan in combination with dexamethasone, asparaginase, and vincristine in pediatric patients with acute lymphoblastic leukemia in first relapse

BACKGROUND: The authors evaluated the response rate, toxicity, and pharmacokinetics of topotecan given before standard induction therapy for childhood acute lymphoblastic leukemia (ALL) in first relapse. METHODS: Patients received topotecan (2.4 mg/m(2) daily as a 30-minute infusion) for 5 days before induction therapy with dexamethasone, vincristine, and asparaginase (native or pegylated Escherichia coli). The pharmacokinetics of topotecan were measured with the first dose of treatment in 23 patients. RESULTS: Twenty-eight of 31 patients with circulating blast cells were evaluable for response to topotecan. Twenty-five patients (89.3%) had a response (>25% decrease in circulating blast cells). The leukocyte count (P = .0001) and blast cell count (P = .0009) declined significantly during topotecan therapy. The median (range) topotecan lactone area under the concentration-time curve after the first dose was 85.4 L/hour/m(2) (range, 38.7-229.3 L/hour/m(2)). At the end of induction, 23 patients (74.2%) had a complete response, 1 patient (3.2%) had a partial response, 5 patients (16.1%) had no response, and 2 patients had died of infection. Six of the 17 patients who were studied for minimal residual disease (MRD) achieved MRD-negative status at the end of induction. The main toxicities were hematologic, gastrointestinal, and hepatic. The estimated 5-year survival rate, event-free survival rate, and cumulative incidence of second relapse were 24.1% +/- 7.9%, 18.2% +/- 7.4%, and 22.8% +/- 8.7%, respectively, in the 29 patients who had a hematologic first relapse. CONCLUSIONS: A regimen comprising single-agent topotecan given with a standard 3-drug combination was effective in inducing remission in pediatric patients with relapsed ALL and was tolerated well.     

Comparison of methods for assessment of minimal residual disease in childhood B-lineage acute lymphoblastic leukemia.

The level of minimal residual disease (MRD) early in treatment of acute lymphoblastic leukemia (ALL) strongly predicts the risk of marrow relapse. As a variety of methods of varying complexity have been separately used for detecting and quantifying MRD, we compared the prognostic utility of three methods measurement of blast percentage on day 14 of treatment, detection of monoclonality on day 14 or day 35, and measurement of MRD by PCR-based limiting dilution analysis on day 14 or day 35. The study group comprised 38 children aged 1-15 with Philadelphia-negative B-lineage ALL who were uniformly treated and followed until relapse or for a minimum of 5 years. We also studied some of the technical factors which influence the ability to detect MRD. Measurement of blast percentage on day 14 by an expert morphologist, detection of monoclonality on day 35, and PCR-based measurement of MRD levels on days 14 and 35 all showed significant ability to divide patients into prognostic groups. Measurement of blast percentage on day 14 by routine morphology or detection of monoclonality on day 14 were not useful. The quality of DNA samples varied greatly, as determined by amplifiability in the PCR. However, virtually all amplifiable leukemic targets in a sample were detectable which suggests that the level of detection achieved by limiting dilution analysis is essentially determined by the amount of DNA which it is practicable to study. We conclude that quantification of MRD at the end of induction provides the full range of prognostic information for marrow relapse but is complex; detection of monoclonality on day 35 is simple and has good positive predictive value; and quantification of MRD on day 14 merits further study. PCR-based methods for measurement of MRD levels should incorporate a correction for variation in DNA amplifiability.     

Relationship between Bax and Bcl-2 Protein Expression and Outcome of Induction Phase Chemotherapy in Pediatric Acute Lymphoblastic Leukemia

Background: Overexpression of the antiapoptotic protein Bcl-2 causes apoptosis to stop and conversely the increased expression of the proapoptotic protein Bax makes lymphoblasts easy to destroy. The Bax/Bcl-2 ratio plays a role in the balance of apoptosis, immortality, resistance, and outcome of chemotherapy. We analyzed the relationship between the Bax/BCl-2 ratio and the outcome of induction phase chemotherapy in pediatric Acute Lymphoblastic Leukemia (ALL). Methods: This research was conducted with a prospective observational study on pediatric ALL aged 1-18 years who were newly diagnosed based on bone marrow aspiration (morphology and immunophenotyping) at Dr. Soetomo General Hospital, Surabaya on October 2020 to March 2021. Expression of Bcl-2, Bax, and Bax/Bcl-2 protein ratio was measured by the flow cytometry method from lymphoblast on bone marrow aspirate samples before and after induction phase chemotherapy according to the 2018 Childhood ALL Indonesian Protocol. The outcomes evaluated were survival and remission rate (lymphoblasts in the bone marrow less than 5%). We used the Mann-Whitney U test and Wilcoxon Signed Rank test to analyze the differences between protein expression with p<0.05 for a two-tailed test. Results: We included 17/26 pediatric ALL, consisting of 88% male, 94% LLA-L1, 76% B cell ALL and 24% T cell ALL. Mean expression of Bax, Bcl-2, and Bax/Bcl-2 protein ratio before chemotherapy among pediatric ALL who alive (N=11) and dead (N=6) were not significantly different (p>0.05). All children who completed the induction phase of chemotherapy went into remission. Bax and Bcl-2 expression before and after chemotherapy showed no difference (p>0.05). The Bax/Bcl-2 ratio increased from 1.74(SD 1.846) to 6.17(4.139) with p=0.021. Conclusion: Expression of Bax, Bcl-2, and Bax/Bcl-2 protein ratio at the beginning of diagnosis did not affect the survival of pediatric ALL after the induction phase of chemotherapy. The Bax/Bcl-2 protein ratio increased 3.5 times in pediatric ALL with remission outcomes, indicating proapoptotic dominance.     

Immunologic monitoring in adults with acute lymphoblastic leukemia

Investigation of minimal residual disease (MRD) by immunophenotyping and molecular techniques has proven to be a powerful approach for disease monitoring in patients with acute leukemia. Multiparameter flow cytometry, through the use of triple or quadruple marker combinations, identifies aberrant or uncommon phenotypic profiles in more than 90% of adult patients with acute lymphoblastic leukemia (ALL) at diagnosis. These profiles allow identification of residual leukemic cells in bone marrow or peripheral blood once morphologic complete remission is achieved. Until now, most immunophenotypic MRD studies in ALL have focused on children. In contrast, information on the value of MRD in adults with ALL is scanty and usually restricted to polymerase chain reaction studies. In this review, we focus on technical aspects of MRD detection by flow cytometry and on the clinical data concerning the value of immunologic MRD studies as a tool for relapse prediction in adult ALL. Although prospective studies are needed, we assert that immunophenotypic MRD studies are clinically useful. Such studies should be incorporated into the routine management of adult ALL patients for identification of those at high risk of relapse, who could benefit from new alternative therapeutic approaches, and to distinguish these patients from others who could be cured with more conventional approaches.     

Methods of Detection of Measurable Residual Disease in AML

The presence of measurable (“minimal”) residual disease (MRD) after induction and/or consolidation chemotherapy is a significant risk factor for relapse in patients with acute myeloid leukemia (AML). In recognition of the clinical significance of AML MRD, the European LeukemiaNet (ELN) recently recommended the establishment of CR-MRD^Negative as a separate category of treatment response. This recommendation represents a major milestone in the integration of AML MRD testing in standard clinical practice. This review article summarizes the methodologies employed in AML MRD detection and their application in clinical studies that provide evidence supporting the clinical utility of AML MRD testing. Future MRD evaluations in AML likely will require an integrated approach combining multi-parameter flow cytometry and high-sensitivity molecular techniques applied to time points during and after completion of therapy in order to provide the most accurate and comprehensive assessment of treatment response.