The incidence of T-cell receptor gene rearrangements in childhood B-lineage acute lymphoblastic leukemia is related to immunophenotype and fusion oncogene expression

Immunoglobulin Heavy Chain High-Throughput Sequencing in Pediatric B-Precursor Acute Lymphoblastic Leukemia: Is the Clonality of the Disease at Diagnosis Related to Its Prognosis?

High-throughput sequencing (HTS) of the immunoglobulin heavy chain (IgH) locus is a recent very efficient technique to monitor minimal residual disease of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). It also reveals the sequences of clonal rearrangements, therefore, the multiclonal structure, of BCP-ALL. In this study, we performed IgH HTS on the diagnostic bone marrow of 105 children treated between 2004 and 2008 in Belgium for BCP-ALL in the European Organization for Research and Treatment of Cancer (EORTC)-58951 clinical trial. Patients were included irrespectively of their outcome. We described the patterns of clonal complexity at diagnosis and investigated its association with patients' characteristics. Two indicators of clonal complexity were used, namely, the number of foster clones, described as clones with similar D-N₂-J rearrangements but other V-rearrangement and N₁-joining, and the maximum across all foster clones of the number of evolved clones from one foster clone. The maximum number of evolved clones was significantly higher in patients with t(12;21)/ETV6:RUNX1. A lower number of foster clones was associated with a higher risk group after prephase and t(12;21)/ETV6:RUNX1 genetic type. This study observes that clonal complexity as accessed by IgH HTS is linked to prognostic factors in childhood BCP-ALL, suggesting that it may be a useful diagnostic tool for BCP-ALL status and prognosis.

Immune Gene Rearrangements: Unique Signatures for Tracing Physiological Lymphocytes and Leukemic Cells

The tremendous diversity of the human immune repertoire, fundamental for the defense against highly heterogeneous pathogens, is based on the ingenious mechanism of immune gene rearrangements. Rearranged immune genes encoding the immunoglobulins and T-cell receptors and thus determining each lymphocyte's antigen specificity are very valuable molecular markers for tracing malignant or physiological lymphocytes. One of their most significant applications is tracking residual leukemic cells in patients with lymphoid malignancies. This so called 'minimal residual disease' (MRD) has been shown to be the most important prognostic factor across various leukemia subtypes and has therefore been given enormous attention. Despite the current rapid development of the molecular methods, the classical real-time PCR based approach is still being regarded as the standard method for molecular MRD detection due to the cumbersome standardization of the novel approaches currently in progress within the EuroMRD and EuroClonality NGS Consortia. Each of the molecular methods, however, poses certain benefits and it is therefore expectable that none of the methods for MRD detection will clearly prevail over the others in the near future.

Perspective: sensitive detection of residual lymphoproliferative disease by NGS and clonal rearrangements-how low can you go?

Malignant lymphoproliferative disorders collectively constitute a large fraction of the hematological cancers, ranging from indolent to highly aggressive neoplasms. Being a diagnostically important hallmark, clonal gene rearrangements of the immunoglobulins enable the detection of residual disease in the clinical course of patients down to a minute fraction of malignant cells. The introduction of next-generation sequencing (NGS) has provided unprecedented assay specificity, with a sensitivity matching that of polymerase chain reaction-based measurable residual disease (MRD) detection down to the 10^-6 level. Although reaching 10^-6 to 10^-7 is theoretically feasible, employing a sufficient amount of DNA and sequencing coverage is placed in the perspective of the practical challenges when relying on clinical samples in contrast to controlled serial dilutions. As we discuss, the randomness of subsampling must be taken into account to accommodate the sensitivity threshold-in terms of both the required number of cells and sequencing coverage. As a substantial part of the reviewed studies do not state the depth of coverage or even amount of DNA in some cases, we call for increased transparency to enable critical assessment of the MRD assays for clinical implementation and feasibility.

Forty-nine cases of acute lymphoblastic leukaemia/lymphoma in pleural and pericardial effusions: A cytological-histological correlation

INTRODUCTION

Acute lymphoblastic leukaemia/lymphoma (ALL/LBL) is an aggressive entity of precursor lymphoid neoplasm and may cause malignant serous effusion (SE). The current study aimed to analyse the characteristics of SE cytology of ALL/LBL including cytomorphology, immunophenotyping, clonality and evaluate the effectiveness of SE cytology as a diagnostic method for ALL/LBL.

METHODS

SE specimens with final diagnosis of ALL/LBL from 2006 to 2016 were reviewed for clinical data, cytomorphological features and ancillary studies. Cytodiagnoses were compared with histodiagnoses, and the discordant cases were analysed.

RESULTS

A total of 49 specimens including 47 pleural fluids and 2 pericardial fluids from 49 patients were evaluated. Cytomorphology revealed lymphoblasts varied from small size with scant cytoplasm, condensed nuclear chromatin and indistinct nucleoli to large size with dispersed nuclear chromatin and multiple variably prominent nucleoli. Nuclear clefts and hand mirror-shaped blasts were demonstrated. The positive rates of CD99 and terminal deoxynucleotidyl transferase were 90.9% and 81.6%, respectively. Both monoclonal immunoglobulin (Ig)H and T-cell receptor-γ gene rearrangements were demonstrated in 1 of 3 cases. Monoclonal T-cell receptor-γ gene rearrangement was found in 10 of 11 cases. Monoclonal IgH and/or Ig? gene rearrangements were revealed in 2 of 3 cases. Cytodiagnoses included 4 ALL/LBL, 3 B-ALL/LBL and 42 T-ALL/LBL. Histodiagnoses were available in 24 cases including 2 ALL/LBL, 2 B-ALL/LBL and 20 T-ALL/LBL. The concordance rates of cytological-histological diagnoses were 66.7%, 0% and 95.2% in the three categories, respectively. There were 3 cases with discrepancies of cell lineages.

CONCLUSIONS

SE cytological evaluation is a reliable and effective method for the diagnosis of ALL/LBL.

Ginsenoside Rh2 and Rg3 inhibit cell proliferation and induce apoptosis by increasing mitochondrial reactive oxygen species in human leukemia Jurkat cells

Ginsenoside Rh2 (GRh2) and ginsenoside Rg3 (GRg3) are primary bioactive components in Panax ginseng. The present study aimed to investigate the underlying mechanisms of apoptotic cell-death induced by GRh2 and GRg3 in human leukemia Jurkat cells. The Cell Counting kit-8 assay was used to determine cell proliferation. Apoptosis was detected by nuclear morphologic observation by Hoechst 33342 staining and Annexin V-allophycocyanin and 7-amino-actinomycin D assay. mitoTEMPO, a mitochondrial reactive oxygen species (ROS) scavenger, was used to examine the effects of mitochondrial ROS on cell viability and mitochondrial membrane potential (MMP). Finally, the expression levels of numerous mitochondrial-associated apoptosis proteins were assessed by western blot analysis. These results demonstrated that GRh2 and GRg3 inhibited cell growth and induced apoptosis, and that GRh2 had greater cytotoxicity than GRg3. GRh2 induced generation of more mitochondrial ROS compared with GRg3 in Jurkat cells; however, this effect was ameliorated by subsequent treatment with mitoTEMPO. Furthermore, excess mitochondrial ROS induced by GRh2 was more potent than GRg3 in inhibiting cell proliferation and reducing MMP. In addition, expression levels of apoptosis-associated proteins were significantly increased in Jurkat cells treated with GRh2 than GRg3. In conclusion, these findings suggested that GRh2 and GRg3 induce mitochondrial-associated apoptosis by increasing mitochondrial ROS in human leukemia Jurkat cells. GRh2 may more effectively inhibit cell growth and accelerate apoptosis than GRg3. This study provides a potential novel strategy for the treatment of acute lymphoblastic leukemia.

Prognostic value of MRD-dynamics in childhood acute lymphoblastic leukemia treated according to the MB-2002/2008 protocols

Detection of minimal residual disease (MRD) during the treatment of acute lymphoblastic leukemia (ALL) by RQ-PCR analysis of clonal Ig/TCR rearrangements is used for risk group stratification in European treatment protocols. In Belarus patients with childhood ALL are treated according to ALL-MB protocols, which do not use MRD-based risk stratification. To evaluate the prognostic significance of MRD for ALL-MB-2002/2008 protocols, MRD was quantified by RQ-PCR in 68 ALL patients at four time points: on day 15, on day 36, before and after maintenance therapy (MT). MRD positivity, as well as quantitative level of MRD were analyzed and compared between patients who stayed in remission and relapsed. Relapse-free survival revealed to be significantly associated with MRD levels at different time points. Unfavorable prognosis was shown for MRD≥10(-3) on day 36 (p<0.001), and any positive MRD before (p<0.001) and after (p=0.001) MT. Multivariate Cox regression analysis proved MRD as independent significant prognosis factor at day 36 (p=0.005) and before MT (p=0.001). We conclude, that MRD quantified by RQ-PCR in children with ALL treated with ALL-MB protocols is feasible and independently associated with outcome. MRD may be a suitable parameter for treatment stratification in MB protocols in future.

[Immunoglobulin genes and T-cell receptors as molecular markers in children with acute lymphoblastic leukaemia]

INTRODUCTION

Acute lymphoblastic leukaemia (ALL) is a malignant clonal disease, one of the most common malignancies in childhood. Contemporary protocols ensure high remission rate and long term free survival. The ability of molecular genetic methods help to establish submicroscopic classification and minimal residual disease (MRD) follow up, in major percent responsible for relapse.

OBJECTIVE

The aim of the study was to detect the frequency of IgH and TCR gene rearrangements and their correlation with clinical parameters.

METHODS

Forty-one children with ALL were enrolled in the study group, with initial diagnosis of IgH and TCR gene rearrangements by polimerase chain reaction (PCR). MRD follow-up was performed in induction phase when morphological remission was expected, and after intensive chemiotherapy.

RESULTS

In the study group IgH rearrangement was detected in 82.9% of children at the diagnosis, while TCR rearrangement was seen in 56.1%. On induction day 33, clonal IgH rearrangements persisted in 39% and TCR rearrangements in 36.5% of children.

CONCLUSION

Molecular analysis of genetic alterations and their correlation with standard prognostic parameters show the importance of risk stratification revision which leads to new therapy intensification approach. MRD stands out as a precise predictive factor for the relapse of disease.

Implementation of the standard strategy for identification of Ig/TCR targets for minimal residual disease diagnostics in B-cell precursor ALL pediatric patients: Polish experience

Introduction:

Minimal residual disease (MRD), detected based on immunoglobulin and T-cell receptor (Ig/TCR) gene rearrangements as markers of residual leukemic cells, is currently the most reliable prognostic factor in acute lymphoblastic leukemia (ALL). A feasibility study is presented of the standard strategy for the identification of Ig/TCR targets for MRD diagnostics in Polish ALL patients by identifying Ig/TCR gene rearrangement pattern using standard primer sets and protocols.

Materials and Methods:

The PCR-heteroduplex approach based on BIOMED-1 and BIOMED-2 protocols (recommended as the European standard) was used to detect IGH, IGK-Kde, TCRD, TCRG, and TCRB rearrangements in 58 Polish B-cell precursor ALL patients. Sequencing and homology analysis between the obtained and germline Ig/TCR sequences enabled identification of the rearrangements. The U-Gauss test was used for statistical analysis of the Ig/TCR rearrangement pattern in Polish patients compared with relevant data on other nationalities.

Results:

The following pattern was identified: IGH: 83% (VH-JH: 74%, DH-JH: 9%), IGK-Kde: 41%, TCRD: 78% (incomplete TCRD: 55%, Vδ2-Dδ3: 45%, Dδ2-Dδ3: 21%, Vδ2-Jα: 35%), TCRG: 50%, and TCRB: 13%. Considerable convergence of the Ig/TCR pattern in Polish patients and those of other nationalities (mainly West Europeans) was demonstrated. Statistically relevant differences were only found between the incidence of DH-JH in Polish (9%) and Dutch patients (24%; p<0.05) and Polish and Italian patients (19%; p<0.05), VH-JH in Polish (74%) and Chilean patients (100%; p<0.05), and TCRG in Polish (50%) and Brazilian patients (69%; p<0.05).

Conclusions:

The convergence of Ig/TCR patterns in Polish and European patients indicates that the strategy for Ig/TCR target identification based on standard primers and protocols might be directly used for the construction of Polish standards and recommendations for MRD diagnostics.