Progress of minimal residual disease studies in childhood acute leukemia

Participation in the College of American Pathologists Laboratory Accreditation Program Decreases Variability in B-Lymphoblastic Leukemia and Plasma Cell Myeloma Flow Cytometric Minimal Residual Disease Testing: A Follow-up Survey

CONTEXT.—

Minimal residual disease (MRD) testing by flow cytometry is ubiquitous in hematolymphoid neoplasm monitoring, especially B-lymphoblastic leukemia (B-ALL), for which it provides predictive information and guides management. Major heterogeneity was identified in 2014. Subsequently, new Flow Cytometry Checklist items required documentation of the sensitivity determination method and required lower level of detection (LLOD) inclusion in final reports. This study assesses Laboratory Accreditation Program (LAP) participation and new checklist items' impact on flow cytometry MRD testing.

OBJECTIVES.—

To survey flow cytometry laboratories about MRD testing for B-ALL and plasma cell myeloma. In particular, enumerate the laboratories performing MRD testing, the proportion performing assays with very low LLODs, and implementation of new checklist items.

DESIGN.—

Supplemental questions were distributed in the 2017-A mailing to 548 flow cytometry laboratories subscribed to the College of American Pathologists FL3 Proficiency Testing Survey (Flow Cytometry-Immunophenotypic Characterization of Leukemia/Lymphoma).

RESULTS.—

The percentage of laboratories performing MRD studies has significantly decreased since 2014. Wide ranges of LLOD and collection event numbers were reported for B-ALL and plasma cell myeloma. Most laboratories determine LLOD by using dilutional studies and include it in final reports; a higher proportion of LAP participants used these practices than nonparticipants.

CONCLUSIONS.—

Several MRD testing aspects vary among laboratories receiving FL3 Proficiency Testing materials. After the survey in 2014, new checklist items were implemented. As compared to 2014, fewer laboratories are performing MRD studies. While LLOD remains heterogeneous, a high proportion of LAP subscribers follow the new checklist requirements and, overall, target LLOD recommendations from disease-specific working groups are met.

Influence of minimal residual disease by multiparametric flow cytometry at day 15 of induction in risk stratification of children with B-cell acute lymphoblastic leukemia treated at a referral hospital in southern Brazil

Background

The minimal residual disease (MRD) is the most important prognostic factor for acute lymphoblastic leukemia (ALL) in children. This study aimed to investigate the influence of detecting the MRD by the multiparametric flow cytometry (MFC) at day 15 (D15) of the induction on the analysis of the risk group classifications of the different childhood ALL treatment protocols used in a referral hospital in southern Brazil.

Method

We retrospectively reviewed the medical records of patients with B-cell ALL, aged 1 to 18 years, treated at a hospital from January 2013 to April 2017.

Main results

Seventy-five patients were analyzed. Regarding the MRD by the MFC at D15, the analyses showed statistical significance when the MRD was grouped into three categories, < 0.1%, 0.1–10%, and > 10%, with the following distribution: 30.7%, 52.0%, and 17.3%, respectively. There was a significant association between D15 MRD-MFC < 0.1% and the likelihood of dying or relapsing and between D15 MRD-MFC > 10% and the likelihood of dying or relapsing. The cumulative hazard ratio for the relapse of patients with D15 MRD-MFC < 0.1%, 0.1–10%, and > 10% was 19.2%, 59.8%, and 80.1%, respectively.

Conclusion

Our analysis suggests D15 MRD-MFC < 0.1% as a cut-off point for patients with more favorable outcomes and that the MRD at D15 in risk classifications is particularly useful for the stratification of patients with a more favorable prognosis.

Clinical Significance of Minimal Residual Disease at the End of Remission Induction Therapy in Childhood Acute Lymphoblastic Leukemia

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.

Bortezomib reinduction chemotherapy in high-risk ALL in first relapse: a report from the Children's Oncology Group

While survival in paediatric acute lymphoblastic leukaemia (ALL) is excellent, survival following relapse is poor. Previous studies suggest proteasome inhibition with chemotherapy improves relapse ALL response rates. This phase 2 Children's Oncology Group study tested the hypothesis that adding the proteasome inhibitor bortezomib to chemotherapy increases complete response rates (CR2). Evaluable patients (n = 135, 103 B-ALL, 22 T-ALL, 10 T-lymphoblastic lymphoma) were treated with reinduction chemotherapy plus bortezomib. Overall CR2 rates were 68 ± 5% for precursor B-ALL patients (<21 years of age), 63 ± 7% for very early relapse (<18 months from diagnosis) and 72 ± 6% for early relapse (18-36 months from diagnosis). Relapsed T-ALL patients had an encouraging CR2 rate of 68 ± 10%. End of induction minimal residual disease (MRD) significantly predicted survival. MRD negative (MRDneg; MRD <0·01%) rates increased from 29% (post-cycle 1) to 64% following cycle 3. Very early relapse, end-of-induction MRDneg precursor B-ALL patients had 70 ± 14% 3-year event-free (EFS) and overall survival (OS) rates, vs. 3-year EFS/OS of 0-3% (P = 0·0001) for MRDpos (MRD ≥0·01) patients. Early relapse patients had similar outcomes (MRDneg 3-year EFS/OS 58-65% vs. MRDpos 10-19%, EFS P = 0·0014). These data suggest that adding bortezomib to chemotherapy in certain ALL subgroups, such as T-cell ALL, is worthy of further investigation. This study is registered at http://www.clinical.trials.gov as NCT00873093.

T-Cell Receptor Rearrangements Determined Using Fragment Analysis in Patients With T-Acute Lymphoblastic Leukemia

Background

Chromosomal abnormalities and common genetic rearrangements related to T-acute lymphoblastic leukemia (T-ALL) are not clear. We investigated T-cell receptor (TCR) rearrangement in Korean T-ALL patients by fragment analysis, examining frequency, association between clinicopathologic characteristics and TCR clonality, and feasibility for detecting minimal residual disease (MRD).

Methods

In 51 Korean patients diagnosed as having T-ALL, TCR rearrangement was analyzed using the IdentiClone TCR gene clonality assay (InVivoScribe Technologies, San Diego, CA, USA) from archived bone marrow specimens. Limit of detection (LOD) and clonal stability at relapse were evaluated. The association between clinical prognosis and TCR clonality was examind by age and immunophenotypic classification.

Results

Thirty-eight patients (74.5%) had 62 clonal products of TCRβ, TCRγ, and/or TCRδ rearrangements at diagnosis. Children with T-ALL (<12 years) showed a higher frequency of clonality (93.8%) than adolescents/adults (65.7%; ≥12 years). Patients with a mature immunophenotype (84.4%) showed a relatively higher frequency of clonality than those with the immature immunophenotype (57.9%). Survival and event-free survival were not influenced by immunophenotype or TCR clonality. The LOD was 1%. Clonal evolution at the relapse period was noted.

Conclusions

The overall detection rate of TCR clonality was 74.5%. Survival did not differ by TCR clonality or immunophenotype and age group. Fragment analysis of TCR rearrangement cannot be used to assess MRD due to low sensitivity. Further research on the relationship between prognosis and frequency of TCR rearrangements is needed, using more sensitive methods to detect clonality and monitor MRD.

[Clinical application of minimal residual disease detection in childhood acute leukemia]

In recent years, great progress has been made in the treatment outcome of childhood acute leukemia with the improvement of chemotherapy regimens and the introduction of risk-stratified therapy; however, minimal residual disease (MRD) is still a difficult problem which affects the prognosis of acute leukemia. MRD influences the selection of chemotherapy regimens and recurrence risk stratification, and meanwhile, it can be used for prognostic prediction. At present, flow cytometry and polymerase chain reaction are mainly used for MRD detection. The next-generation sequencing also plays an important role in MRD detection, especially in MRD detection after stem cell transplantation. This article reviews the methodology and significance of MRD detection in childhood acute leukemia.

[Clinical application of minimal residual disease detection in childhood acute leukemia]

In recent years, great progress has been made in the treatment outcome of childhood acute leukemia with the improvement of chemotherapy regimens and the introduction of risk-stratified therapy; however, minimal residual disease (MRD) is still a difficult problem which affects the prognosis of acute leukemia. MRD influences the selection of chemotherapy regimens and recurrence risk stratification, and meanwhile, it can be used for prognostic prediction. At present, flow cytometry and polymerase chain reaction are mainly used for MRD detection. The next-generation sequencing also plays an important role in MRD detection, especially in MRD detection after stem cell transplantation. This article reviews the methodology and significance of MRD detection in childhood acute leukemia.

Perceptions of parents and paediatricians on pain induced by bone marrow aspiration and lumbar puncture among children with acute leukaemia: a qualitative study in China

OBJECTIVE

To obtain in-depth insight into the perceptions of parents and paediatricians in China regarding current procedural pain management on bone marrow aspirations and lumbar punctures in paediatric haemato-oncology department.

DESIGN, SETTING AND PARTICIPANTS

This qualitative study was conducted in a 4500-bed university hospital in northwest China. To collect data, in-depth semistructured interviews were conducted with parents of children with acute leukaemia (n=12) and haemato-oncology paediatricians (n=11) using purposive sampling. Interviews were audiotaped and transcribed and subjected to thematic analysis.

RESULTS

The suffering of procedural pain among paediatric patients was not adequately recognised and properly treated at the paediatric haemato-oncology department. The current paediatric procedural pain management is inadequate for paediatric patients. Crucial factors were identified including lack of awareness about the damage of uncontrolled pain in children, parents' low supportive ability, the limited capacity to provide general analgesia by anaesthetists, inadequate knowledge in the usage of analgesia and sedation and lack of efficient analgesic for children's procedural pain. The participants strongly expected optimal interventions to improve paediatric procedural pain management.

CONCLUSIONS

The result suggested a perceived and actual poor management of paediatric procedural pain in haemato-oncology department in northwest China. A relevant pain management education programme for paediatricians and parents as well as an effective pain medication are urgently needed in northwest China.

TRIAL REGISTRATION

Chinese Clinical Trial Registry. Identifier: ChiCTR-INR-16007989.

Real-world outcomes of treatment for acute lymphoblastic leukemia during adolescence in a financially restricted environment: Results at a single center in Latin America

OBJECTIVE

There is a paucity of the studies of adolescents with acute lymphoblastic leukemia (ALL). This is more noticeable in low- and middle-income countries. The international 5-year event-free survival (EFS) and overall survival (OS) for this age group is around 80%, with pediatric-inspired protocols offering better results.

METHODS

A retrospective analysis of adolescents aged 16-20 diagnosed with ALL during the period 2004-2015 treated with a high-risk pediatric protocol at an academic center from a middle-income country was performed. Five-year OS and EFS were estimated by the Kaplan-Meier analysis. Hazard ratios of relapse and death were estimated by the Cox regression model.

RESULTS

Five-year EFS and OS for 57 adolescents were 23.3% and 48.9%, respectively. From the 41 patients who achieved complete remission, 24 (58.5%) relapsed. Bone marrow and central nervous system were the most frequent sites of relapse. Hazard ratio of treatment failure and death for patients with organomegaly at diagnosis was 2.026 and 2.970, respectively. Treatment-related toxicity developed in 31 (54.4%) patients and febrile neutropenia was the most frequent in 14 (24.6%) cases. Twelve patients (21.1%) had poor adherence to treatment.

CONCLUSIONS

High relapse rate and low 5-year EFS compared with international standards, was documented. Use of intensified pediatric regimens, adherence to proven effective medications, improved supportive care, and prevention of abandonment are necessary to improve survival rates in these patients.

Relapse of childhood acute lymphoblastic leukemia and outcomes at a reference center in Latin America: organomegaly at diagnosis is a significant clinical predictor

OBJECTIVE

Relapse is the major cause of treatment failure in acute lymphoblastic leukemia (ALL) of childhood; it is more frequent among high-risk patients from low-middle income than from high-income countries. The frequency, sites and outcome of relapsed ALL in children of northeast Mexico over a decade was documented.

METHODS

A retrospective analysis of 246 children belonging to a low-income group <16 years with de novo ALL during 2004-2015 was performed. Five-year overall survival (OS) and event-free survival was estimated by Kaplan-Meier analysis. Data on time, site, response to therapy and final outcome of relapse were analyzed. Hazard ratios (HRs) of relapse and death were estimated by the Cox regression model. Very early relapse was defined as that occurring in <18 months, early relapse between 18 and 36 months, and late relapse >36 months from diagnosis, respectively.

RESULTS

Eighty-seven (35.4%) children relapsed. Five-year OS was 82.6% in children without relapse vs. 42% for relapsed patients. Bone marrow (BM) was the most frequent site of relapse (51.72%). Isolated central nervous system (CNS) relapses occurred in 29.9%. Five-year OS was 11.2% for BM and 15.5% for early relapse. HR of relapse for organomegaly was 3.683, 2.247 for an initial white blood cell count >50 000 × 10⁹/l and 1.169 for positive minimal residual disease status.

CONCLUSION

A high rate of very early, CNS, and BM relapse with a considerably low 5-year OS requiring reassessment of therapy was documented. Organomegaly at diagnosis was a highly significant clinical predictor for relapse.

Evaluation of new markers for minimal residual disease monitoring in B-cell precursor acute lymphoblastic leukemia: CD73 and CD86 are the most relevant new markers to increase the efficacy of MRD 2016; 00B: 000-000

BACKGROUND

Multiparametric flow cytometry (MFC) is a popular technique for minimal residual disease (MRD) analysis. However, its applicability is still limited to 90% of B-cell precursor acute lymphoblastic leukemia (BCPALL) due to two major issues, i.e. a proportion of cases do not express adequate leukemia associated immunophenotype (LAIPs) with currently used markers and drug-induced antigen modulation. Hence, the incorporation of additional reliable markers is required for the further improvement of MFC-based MRD evaluation. We studied the utility of new markers in improvising MFC-based MRD detection in BCPALL.

METHODS

Expression-patterns of six new markers, i.e. CD24, CD44, CD72, CD73, CD86, and CD200 were studied in leukemic-blasts from ninety childhood BCPALL patients and in hematogones from 20 uninvolved staging bone marrow (BM) and ten postinduction non-BCPALL BM samples using eight-color MFC. The utility of these new markers in the day 35 postinduction MRD evaluation was determined.

RESULTS

Frequencies of LAIPs of CD73, CD86, CD72, CD44, CD200, and CD24 in diagnostic samples were 76.7, 56.7, 55.6, 50, 28.9, and 20%, respectively. Differential expression of all new markers was highly significant (P < 0.01) between early (CD10+ CD19+ CD34+) hematogones, late (CD10+ CD19+ CD34-) hematogones and BCPALL blasts except between early hematogones and BCPALL blasts for CD200 (P = 0.1). In MRD-positive samples, CD73 showed the maximum (83%) frequency of LAIP and CD86 showed the highest (100%) stability of aberrant expression. Inclusion of CD73 and CD86 increased the applicability of MFC-MRD assay to 98.9% MRD samples.

CONCLUSION

CD73 and CD86 are the most relevant markers to incorporate in the routine MRD evaluation of BCPALL. © 2016 International Clinical Cytometry Society.

Current Strategies for the Detection of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common cancer in children. Current treatment strategies for childhood ALL result in long-term remission for approximately 90% of patients. However, the therapeutic response is worse among those who relapse. Several risk stratification approaches based on clinical and biological aspects have been proposed to intensify treatment in patients with high risk of relapse and reduce toxicity on those with a greater probability of cure.

The detection of residual leukemic cells (minimal residual disease, MRD) is the most important prognostic factor to identify high-risk patients, allowing redefinition of chemotherapy. In the last decades, several standardized research protocols evaluated MRD using immunophenotyping by flow cytometry and/or real-time quantitative polymerase chain reaction at different time points during treatment. Both methods are highly sensitive (10⁻³ a 10⁻⁵), but expensive, complex, and, because of that, require qualified staff and frequently are restricted to reference centers.

The aim of this article was to review technical aspects of immunophenotyping by flow cytometry and real-time quantitative polymerase chain reaction to evaluate MRD in ALL.

Effects of dendritic cell-activated and cytokine-induced killer cell therapy on 22 children with acute myeloid leukemia after chemotherapy

The efficiency of dendritic cell-activated and cytokine-induced killer cell (DC-CIK) therapy on children with acute myeloid leukemia (AML) after chemotherapy was investigated. Mononuclear cells were collected from children achieving complete remission after chemotherapy, cultured in vitro and transfused back into the same patient. Interleukin-2 (IL-2) was injected subcutaneously every other day 10 times at the dose of 1 × 10(6) units. Peripheral blood lymphocyte subsets and minimal residual disease (MRD) were detected by flow cytometry. Function of bone marrow was monitored by methods of morphology, immunology, cytogenetics and molecular biology. The side effects were also observed during the treatment. The average follow-up period for all the 22 patients was 71 months and relapse occurred in two AML patients (9.1%). The percentage of CD3(+)/CD8(+) cells in peripheral blood of 15 patients at the 3rd month after DC-CIK treatment (36.73% ± 12.51%) was dramatically higher than that before treatment (29.20% ± 8.34%, P < 0.05). The MRD rate was >0.1% in 5 patients before the treatment, and became lower than 0.1% 3 months after the treatment. During the transfusion of DC-CIK, side effects including fever, chills and hives appeared in 7 out of 22 (31.82%) cases but disappeared quickly after symptomatic treatments. There were no changes in electrocardiography and liver-renal functions after the treatment. MRD in children with AML can be eliminated by DC-CIK therapy which is safe and has fewer side effects.

Inhibition of tumor necrosis factor-α enhances apoptosis induced by nuclear factor-κB inhibition in leukemia cells

Inhibition of nuclear factor-κB (NF-κB) results in antitumor activity in leukemia cells, and may be a potential therapeutic strategy for the treatment of leukemia. However, a significant limitation of NF-κB inhibition in the treatment of leukemia is the low efficiency of this technique. NF-κB inhibitor treatment induces apoptosis in leukemia cells; however, it additionally causes inflammatory molecules to induce increased sensitivity of healthy hematopoietic cells to cell death signals, therefore limiting its clinical applications. Tumor necrosis factor-α (TNF-α) is a key regulator of inflammation, and induces a variety of actions in leukemic and healthy hematopoietic cells. TNF-α induces NF-κB-dependent and -independent survival signals, promoting the proliferation of leukemia cells. However, in healthy hematopoietic cells, TNF-α induces death signaling, an effect which is enhanced by the inhibition of NF-κB. Based on these observations, the present study hypothesized that inhibition of TNF-α signaling may be able to protect healthy hematopoietic cells and other tissue cells, while increasing the anti-leukemia effects of NF-κB inhibition on leukemia cells. The role and underlying molecular mechanisms of TNF-α inhibition in the regulation of NF-κB inhibition-induced apoptosis in leukemia cells was therefore investigated in the present study. The results indicated that inhibition of TNF-α enhanced NF-κB inhibition-induced apoptosis in leukemia cells. It was also revealed that protein kinase B was significant in the regulation of TNF-α and NF-κB inhibition-induced apoptosis. During this process, intrinsic apoptotic pathways were activated. A combination of NF-κB and TNF-α inhibition may be a potential specific and effective novel therapeutic strategy for the treatment of leukemia.

Transcriptome Analysis of Minimal Residual Disease in Subtypes of Pediatric B Cell Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer and the leading cause of cancer-related death in children and adolescents. Minimal residual disease (MRD) is a strong, independent prognostic factor. The objective of this study was to identify molecular signatures distinguishing patients with positive MRD from those with negative MRD in different subtypes of ALL, and to identify molecular networks and biological pathways deregulated in response to positive MRD at day 46. We compared gene expression levels between patients with positive MRD and negative MRD in each subtype to identify differentially expressed genes. Hierarchical clustering was applied to determine their functional relationships. We identified subtype-specific gene signatures distinguishing patients with positive MRD from those with negative MRD. We identified the genes involved in cell cycle, apoptosis, transport, and DNA repair. We also identified molecular networks and biological pathways dysregulated in response to positive MRD, including Granzyme B, B-cell receptor, and PI3K signaling pathways.

Minimal residual disease analysis by eight-color flow cytometry in relapsed childhood acute lymphoblastic leukemia

Multiparametric flow cytometry is an alternative approach to the polymerase chain reaction method for evaluating minimal residual disease in treatment protocols for primary acute lymphoblastic leukemia. Given considerable differences between primary and relapsed acute lymphoblastic leukemia treatment regimens, flow cytometric assessment of minimal residual disease in relapsed leukemia requires an independent comprehensive investigation. In the present study we addressed evaluation of minimal residual disease by flow cytometry in the clinical trial for childhood relapsed acute lymphoblastic leukemia using eight-color flow cytometry. The major challenge of the study was to reliably identify low amounts of residual leukemic cells against the complex background of regeneration, characteristic of follow-up samples during relapse treatment. In a prospective study of 263 follow-up bone marrow samples from 122 patients with B-cell precursor acute lymphoblastic leukemia, we tested various B-cell markers, adapted the antibody panel to the treatment protocol, and evaluated its performance by a blinded parallel comparison with the polymerase chain reaction data. The resulting eight-color single-tube panel showed a consistently high overall concordance (P<0.001) and, under optimal conditions, sensitivity similar to that of the reference polymerase chain reaction method. Overall, evaluation of minimal residual disease by flow cytometry can be successfully integrated into the clinical management of relapsed childhood acute lymphoblastic leukemia either as complementary to the polymerase chain reaction or as an independent risk stratification tool. ALL-REZ BFM 2002 clinical trial information: NCT00114348.

Marked Variability in Reported Minimal Residual Disease Lower Level of Detection of 4 Hematolymphoid Neoplasms: A Survey of Participants in the College of American Pathologists Flow Cytometry Proficiency Testing Program

Context

Flow cytometry is often applied to minimal residual disease (MRD) testing in hematolymphoid neoplasia. Because flow-based MRD tests are developed in the laboratory, testing methodologies and lower levels of detection (LODs) are laboratory dependent.

Objectives

To broadly survey flow cytometry laboratories about MRD testing in laboratories, if performed, including indications and reported LODs.

Design

Voluntary supplemental questions were sent to the 549 laboratories participating in the College of American Pathologists (CAP) FL3-A Survey (Flow Cytometry—Immunophenotypic Characterization of Leukemia/Lymphoma) in the spring of 2014.

Results

A total of 500 laboratories (91%) responded to the supplemental questions as part of the FL3-A Survey by April 2014; of those 500 laboratories, 167 (33%) currently perform MRD for lymphoblastic leukemia, 118 (24%) for myeloid leukemia, 99 (20%) for chronic lymphocytic leukemia, and 91 (18%) for plasma cell myeloma. Other indications include non-Hodgkin lymphoma, hairy cell leukemia, neuroblastoma, and myelodysplastic syndrome. Most responding laboratories that perform MRD for lymphoblastic leukemia reported an LOD of 0.01%. For myeloid leukemia, chronic lymphocytic leukemia, and plasma cell myeloma, most laboratories indicated an LOD of 0.1%. Less than 3% (15 of 500) of laboratories reported LODs of 0.001% for one or more MRD assays performed.

Conclusions

There is major heterogeneity in the reported LODs of MRD testing performed by laboratories subscribing to the CAP FL3-A Survey. To address that heterogeneity, changes to the Flow Cytometry Checklist for the CAP Laboratory Accreditation Program are suggested that will include new requirements that each laboratory (1) document how an MRD assay's LOD is measured, and (2) include the LOD or lower limit of enumeration for flow-based MRD assays in the final diagnostic report.

Detection of minimal residual disease in B lymphoblastic leukemia by high-throughput sequencing of IGH

PURPOSE

High-throughput sequencing (HTS) of immunoglobulin heavy-chain genes (IGH) in unselected clinical samples for minimal residual disease (MRD) in B lymphoblastic leukemia (B-ALL) has not been tested. As current MRD-detecting methods such as flow cytometry or patient-specific qPCR are complex or difficult to standardize in the clinical laboratory, sequencing may enhance clinical prognostication.

EXPERIMENTAL DESIGN

We sequenced IGH in paired pretreatment and day 29 post-treatment samples using residual material from consecutive, unselected samples from the Children's Oncology Group AALL0932 trial to measure MRD as compared with flow cytometry. We assessed the impact of ongoing recombination at IGH on MRD detection in post-treatment samples. Finally, we evaluated a subset of cases with discordant MRD results between flow cytometry and sequencing.

RESULTS

We found clonal IGH rearrangements in 92 of 98 pretreatment patient samples. Furthermore, while ongoing recombination of IGH was evident, index clones typically prevailed in MRD-positive post-treatment samples, suggesting that clonal evolution at IGH does not contribute substantively to tumor fitness. MRD was detected by sequencing in all flow cytometry-positive cases with no false-negative results. In addition, in a subset of patients, MRD was detected by sequencing, but not by flow cytometry, including a fraction with MRD levels within the sensitivity of flow cytometry. We provide data that suggest that this discordance in some patients may be due to the phenotypic maturation of the transformed cell.

CONCLUSION

Our results provide strong support for HTS of IGH to enhance clinical prognostication in B-ALL.

Validation of DNA methylation biomarkers for diagnosis of acute lymphoblastic leukemia

BACKGROUND

DNA methylation biomarkers capable of diagnosis and subtyping have been found for many cancers. Fifteen such markers have previously been identified for pediatric acute lymphoblastic leukemia (ALL). Validation of these markers is necessary to assess their clinical utility for molecular diagnostics. Substantial efficiencies could be achieved with these DNA methylation markers for disease tracking with potential to replace patient-specific genetic testing.

METHODS

We evaluated DNA methylation of promoter regions of TLX3 (T-cell leukemia homeobox) and FOXE3 (forkhead box E3) in bone marrow biopsies from 197 patients classified as leukemic (n = 95) or clear of the disease (n = 102) by MALDI-TOF. Using a single nucleotide extension assay (methylSABER), we tested 10 bone marrow biopsies collected throughout the course of patient chemotherapy. Using reference materials, diagnostic thresholds and limits of detection were characterized for both methods.

RESULTS

Reliable detection of DNA methylation of TLX3 and FOXE3 segregated ALL from those clear of disease with minimal false-negative and false-positive results. The limit of detection with MALDI-TOF was 1000-5000 copies of methylated allele. For methylSABER, the limit of detection was 10 copies of methylated TLX3, which enabled monitoring of minimal residual disease in ALL patients.

CONCLUSIONS

Mass spectrometry procedures can be used to regionally multiplex and detect rare DNA methylation events, establish DNA methylation loci as clinically applicable biomarkers for disease diagnosis, and track pediatric ALL.

Treatment of Philadelphia-positive acute lymphoid leukemia

SUMMARY Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) represents approximately 15–30% of ALL in adults and is characterized by the expression of the fusion protein BCR–ABL with oncogenic activity. Remission and survival rates were lower whereas relapse risk was increased in Ph+ compared with Philadelphia-negative ALL, until remarkable improvements in the management of Ph+ ALL were achieved through the introduction of tyrosine kinase inhibitors that reduce the activity of the BCR–ABL protein. However, in patients achieving complete remission, allogeneic hematopoietic stem cell transplantation is in most cases a mandatory therapeutic step because rate of relapses are still high. This review will illustrate the current therapeutic options for the management of Ph+ ALL and indicate how better curative options may stem from appropriate implementation of tyrosine kinase inhibitors and novel antitumoral agents.

Prognostic significance of flow cytometric residual disease, dysregulated neutrophils/monocytes, and hematogones in adult acute myeloid leukemia in first remission

Fifty-one consecutive non-M3 acute myeloid leukemia (AML) patients who had achieved morphologic complete remission (mCR) after induction chemotherapy were enrolled in the present study. Three characteristics of bone marrow (BM) composition analyzed by flow cytometry were combined to determine the prognostic impact. A standardized panel of reagents was used to detect residual disease of aberrant myeloid progenitor cells (RD), identify neutrophils/monocytes with dysregulated immunophenotype (dysregulated neutro/mono) and quantify the appearance of CD34(+) B-progenitor-related cluster (hematogones) simultaneously in post-induction BM of adult AML patients. Patients who had detectable RD ≥0.2 % exhibited significantly lower median leukemia-free survival (LFS) than those who did not (13.5 vs. 48.0 months; P = 0.042). Dysregulated neutro/mono abnormalities assessed by this flow cytometric scoring system (FCSS ≥2) predicted shorter LFS (8.0 vs. 39.0 months; P = 0.008). While B-progenitor-related cluster size ≥5 % predicted improved outcome, with longer LFS (not reached vs. 13.5 months; P = 0.023) and better overall survival (not reached vs. 24.0 months; P = 0.027). The proposed RD/dysregulated neutro/mono/hematogones score showed a new risk groups with different LFS in the overall patients (P = 0.0006) as well as in the subgroup of intermediate cytogenetic risk (P = 0.001). The RD/dysregulated neutro/mono/hematogones score assessed by flow cytometry for adult AML in mCR may offer a rapid and practical risk assessment providing better refinement in risk-adapted management after induction chemotherapy.

Use of allogeneic hematopoietic stem-cell transplantation based on minimal residual disease response improves outcomes for children with relapsed acute lymphoblastic leukemia in the intermediate-risk group

PURPOSE

In children with intermediate risk of relapse of acute lymphoblastic leukemia (ALL), it is essential to identify patients in need of treatment intensification. We hypothesized that the prognosis of patients with unsatisfactory reduction of minimal residual disease (MRD) can be improved by allogeneic hematopoietic stem-cell transplantation (HSCT).

PATIENTS AND METHODS

In the Acute Lymphoblastic Leukemia-Relapse Study of the Berlin-Frankfurt-Münster Group (ALL-REZ BFM) 2002, patients with an MRD level of ≥ 10(-3) (n = 99) at the end of induction therapy were allocated to HSCT, whereas those with an MRD level less than 10(-3) (n = 109) continued to receive chemotherapy. MRD was quantified by real-time polymerase chain reaction for clone-specific T-cell receptor/immunoglobulin gene rearrangements.

RESULTS

The probability of event-free survival for patients with MRD ≥ 10(-3) was 64% ± 5% in ALL-REZ BFM 2002 compared with 18% ± 7% in the predecessor study ALL-REZ BFM P95/96 (P < .001). This was mainly achieved by reducing the cumulative incidence of subsequent relapse (CIR) at 8 years from 59% ± 9% to 27% ± 5% (P < .001). The favorable prognosis of patients with MRD less than 10(-3) could be confirmed in those with a late combined or isolated bone marrow B-cell precursor (BCP) -ALL relapse (CIR, 20% ± 5%), whereas patients with an early combined BCP-ALL relapse had an unfavorable outcome (CIR, 63% ± 13%; P < .001).

CONCLUSION

Allogeneic HSCT markedly improved the prognosis of patients with intermediate risk of relapse of ALL and unsatisfactory MRD response. As a result, outcomes in this group approximated those of patients with favorable MRD response. Patients with early combined relapse require treatment intensification even in case of favorable MRD response, demonstrating the prognostic impact of time to relapse.

Multistep targeted nano drug delivery system aiming at leukemic stem cells and minimal residual disease

Refractory leukemia remains the most common therapeutic problem in clinical treatment of leukemia. The key therapy of refractory leukemia is to kill, thoroughly, the minimal residual disease and leukemia stem cells in the highly vascularized red marrow areas. In this study, two new conjugates, alendronate-polyethylene glycol (100) monostearate and folate-polyethylene glycol (100) monostearate, were synthesized to develop a multistep targeting nanostructured lipid carriers by enhancing drug transport to the high bone turnover areas adjacent to the red marrow and targeting the minimal residual disease and leukemia stem cells. This dual targeting system demonstrated a great binding affinity to hydroxyapatite, a model component of bone minerals, and higher cell uptake (in the form of carriers but not drug) and cytotoxicity in the K562 cell line, a leukemia cell line with overexpressed folate receptors, were observed in vitro compared to unmodified carriers, especially when the cells were pretreated and the receptors were up-regulated by all-trans retinoic acid. The comodel test of K562 cells and HA showed that this dual targeting system could desorb from bone surface and be taken up by leukemia cells. For the in vivo study, this dual targeting system exhibited a significant increase in plasma half-life and could specifically accumulate in the bone tissue of rats or mice after intravenous injection. Ex vivo imaging of mice femurs and confocal laser scanning microscope imaging of mice femur slices further confirmed that this dual targeting system could favorably deposit to the osteoblast-enriched areas of high bone turnover in regions of trabecular bone surrounded by red marrow. In vivo antitumor activity in K562/BALB/c-nu leukemia mice showed that the treatment of this dual targeting system significantly reduced the white blood cell (WBC) number in peripheral blood and bone marrow to the normal level. In conclusion, this dual targeting system could precisely target to the regions where the minimal residual disease and leukemia stem cells are located and then be specifically uptaken in large amounts, which is a valuable target for refractory leukemia therapy.

Engraftment of low numbers of pediatric acute lymphoid and myeloid leukemias into NOD/SCID/IL2Rcγnull mice reflects individual leukemogenecity and highly correlates with clinical outcome

Although immortalized cell lines have been extensively used to optimize treatment strategies in cancer, the usefulness of such in vitro systems to recapitulate primary disease is limited. Therefore, the design of in vivo models ideally utilizing patient-derived material is of critical importance. In this regard, NOD.Cg-Prkdc(scid) IL2rg(tmWjl) /Sz (NSG) mice have been reported to provide superior engraftment rates. However, limited data exist on the validity of such a model to constitute a surrogate marker for clinical parameters. We studied primary and serial engraftment on more than 200 NSG mice with 54 primary pediatric B cell precursor acute lymphatic leukemia (B-ALL), myeloid leukemia (AML) and T cell leukemia (T-ALL) samples, characterized the leukemogenic profile and correlated engraftment kinetics with clinical outcome. Median time to engraftment was 7-10 weeks and 90% of the mice engrafted. Male recipients conferred significantly higher engraftment levels than female recipients (p ≤ 0.004). PCR-based minimal residual disease marker expression and fluorescence in situ hybridization confirmed the presence of patient-specific genetic aberrations in mice. Transcriptome cluster analysis of genes known to be important in the leukemogenesis of all three diseases revealed that well-known tumor-regulating genes were expressed to a comparable extent in mice and men. The extent of engraftment and overall survival of NSG mice highly correlated with the individual prognosis of B-ALL, AML and T-ALL patients. Thus, we propose an in vivo model that provides a valuable preclinical tool to explore the heterogeneity of leukemic disease and exploit patient-tailored leukemia-targeting strategies within multivariate analyses.

The degree of tumor volume reduction during the early phase of induction chemotherapy is an independent prognostic factor in patients with high-risk neuroblastoma

BACKGROUND

In patients with high-risk neuroblastoma, the reduction in primary tumor volume was measured during the early phase of induction chemotherapy as an indicator of early tumor response, and the authors investigated whether the degree of tumor volume reduction could predict outcome in these patients.

METHODS

Primary tumor volumes were measured both at diagnosis and at the first tumor response evaluation (after 2 or 3 cycles of induction chemotherapy) in 90 patients with high-risk neuroblastoma who had volumetrically evaluable computed tomography or magnetic resonance scans. If the tumor volume at the first response evaluation was >40% of the initial tumor volume, then the patient was categorized as a poor responder; otherwise, the patient was categorized as a good responder. Outcomes were compared according to the degree of tumor volume reduction at the first response evaluation.

RESULTS

The tumor volume reduction was greater in patients who remained relapse free than in patients who had a relapsed tumor (median percentage tumor volume, 21% vs 41.5%; P = .037). The 5-year relapse-free survival rate was higher in the good responders than in the poor responders (83% [95% confidence interval, 72%-94%] vs 51% [95% confidence interval, 31%-71%]; P = .002). In a multivariate analysis of relapse-free survival, a poor early response was identified as an independent, unfavorable prognostic factor (hazard ratio, 4.24; 95% confidence interval, 1.59-11.29; P = .004).

CONCLUSIONS

A greater reduction in tumor volume reduction the early phase of induction chemotherapy was associated with a better outcome in patients with high-risk neuroblastoma. Tailoring treatment intensity according to the early tumor response to induction chemotherapy may improve patient outcomes.

Prognostic and therapeutic implications of minimal residual disease at the time of transplantation in acute leukemia

Relapse remains the major cause of treatment failure after hematopoietic cell transplantation (HCT) in acute leukemia, even in patients transplanted in morphologic CR. Various techniques now enable the sensitive quantification of 'minimal' amounts of residual disease (MRD) in patients with acute leukemia in remission. Numerous studies convincingly demonstrate that MRD at the time of transplantation is a powerful, independent predictor of subsequent relapse, with current detection levels of one leukemic cell in 10(5)-10(6) normal cells being prognostically relevant. This recognition provides the rationale to assign patients with detectable MRD (that is, 'MRD(+)' patients) to intensified therapies before, during, or after transplantation, although data supporting these strategies are still sparse. Limited evidence from observational studies suggests that outcomes with autologous HCT are so poor that MRD(+) patients should preferentially be assigned to allogeneic HCT, which can cure a subgroup of these patients, particularly if unmanipulated (T-cell replete) grafts and/or minimized immunosuppression are used to optimize the graft-vs-leukemia effect. Emerging data suggest that additional therapy with non-cross-resistant agents to decrease residual tumor burden before transplantation in MRD(+) patients might be beneficial. Further, other studies hint at immunotherapy (for example, rapid withdrawal of immunosuppression and/or donor lymphocyte infusions) as a means to prevent overt relapse if patients remain, or become, MRD(+) after HCT. Ultimately, controlled clinical studies are needed to define the value of MRD-directed therapies, and patients should be encouraged to enter such trials.

Allogeneic hematopoietic cell transplantation for acute lymphoblastic leukemia in adults

PURPOSE OF REVIEW

Acute lymphoblastic leukemia (ALL) is a heterogeneous disease, for which treatment guidelines are still evolving. Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapeutic modality for ALL, and this review describes the recent studies and current practice patterns concerning the who, when, and how of allo-HCT in the management of ALL.

RECENT FINDINGS

Allogeneic stem cell transplantation is the treatment of choice for patients with ALL after first relapse and is also recommended for high-risk patients in first complete remission (CR1). Minimal residual disease evaluation and monitoring is developing as an important prognostic factor and could guide physicians in determining which patients, especially those with standard risk, might require transplant. Tyrosine kinase inhibitor (TKI) therapy allows a much higher proportion of Philadelphia-chromosome-positive ALL patients to attain remission and proceed to transplant with improved results; posttransplant TKI maintenance therapy may also provide survival benefit. Reduced-intensity conditioning regimens are a reasonable alternative for patients who would otherwise be ineligible for transplant because of age or comorbidity.

SUMMARY

For patients with high-risk features, there is general agreement that allo-HCT in CR1 is a potentially curative option; however, there is no consensus on early transplant for standard-risk patients.

Beyond morphology: minimal residual disease detection in acute myeloid leukemia

PURPOSE OF REVIEW

Improved laboratory diagnostics over the past decade has resulted in identifiable genetic alterations and/or abnormal expression patterns in the majority of acute myeloid leukemia (AML). These leukemic patterns can then be monitored once patients achieve a morphologic remission. The role of various methodologies to detect minimal residual disease (MRD) in AML is reviewed, as well as the emerging role of MRD detection in prognostication and treatment decisions.

RECENT FINDINGS

Assessment of MRD in AML is now possible using updated methods including real-time quantitative PCR (RQ-PCR) for abnormal fusion transcripts, RQ-PCR for proteins known to be overexpressed in AML such as Wilms' tumor gene, and multiparameter flow cytometry to detect leukemia-associated phenotypes. Using these techniques, MRD analysis has shown value in terms of risk assessment, continued patient monitoring, and for therapeutic decision-making.

SUMMARY

MRD assessment can detect residual leukemia burden after treatment with improved sensitivity compared to morphology alone. There are now extensive data to support the prognostic value of MRD detection both after chemotherapy and in the pre and posttransplant setting, and emerging evidence to suggest there is a clinically relevant value to treatment decisions based on MRD results. The need for standardization of MRD technologies and interpretation is, thus, of critical importance.

Application of flow cytometry in pediatric hematology-oncology

Applications of flow cytometry in pediatric cancers have expanded substantially in recent years. In acute leukemias, the commonest childhood cancer, flow cytometry can now define complex antigenic profiles that are associated with specific cytogenetic/molecular defects and can also directly identify BCR-ABL fusion protein. Flow cytometry based scoring system has been described for diagnosis of myelodysplastic syndromes. In solid tumors, flow cytometry was previously used mainly to determine DNA content for prognosis; however, recent studies in children with neuroblastoma and Ewing sarcoma have identified its diagnostic utility. In this review, we will discuss the current and future applications of flow cytometry in pediatric hematology-oncology.

Cost-effective multiplexing before capture allows screening of 25 000 clinically relevant SNPs in childhood acute lymphoblastic leukemia

Genetic variants, including single-nucleotide polymorphisms (SNPs), are key determiners of interindividual differences in treatment efficacy and toxicity in childhood acute lymphoblastic leukemia (ALL). Although up to 13 chemotherapeutic agents are used in the treatment of this cancer, it remains a model disease for exploring the impact of genetic variation due to well-characterized cytogenetics, drug response pathways and precise monitoring of minimal residual disease. Here, we have selected clinically relevant genes and SNPs through literature screening, and on the basis of associations with key pathways, protein-protein interactions or downstream partners that have a role in drug disposition and treatment efficacy in childhood ALL. This allows exploration of pathways, where one of several genetic variants may lead to similar clinical phenotypes through related molecular mechanisms. We have designed a cost-effective, high-throughput capture assay of ∼25,000 clinically relevant SNPs, and demonstrated that multiple samples can be tagged and pooled before genome capture in targeted enrichment with a sufficient sequencing depth for genotyping. This multiplexed, targeted sequencing method allows exploration of the impact of pharmacogenetics on efficacy and toxicity in childhood ALL treatment, which will be of importance for personalized chemotherapy.

Adolescents and Young Adults with Acute Lymphoblastic Leukemia

During the last decade, increasing attention has been paid to a unique group of patients with acute lymphoblastic leukemia (ALL) who lie at the crossroad of therapeutic care by pediatric and adult hematologists/oncologists. ALL is a disease that affects infants, children, adolescents, and adult patients. With current therapies, the vast majority of children with ALL are now long-term survivors; unfortunately, the same good results have not yet been obtained for adults with ALL. This review will describe current controversies surrounding the treatment of adolescents and young adults with ALL—a group who finds themselves in the transition from “pediatric” to “adult” treatment approaches. The review focuses on recent insights into disease biology, prognostic factors, and treatment outcomes that have led to a series of prospective clinical trials specifically designed for adolescents and younger adults (AYAs) with ALL. These trials have been designed to provide important new clinical, psychosocial, and biological insights, and to further improve the survival of this challenging and unique group of patients.

T-lineage lymphoblastic lymphoma and leukemia-a MASSive problem

T cell precursor malignancies may present as T-lymphoblastic lymphoma (T-LBL) with marked enlargement of lymph nodes or acute T-lymphoblastic leukemia (T-ALL) with little lymph node enlargement. In this issue of Cancer Cell, Feng et al. show that dysregulation of BCL2, AKT signaling, and cell adhesion pathways are hallmarks of T-LBL.