Childhood acute lymphoblastic leukemia: Integrating genomics into therapy

The gut microbiome: an important factor influencing therapy for pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most prevalent form of pediatric leukemia. The gut microbiome (GM) is crucial for proper nutrition, immunity, and biological conflict. Since the relationship between ALL and GM is bidirectional, ALL occurrence and treatment are closely related to GM destruction and the development of impaired immunity. Studies have discovered significant GM alterations in patients with ALL, including decreased diversity, that are likely directly caused by the development of ALL. Chemotherapy, antibiotic therapy, and hematopoietic stem cell transplantation (HSCT) are the mainstays of treatment for pediatric ALL. These approaches affect the composition, diversity, and abundance of intestinal microorganisms, which in turn affects therapeutic efficiency and can cause a variety of complications. Modulating the GM can aid the recovery of patients with ALL. This article discusses the various treatment modalities for pediatric ALL and their corresponding effects on the GM, as well as the changes in the GM that occur in children with ALL from diagnosis to treatment. Gaining a greater understanding of the link between ALL and the GM is expected to help improve treatment for pediatric ALL in the future.

Mechanism of co-operation of mutant IL-7Rα and mutant NRAS in acute lymphoblastic leukemia: role of MYC

Acute lymphoblastic leukemia (ALL) is an aggressive leukemia which can be derived from either T-cell or B-cell precursors. With current treatments, the survival rate is high, but the treatments are highly toxic with severe side effects. Individual mutations in IL7Ra and RAS pathways have been previously shown to be prevalent in ALL, and especially in relapsed patients. The relationship of IL-7Ra and RAS was investigated by transducing immature mouse thymocytes with the combination of these mutants. The resultant ALL cells were analyzed to identify the regulators and the oncoproteins that are up-regulated or down-regulated by the combination of IL7Ra with NRAS. Leukemia cells showed a significant increase in IL7Ra-mediated BCL2 expression, and an increase in MYC protein levels was mainly induced by NRAS signaling. MYC was both necessary and sufficient to replace mutant NRAS, and drugs targeting the MYC pathway showed a therapeutic benefit in IL-7Ra/NRAS T-ALL. We suggest that MYC protein stability can be regulated by PLK-1 kinase, which was increased mainly by the NRAS signal. These studies identify novel pathways of oncogenesis and new targets for intervention that could lead to better therapeutic development.

Regulating TKT activity inhibits proliferation of human acute lymphoblastic leukemia cells

Among pediatric blood cancers, acute lymphoblastic leukemia (ALL) is the most common hematologic malignancy. Within ALL, T-cell acute lymphoblastic leukemia (T-ALL) accounts for 10 to 15% of all pediatric cases, and ~25% of adult cases. For T-ALL, its recurrence and relapse after treatment remain problematic. Therefore, it is necessary to develop new therapies for T-ALL. Recent studies suggested regulating energy metabolism is a novel approach to inhibit tumor growth, likely a promising treatment. Transketolase (TKT) is an important enzyme for modulating glucose metabolize in the pentose phosphate pathway (PPP). In this study, we treated T-ALL cells with different doses of niclosamide and primary T-ALL PBMCs were analyzed by RNA sequencing. T-ALL cells treated with niclosamide were analyzed with the Western blotting and TKT activity assay. Metabolism of T-ALL cells was evaluated by ATP assay and seahorse analyses. Lastly, we used a T-ALL xenograft murine model to determine effects of TKT knockdown on T-ALL tumor growth. Tumor samples were analyzed by H&E and IHC stainings. We found that niclosamide reduced T-ALL cell viability, and reduced expressions of TKT, Transketolase-Like Protein 1/2 (TKTL1/2) and transaldolase. In addition, niclosamide inhibited TKT enzyme activity, aerobic metabolism and glycolysis, finally leading to lower production of ATP. TKT knockdown inhibited tumor growth of xenograft T-ALL mice. Findings showed that niclosamide inhibits T-ALL cell growth by inhibiting TKT and energy metabolism.

The PedAL/EuPAL Project: A Global Initiative to Address the Unmet Medical Needs of Pediatric Patients with Relapsed or Refractory Acute Myeloid Leukemia

The prognosis of children with acute myeloid leukemia (AML) has improved incrementally over the last few decades. However, at relapse, overall survival (OS) is approximately 40-50% and is even lower for patients with chemo-refractory disease. Effective and less toxic therapies are urgently needed for these children. The Pediatric Acute Leukemia (PedAL) program is a strategic global initiative that aims to overcome the obstacles in treating children with relapsed/refractory acute leukemia and is supported by the Leukemia and Lymphoma Society in collaboration with the Children's Oncology Group, the Innovative Therapies for Children with Cancer consortium, and the European Pediatric Acute Leukemia (EuPAL) foundation, amongst others. In Europe, the study is set up as a complex clinical trial with a stratification approach to allocate patients to sub-trials of targeted inhibitors at relapse and employing harmonized response and safety definitions across sub-trials. The PedAL/EuPAL international collaboration aims to determine new standards of care for AML in a first and second relapse, using biology-based selection markers for treatment stratification, and deliver essential data to move drugs to front-line pediatric AML studies. An overview of potential treatment targets in pediatric AML, focused on drugs that are planned to be included in the PedAL/EuPAL project, is provided in this manuscript.

Integrating RNA-seq and scRNA-seq to explore the biological significance of NAD + metabolism-related genes in the initial diagnosis and relapse of childhood B-cell acute lymphoblastic leukemia

BACKGROUND

Nicotinamide Adenine Dinucleotide (NAD) depletion is reported to be a potential treatment for B-cell Acute Lymphoblastic Leukemia (B-ALL), but the mechanism of NAD metabolism-related genes (NMRGs) in B-ALL relapse remains unclear.

METHODS

Transcriptome data (GSE3912), and single-cell sequencing data (GSE130116) of B-ALL patients were downloaded from Gene Expression Omnibus (GEO) database. NMRGs were sourced from Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome databases. Further, the differentially expressed NMRGs (DE-NMRGs) were selected from the analysis between initial diagnosis and relapse B-ALL samples, which further performed functional enrichment analyses. The biomarkers were obtained through random forest (RF) algorithm and repeated cross validation. Additionally, cell type identification by estimating relative subsets of RNA transcripts (CIBERSORT) algorithm was used to evaluate the immune cell differences between the initial diagnosis and relapse samples, and the correlations between biomarkers and gene markers of differential immune cells were analyzed. Furthermore, single cell RNA sequencing was conducted in the GSE130116 dataset to find key cell clusters. In addition, according to biomarkers expressions, cell clusters were categorized into high and low biomarker expression groups, and Gene Set Enrichment Analysis (GSEA) analysis was performed on them. Finally, the cell clusters with the highest expression of biomarkers were selected to explore the roles of biomarkers in different cell clusters and identify transcription factors (TFs) influencing biological markers.

RESULTS

23 DE-NMRGs were screened out, which were mainly enriched in nucleoside phosphate metabolic process, nucleotide metabolic process, and Nicotinate and nicotinamide metabolism. Moreover, 3 biomarkers (NADSYN1, SIRT3, and PARP6) were identified from the machine learning. CIBERSORT results demonstrated that four types of immune cells (B Cells naive, Monocyte, Neutrophils, and T cells CD4 memory Activated) were significantly different between the initial diagnosis and the relapse B-ALL samples, and there were strong correlations between biomarkers and differential immune cells such as positive correlation between NADSYN1 and B Cells naive. The single cell analyses showed that the biomarkers were highly expressed in common myeloid progenitors (CMP), granulocyte-macrophage progenitor (GMP), and megakaryocyte-erythroid progenitor (MEP) cell clusters. Gene set enrichment analysis (GSEA) results indicated that 55 GO terms and 3 KEGG pathways were enriched by the genes in high and low biomarker expression groups. It was found that TF CREB3L2(+) was significantly reduced in the high expression group, which may be the TF affecting biomarkers in the high expression group.

CONCLUSION

This study identified NADSYN1, SIRT3, and PARP6 as the biomarkers of B-ALL, explored biological significance of NMRGs in the initial diagnosis and relapse of B-ALL, and revealed mechanism of biomarkers at the level of the single cell.

Epigenomic profiling of glucocorticoid responses identifies cis-regulatory disruptions impacting steroid resistance in childhood acute lymphoblastic leukemia

Glucocorticoids (GCs) are a mainstay of contemporary, multidrug chemotherapy in the treatment of childhood acute lymphoblastic leukemia (ALL), and resistance to GCs remains a major clinical concern. Resistance to GCs is predictive of ALL relapse and poor clinical outcome, and therefore represents a major hurdle limiting further improvements in survival rates. While advances have been made in identifying genes implicated in GC resistance, there remains an insufficient understanding of the impact of cis-regulatory disruptions in resistance. To address this, we mapped the gene regulatory response to GCs in two ALL cell lines using functional genomics and high-throughput reporter assays and identified thousands of GC-responsive changes to chromatin state, including the formation of over 250 GC-responsive super-enhancers and a depletion of AP-1 bound cis-regulatory elements implicated in cell proliferation and anti-apoptotic processes. By integrating our GC response maps with genetic and epigenetic datasets in primary ALL cells from patients, we further uncovered cis-regulatory disruptions at GC-responsive genes that impact GC resistance in childhood ALL. Overall, these data indicate that GCs initiate pervasive effects on the leukemia epigenome, and that alterations to the GC gene regulatory network contribute to GC resistance.

Neonatal congenital leukemia caused by several missense mutations and AFF1‑KMT2A fusion: A case report

Neonatal leukemia, a congenital form of leukemia, is a rare and fatal disease occurring in the neonatal period. Its etiology and pathogenesis have remained to be fully elucidated and the clinical manifestations differ due to age variability. Acute myeloid leukemia (AML) occurring after birth indicates genetic abnormalities and possibly intrauterine exposure to radiation, drugs or other toxins. The present report described the case of a premature neonate without phenotypic signs of Down syndrome, but with an elevated white blood cell count, mainly pertaining to the monocytes of peripheral blood. At 31 weeks of gestation, delivery by Caesarean section was performed due to fetal distress; however, the infant died three days after birth. Further laboratory examination indicated pediatric myeloid leukemia. The present case report described a case of fetal AML. According to the results of peripheral blood smear and targeted-panel sequencing, 5 missense mutations with clinical significance and a novel AFF1-KMT2A fusion gene were detected, which may be the main causes of AML and death.

S100A8 inhibition in leukemic lymphoblasts induces sensitivity to chemotherapy and inhibition of disease relapse

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children and relapsed B-ALL is the leading cause of mortality in children with leukemia due to a lack of response to treatment. S100A8 is a low molecular weight calcium-binding intracellular protein that is expressed in certain cells, and its increased expression is seen in most tumors as well as in relapsed childhood B-ALL cases. The present study indicates the important role of S100A8 in improving viability and resistance to chemotherapy in relapsed B-ALL lymphoblasts. S100A8 levels were compared in B-ALL and relapsed B-ALL lymphoblasts that were sensitive and resistant to Vincristine, respectively. S100A8 was inhibited in the lymphoblasts of two patients by antisense locked nucleic acid (LNA) GapmeRs and the decreased expression of S100A8 was evaluated using quantitative real-time PCR and ELISA. Then, the S100A8 antisense LNA GapmeRs-transfected cells were treated with Vincristine and the expression levels of S100A8 mRNA and S100A8 protein were re-determined. At all of these stages, cell viability and LC50 were assessed by MTT assay. The results showed that S100A8 levels in relapsed B-ALL lymphoblasts were significantly higher than B-ALL lymphoblasts. Moreover, the increase in S100A8 expression was proportionate to the increase in Vincristine resistance in these cells. The S100A8 knockdown procedure using antisense LNA GapmeRs decreased the cell viability and increased vincristine sensitivity in lymphoblasts of two patients, and it also increased the sensitivity to chemotherapy in relapsed B-ALL lymphoblasts. According to the findings of the present study, S100A8 is effective in developing lymphoblast resistance to chemotherapy, and its enhanced expression may contribute to shifting B-ALL into the relapse phase of the illness. As a result, S100A8 may be a valuable target for managing and improving relapses B-ALL.

A case report of pediatric acute lymphoblastic leukemia with e8a2 BCR/ABL1 fusion transcript

Background

Acute lymphoblastic leukemia is the most common type of cancer in children. Most often it affects the age group between 2 and 5 years of age. Studies have shown an improvement in general survivability, more than 90% 5-year overall survival (OS). Current treatment protocols for acute lymphoblastic leukemia require verification of the presence of favorable and unfavorable genetic abnormalities, which help qualify patients to the appropriate risk group and select a more suitable treatment. The presence of the BCR/ABL1 fusion gene stratifies the patient into a high-risk group and requires special treatment with tyrosine kinase inhibitors (TKI). The three dominant mRNA transcripts are e1a2, e13a2, and e14a2. Nevertheless, cases of atypical BCR/ABL1 transcripts have also been reported.

Case presentation

This paper presents the case of a pediatric patient with Ph + B-cell precursor acute lymphoblastic leukemia with rare atypical e8a2 BCR/ABL1 fusion transcript. Our patient achieved complete remission after 33 days of treatment. Molecular and cytogenetic studies in TP1 did not reveal the presence of the BCR/ABL1 transcript. The PCR-MRD test in TP1b was negative, the patient did not require hematopoietic stem cell transplantation.

Conclusion

Genetic evaluation of the bone marrow sample is crucial in the initial stage of the diagnosis. Fluorescent in situ hybridization and reverse transcriptase polymerase chain reaction with Sanger sequencing are the appropriate methods used in the detection of rare variants of BCR/ABL1 transcripts.

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.

High expression of Myosin 1g in pediatric acute lymphoblastic leukemia

Acute Lymphoblastic Leukemia (ALL) is the most frequent cancer in pediatric population. Although the treatment has improved and almost 85% of the children are cured about 20% suffer relapse, therefore finding molecules that participate in the pathogenesis of the disease for the identification of relapse and patients at risk is an urgent unmet need. Class I myosins are molecular motors involved in membrane tension, endocytosis, phagocytosis and cell migration and recently they have been shown important for development and aggressiveness of diverse cancer types, however Myo1g an hematopoietic specific myosin has not been studied in cancer so far. We evaluated the expression of Myo1g by qRT-PCR, Immunocytochemistry and Immunofluorescence in a cohort of 133 ALL patients and correlated the expression at diagnosis and after treatment with clinical features and treatment outcomes. We found high expression levels of Myo1g in Peripheral Blood Mononuclear Cells (PBMCs) from patients with ALL at diagnosis and those levels decreased after complete remission; furthermore, we found an increase in Myo1g expression on patients with 9:22 translocation and those who relapse. This study show that Myo1g is over expressed in ALL and that may participate in the pathogenesis of the disease specially in high-risk patients.

Identification of CSF3R Mutations in B-Lineage Acute Lymphoblastic Leukemia Using Comprehensive Cancer Panel and Next-Generation Sequencing

B-lineage acute lymphocytic leukemia (B-ALL) is characterized by different genetic aberrations at a chromosomal and gene level which are very crucial for diagnosis, prognosis and risk assessment of the disease. However, there is still controversial arguments in regard to disease outcomes in specific genetic abnormalities, e.g., 9p-deletion. Moreover, in absence of cytogenetic abnormalities it is difficult to predict B-ALL progression. Here, we use the advantage of Next-generation sequencing (NGS) technology to study the mutation landscape of 12 patients with B-ALL using Comprehensive Cancer Panel (CCP) which covers the most common mutated cancer genes. Our results describe new mutations in CSF3R gene including S661N, S557G, and Q170X which might be associated with disease progression.

Intrachromosomal Amplification of Chromosome 21 in Childhood Acute Lymphoblastic Leukemia: Study of 3 Cases

Acute lymphoblastic leukemia (ALL) is the most common malignancy of childhood. The presence or absence of a characteristic genetic abnormality usually observed in childhood ALL plays a very important role in determining the prognosis and stratification for treatment. Intrachromosomal amplification of chromosome 21 (iAMP21) is an uncommon high-risk chromosomal abnormality than can occur only in 2% of childhood B-cell precursor lymphoblastic leukemia. Molecular genetic analysis and the fluorescence in situ hybridization (FISH) technique are the basic methods used to detect the presence of the most common genetic abnormalities, the presence or absence of which has an impact on the patient's classification into the appropriate risk group. This work presents 3 BCP-ALL iAMP21-positive patients who were detected during routine genetic diagnostics using the FISH method and microarray test. iAMP21 is associated with a poor prognosis and high risk for relapse. Children with B-cell precursor lymphoblastic leukemia with this genetic entity are associated with a delayed treatment response. The FISH method and single-nucleotide polymorphism array provides a useful method to detect characteristic genetic changes.

Prognostic Value and Outcome for ETV6/RUNX1-Positive Pediatric Acute Lymphoblastic Leukemia: A Report From the South China Children's Leukemia Group

PURPOSE

To analyzed the outcome of ETV6/RUNX1-positive pediatric acute B lymphoblastic leukemia (B-ALL) with the aim of identifying prognostic value.

METHOD

A total of 2,530 pediatric patients who were diagnosed with B-ALL were classified into two groups based on the ETV6/RUNX1 status by using a retrospective cohort study method from February 28, 2008, to June 30, 2020, at 22 participating ALL centers.

RESULTS

In total, 461 (18.2%) cases were ETV6/RUNX1-positive. The proportion of patients with risk factors (age <1 year or ≥10 years, WB≥50×10⁹/L) in ETV6/RUNX1-positive group was significantly lower than that in negative group (P<0.001), while the proportion of patients with good early response (good response to prednisone, D15 MRD < 0.1%, and D33 MRD < 0.01%) in ETV6/RUNX1-positive group was higher than that in the negative group (P<0.001, 0.788 and 0.004, respectively). Multivariate analysis of 2,530 patients found that age <1 or ≥10 years, SCCLG-ALL-2016 protocol, and MLL were independent predictor of outcome but not ETV6/RUNX1. The EFS and OS of the ETV6/RUNX1-positive group were significantly higher than those of the negative group (3-year EFS: 90.11 ± 4.21% vs 82 ± 2.36%, P<0.0001, 3-year OS: 91.99 ± 3.92% vs 88.79 ± 1.87%, P=0.017). Subgroup analysis showed that chemotherapy protocol, age, prednisone response, and D15 MRD were important factors affecting the prognosis of ETV6/RUNX1-positive children.

CONCLUSIONS

ETV6/RUNX1-positive pediatric ALL showed an excellent outcome but lack of independent prognostic significance in South China. However, for older patients who have the ETV6/RUNX1 fusion and slow response to therapy, to opt for more intensive treatment.

Identification of Early Recurrence Factors in Childhood and Adolescent B-Cell Acute Lymphoblastic Leukemia Based on Integrated Bioinformatics Analysis

Over the past 50 years, great progress has been made in the diagnosis and treatment of acute lymphoblastic leukemia (ALL), especially in pediatric patients. However, early recurrence is still an important threat to the survival of patients. In this study, we used integrated bioinformatics analysis to look for biomarkers of early recurrence of B-cell ALL (B-ALL) in childhood and adolescent patients. Firstly, we obtained gene expression profiles from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database and the Gene Expression Omnibus (GEO) database. Then, we identified differentially expressed genes (DEGs) based on whether the disease relapsed early. LASSO and Cox regression analysis were applied to identify a subset of four genes: HOXA7, S100A11, S100A10, and IFI44L. A genetic risk score model was constructed based on these four optimal prognostic genes. Time-dependent receiver operating characteristic (ROC) curves were used to evaluate the predictive value of this prognostic model (3-, 5-, and 10-year AUC values >0.7). The risk model was significantly associated with overall survival (OS) and event-free survival in B-ALL (all p < 0.0001). In addition, a high risk score was an independent poor prognostic risk factor for OS (p < 0.001; HR = 3.396; 95% CI: 2.387-4.832). Finally, the genetic risk model was successfully tested in B-ALL using an external validation set. The results suggested that this model could be a novel predictive tool for early recurrence and prognosis of B-ALL.

Expression Profile of LncRNAs in Childhood Acute Lymphoblastic Leukemia: A Pilot Study

Background: Childhood acute lymphoblastic leukemia (ALL) explains 26% of pediatricmalignancies and is one of the leading causes of disease-related deaths in children. A novelmolecular class of non-coding genes, long non-coding RNAs (lncRNAs) having over 200nucleotides, have been defined as regulators of different cellular processes including pluripotency,oncogenesis, and transcription. It has been demonstrated that lncRNA transcription profilescan distinguish pre B-cell subtype of ALL accurately and act as early diagnostic and prognosticbiomarkers. Hence, the aim of this pilot study was the prior evaluation of expression profileof several lncRNA candidates including RP11-68I18.10, RP11-624C23.1, RP11-446E9, RP11-137H2.4, and RP11-203E8 in patients with ALL. Methods: In this study, 80 blood samples were obtained from patients, definitely diagnosed bypathologists with ALL, and from healthy subjects. Total RNA was extracted from blood samples,and cDNA was synthesized. Real-time PCR was applied to determine the expression of lncRNAs.A P-value of 0.010 was considered statistically significant. Results: Our findings revealed that the expression levels of lncRNAs RP11-624C23.1, RP11-446E9, RP11-137H2.4, RP11-68I18.10, and RP11-203E8 were significantly decreased in ALLsamples compared to those of healthy samples (P<0.0001, P =0.0616, P =0.0292, P<0.0001, andP = 0.0007). Moreover, the relationship between these five lncRNA expression changes and theimmunophenotype in ALL patients was not significant. Conclusion: The dysregulation of lncRNAs in ALL samples could provide a novel and interestingpossibility for early diagnosis and prognosis, as well as mastering the treatment of ALL.

DUX Hunting-Clinical Features and Diagnostic Challenges Associated with DUX4-Rearranged Leukaemia

Simple Summary

DUX4-rearrangement (DUX4r) is a recently discovered recurrent genomic lesion reported in 4–7% of childhood B cell acute lymphoblastic leukaemia (B-ALL) cases. This subtype has favourable outcomes, especially in children and adolescents treated with intensive chemotherapy. The fusion most commonly links the hypervariable IGH gene to DUX4 a gene located within the D4Z4 macrosatellite repeat on chromosome 4. DUX4r is cryptic to most standard diagnostic techniques, and difficult to identify even with next generation sequencing assays. This review summarises the clinical features and molecular genetics of DUX4r B-ALL and proposes prospective new diagnostic methods.

Abstract

DUX4-rearrangement (DUX4r) is a recently discovered recurrent genomic lesion reported in 4–7% of childhood B cell acute lymphoblastic leukaemia (B-ALL) cases. This subtype has favourable outcomes, especially in children and adolescents treated with intensive chemotherapy. The fusion most commonly links the hypervariable IGH gene to DUX4 a gene located within the D4Z4 macrosatellite repeat on chromosome 4, with a homologous polymorphic repeat on chromosome 10. DUX4r is cryptic to most standard diagnostic techniques, and difficult to identify even with next generation sequencing assays. This review summarises the clinical features and molecular genetics of DUX4r B-ALL and proposes prospective new diagnostic methods.

A Nomogram for the Prediction of Progression and Overall Survival in Childhood Acute Lymphoblastic Leukemia

Background: Advances in treatment and supportive care have significantly improved the overall survival (OS) of pediatric patients with acute lymphoblastic leukemia (ALL). However, there is a large number of these patients who continue to relapse after receiving standard treatment. Accurate identification of patients at high risk of relapse and targeted therapy may significantly improve their prognosis. Therefore, the aim of this study was to identify significant prognostic factors for pediatric ALL and establish a novel nomogram for the prediction of survival.

Methods: The ALL clinical data of Phases I and II of the Therapeutic Applicable Research to Generate Effective Treatments (TARGET) project were merged and randomly divided into training and validation groups. The LASSO regression model was used to select the specific factors related to the OS of the training group and generate prognostic nomograms according to the selected characteristics. The predictive accuracy of the nomogram for OS was verified using the concordance index of the training and validation groups, the area under the receiver operating characteristic curve for prognostic diagnosis, and the calibration curve.

Results: A total of 1,000 children with ALL were included in the TARGET project. Of those, 489 patients had complete follow-up data for further analysis. The data were randomly divided into the training group (n = 345) and the validation group (n = 144). Seven clinical characteristics, namely age at diagnosis, peripheral white blood cells, bone marrow and CNS site of relapse, ETV6/RUNX1 fusion, TCF3/PBX1, and BCR/ABL1 status, were selected to construct the nomogram. The concordance indices of the training and validation groups were 0.809 (95% confidence interval: 0.766–0.852) and 0.826 (95% confidence interval: 0.767–0.885), respectively. The areas under the receiver operating characteristic curve of the 3-year, 5-year, and 10-year OS in the training group were 0.804, 0.848, and 0.885, respectively, while that of the validation group were 0.777, 0.825, and 0.863, respectively. Moreover, the calibration curves demonstrated a favorable consistency between the predicted and actual survival probabilities.

Conclusions: Independent predictors of OS in children with ALL included age at diagnosis, white blood cells, bone marrow site of relapse, CNS site of relapse, ETV6/RUNX1 fusion, TCF3/PBX1, and BCR/ABL1 status. The nomograms developed using these high-risk factors can more simply, accurately, and quantitatively predict the survival of children, and improve treatment and prognosis.

Cannabinoid CP55940 selectively induces apoptosis in Jurkat cells and in ex vivo T-cell acute lymphoblastic leukemia through H2O2 signaling mechanism

T-cell acute lymphoblastic leukemia (T-ALL) is a highly heterogeneous malignant hematological disorder arising from T-cell progenitors. This study was aimed to evaluate the cytotoxic effect of CP55940 on human peripheral blood lymphocytes (PBL) and on T-ALL cells (Jurkat). PBL and Jurkat cells were treated with CP55940 (0-20 μM), and morphological changes in the cell nucleus/ DNA, mitochondrial membrane potential (ΔΨm), and intracellular reactive oxygen species levels were determined by fluorescence microscopy and flow cytometry. Cellular apoptosis markers were also evaluated by western blotting, pharmacological inhibition and immunofluorescence. CP55940 induced apoptotic cell death in Jurkat cells, but not in PBL, in a dose-response manner with increasing fragmentation of DNA, arrest of cell cycle and damage of ΔΨm. CP55940 increased dichlorofluorescein fluorescence (DCF) intensity, increased DJ-1 Cys¹⁰⁶- sulfonate, a marker of intracellular stress, induced the up-regulation of p53 and phosphorylation of transcription factor c-JUN. It increased the expression of BAX and PUMA, up-regulated mitochondrial proteins PINK1 and Parkin, and activated CASPASE-3. Antioxidant NAC, pifithrin-α, and SP600125 blocked CP55940 deleterious effect on Jurkat cells. However, the potent and highly specific cannabinoid CB1 and CB2 receptor inverse agonist SR141716 and SR144528 were unable to blunt CP55940-induced apoptosis in Jurkat cells. Conclusively CP55940 provokes cell death in Jurkat through CBR-independent mechanism. Interestingly, CP55940 was also cytotoxic to ex vivo T-ALL cells from chemotherapy-resistant pediatric patients. In conclusion, CP55940 selectively induces apoptosis in Jurkat cells through a H₂O₂-mediated signaling pathway. Our findings support the use of cannabinoids as a potential treatment for T-ALL cells.

Enrichment of atypical hyperdiploidy and IKZF1 deletions detected by SNP-microarray in high-risk Australian AIEOP-BFM B-cell acute lymphoblastic leukaemia cohort

Acute lymphoblastic leukaemia (ALL) is the most common childhood malignancy with the majority of patients being classified as B-cell lineage (B-ALL). The sub-classification of B-ALL is based on genomic architecture. Recent studies have demonstrated the capability of SNP-microarrays to detect genomic changes in B-ALL which cannot be observed by conventional cytogenetic methods. In current clinical trials, B-ALL patients at high risk of relapse are mainly identified by adverse cancer genomics and/or poor response to early therapy. To test the hypothesis that inclusion of SNP-microarrays in frontline diagnostics could more efficiently and accurately identify adverse genomic factors than conventional techniques, we evaluated the Australian high-risk B-ALL cohort enrolled on AIEOP-BFM ALL 2009 study (n = 33). SNP-microarray analysis identified additional aberrations in 97% of patients (32/33) compared to conventional techniques. This changed the genomic risk category of 24% (8/33) of patients. Additionally, 27% (9/33) of patients exhibited a 'hyperdiploid' genome, which is generally associated with a good genomic risk and favourable outcomes. An enrichment of IKZF1 deletions was observed with one third of the cohort affected. Our findings suggest the current classification system could be improved and highlights the need to use more sensitive techniques such as SNP-microarray for cytogenomic risk stratification in B-ALL.

Prognostic significance of the tumor suppressor protein p53 gene in childhood acute lymphoblastic leukemia

The tumor suppressor protein p53 (TP53) gene is associated with various types of cancer; however, little is known about TP53 expression in patients with childhood acute lymphoblastic leukemia (ALL). The aim of the present study was to investigate the prognostic value of TP53 expression in childhood ALL. To achieve this, TP53 mRNA levels of 146 children with ALL and 23 child donors with idiopathic thrombocytopenic purpura were determined by reverse transcription-quantitative PCR. Relapse-free survival (RFS) and overall survival (OS) were analyzed using the Kaplan-Meier method. The results demonstrated that TP53 mRNA level in patients with ALL was higher compared with that in the ITP donors (P=0.019). Patients with highly-expressed TP53 exhibited lower percentages of peripheral blood blast, higher platelet counts and inferior complete remission rates compared with patients with low expression of TP53. Survival analyses revealed that high TP53 expression was associated with poor OS and RFS in childhood ALL (P=0.018 and P=0.028, respectively) and was an independent prognostic factor in multivariate analysis for poor RFS (P<0.001) and OS (P<0.001). In conclusion, high TP53 expression is associated with poor outcomes and may be used as a molecular prognostic marker to be incorporated into an improved risk classification system for childhood ALL.

Immune Thrombocytopenia: Are We Stuck in the Mud or Is There Light at the End of the Tunnel?

The differences in diagnosis and management between immune thrombocytopenia (ITP) and leukemia are striking. Leukemia diagnosis and management have evolved substantially over the past 30 years and are now relatively precise. The tendency for leukemic cells to be the overwhelming majority of circulating and/or bone marrow cells certainly continues to facilitate developments, as does improved molecular assessment. Furthermore, randomized controlled clinical trials of competing regimens in well-defined populations have advanced treatment as well. Currently, ITP diagnosis and management depend very much on the experience and preferences of the hematologist. There are no unequivocally useful molecular tests, no agreement on which testing needs to be performed, and no consensus on treatment. Future studies using advanced techniques would ideally change this over time but, thus far, progress in ITP has been slow. However, the increasing ability to do single-cell DNA and RNA studies and flow cytometric dissection of small populations of cells could radically change the approach to ITP if critical distinctions were uncovered.

Influence of Inflammatory and Oxidative Stress Pathways on Longitudinal Symptom Experiences in Children With Leukemia

PURPOSE

The purpose of this study was to explore the influence of oxidative stress (F2-isoprostanes) and inflammatory (interleukin [IL]-8) biomarkers on symptom trajectories during the first 18 months of childhood leukemia treatment.

METHOD

A repeated-measures design was used to evaluate symptoms experienced by 218 children during treatment. A symptom cluster (fatigue, pain, and nausea) was explored over four time periods: initiation of post-induction therapy, 4 and 8 months into post-induction therapy, and the beginning of maintenance therapy (12 months postinduction). F2-isoprostanes and IL-8 were evaluated in cerebrospinal fluid (CSF) samples collected at baseline (diagnosis) and then at the four time periods. The longitudinal relationships of these biomarkers with the symptom cluster were examined using the longitudinal parallel process.

RESULTS

Pain and fatigue levels were highest during the post-induction phases of treatment and decreased slightly during maintenance therapy, while nausea scores were relatively stable. Even in the later phases of treatment, children continued to experience symptoms. CSF levels of the biomarkers increased during the post-induction phases of treatment. Early increases in the biomarkers were associated with more severe symptoms during the same period; patients who had increased biomarkers over time also experienced more severe symptoms over time.

CONCLUSIONS

Findings reveal that children experienced symptoms throughout the course of leukemia treatment and support hypothesized longitudinal relationships of oxidative stress and inflammatory biomarkers with symptom severity. Activation of the biomarker pathways during treatment may explain underlying mechanisms of symptom experiences and identify which children are at risk for severe symptoms.

Genetic polymorphisms of ARID5B rs7089424 and rs10994982 are associated with B-lineage ALL susceptibility in Chinese pediatric population

BACKGROUND

Several ARID5B single nucleotide polymorphisms (SNPs) were confirmed to be significantly associated with the susceptibility of childhood acute lymphoblastic leukemia (ALL) based on Caucasian populations in previous studies. Similar investigations in Asian populations were less. The aim of this study is to explore the relationship between ARID5B SNPs rs7089424, rs10994982, and the risk of ALL in Chinese pediatric population.

METHODS

A total of 190 pediatric ALL patients and 270 controls were enrolled in this study. PCR amplification combined with mass spectrometry were used to evaluate the genotypes of ARID5B rs7089424 and rs10994982. χ test was used in allele frequencies and genotype distributions of the SNPs for analyzing statistical differences between patients and controls.

RESULTS

There were significant differences in the risk allele frequencies of ARID5B rs7089424 and rs10994982 between B-lineage ALL (B-ALL) patients and controls (rs7089424, G allele: p = 0.001; rs10994982, A allele: p = 0.000). The genotype distributions of ARID5B rs7089424 and rs10994982 were also statistically different in B-ALL patients compared with controls (rs7089424, p = 0.004; rs10994982, p = 0.001). Further analyzing the relevance of ARID5B rs7089424 and rs10994982 genotypes to clinical risk classification of ALL showed GG genotype of rs7089424 and AA genotype of rs10994982 were strikingly correlated with the medium-risk and low-risk groups of B-ALL. Finally, GG and GT genotypes of rs7089424 and AA genotype of rs10994982 seemed to be responsible for the hyperdiploid subtype susceptibility of childhood B-ALL.

CONCLUSION

ARID5B rs7089424 and rs10994982 might serve as genetic susceptibility markers for B-ALL in Chinese pediatric population. Moreover, the two ARID5B SNPs are associated with the risk of B-hyperdiploid ALL, which had a better therapeutic response than other ALL subtypes.

Genome wide mapping of ETV6 binding sites in pre-B leukemic cells

Genetic alterations in the transcriptional repressor ETV6 are associated with hematological malignancies. Notably, the t(12;21) translocation leading to an ETV6-AML1 fusion gene is the most common genetic alteration found in childhood acute lymphoblastic leukemia. Moreover, most of these patients also lack ETV6 expression, suggesting a tumor suppressor function. To gain insights on ETV6 DNA-binding specificity and genome wide transcriptional regulation capacities, we performed chromatin immunoprecipitation experiments coupled to deep sequencing in a t(12;21)-positive pre-B leukemic cell line. This strategy led to the identification of ETV6-bound regions that were further associated to gene expression. ETV6 binding is mostly cell type-specific as only few regions are shared with other blood cell subtypes. Peaks localization and motif enrichment analyses revealed that this unique binding profile could be associated with the ETV6-AML1 fusion protein specific to the t(12;21) background. This study underscores the complexity of ETV6 binding and uncovers ETV6 transcriptional network in pre-B leukemia cells bearing the recurrent t(12;21) translocation.

Precision medicine approaches may be the future for CRLF2 rearranged Down Syndrome Acute Lymphoblastic Leukaemia patients

Breakthrough studies over the past decade have uncovered unique gene fusions implicated in acute lymphoblastic leukaemia (ALL). The critical gene, cytokine receptor-like factor 2 (CRLF2), is rearranged in 5-16% of B-ALL, comprising 50% of Philadelphia-like ALL and cooperates with genomic lesions in the Jak, Mapk and Ras signalling pathways. Children with Down Syndrome (DS) have a predisposition to developing CRLF2 rearranged-ALL which is observed in 60% of DS-ALL patients. These patients experience a poor survival outcome. Mutations of genes involved in epigenetic regulation are more prevalent in DS-ALL patients than non-DS ALL patients, highlighting the potential for alternative treatment strategies. DS-ALL patients also suffer greater treatment-related toxicity from current ALL treatment regimens compared to non-DS-ALL patients. An increased gene dosage of critical genes on chromosome 21 which have roles in purine synthesis and folate transport may contribute. As the genomic landscape of DS-ALL patients is different to non-DS-ALL patients, targeted therapies for individual lesions may improve outcomes. Therapeutically targeting each rearrangement with targeted or combination therapy that will perturb the transforming signalling pathways will likely improve the poor survival rates of this subset of patients.

[Multicenter clinical trial of acute lymphoblastic leukemia in elder children and adolescents]

Objective: To analyze the clinical characteristics and long-term outcomes with multicenter study for acute lymphoblastic leukemia (ALL) in children over 10 years old and adolescents. Method: Newly diagnosed ALL patients aged from 10 to 18 years old in three hospitals were included in the study from May 1(st) 2005 to April 30(th) 2015. They were received ALL-2005/2009 protocol following up to December 31(st) 2016. The clinical characteristics, outcomes and the prognostic analysis were evaluated between the two protocols. Results: Totally, 237 patients were involved in the study, 76 cases for ALL-2005 and 161 cases for ALL-2009 protocol. Complete remission (CR) after induction therapy was 94.5%. 64 (28.6%) patients relapsed with a median time of 14.5 months and 70 (29.5%) patients passed away during the following time. In long-term follow-up, the 5-year event-free survival (EFS) and 5-year overall survival (OS) of ALL patients were (63.1±3.3)% and (68.4±3.2)%. The 7-year EFS and OS were (61.0±3.5)% and (67.6±3.3)%.The 5-year EFS of intermediate risk group in ALL-2005 and ALL-2009 protocol were (73.6±6.1)% and (71.7±4.3)% with no difference (χ(2)=0.064, P=0.801). The 5-year EFS of high risk group in two protocols were (27.6±9.6)% and (33.9±9.3)%, showing no significant difference (χ(2)=0.296, P=0.586). Five years relapsed rate of two protocols were (33.8±5.7)% and (32.6±4.1)% with no difference (χ(2)=0.055, P=0.815). The mortalities were 36.8% and 29.8% separately (χ(2)=2.869, P=0.090). Univariate analysis indicated that age, male, risk, BCR/ABL translocation/t(9;22) and resistant to induction were risk prognostic factors in long-term survival (χ(2)=4.764, 4.796, 46.410, 9.560, 25.450; P=0.029, 0.029, <0.001, 0.049, <0.001). Cox multivariate analysis showed male, risk and resistant to induction were independent risk prognostic factors (RR=1.790, 2.727, 2.719; P=0.021, 0.000, 0.012). Conclusion: Protocol ALL-2009 enhanced the chemotherapy intensity in intermediate risk group with no benefit of survival. BCR-ABL fusion or t(9;22) translocation was still the risk factor of prognosis. TKI inhibitor used in these patients could improve survival. EFS rate was increased a little and death rate was decreased in ALL-2009 protocol with no significant lower relapsed rate comparing with ALL-2005 protocol.

Genomics and pharmacogenomics of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukaemia (ALL) is a prevalent form of pediatric cancer that accounts for 70-80% of all leukemias. Genome-based analysis, exome sequencing, transcriptomics and proteomics have provided insight into genetic classification of ALL and helped identify novel subtypes of the disease. B and T cell-based ALL are two well-characterized genomic subtypes, significantly marked by bone marrow disorders, along with mutations in trisomy 21 and T53. The other ALLs include Early T-cell precursor ALL, Philadelphia chromosome-like ALL, Down syndrome-associated ALL and Relapsed ALL. Chromosomal number forms a basis of classification, such as, hypodiploid ALL, near-haploid, low-hypodiploid, high-hypodiploid and hypodiploid-ALL. Advances in therapies targeting ALL have been noteworthy, with significant pre-clinical and clinical studies on drug pharmacokinetics and pharmacodynamics. Methotrexate and 6-mercaptopurine are leading drugs with best demonstrated efficacies against childhood ALL. The drugs in combination, following dose titration, have also been used for maintenance therapy. Methotrexate-polyglutamate is a key metabolite that specifically targets the disease pathogenesis, and 6-thioguanine nucleotides, derived from 6-mercaptopurine, impede replication and transcription processes, inducing cytotoxicity. Additionally, glucocorticoids, asparaginase, anthracycline, vincristine and cytarabine that trans-repress gene expression, deprives cells of asparagine, triggers cell cycle arrest, influences cytochrome-P450 polymorphism and inhibits DNA polymerase, respectively, have been used in chemotherapy in ALL patients. Overall, this review covers the progress in genome technology related to different sub-types of ALL and pharmacokinetics and pharmacodynamics of its medications. It also enlightens adverse effects of current drugs, and emphasizes the necessity of genome-wide association studies for restricting childhood ALL.

Changes in Oxidant Defense, Apoptosis, and Cognitive Abilities During Treatment for Childhood Leukemia

Aggressive central nervous system (CNS)-directed treatment for acute lymphoblastic leukemia (ALL), the most prevalent cancer among children and adolescents, prevents metastasis of leukemia cells into the brain. Up to 60% of survivors experience cognitive problems, but knowledge about risk factors for and mechanisms of neurologic injury is lacking. Objectives of the present study were to (1) quantify changes in oxidant defense and apoptosis over the course of ALL therapy and (2) elucidate risk factors for long-term cognitive problems. The sample included 71 children with ALL. Cerebrospinal fluid (CSF) samples were collected at diagnosis and during intrathecal chemotherapy administration. Oxidant defense was measured by reduced glutathione (GSH), oxidized glutathione (GSSG), and the ratio of GSH:GSSG. Apoptosis was measured by activity of several cysteine-dependent aspartate-specific protease (abbreviated as caspase) enzymes that initiate (caspases 8 and 9) or execute (caspases 3/7) apoptosis. Cognitive abilities were assessed by standardized measures of short-term memory, visual-motor integration, and attention 3 years after ALL diagnosis. GSH and GSSG concentration increased significantly during ALL therapy, and a low GSH:GSSG ratio was indicative of an oxidized extracellular environment. Caspase enzyme activity increased significantly, and caspases 3/7 activity was significantly and negatively associated with performance on measures of cognitive abilities. Younger age at time of ALL diagnosis was associated with some measures of attention. Efflux of glutathione into CSF maintains oxidant defense by scavenging free radicals and other reactive oxygen species and is an early event in apoptosis. These mechanisms may be involved in neurologic injury associated with CNS-directed treatment and subsequent cognitive problems.

SLC19A1 Polymorphism and Serum Methotrexate in Patients with Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a common pediatric malignancy. Methotrexate is the widely used chemotherapy for ALL. The polymorphism (rs1051296) of SLC19A1 is proposed for its effect on serum methotrexate. To explain this observation, the authors hereby studied the interrelationship between SLC19A1 polymorphism and blood methotrexate level in the patients with ALL. Here, the authors use a quantum chemistry analysis for explaining of this observation.

Novel non-neutral mitochondrial DNA mutations found in childhood acute lymphoblastic leukemia

Mitochondria produce adenosine triphosphate (ATP) for energy requirements via the mitochondrial oxidative phosphorylation (OXPHOS) system. One of the hallmarks of cancer is the energy shift toward glycolysis. Low OXPHOS activity and increased glycolysis are associated with aggressive types of cancer. Mitochondria have their own genome (mitochondrial DNA [mtDNA]) encoding for 13 essential subunits of the OXPHOS enzyme complexes. We studied mtDNA in childhood acute lymphoblastic leukemia (ALL) to detect potential pathogenic mutations in OXPHOS complexes. The whole mtDNA from blood and bone marrow samples at diagnosis and follow-up from 36 ALL patients were analyzed. Novel or previously described pathogenic mtDNA mutations were identified in 8 out of 36 patients. Six out of these 8 patients had died from ALL. Five out of 36 patients had an identified poor prognosis genetic marker, and 4 of these patients had mtDNA mutations. Missense or nonsense mtDNA mutations were detected in the genes encoding subunits of OXPHOS complexes, as follows: MT-ND1, MT-ND2, MT-ND4L and MT-ND6 of complex I; MT-CO3 of complex IV; and MT-ATP6 and MT-ATP8 of complex V. We discovered mtDNA mutations in childhood ALL supporting the hypothesis that non-neutral variants in mtDNA affecting the OXPHOS function may be related to leukemic clones.

Survival among children diagnosed with acute lymphoblastic leukemia in the United States, by race and age, 2001 to 2009: Findings from the CONCORD-2 study

BACKGROUND

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. This report describes the survival of children with ALL in the United States using the most comprehensive and up-to-date cancer registry data.

METHODS

Data from 37 state cancer registries that cover approximately 80% of the US population were used. Age-standardized survival up to 5 years was estimated for children aged 0-14 years who were diagnosed with ALL during 2 periods (2001-2003 and 2004-2009).

RESULTS

In total, 17,500 children with ALL were included. The pooled age-standardized net survival estimates for all US registries combined were 95% at 1 year, 90% at 3 years, and 86% at 5 years for children diagnosed during 2001-2003, and 96%, 91%, and 88%, respectively, for those diagnosed during 2004-2009. Black children who were diagnosed during 2001-2003 had lower 5-year survival (84%) than white children (87%) and had less improvement in survival by 2004-2009. For those diagnosed during 2004-2009, the 1-year and 5-year survival estimates were 96% and 89%, respectively, for white children and 96% and 84%, respectively, for black children. During 2004-2009, survival was highest among children aged 1 to 4 years (95%) and lowest among children aged <1 year (60%).

CONCLUSIONS

The current results indicate that overall net survival from childhood ALL in the United States is high, but disparities by race still exist, especially beyond the first year after diagnosis. Clinical and public health strategies are needed to improve health care access, clinical trial enrollment, treatment, and survivorship care for children with ALL. Cancer 2017;123:5178-89. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Analysis of common cytogenetic abnormalities in New Zealand pediatric ALL shows ethnically diverse carriage of ETV6-RUNX1, without a corresponding difference in survival

BACKGROUND

The frequency of common cytogenetic abnormalities in pediatric acute lymphoblastic leukemia (ALL) is known to vary by geographic location and ethnic origin. This study aimed to determine the frequency of hypodiploidy, ETV6-RUNX1, BCR-ABL1, and MLL rearrangement within New Zealand's pediatric ALL population and to assess whether the frequency of these ALL prognostic markers varies according to ethnicity.

PROCEDURE

The New Zealand Children's Cancer Registry provided information for all registered pediatric ALL patients that were diagnosed between 2000 and 2009, with medical records available for 246 patients. Each patient's medical record was reviewed to determine the frequency of hypodiploidy, ETV6-RUNX1, BCR-ABL1, MLL rearrangement, and cell lineage. Chi-square tests for independence were undertaken to compare the frequencies of cytogenetic abnormalities according to prioritized ethnicity.

RESULTS

The frequency of cytogenetic ALL abnormalities in the New Zealand pediatric population were consistent with international reference values. A low frequency of ETV6-RUNX1 was evident for Maori pediatric ALL patients (5.4%, P = 0.018), when compared to Pacific peoples (21.1%) and non-Maori/non-Pacific peoples (27.4%). This has not impacted on outcome, however, with equivalent 5-year overall survival being observed in Maori (89.4%) compared to Pacific peoples (92.0%) and non-Maori/non-Pacific peoples (90.2%).

CONCLUSIONS

A lower frequency of the favorable prognostic marker ETV6-RUNX1 was observed in Maori pediatric ALL patients. This did not translate into poorer survival. Future research into biological and nonbiological prognostic factors in this patient population may assist in explaining this finding.

Acute lymphoblastic leukemia cells are sensitive to disturbances in protein homeostasis induced by proteasome deubiquitinase inhibition

The non-genotoxic nature of proteasome inhibition makes it an attractive therapeutic option for the treatment of pediatric malignancies. We recently described the small molecule VLX1570 as an inhibitor of proteasome deubiquitinase (DUB) activity that induces proteotoxic stress and apoptosis in cancer cells. Here we show that acute lymphoblastic leukemia (ALL) cells are highly sensitive to treatment with VLX1570, resulting in the accumulation of polyubiquitinated proteasome substrates and loss of cell viability. VLX1570 treatment increased the levels of a number of proteins, including the chaperone HSP70B', the oxidative stress marker heme oxygenase-1 (HO-1) and the cell cycle regulator p21Cip1. Unexpectedly, polybiquitin accumulation was found to be uncoupled from ER stress in ALL cells. Thus, increased phosphorylation of eIF2α occurred only at supra-pharmacological VLX1570 concentrations and did not correlate with polybiquitin accumulation. Total cellular protein synthesis was found to decrease in the absence of eIF2α phosphorylation. Furthermore, ISRIB (Integrated Stress Response inhibitor) did not overcome the inhibition of protein synthesis. We finally show that VLX1570 can be combined with L-asparaginase for additive or synergistic antiproliferative effects on ALL cells. We conclude that ALL cells are highly sensitive to the proteasome DUB inhibitor VLX1570 suggesting a novel therapeutic option for this disease.

New targeted therapies for relapsed pediatric acute lymphoblastic leukemia

INTRODUCTION

The improvement in outcomes for children with acute lymphoblastic leukemia (ALL) is one of the greatest success stories of modern oncology however the prognosis for patients who relapse remains dismal. Recent discoveries by high resolution genomic technologies have characterized the biology of relapsed leukemia, most notably pathways leading to the drug resistant phenotype. These observations open the possibility of targeting such pathways to prevent and/or treat relapse. Likewise, early experiences with new immunotherapeutic approaches have shown great promise. Areas covered: We performed a literature search on PubMed and recent meeting abstracts using the keywords below. We focused on the biology and clonal evolution of relapsed disease highlighting potential new targets of therapy. We further summarized the results of early trials of the three most prominent immunotherapy agents currently under investigation. Expert commentary: Discovery of targetable pathways that lead to drug resistance and recent breakthroughs in immunotherapy show great promise towards treating this aggressive disease. The best way to treat relapse, however, is to prevent it which makes incorporation of these new approaches into frontline therapy the best approach. Challenges remain to balance efficacy with toxicity and to prevent the emergence of resistant subclones which is why combining these newer agents with conventional chemotherapy will likely become standard of care.

Effective control of acute myeloid leukaemia and acute lymphoblastic leukaemia progression by telomerase specific adoptive T-cell therapy

Telomerase (TERT) is a ribonucleoprotein enzyme that preserves the molecular organization at the ends of eukaryotic chromosomes. Since TERT deregulation is a common step in leukaemia, treatments targeting telomerase might be useful for the therapy of hematologic malignancies. Despite a large spectrum of potential drugs, their bench-to-bedside translation is quite limited, with only a therapeutic vaccine in the clinic and a telomerase inhibitor at late stage of preclinical validation. We recently demonstrated that the adoptive transfer of T cell transduced with an HLA-A2-restricted T-cell receptor (TCR), which recognize human TERT with high avidity, controls human B-cell chronic lymphocytic leukaemia (B-CLL) progression without severe side-effects in humanized mice. In the present report, we show the ability of our approach to limit the progression of more aggressive leukemic pathologies, such as acute myeloid leukaemia (AML) and B-cell acute lymphoblastic leukaemia (B-ALL). Together, our findings demonstrate that TERT-based adoptive cell therapy is a concrete platform of T cell-mediated immunotherapy for leukaemia treatment.

Increased Risk of Thai Childhood Acute Lymphoblastic Leukemia with the MiR196a2 T>C Polymorphism

Objectives:

This study assessed associations of the miR196a2 (rs11614913) T>C polymorphism withsusceptibility to childhood acute lymphoblastic leukemia (ALL) and clinical outcomes.

Materials and Methods:

Blood DNA samples from 104 childhood ALL patients and 180 healthy children were studied for the miR-196a2 (rs11614913) polymorphism using a polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) approach.

Results:

The frequency of the miR-196a2 (rs11614913) T allele in controls was 0.51 compared with 0.33 in ALL cases. In this study, CC, TC heterozygote and CC/TC genotypes were significantly associated with increase childhood ALL susceptibility compared with the TT wild type (OR =4.321, 95% CI = 2.091-8.930 p=0.000, OR = 2.248, 95% CI =1.103-4.579, p=0.024, OR = 2.921, 95% CI = 1.504-5.673 p=0.001, respectively). However, the miR-196a2 (rs11614913) T>C polymorphism was not associated with demographic data or clinico-pathological data in ALL cases.

Conclusion:

CC, TC and CC+TC genotypes of miR-196a2 (rs11614913) was significantly associated with increased susceptibility in Thai childhood ALL but not with clinical variables.

Genomic characterization of paediatric acute lymphoblastic leukaemia: an opportunity for precision medicine therapeutics

Major advances in genetic and epigenetic profiling of acute lymphoblastic leukaemia (ALL) have enhanced the understanding of key biological subsets of de novo and relapsed ALL, which has led to improved risk stratification of patients. These achievements have further defined critical leukaemia-associated pathways and somatic alterations that may be preferentially sensitive to treatment with kinase inhibitors, epigenetic therapy or other novel agents. Therapeutic success in childhood ALL currently relies upon refined risk stratification of patients based on (i) underlying biological and clinical characteristics, and (ii) depth of initial treatment response with appropriate modulation of chemotherapy intensity. This review describes the current mutational landscape of childhood ALL and discusses opportunities for substantial improvements in survival with implementation of molecularly targeted therapies.

Ph-like acute lymphoblastic leukemia

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a newly identified high-risk (HR) B-lineage ALL subtype, accounting for ∼15% of children with National Cancer Institute-defined HR B-ALL. It occurs more frequently in adolescents and adults, having been reported in as much as 27% of young adults with ALL between 21 and 39 years of age. It exhibits adverse clinical features, confers a poor prognosis, and harbors a diverse range of genetic alterations that activate cytokine receptor genes and kinase signaling pathways, making it amenable to treatment with tyrosine kinase inhibitor (TKI) therapy. Multiple groups are currently conducting clinical trials to prospectively screen patients with Ph-like ALL and incorporate the relevant TKI for those harboring ABL-class gene rearrangements or those with JAK-STAT pathway alterations. The success of combinatorial treatment of TKI with chemotherapy in the setting of Ph-positive ALL suggests that this approach may similarly improve outcomes for patients with Ph-like ALL. Hence, Ph-like ALL illustrates the modern treatment paradigm of precision medicine and presents unique opportunities for harnessing international collaborations to further improve outcomes for patients with ALL.

CLIC5: a novel ETV6 target gene in childhood acute lymphoblastic leukemia

The most common rearrangement in childhood precursor B-cell acute lymphoblastic leukemia is the t(12;21)(p13;q22) translocation resulting in the ETV6-AML1 fusion gene. A frequent concomitant event is the loss of the residual ETV6 allele suggesting a critical role for the ETV6 transcriptional repressor in the etiology of this cancer. However, the precise mechanism through which loss of functional ETV6 contributes to disease pathogenesis is still unclear. To investigate the impact of ETV6 loss on the transcriptional network and to identify new transcriptional targets of ETV6, we used whole transcriptome analysis of both pre-B leukemic cell lines and patients combined with chromatin immunoprecipitation. Using this integrative approach, we identified 4 novel direct ETV6 target genes: CLIC5, BIRC7, ANGPTL2 and WBP1L To further evaluate the role of chloride intracellular channel protein CLIC5 in leukemogenesis, we generated cell lines overexpressing CLIC5 and demonstrated an increased resistance to hydrogen peroxide-induced apoptosis. We further described the implications of CLIC5's ion channel activity in lysosomal-mediated cell death, possibly by modulating the function of the transferrin receptor with which it colocalizes intracellularly. For the first time, we showed that loss of ETV6 leads to significant overexpression of CLIC5, which in turn leads to decreased lysosome-mediated apoptosis. Our data suggest that heightened CLIC5 activity could promote a permissive environment for oxidative stress-induced DNA damage accumulation, and thereby contribute to leukemogenesis.

Potent efficacy of combined PI3K/mTOR and JAK or ABL inhibition in murine xenograft models of Ph-like acute lymphoblastic leukemia

Philadelphia chromosome (Ph)-like B-cell acute lymphoblastic leukemia (Ph-like ALL) is associated with activated JAK/STAT, Abelson kinase (ABL), and/or phosphatidylinositol 3-kinase (PI3K) signaling and poor clinical outcomes. PI3K pathway signaling inhibitors have been minimally investigated in Ph-like ALL. We hypothesized that targeted inhibition of PI3Kα, PI3Kδ, PI3K/mTOR, or target of rapamycin complex 1/2 (TORC1/TORC2) would decrease leukemia proliferation and abrogate aberrant kinase signaling and that combined PI3K pathway and JAK inhibition or PI3K pathway and SRC/ABL inhibition would have superior efficacy compared to inhibitor monotherapy. We treated 10 childhood ALL patient-derived xenograft models harboring various Ph-like genomic alterations with 4 discrete PI3K pathway protein inhibitors and observed marked leukemia reduction and in vivo signaling inhibition in all models. Treatment with dual PI3K/mTOR inhibitor gedatolisib resulted in near eradication of ALL in cytokine receptor-like factor 2 (CRLF2)/JAK-mutant models with mean 92.2% (range, 86.0%-99.4%) reduction vs vehicle controls (P < .0001) and in prolonged animal survival. Gedatolisib also inhibited ALL proliferation in ABL/platelet-derived growth factor receptor (PDGFR)-mutant models with mean 66.9% (range, 42.0%-87.6%) reduction vs vehicle (P < .0001). Combined gedatolisib and ruxolitinib treatment of CRLF2/JAK-mutant models more effectively inhibited ALL proliferation than either inhibitor alone (P < .001) and further enhanced survival. Similarly, superior efficacy of combined gedatolisib and dasatinib was observed in ABL/PDGFR-mutant models (P < .001). Overall, PI3K/mTOR inhibition potently decreased ALL burden in vivo; antileukemia activity was further enhanced with combination inhibitor therapy. Clinical trials testing combinations of kinase inhibitors in Ph-like ALL patients are indicated.