Current Management of Childhood Acute Myeloid Leukemia

Evolving Horizons in Pediatric Leukemia: Novel Insights, Challenges, and the Journey Ahead

Pediatric leukemia, encompassing acute lymphoblastic leukemia (ALL) and acute myeloid leukemia, remains a formidable challenge despite significant treatment advancements. This review examines recent developments in immunotherapy, chemotherapy, and bone marrow transplantation for pediatric leukemia through a comprehensive analysis of recent literature, focusing on critical studies and clinical trials. Immunotherapy, including monoclonal antibodies, such as blinatumomab and inotuzumab ozogamicin, and chimeric antigen receptor T-cell therapies, such as tisagenlecleucel and brexucabtagene autoleucel, have demonstrated promising results in relapsed or refractory B-cell ALL (B-ALL), achieving notable remission rates with manageable side effects. Chemotherapy continues to be the primary treatment, utilizing multiphase regimens tailored to individual risk profiles. Bone marrow transplantation, especially allogeneic stem cell transplantation, offers potential cures for high-risk or relapsed cases, though it poses risks including graft-versus-host disease and infections. Despite these advancements, treatment resistance, toxicity, and accessibility persist. This review also discusses the long-term outcomes among pediatric leukemia survivors, focusing on late-onset side effects associated with treatments such as chemotherapy and bone marrow transplantation, encompassing secondary malignancies, organ dysfunction, and neurocognitive impacts. Ongoing research and clinical trials are crucial to refine these therapies, enhance their efficacy, and reduce adverse effects, ultimately improving young patients' survival and quality of life.

Integrated drug resistance and leukemic stemness gene-expression scores predict outcomes in large cohort of over 3500 AML patients from 10 trials

In this study, we leveraged machine-learning tools by evaluating expression of genes of pharmacological relevance to standard-AML chemotherapy (ara-C/daunorubicin/etoposide) in a discovery-cohort of pediatric AML patients (N = 163; NCT00136084 ) and defined a 5-gene-drug resistance score (ADE-RS5) that was predictive of outcome (high MRD1 positivity p = 0.013; lower EFS p < 0.0001 and OS p < 0.0001). ADE-RS5 was integrated with a previously defined leukemic-stemness signature (pLSC6) to classify patients into four groups. ADE-RS5, pLSC6 and integrated-score was evaluated for association with outcome in one of the largest assembly of ~3600 AML patients from 10 independent cohorts (1861 pediatric and 1773 adult AML). Patients with high ADE-RS5 had poor outcome in validation cohorts and the previously reported pLSC6 maintained strong significant association in all validation cohorts. For pLSC6/ADE-RS5-integrated-score analysis, using Group-1 (low-scores for ADE-RS5 and pLSC6) as reference, Group-4 (high-scores for ADE-RS5 and pLSC6) showed worst outcome (EFS: p < 0.0001 and OS: p < 0.0001). Groups-2/3 (one high and one low-score) showed intermediate outcome (p < 0.001). Integrated score groups remained an independent predictor of outcome in multivariable-analysis after adjusting for established prognostic factors (EFS: Group 2 vs. 1, HR = 4.68, p < 0.001, Group 3 vs. 1, HR = 3.22, p = 0.01, and Group 4 vs. 1, HR = 7.26, p < 0.001). These results highlight the significant prognostic value of transcriptomics-based scores capturing disease aggressiveness through pLSC6 and drug resistance via ADE-RS5. The pLSC6 stemness score is a significant predictor of outcome and associates with high-risk group features, the ADE-RS5 drug resistance score adds further value, reflecting the clinical utility of simultaneous testing of both for optimizing treatment strategies.

In silico predicted compound targeting the IQGAP1-GRD domain selectively inhibits growth of human acute myeloid leukemia

Acute myeloid leukemia (AML) is fatal in the majority of adults. Identification of new therapeutic targets and their pharmacologic modulators are needed to improve outcomes. Previous studies had shown that immunization of rabbits with normal peripheral WBCs that had been incubated with fluorodinitrobenzene elicited high titer antibodies that bound to a spectrum of human leukemias. We report that proteomic analyses of immunoaffinity-purified lysates of primary AML cells showed enrichment of scaffolding protein IQGAP1. Immunohistochemistry and gene-expression analyses confirmed IQGAP1 mRNA overexpression in various cytogenetic subtypes of primary human AML compared to normal hematopoietic cells. shRNA knockdown of IQGAP1 blocked proliferation and clonogenicity of human leukemia cell-lines. To develop small molecules targeting IQGAP1 we performed in-silico screening of 212,966 compounds, selected 4 hits targeting the IQGAP1-GRD domain, and conducted SAR of the 'fittest hit' to identify UR778Br, a prototypical agent targeting IQGAP1. UR778Br inhibited proliferation, induced apoptosis, resulted in G2/M arrest, and inhibited colony formation by leukemia cell-lines and primary-AML while sparing normal marrow cells. UR778Br exhibited favorable ADME/T profiles and drug-likeness to treat AML. In summary, AML shows response to IQGAP1 inhibition, and UR778Br, identified through in-silico studies, selectively targeted AML cells while sparing normal marrow.

Cytogenetic abnormalities predict survival after allogeneic hematopoietic stem cell transplantation for pediatric acute myeloid leukemia: a PDWP/EBMT study

Poor-risk (PR) cytogenetic/molecular abnormalities generally direct pediatric patients with acute myeloid leukemia (AML) to allogeneic hematopoietic stem cell transplant (HSCT). We assessed the predictive value of cytogenetic risk classification at diagnosis with respect to post-HSCT outcomes in pediatric patients. Patients younger than 18 years at the time of their first allogeneic HSCT for AML in CR1 between 2005 and 2022 who were reported to the European Society for Blood and Marrow Transplantation registry were subgrouped into four categories. Of the 845 pediatric patients included in this study, 36% had an 11q23 abnormality, 24% had monosomy 7/del7q or monosomy 5/del5q, 24% had a complex or monosomal karyotype, and 16% had other PR cytogenetic abnormalities. In a multivariable model, 11q23 (hazard ratio [HR] = 0.66, P = 0.03) and other PR cytogenetic abnormalities (HR = 0.55, P = 0.02) were associated with significantly better overall survival when compared with monosomy 7/del7q or monosomy 5/del5q. Patients with other PR cytogenetic abnormalities had a lower risk of disease relapse after HSCT (HR = 0.49, P = 0.01) and, hence, better leukemia-free survival (HR = 0.55, P = 0.01). Therefore, we conclude that PR cytogenetic abnormalities at diagnosis predict overall survival after HSCT for AML in pediatric patients.

Pediatric acute myeloid leukemia and hyperleukocytosis with WBC count greater than 50 × 109/L

BACKGROUND

Acute myeloid leukemia (AML) and hyperleukocytosis have an unfavorable prognosis, but the impact of hyperleukocytosis on the prognosis of pediatric AML remains uncertain. We investigated the clinical characteristics and prognosis of pediatric AML with hyperleukocytosis, defined as WBC ≥ 50 × 109/L.

METHODS

A total of 132 patients with newly diagnosed childhood AML with hyperleukocytosis were consecutively enrolled at our center from September 2009 to August 2021 to investigate prognostic factors and clinical outcomes.

RESULTS

Hyperleukocytosis occurred in 27.4% of AML patients. Pediatric patients with hyperleukocytosis had similar CR and OS rates to those without hyperleukocytosis, but had a lower EFS rate. In our study, rates of CR1, mortality, relapsed/refractory disease, and HSCT were comparable between AML patients with WBC counts of 50-100 × 109/L and ≥ 100 × 109/L. AML patients with a WBC count of 50-100 × 109/L had a similar 5-year OS rate to patients with a WBC count ≥ 100 × 109/L (74.6% vs. 75.4%, P = 0.921). Among all patients with hyperleukocytosis, the FAB M5 subtype was associated with significantly inferior survival, and the prognosis of CBF-AML was good.

CONCLUSIONS

Pediatric AML patients with hyperleukocytosis have the similar prognosis regardless of whether their WBC count is 50-100 × 109/L or ≥ 100 × 109/L.

Using published pathway figures in enrichment analysis and machine learning

Pathway Figure OCR (PFOCR) is a novel kind of pathway database approaching the breadth and depth of Gene Ontology while providing rich, mechanistic diagrams and direct literature support. Here, we highlight the utility of PFOCR in disease research in comparison with popular pathway databases through an assessment of disease coverage and analytical applications. In addition to common pathway analysis use cases, we present two advanced case studies demonstrating unique advantages of PFOCR in terms of cancer subtype and grade prediction analyses.

A Review of Childhood Acute Myeloid Leukemia: Diagnosis and Novel Treatment

Acute myeloid leukemia (AML) is the second most common hematologic malignancy in children. The incidence of childhood AML is much lower than acute lymphoblastic leukemia (ALL), which makes childhood AML a rare disease in children. The role of genetic abnormalities in AML classification, management, and prognosis prediction is much more important than before. Disease classifications and risk group classifications, such as the WHO classification, the international consensus classification (ICC), and the European LeukemiaNet (ELN) classification, were revised in 2022. The application of the new information in childhood AML will be upcoming in the next few years. The frequency of each genetic abnormality in adult and childhood AML is different; therefore, in this review, we emphasize well-known genetic subtypes in childhood AML, including core-binding factor AML (CBF AML), KMT2Ar (KMT2A/11q23 rearrangement) AML, normal karyotype AML with somatic mutations, unbalanced cytogenetic abnormalities AML, NUP98 11p15/NUP09 rearrangement AML, and acute promyelocytic leukemia (APL). Current risk group classification, the management algorithm in childhood AML, and novel treatment modalities such as targeted therapy, immune therapy, and chimeric antigen receptor (CAR) T-cell therapy are reviewed. Finally, the indications of hematopoietic stem cell transplantation (HSCT) in AML are discussed.

Using Published Pathway Figures in Enrichment Analysis and Machine Learning

Pathway Figure OCR (PFOCR) is a novel kind of pathway database approaching the breadth and depth of Gene Ontology while providing rich, mechanistic diagrams and direct literature support. PFOCR content is extracted from published pathway figures currently emerging at a rate of 1000 new pathways each month. Here, we compare the pathway information contained in PFOCR against popular pathway databases with respect to overall and disease-specific coverage. In addition to common pathways analysis use cases, we present two advanced case studies demonstrating unique advantages of PFOCR in terms of cancer subtype and grade prediction analyses.

Identification of Circular RNA Circ_0003256 as a Novel Player in Pediatric Acute Myeloid Leukemia

BACKGROUND

Aberrant expression of circular RNAs (circRNAs) is tightly associated with the pathogenesis of human cancers, including pediatric acute myeloid leukemia (AML). In this report, we sought to define the precise action of circ_0003256 in the pathogenesis of pediatric AML.

MATERIALS AND METHODS

Circ_0003256, microRNA (miR)-582-3p, and protein kinase cAMP-activated catalytic subunit beta (PRKACB) were quantified by quantitative real-time polymerase chain reaction and Western blot. Cell proliferation, cycle distribution, and apoptosis were estimated by MTT, 5-ethynyl-2'-deoxyuridine, and flow cytometry assays, respectively. Direct relationships among circ_0003256, miR-582-3p, and PRKACB were verified by a dual-luciferase reporter and RNA pull-down assays.

RESULTS

Our data indicated that circ_0003256 was highly expressed in pediatric AML patients and cells. Suppression of circ_0003256 hindered cell proliferation and promoted apoptosis in THP-1 and MV4-11 cells. Mechanistically, circ_0003256 contained functional binding sites for miR-582-3p, and circ_0003256 suppression influenced cell behaviors by upregulating miR-582-3p. MiR-582-3p directly targeted and inhibited PRKACB and the inhibition of PRKACB phenocopied miR-582-3p overexpression in regulating cell functional behaviors. Moreover, circ_0003256 involved the posttranscriptional regulation of PRKACB through miR-582-3p.

CONCLUSION

Our findings identify that suppression of circ_0003256 impedes the malignant behaviors of pediatric AML cells by regulating PRKACB expression by competing for shared miR-582-3p.

Analysis of rare driving events in pediatric acute myeloid leukemia

Elucidating genetic aberrations in pediatric acute myeloid leukemia (AML) provides insight in biology and may impact on risk-group stratification and clinical outcome. This study aimed to detect such aberrations in a selected series of samples without known (cyto)genetic aberration using molecular profiling. A cohort of 161 patients was selected from various study groups: DCOG, BFM, SJCRH, NOPHO and AEIOP. Samples were analyzed using RNA sequencing (n=152), whole exome (n=135) and/or whole genome sequencing (n=100). In 70 of 156 patients (45%), of whom RNA sequencing or whole genome sequencing was available, rearrangements were detected, 22 of which were novel; five involving ERG rearrangements and four NPM1 rearrangements. ERG rearrangements showed self-renewal capacity in vitro, and a distinct gene expression pattern. Gene set enrichment analysis of this cluster showed upregulation of gene sets derived from Ewing sarcoma, which was confirmed comparing gene expression profiles of AML and Ewing sarcoma. Furthermore, NPM1-rearranged cases showed cytoplasmic NPM1 localization and revealed HOXA/B gene overexpression, as described for NPM1 mutated cases. Single-gene mutations as identified in adult AML were rare. Patients had a median of 24 coding mutations (range, 7-159). Novel recurrent mutations were detected in UBTF (n=10), a regulator of RNA transcription. In 75% of patients an aberration with a prognostic impact could be detected. Therefore, we suggest these techniques need to become standard of care in diagnostics.

Metabolic Reprogramming and Cell Adhesion in Acute Leukemia Adaptation to the CNS Niche

Involvement of the Central Nervous System (CNS) in acute leukemia confers poor prognosis and lower overall survival. Existing CNS-directed therapies are associated with a significant risk of short- or long-term toxicities. Leukemic cells can metabolically adapt and survive in the microenvironment of the CNS. The supporting role of the CNS microenvironment in leukemia progression and dissemination has not received sufficient attention. Understanding the mechanism by which leukemic cells survive in the nutrient-poor and oxygen-deprived CNS microenvironment will lead to the development of more specific and less toxic therapies. Here, we review the current literature regarding the roles of metabolic reprogramming in leukemic cell adhesion and survival in the CNS.

Unifying heterogeneous expression data to predict targets for CAR-T cell therapy

Chimeric antigen receptor (CAR) T-cell therapy combines antigen-specific properties of monoclonal antibodies with the lytic capacity of T cells. An effective and safe CAR-T cell therapy strategy relies on identifying an antigen that has high expression and is tumor specific. This strategy has been successfully used to treat patients with CD19+ B-cell acute lymphoblastic leukemia (B-ALL). Finding a suitable target antigen for other cancers such as acute myeloid leukemia (AML) has proven challenging, as the majority of currently targeted AML antigens are also expressed on hematopoietic progenitor cells (HPCs) or mature myeloid cells. Herein, we developed a computational method to perform a data transformation to enable the comparison of publicly available gene expression data across different datasets or assay platforms. The resulting transformed expression values (TEVs) were used in our antigen prediction algorithm to assess suitable tumor-associated antigens (TAAs) that could be targeted with CAR-T cells. We validated this method by identifying B-ALL antigens with known clinical effectiveness, such as CD19 and CD22. Our algorithm predicted TAAs being currently explored preclinically and in clinical CAR-T AML therapy trials, as well as novel TAAs in pediatric megakaryoblastic AML. Thus, this analytical approach presents a promising new strategy to mine diverse datasets for identifying TAAs suitable for immunotherapy.

Recent Advances in the Management of Pediatric Acute Myeloid Leukemia-Report of the Hungarian Pediatric Oncology-Hematology Group

Simple Summary

The outcome of pediatric AML improved considerably worldwide during the past few decades. Hereby, we summarize the therapeutic results of pediatric AML patients registered between 2012 and 2019 in Hungary. As compared to our previous results, improvement was registered in event-free (EFS) and overall (OS) survival, which can be attributed to the application of contemporary diagnostic and therapeutic guidelines, advanced supportation, and higher efficacy of hematopoietic stem cell transplantation. Between 2016 and 2019, a statistically significant increment of 2-year EFS was confirmed over the period between 2012 and 2015. The most prominent progress was observed in acute promyelocytic leukemia (APL). Multidimensional flow cytometry made possible the prompt introduction of ATRA in two cases with M3v, who also represent the first pediatric APL patients in Hungary to be treated with arsenic-trioxide. Besides joining multinational pediatric AML treatment groups, our future aims include the introduction of centralized treatment centers and diagnostic facilities.

Abstract

Outcome measures of pediatric acute myeloid leukemia (AML) improved considerably between 1990 and 2011 in Hungary. Since 2012, efforts of the Hungarian Pediatric Oncology-Hematology Group (HPOG) included the reduction in the number of treatment centers, contemporary diagnostic procedures, vigorous supportation, enhanced access to hematopoietic stem cell transplantation (HSCT), and to targeted therapies. The major aim of our study was to evaluate AML treatment results of HPOG between 2012 and 2019 with 92 new patients registered (52 males, 40 females, mean age 7.28 years). Two periods were distinguished: 2012–2015 and 2016–2019 (55 and 37 patients, respectively). During these periods, 2 y OS increased from 63.6% to 71.4% (p = 0.057), and the 2 y EFS increased significantly from 56.4% to 68.9% (p = 0.02). HSCT was performed in 37 patients (5 patients received a second HSCT). We demonstrate advances in the diagnosis and treatment of acute promyelocytic leukemia (APL) in two cases. Early diagnosis and follow-up were achieved by multidimensional flow cytometry and advanced molecular methods. Both patients were successfully treated with all-trans retinoic acid and arsenic-trioxide, in addition to chemotherapy. In order to meet international standards of pediatric AML management, HPOG will further centralize treatment centers and diagnostic facilities and join efforts with international study groups.

Dynamin inhibition causes context-dependent cell death of leukemia and lymphoma cells

Current chemotherapy for treatment of pediatric acute leukemia, although generally successful, is still a matter of concern due to treatment resistance, relapses and life-long side effects for a subset of patients. Inhibition of dynamin, a GTPase involved in clathrin-mediated endocytosis and regulation of the cell cycle, has been proposed as a potential anti-cancer regimen, but the effects of dynamin inhibition on leukemia cells has not been extensively addressed. Here we adopted single cell and whole-population analysis by flow cytometry and live imaging, to assess the effect of dynamin inhibition (Dynasore, Dyngo-4a, MitMAB) on pediatric acute leukemia cell lines (CCRF-CEM and THP-1), human bone marrow biopsies from patients diagnosed with acute lymphoblastic leukemia (ALL), as well as in a model of lymphoma (EL4)-induced tumor growth in mice. All inhibitors suppressed proliferation and induced pronounced caspase-dependent apoptotic cell death in CCRF-CEM and THP-1 cell lines. However, the inhibitors showed no effect on bone marrow biopsies, and did not prevent EL4-induced tumor formation in mice. We conclude that dynamin inhibition affects highly proliferating human leukemia cells. These findings form a basis for evaluation of the potential, and constraints, of employing dynamin inhibition in treatment strategies against leukemia and other malignancies.

Exosomal circ_0004136 enhances the progression of pediatric acute myeloid leukemia depending on the regulation of miR-570-3p/TSPAN3 axis

Circular RNAs (circRNAs) have been implicated in the progression of pediatric acute myeloid leukemia (AML). Although circ_0004136 has been found to play a crucial role in AML, our understanding of its molecular mechanism remains very limited. The levels of circ_0004136, miR-570-3p and tetraspanin 3 (TSPAN3) were determined by quantitative real-time PCR or western blot. Cell viability, migration, invasion, cell cycle and apoptosis were detected using the Cell Counting Kit-8, transwell and flow cytometry assays. Targeted relationships among circ_0004136, miR-570-3p and TSPAN3 were validated by dual-luciferase reporter and RNA immunoprecipitation assays. Our data showed that circ_0004136 could be transmitted by exosomes, and exosomal circ_0004136 was highly expressed in AML serum and cells. Circ_0004136 was unusually stable and mainly localized in the cytoplasm. Circ_0004136 knockdown mediated by exosomes hampered AML cell viability, cell cycle progression, migration and invasion, and promoted cell apoptosis. Moreover, circ_0004136 worked as a sponge of miR-570-3p and TSPAN3 was a functional target of miR-370-3p in AML cells. The suppression of circ_0004136 knockdown mediated by exosomes on AML cell malignant progression was reversed by miR-570-3p downregulation, and the increased miR-570-3p expression hindered the progression of aggressive AML by downregulating TSPAN3. Furthermore, circ_0004136 worked as a miR-570-3p sponge to modulate TSPAN3 expression. Our findings identified a novel regulatory mechanism in which exosome-mediated circ_0004136 knockdown restrained AML cell malignant progression at least partly through targeting the miR-570-3p/TSPAN3 axis, highlighting a novel therapeutic strategy for AML management.

[Unrelated cord blood stem cell transplantation for high-risk/refractory childhood acute myeloid leukemia: a clinical analysis of 160 cases]

Objective: To retrospectively analyze the clinical outcomes of single unrelated cord blood transplantation (UCBT) in children with high risk and refractory acute myeloid leukemia (AML) . Methods: Between June 2008 and December 2018, a total of 160 consecutive pediatric patients with AML received single UCBT (excluding acute promyelocytic leukemia) . Myeloablative conditioning (MAC) regimen were applied. All patients received a combination of cyclosporine A (CsA) and mycophenolate mofetil (MMF) for the prophylaxis of graft -versus- host disease (GVHD) . Results: The cumulative incidence of neutrophil cells engraftment at day +42 and platelet recovery at day +120 was 95.0% (95% CI 90.0%-97.5%) at a median of 16 days after transplantation (range, 11-38 days) and 85.5% (95%CI 83.3%-93.4%) with a median time to recovery of 35 days (range, 13-158) , respectively. Incidence of grades Ⅱ-Ⅳ and Ⅲ-Ⅳ acute GVHD and chronic GVHD were 37.3% (95%CI 29.3%-45.2%) , 27.3% (95%CI 20.0%-35.0%) and 22.4% (95%CI 15.5%-28.7%) , respectively. The transplant-related mortality (TRM) at 360 day was 13.1% (95%CI 8.4%-18.9%) . The 5-year cumulative incidence of relapse was 13.8% (95%CI 8.5%-20.3%) . The 5-year disease-free survival (DFS) and overall survival (OS) were 71.7% (95%CI 62.7%-77.8%) and 72.2% (95%CI 64.1%-78.7%) , respectively. The 5-year GVHD and relapse free survival (GRFS) was 56.1% (95%CI 46.1%-64.9%) . The 5-year cumulative recurrence rates of CR1, CR2, and NR groups were 5.3%, 19.9%, and 30.9% (P=0.001) , and the 5-year OS rates were 79.9% (95%CI 70.3%-86.7%) , 71.1% (95%CI 50.4%-84.4%) and 52.9% (95%CI 33.0%-69.3%) (χ(2)=7.552, P=0.020) , respectively. Conclusions: For pediatric patients with high risk and refractory AML, UCBT is a safe and effective treatment option, and it is favorable to improve the survival rate in CR1 stage.

Results of a phase 2, multicenter, single-arm, open-label study of lenalidomide in pediatric patients with relapsed or refractory acute myeloid leukemia

BACKGROUND

Outcomes after relapse remain poor in pediatric patients with acute myeloid leukemia (AML), and new therapeutic approaches are needed. Lenalidomide has demonstrated activity in adults with lower risk myelodysplastic syndromes and older adults with relapsed or refractory (R/R) AML.

METHODS

In this phase 2 study (NCT02538965), pediatric patients with R/R AML who received two or more prior therapies were treated with lenalidomide (starting dose 2 mg/kg/day on days 1-21 of each 28-day cycle) for a maximum of 12 cycles. The primary endpoint was rate of complete response (CR) and CR with incomplete blood count recovery (CRi) within the first four cycles.

RESULTS

Seventeen patients enrolled and received one or more dose of lenalidomide. Median age was 12 years (range 5-18 years), median white blood cell count was 3.7 × 10⁹ /L, and median peripheral blood blast count was 1.0 × 10⁹ /L. One patient (5.9%) with a complex karyotype including del(5q) achieved CRi after two cycles of lenalidomide. This responder proceeded to a second hematopoietic stem cell transplantation and has remained without evidence of disease for 3 years. All patients experienced one or more of grades 3-4 treatment-emergent adverse event (TEAE). The most common grades 3-4 TEAEs were thrombocytopenia (58.8%), febrile neutropenia (47.1%), anemia (41.2%), and hypokalemia (41.2%).

CONCLUSIONS

In this population of pediatric patients with R/R AML, safety data were consistent with the known safety profile of lenalidomide. As only one patient responded, further evaluation of lenalidomide at the dose and schedule studied is not warranted in pediatric AML, with the possible exception of patients with del(5q).

Silencing of circTASP1 inhibits proliferation and induces apoptosis of acute myeloid leukaemia cells through modulating miR-515-5p/HMGA2 axis

Acute myeloid leukaemia (AML) is a common hematopoietic disease that is harmful to the lives of children and adults. CircRNAs are aberrantly expressed in the haematologic malignancy cells. However, the expression of circTASP1 and its function in AML remain unclear. In this study, we showed that circTASP1 was significantly up‐regulated in AML peripheral blood samples and cells. Knockdown of circTASP1 inhibited proliferation and promoted apoptosis of HL60 and THP‐1 cells in vitro. Bioinformatics prediction and luciferase reporter assay proved that circTASP1 sponged miR‐515‐5p and negatively regulated miR‐515‐5p expression in HL60 and THP‐1 cells. High mobility group A2 (HMGA2) was proved to be a downstream target of miR‐515‐5p. The rescue experiments confirmed that knockdown of circTASP1 inhibited proliferation and induced apoptosis by modulating miR‐515‐5p/HMGA2 pathway. Moreover, the in vivo experiment indicated that knockdown of circTASP1 suppressed tumour growth. In conclusion, circTASP1 acts as a sponge for miR‐515‐5p to regulate HMGA2, thereby promoting proliferation and inhibiting apoptosis during AML progression. Thus, circTASP1 has the potential to be explored as a therapeutic target for AML treatment.

Long noncoding RNA GAS6 antisense RNA1 silencing attenuates the tumorigenesis of acute myeloid leukemia cells through targeting microRNA-370-3p/Tetraspanin3 axis

PURPOSE

Acute myeloid leukemia (AML) is a type of hematologic malignancy. This study was attempt to explore the effect of long noncoding RNA GAS6 antisense RNA1 (GAS6-AS1) on pediatric AML and the regulation mechanisms.

METHODS

GAS6-AS1, microRNA-370-3p (miR-370-3p), and Tetraspanin3 (TSPAN3) expression in bone marrow (BM) tissues and cells was determined by qRT-PCR. The correlation between GAS6-AS1 and clinicopathological features of pediatric patients with AML was assessed. In vitro, viability and migration and invasion of AML cells were evaluated via MTT and transwell assays, respectively. Interactions among GAS6-AS1, miR-370-3p, and TSPAN3 were revealed by dual-luciferase reporter assays. Western blot was applied to confirm the protein expression of TSPAN3.

RESULTS

GAS6-AS1 and TSPAN3 expression was elevated in BM tissues of pediatric patients with AML and AML cells, but miR-370-3p expression was reduced. GAS6-AS1 expression was positively related to French-American-British (FAB) classification in pediatric patients with AML. In vitro, GAS6-AS1 deficiency restrained the viability, migration, and invasion of AML cells. Additionally, GAS6-AS1 mediated miR-370-3p expression indeed and TSPAN3 was identified as a target of miR-370-3p. Furthermore, miR-370-3p overexpression repressed the protein expression of TSPAN3. The feedback experiments demonstrated that miR-370-3p inhibition or TSPAN3 overexpression mitigated the suppressive effect of sh-GAS6-AS1 on the tumorigenesis of AML cells.

CONCLUSION

GAS6-AS1 silencing restrained AML cell viability, migration, and invasion by targeting miR-370-3p/TSPAN3 axis, affording a novel therapeutic target for pediatric AML.

Minimal residual disease monitoring via AML1-ETO breakpoint tracing in childhood acute myeloid leukemia

Relapse of childhood AML1-ETO (AE) acute myeloid leukemia is the most common cause of treatment failure. Optimized minimal residual disease monitoring methods is required to prevent relapse. In this study, we used next-generation sequencing to identify the breakpoints in the fusion gene and the DNA-based droplet digital PCR (ddPCR) method was used for dynamic monitoring of AE-DNA. The ddPCR technique provides more sensitive and precise quantitation of the AE gene during disease progression and relapse. Quantification of the AE fusion gene by ddPCR further contributes to improved prognosis. Our study provides valuable methods for dynamic surveillance of AE fusion DNA and assistance in determining the prognosis.

Predictive impact of residual disease detected using multiparametric flow cytometry on risk stratification of paediatric acute myeloid leukaemia with normal karyotype

INTRODUCTION

Residual disease (RD) detected using multiparametric flow cytometry (MFC) is an independent predictive variable of relapse in acute myeloid leukaemia (AML). However, RD thresholds and optimal assessment time points remain to be validated.

MATERIAL AND METHODS

We investigated the significance of RD after induction therapy in paediatric AML with normal karyotype between June 2008 and June 2018. Bone marrow samples from 73 patients were collected at the end of the first (BMA-1) and second (BMA-2) induction courses to monitor RD using MFC.

RESULTS

Presence of RD after BMA-1 and/or BMA-2 correlated with poor relapse-free (RFS) and overall survival at 0.1% RD cutoff level. Receiver operating characteristic curve showed that RD cutoff levels of 1.3% and 0.5% after BMA-1 and BMA-2, respectively, predicted events with the highest sensitivity and specificity. In multivariable analysis, RD after BMA-2 was the strongest independent risk predictor for poor RFS (hazard ratio 2.934; 95% confidence interval: 1.106-7.782; P = .031).

CONCLUSIONS

Our study therefore suggests that an RD level ≥0.5% after BMA-2 has a significant predictive impact on the prognosis of AML patients having normal karyotype and thus guide the stratification of treatment strategies.

Lymphoid markers predict prognosis of pediatric and adolescent acute myeloid leukemia

Acute Myeloid Leukemia (AML) is a complex and highly aggressive disease. To characterize the prognostic factors of pediatric patients with AML relapse, a retrospective cohort study was performed to collect data from children and adolescents, at a hematological oncology reference center, over 11 years. We selected 51 cases of the disease, diagnosed and treated uniformly, divided into two groups: with complete remission (n = 33; 65 %) and with relapse (n = 18; 35 %). The groups were homogeneous concerning demographic characteristics and hematological parameters at diagnosis. AML M3 was the most common subtype (n = 19; 37 %) and was associated with a good prognosis. The highest rate of relapse was with AML M0 (n = 3 of 5 patients; 60 %). The most predominant gene mutation, FLT3-ITD, did not influence the prognosis in our study. The complete remission group presented a higher mean frequency of positive cells for the granulocytic marker CD13a at diagnosis. In cases with AML relapse, CD36, CD4, CD7, and CD22 were the most expressed markers. Increase incidence of recurrence was associated with CD7 (HR 1.035; p = 0.003), CD4 (HR 1.032, p = 0.001) and CD22 (HR 1.042; p = 0.049). Our results highlight the importance of analyzing immunophenotypic markers to help predict the outcome of AML in children and adolescents.

Outcome of pediatric acute myeloid leukemia (AML) in low- and middle-income countries: a systematic review of the literature

Introduction: Survival rates of pediatric acute myeloid leukemia (AML) in low- and middle-income countries (LMICs) seem extremely poor, and the available literature on the matter is scarce. Accordingly, there is a limited understanding of poor treatment outcomes seen in this population.Areas covered: We provide an overview of the available literature with respect to treatment outcomes of pediatric AML in LMICs yielding poor outcomes compared to high-income countries. Moreover, treatment outcomes vary markedly between LMICs. In addition, there is a wide variation among studies in how treatment outcomes are reported and analyzed.Expert opinion: The substantially inferior treatment outcomes of pediatric AML in LMICs emphasize the unprecedented importance of global initiatives and international collaborations to improve the survival of these patients. A coordinated approach is necessary to carry out country-specific situational analyses. These analyses will result in operational plans on how to structurally implement childhood cancer registries, align healthcare infrastructure, build on capacities, and provide universal health coverage in LMICs. In addition, we strongly recommend that, in the future, LMICs document, analyze, and publish pediatric AML treatment outcomes in a more structured and uniform manner.

High-throughput drug screening reveals Pyrvinium pamoate as effective candidate against pediatric MLL-rearranged acute myeloid leukemia

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Drug library screening identified pyrvinium to be effective against MLL-rearranged AML.

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Pyrvinium targets the mitochondria of MLL-rearranged AML cells.

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Pyrvinium does not antagonize with standard chemotherapy in MLL-rearranged AML.

Pediatric MLL-rearranged acute myeloid leukemia (AML) has a generally unfavorable outcome, primarily due to relapse and drug resistance. To overcome these difficulties, new therapeutic agents are urgently needed. Yet, implementing novel drugs for clinical use is a time-consuming, laborious, costly and high-risk process. Therefore, we applied a drug-repositioning strategy by screening drug libraries, comprised of >4000 compounds that are mostly FDA-approved, in a high-throughput format on primary MLL-rearranged AML cells. Here we identified pyrvinium pamoate (pyrvinium) as a novel candidate drug effective against MLL-rearranged AML, eliminating all cell viability at <1000 nM. Additional screening of identified drug hits on non-leukemic bone marrow samples, resulted in a decrease in cell viability of ∼50% at 1000 nM pyrvinium, suggesting a therapeutic window for targeting leukemic cells specifically. Validation of pyrvinium on an extensive panel of AML cell lines and primary AML samples showed comparable viabilities as the drug screen data, with pyrvinium achieving IC₅₀ values of <80 nM in these samples. Remarkably, pyrvinium also induced cell toxicity in primary MLL-AF10⁺ AML cells, an MLL-rearrangement associated with a poor outcome. While pyrvinium is able to inhibit the Wnt pathway in other diseases, this unlikely explains the efficacy we observed as β-catenin was not expressed in the AML cells tested. Rather, we show that pyrvinium co-localized with the mitochondrial stain in cells, and hence may act by inhibiting mitochondrial respiration. Overall, this study shows that pyrvinium is highly effective against MLL-rearranged AML in vitro, and therefore represents a novel potential candidate for further studies in MLL-rearranged AML.

Treatment Outcomes of Pediatric Acute Myeloid Leukemia in the Yeungnam Region: A Multicenter Retrospective Study of the Study Alliance of Yeungnam Pediatric Hematology-Oncology (SAYPH)

Acute myeloid leukemia (AML) is the second most common pediatric leukemia, with a survival rate of 70%. In this retrospective study, we evaluated the treatment outcomes of pediatric AML among 144 patients diagnosed between 2000 and 2013. After induction, 80.6% of patients achieved complete remission (CR). The 5-year overall survival (OS) and event-free survival (EFS) rates were 58.8 ± 4.2% and 49.8 ± 4.2%, respectively. Based on the response to induction therapy, the 5-year OS was 66.9 ± 5.7% in patients with CR (p < 0.001). Ninety-nine patients with CR after induction therapy were examined, and their 5-year OS and EFS were 66.4 ± 4.9% and 56.3 ± 5.1%, respectively. The 5-year OS rates according to treatment were 59.9 ± 7.4% in the chemotherapy group and 72.3 ± 6.3% in the hematopoietic stem cell transplantation (HSCT) group (p = 0.089). The EFS was 50.1 ± 7.4% in the chemotherapy group and 61.7 ± 6.9% in the HSCT group (p = 0.098). OS and EFS according to cytogenetics were insignificant. Our findings confirmed that the response to induction treatment was important for survival and HSCT had no significant survival benefits compared with those of chemotherapy. Moreover, many early induction deaths under the age of 2 years were observed.

Excellent Survival Outcomes of Pediatric Patients With Acute Myeloid Leukemia Treated With the MASPORE 2006 Protocol

PURPOSE

To determine the prognostic factors in pediatric patients with acute myeloid leukemia (AML) and to assess whether their outcomes have improved over time.

PATIENTS AND METHODS

Sixty-two patients with AML excluding acute promyelocytic leukemia were retrospectively analyzed. Patients in the earlier cohort (n = 36) were treated on the Medical Research Council (MRC) AML12 protocol, whereas those in the recent cohort (n = 26) were treated on the Malaysia-Singapore AML protocol (MASPORE 2006), which differed in terms of risk group stratification, cumulative anthracycline dose, and timing of hematopoietic stem-cell transplantation for high-risk patients.

RESULTS

Significant improvements in 10-year overall survival and event-free survival were observed in patients treated with the recent MASPORE 2006 protocol compared to the earlier MRC AML12 protocol (overall survival: 88.0% ± 6.5% vs 50.1% ± 8.6%, P = .002; event-free survival: 72.1% ± 9.0 vs 50.1% ± 8.6%, P = .045). In univariate analysis, patients in the recent cohort had significantly lower intensive care unit admission rate (11.5% vs 47.2%, P = .005) and numerically lower relapse rate (26.9% vs 50.0%, P = .068) compared to the earlier cohort. Multivariate analysis showed that treatment protocol was the only independent predictive factor for overall survival (hazard ratio = 0.21; 95% confidence interval, 0.06-0.73, P = .014).

CONCLUSION

Outcomes of pediatric AML patients have improved over time. The more recent MASPORE 2006 protocol led to significant improvement in long-term survival rates and reduction in intensive care unit admission rate.

Expanded activated autologous lymphocyte infusions improve outcomes of low- and intermediate-risk childhood acute myeloid leukemia with low level of minimal residual disease

The presence of minimal residual disease (MRD) is a risk factor for relapse among children with acute myeloid leukemia (AML), and eliminating MRD can usually improve survival rates. To investigate the effect of expanded activated autologous lymphocytes (EAALs) combined with chemotherapy on eliminating MRD and improving survival rates of children with AML, we retrospectively analyzed the results of 115 children with low- or intermediate-risk AML with MRD treated at the Pediatric Hematological Center, Peking University People's Hospital, between January 2010 and January 2016. The patients were assigned to the chemotherapy plus EAAL (combined therapy) group (n = 61) and chemotherapy group (n = 54). The MRD-negativity rates were 95.1% (58/61) in the combined therapy group and 63.0% (34/54) in the chemotherapy group (P < 0.0001) during consolidation treatment. The 5-year event-free survival rate was higher in the combined therapy group than in the chemotherapy group (86.3 ± 4.6% vs. 72.1 ± 6.1%, P = 0.025). No severe adverse event was observed after EAAL infusion. The present study showed that EAAL combined with chemotherapy could improve the MRD-negativity rate and event-free survival rate among children with AML with low level MRD-positive status.

TPEN exerts selective anti-leukemic efficacy in ex vivo drug-resistant childhood acute leukemia

Despite some advances in the treatment of acute lymphoblastic (ALL) and myeloid leukemia (AML) in recent years, there is still a prominent percentage of pediatric patients with a reduced overall prognosis. Therefore, other therapeutic approaches are needed to treat those patients. In the present study, we report that the metal chelator TPEN affected ΔΨ_m and DNA content in isolated CD34⁺ refractory cells from bone marrow ALL (n = 7; B-cell, n = 4; T-cell, n = 3) and AML (n = 3) pediatric patients. Furthermore, TPEN induced oxidation of hydrogen peroxide (H₂O₂) sensor protein DJ-1, induced up-regulation of BH3-only pro-apoptotic protein PUMA, transcription factor p53 and activated the executor protease CASPASE-3 as apoptosis markers, and reduced the reactivity of the cellular proliferating marker Ki-67 in all acute leukemic groups, and reduced the phosphorylation of c-ABL protein signal in an AML case. Remarkably, bone marrow cells from non-leukemic patients' cells (n = 2) displayed neither loss of ΔΨ_m nor loss of DNA content when exposed to TPEN. We conclude that TPEN selectively induces apoptosis in acute leukemic cells via reactive oxygen species (ROS) signaling mechanism. Understanding the pathways of TPEN-induced cell death may provide insight into more effective therapeutic ROS-inducing anticancer agents.

Oncogenic Long Noncoding RNA DARS-AS1 in Childhood Acute Myeloid Leukemia by Binding to microRNA-425

OBJECTIVE

Acute myeloid leukemia (AML) represents a hematological cancer. The aim of the investigation was to probe the regulatory relevance of long non-coding RNA (lncRNA) aspartyl-tRNA synthetase anti-sense 1 (DARS-AS1)/microRNA-425 (miR-425)/transforming growth factor-beta 1 (TGFB1) to the development of AML.

METHODS

The DARS-AS1 expression in bone marrow tissues was first analyzed in healthy subjects and AML patients. Subsequently, AML cell lines with DARS-AS1 knockdown were constructed, followed by cell proliferation and apoptosis assays. Afterward, downstream miRNA of DARS-AS1 and target mRNA of the miRNA were analyzed by bioinformatics, and their binding relationships were verified. Functional rescue experiments were then implemented. Finally, activation of the Smad2/3 signaling in MV4-11 and BF-24 cells were detected by western blot.

RESULTS

DARS-AS1 was overexpressed in bone marrow tissues of AML patients and cells, and DARS-AS1 knockdown suppressed the proliferation of AML cells and induced apoptosis. DARS-AS1 bound to and negatively correlated with miR-425. Further results suggested that TGFB1 might be a target gene of miR-425 and could promote Smad2/3 phosphorylation and nuclear translocation. Finally, DARS-AS1 depletion could diminish the tumor volume in vivo.

CONCLUSION

All in all, we highlighted here that DARS-AS1 enhanced the expression of TGFB1 through binding to miR-425 to modulate AML progression via the Smad2/3 pathway, which might perform as a therapeutic target for AML.

A three-gene signature and clinical outcome in pediatric acute myeloid leukemia

BACKGROUND

Although the 5-year survival rates in pediatric acute myeloid leukemia (AML) have improved over the last decades, there is a high relapse rate for Pediatric AML patients.

METHODS

In the present study, we mainly combine PCA with the LASSO technique to identify prognostic markers for Pediatric AML patients coming from the NCI TARGET database.

RESULTS

Three key genes (EEF1A1, RPLP2, RPL19) associated with poor prognosis of pediatric AML has been screened by both PCA and LASSO Cox regression analysis. Simultaneously, we developed a risk score model to predict the prognosis of pediatric AML, according to risk scores, the patients were divided into high- and low-risk groups based on the median risk score. Kaplan-Meier survival analysis indicated that Pediatric AML patients with the high-risk group have a poorer survival rate than those with a low-risk group (p < 0.000). The receiver operating characteristic (ROC) analysis showed that the risk model has a good performance (AUC:0.669). Moreover, the clinicopathologic correlation showed that the expression levels of three genes were related to the central nervous system (CNS) disease and chloroma. GSEA identified that those pathways including oxidative phosphorylation, apoptosis and TGFB signaling pathway were differentially enriched.

CONCLUSION

Taken together, those studies suggested that a gene panel that consists of three genes (EEF1A1, RPLP2, RPL19) may act as a potential prognostic marker.

Allogeneic Hematopoietic Stem Cell Transplantation for Children and Adolescents with Acute Myeloid Leukemia in Brazil: A Multicentric Retrospective Study

The survival rates of children with high-risk acute myeloid leukemia (AML) treated with hematopoietic stem cell transplant (HSCT) range from 60% to 70% in high-income countries. The corresponding rate for Brazilian children with AML who undergo HSCT is unknown. We conducted a retrospective analysis of 114 children with AML who underwent HSCT between 2008 and 2012 at institutions participating in the Brazilian Pediatric Bone Marrow Transplant Working Group. At transplant, 38% of the children were in first complete remission (CR1), 37% were in CR2, and 25% were in CR3+ or had persistent disease. The donors included 49 matched-related, 59 matched-unrelated, and six haploidentical donors. The most frequent source of cells was bone marrow (69%), followed by the umbilical cord (19%) and peripheral blood (12%). The 4-year overall survival was 47% (95% confidence interval [CI] 30%–57%), and the 4-year progression-free survival was 40% (95% CI 30%–49%). Relapse occurred in 49 patients, at a median of 122 days after HSCT. There were 65 deaths: 40 related to AML, 19 to infection, and six to graft versus host disease. In conclusion, our study suggests that HSCT outcomes for children with AML in CR1 or CR2 are acceptable and that this should be considered in the overall treatment planning for children with AML in Brazil. Therapeutic standardization through the adoption of multicentric protocols and appropriate supportive care treatment will have a significant impact on the results of HSCT for AML in Brazil and possibly in other countries with limited resources.

Prognostic Impact of Extramedullary Infiltration in Pediatric Low-risk Acute Myeloid Leukemia: A Retrospective Single-center Study Over 10 Years

BACKGROUND

The impact of extramedullary infiltration (EMI) on the clinical outcomes of pediatric patients with acute myeloid leukemia (AML) are controversial.

PATIENTS AND METHODS

A total of 214 pediatric patients with low-risk AML were classified as having EMI (central nervous leukemia [CNSL] and/or myeloid sarcoma [MS]) and not having EMI. Patients with isolated MS before AML diagnosis by bone marrow examination were confirmed with histopathologic examination. For patients diagnosed with AML by bone marrow examination, a thorough physical examination and radiologic imaging were used to confirm MS.

RESULTS

Male gender, a high white blood cell count, the FAB-M5 subtype, t(8;21) and t(1;11) abnormalities, and c-KIT mutations were associated with EMI. The presence of MS was associated with a low complete remission rate (63.6% vs. 79.4%; P = .000) and poor 3-year relapse-free survival (RFS) (62.6% ± 7.5% vs. 87.0% ± 2.8%; P = .000) and 3-year overall survival (73.5% ± 7% vs. 88.8% ± 2.6%; P = .011). Multivariate analysis revealed that MS was a poor prognostic factor for RFS and overall survival. Bone infiltration was an independent risk factor for inferior RFS with MS. Patients with CNSL had a low complete remission rate (58.3% vs. 77.2%; P = .045); however, CNSL did not significantly affect the survival of low-risk patients with AML.

CONCLUSION

MS should be considered an independent risk factor to guide stratified treatment.

Genetic aberrations involved in relapse of pediatric acute myeloid leukemia: A literature review

Globally, 15-20% of all children diagnosed with leukemia suffer from acute myeloid leukemia (AML), a rapidly progressive, clinically and biologically heterogeneous disease leading to the impaired differentiation of myeloid blast cells. Although 80% of patients achieve complete remission after induction chemotherapy, many relapse, negatively affecting overall out comes. The mechanisms underlying relapse have not been fully elucidated. This review aims to provide an overview of genetic aberrations involved in relapse of disease. A literature review on molecular mechanisms implicated in pediatric AML relapse spanning from 2003 to 2017 was conducted. PubMed, Medline, and Google Scholar were interrogated using relevant search terms. Of note, we examined a total of final 10 research papers from four large study groups that have utilized whole genome sequencing and molecular targeting of trio or paired samples of initial diagnosis, remission, and relapse. Their findings reveal that the genomic landscape of pediatric AML varies from diagnosis to relapse in different populations. Pediatric AML relapse is a systemic evolutionary illness accompanied by synchronized mutational hits impairing differentiation function. The irregular proliferative function is a consequence of mutations in signal transduction genes such as FLT3, RAS, PTPN11, and c-KIT and genes that code for transcription factors such as CEBPα, WT1, SATB1, GFI1, KLF2, and TBP are associated with relapse of disease. Identification of molecular markers unique to different stages of the disease in distinct populations can provide valuable information about disease prognosis and management.

Long non-coding RNA UCA1 promotes autophagy by targeting miR-96-5p in acute myeloid leukaemia

Long non-coding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) has been identified as an oncogene and is involved in acute myeloid leukaemia (AML). Autophagy contributes to tumourigenesis and cancer cell survival. The purpose of this study was to investigate the regulatory role and mechanism of UCA1 in AML cell viability by its effect on autophagy. The expression of UCA1, miR-96-5p, and ATG7 was determined by qRT-PCR and western blot. Cell proliferation was examined by MTT assay. The autophagy level was assessed by green fluorescent protein (GFP)-LC3 immunofluorescence and western blot. The interaction between UCA1 and miR-96-5p or ATG7 was analyzed by luciferase reporter activity. The results showed that UCA1 promoted AML cell proliferation by inducing autophagy. Mechanistically, UCA1 acted as a sponge of miR-96-5p by binding to miR-96-5p. ATG7 was a direct target of miR-96-5p and positively regulated by UCA1. Further results showed that the miR-96-5p mimic effectively counteracted the UCA1 overexpression-mediated induction of the ATG7/autophagy pathway. Collectively, UCA1 functions as a sponge of miR-96-5p to upregulate its target ATG7, thereby resulting in autophagy induction. Our findings reveal a UCA1-mediated molecular mechanism responsible for autophagy induction in AML and help to improve the understanding of the molecular mechanism of AML progression.

Effect of Dexrazoxane on Left Ventricular Systolic Function and Treatment Outcomes in Patients With Acute Myeloid Leukemia: A Report From the Children's Oncology Group

PURPOSE

To determine whether dexrazoxane provides effective cardioprotection during frontline treatment of pediatric acute myeloid leukemia (AML) without increasing relapse risk or noncardiac toxicities of the chemotherapy regimens.

PATIENTS AND METHODS

This was a multicenter study of all pediatric patients with AML without high allelic ratio FLT3/ITD treated in the Children's Oncology Group trial AAML1031 between 2011 and 2016. Median follow-up was 3.5 years. Dexrazoxane was administered at the discretion of treating physicians and documented at each course. Ejection fraction (EF) and shortening fraction (SF) were recorded after each course and at regular intervals in follow-up. Per protocol, anthracyclines were to be withheld if there was evidence of left ventricular systolic dysfunction (LVSD) defined as SF < 28% or EF < 55%. Occurrence of LVSD, trends in EF and SF, 5-year event-free survival (EFS) and overall survival (OS), and treatment-related mortality (TRM) were compared by dexrazoxane exposure.

RESULTS

A total of 1,014 patients were included in the analyses; 96 were exposed to dexrazoxane at every anthracycline course, and 918 were never exposed. Distributions of sex, age, race, presenting WBC count, risk group, treatment arm, and compliance with cardiac monitoring were similar for dexrazoxane-exposed and -unexposed patients. Dexrazoxane-exposed patients had significantly smaller EF and SF declines than unexposed patients across courses and a lower risk for LVSD (26.5% v 42.2%; hazard ratio, 0.55; 95% CI, 0.36 to 0.86; P = .009). Dexrazoxane-exposed patients had similar 5-year EFS (49.0% v 45.1%; P = .534) and OS (65.0% v 61.9%; P = .613) to those unexposed; however, there was a suggestion of lower TRM with dexrazoxane (5.7% v 12.7%; P = .068).

CONCLUSION

Dexrazoxane preserved cardiac function without compromising EFS and OS or increasing noncardiac toxicities. Dexrazoxane should be considered for cardioprotection during frontline treatment of pediatric AML.

Long non-coding RNA UCA1 modulates cell proliferation and apoptosis by regulating miR-296-3p/Myc axis in acute myeloid leukemia

Acute myeloid leukemia (AML) is a common hematopoietic malignancy with a generally poor prognosis. Long non-coding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) has been identified as an oncogene in various malignancies including AML. However, the role and mechanisms of UCA1 in AML tumorigenesis were incompletely understood. Hence, this study aims to investigate whether UCA1 regulates AML progression by miR-296-3p/Myc axis. Cell proliferation and apoptosis were evaluated by MTT assay and flow cytometry, respectively. Luciferase reporter assay was performed to analyze the interaction between miR-296-3p and UCA1 or Myc. The results showed that UCA1 knockdown inhibited proliferation and induced apoptosis in AML cells (U937 and HL60). Mechanistically, UCA1 acted as a sponge of miR-296-3p by binding to miR-296-3p. Myc, a target of miR-296-3p, was positively regulated by UCA1. Functional assay showed that the anti-AML effect of UCA1 knockdown could be abrogated by miR-296-3p inhibition and Myc overexpression. Moreover, UCA1 knockdown inhibited AML cell tumorigenesis in vivo, which was associated with regulation of miR-296-3p and Myc expression. In conclusion, UCA1 modulates AML progression by regulating miR-296-3p/Myc axis.

Re-induction with modified CLAG regimen in relapsed or refractory acute myeloid leukemia in children bridging to allogeneic hematopoietic stem cell transplantation

BACKGROUND

The prognosis for relapsed or refractory acute myeloid leukemia (RR-AML) in children is poor, and the preferred salvage chemotherapy is unclear. One regimen is cladribine, cytarabine, and granulocyte-colony stimulating factor (CLAG), but little is known about its efficacy and safety in children with RR-AML.

METHODS

We enrolled RR-AML patients aged 0-18 years who received modified CLAG regimen for re-induction between July 1, 2015 and April 1, 2018, or conventional induction between August 1, 2011 and April 1, 2018. Patients were followed up to March 31, 2019. Patients underwent allogeneic stem cell transplantation (allo-SCT) or chemotherapy after the induction of complete remission (CR). The CR rate, survival, and side effects were analyzed.

RESULTS

The CR rate for induction was 66.7% after one cycle and 75.0% after two cycles of the CLAG regimen in 12 children. The nine children who received conventional chemotherapy had a CR rate of 22.2% after one cycle and 33.3% after two cycles (P = 0.087 vs. CLAG). The 3-year event-free survival (EFS) of the CLAG group and the conventional treatment group were 44.4 ± 15.7% and 22.2 ± 13.8% (P = 0.112). The 3-year overall survival of the two groups were 59.5 ± 16.2% and 22.2% ± 13.8% (P = 0.057). The 3-year EFS for allo-SCT and chemotherapy after CLAG regimen was 66.7 ± 19.2% and 25.0 ± 21.7% (P = 0.015). A single case of chemotherapy-related death was recorded.

CONCLUSION

Our data suggest a promising CR rate using CLAG salvage treatment in childhood RR-AML. Allo-SCT after CR may improve the long-term outcome in these patients.

CE: Hematologic Childhood Cancers: An Evidence-Based Review

Every year in the United States, thousands of children and adolescents are diagnosed with a hematologic cancer. That diagnosis and the prescribed course of treatment profoundly affect both the child and the family. This article provides a brief overview of the therapies used to treat such cancers, describes the presentations and diagnoses of the various hematologic cancers, and explains the treatments specific to each. Nursing care of the child and family is discussed, with an emphasis on education and supportive care.

Sorafenib Population Pharmacokinetics and Skin Toxicities in Children and Adolescents with Refractory/Relapsed Leukemia or Solid Tumor Malignancies

PURPOSE

To determine the pharmacokinetics and skin toxicity profile of sorafenib in children with refractory/relapsed malignancies.

PATIENTS AND METHODS

Sorafenib was administered concurrently or sequentially with clofarabine and cytarabine to patients with leukemia or with bevacizumab and cyclophosphamide to patients with solid tumor malignancies. The population pharmacokinetics (PPK) of sorafenib and its metabolites and skin toxicities were evaluated.

RESULTS

In PPK analysis, older age, bevacizumab and cyclophosphamide regimen, and higher creatinine were associated with decreased sorafenib apparent clearance (CL/f; P < 0.0001 for all), and concurrent clofarabine and cytarabine administration was associated with decreased sorafenib N-oxide CL/f (P = 7e-4). Higher bilirubin was associated with decreased sorafenib N-oxide and glucuronide CL/f (P = 1e-4). Concurrent use of organic anion-transporting polypeptide 1B1 inhibitors was associated with increased sorafenib and decreased sorafenib glucuronide CL/f (P < 0.003). In exposure-toxicity analysis, a shorter time to development of grade 2-3 hand-foot skin reaction (HFSR) was associated with concurrent (P = 0.0015) but not with sequential (P = 0.59) clofarabine and cytarabine administration, compared with bevacizumab and cyclophosphamide, and with higher steady-state concentrations of sorafenib (P = 0.0004) and sorafenib N-oxide (P = 0.0275). In the Bayes information criterion model selection, concurrent clofarabine and cytarabine administration, higher sorafenib steady-state concentrations, larger body surface area, and previous occurrence of rash appeared in the four best two-predictor models of HFSR. Pharmacokinetic simulations showed that once-daily and every-other-day sorafenib schedules would minimize exposure to sorafenib steady-state concentrations associated with HFSR.

CONCLUSIONS

Sorafenib skin toxicities can be affected by concurrent medications and sorafenib steady-state concentrations. The described PPK model can be used to refine exposure-response relations for alternative dosing strategies to minimize skin toxicity.

A personalized approach to acute myeloid leukemia therapy: current options

Therapeutic options for acute myeloid leukemia (AML) have remained unchanged for nearly the past 5 decades, with cytarabine and anthracyclines and use of hypomethylating agents for less intensive therapy. Implementation of large-scale genomic studies in the past decade has unraveled the genetic landscape and molecular etiology of AML. The approval of several novel drugs for targeted therapy, including midostaurin, enasidenib, ivosidenib, gemtuzumab–ozogamicin, and CPX351 by the US Food and Drug Administration has widened the treatment options for clinicians treating AML. This review focuses on some of these novel therapies and other promising agents under development, along with key clinical trial findings in AML.

Seroprevalence of Hepatitis A Virus in Pediatric Patients with Hematologic Malignancies after Chemotherapy and Hematopoietic Cell Transplantation

This retrospective study was performed to determine the seroprevalence of hepatitis A virus (HAV) in children and adolescents with hematologic malignancies after the completion of chemotherapy and hematopoietic cell transplantation (HCT). Of 97 enrolled patients, 60 (61.9%) were seropositive for HAV. The seroprevalences in patients undergoing chemotherapy and HCT were 60.3% (41/68) and 65.5% (19/29), respectively (P = 0.628). No significant factors associated with seropositivity for HAV after chemotherapy and HCT were identified. Anti-HAV tests and HAV re-vaccinations can be considered in children and adolescents with underlying hematologic malignancies after chemotherapy and HCT based on the anti-HAV results.

The Role of Forkhead Box Proteins in Acute Myeloid Leukemia

Forkhead box (FOX) proteins are a group of transcriptional factors implicated in different cellular functions such as differentiation, proliferation and senescence. A growing number of studies have focused on the relationship between FOX proteins and cancers, particularly hematological neoplasms such as acute myeloid leukemia (AML). FOX proteins are widely involved in AML biology, including leukemogenesis, relapse and drug sensitivity. Here we explore the role of FOX transcription factors in the major AML entities, according to "The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia", and in the context of the most recurrent gene mutations identified in this heterogeneous disease. Moreover, we report the new evidences about the role of FOX proteins in drug sensitivity, mechanisms of chemoresistance, and possible targeting for personalized therapies.

Knockdown of ZFAS1 suppresses the progression of acute myeloid leukemia by regulating microRNA-150/Sp1 and microRNA-150/Myb pathways

Leukemia is the most frequent malignancy in children with acute myeloid leukemia (AML) as the second commonest type. Long non-coding RNA zinc finger antisense 1 (ZFAS1) has been widely reported as an oncogenic factor in multiple malignancies including AML. However, the roles and molecular mechanisms of ZFAS1 in the tumorigenesis of AML are poor defined till now. In the present study, RT-qPCR assay showed that ZFAS1 was highly expressed in bone marrow of acute leukemia patients and AML cell lines. Loss-of-function analyses revealed that ZFAS1 knockdown inhibited proliferation and promoted apoptosis in AML cells and curbed AML xenograft growth in vivo. Bioinformatics analysis and luciferase reporter assay unveiled that microRNA-150 (miR-150) could interact with ZFAS1, Myb 3' UTR and Sp1 3' UTR. Moreover, ZFAS1 acted as a molecular sponge of miR-150, giving rise to the downregulation of miR-150 level and upregulation of Myb and Sp1 levels. Moreover, miR-150 overexpression resulted in the reduction of AML cell proliferative ability and the increase of cell apoptotic rate. Additionally, the inhibition of miR-150 abrogated ZFAS1 loss-mediated anti-leukemia effects. In summary, our data demonstrated that ZFAS1 knockdown hampered AML progression by regulating miR-150/Myb and miR-150/Sp1 pathways, providing some potential biomarkers or targets for the diagnosis and treatment of leukemia.

Occurrence of Treatment-Related Cardiotoxicity and Its Impact on Outcomes Among Children Treated in the AAML0531 Clinical Trial: A Report From the Children's Oncology Group

PURPOSE

Late cardiotoxicity after pediatric acute myeloid leukemia therapy causes substantial morbidity and mortality. The impact of early-onset cardiotoxicity on treatment outcomes is less well understood. Thus, we evaluated the risk factors for incident early cardiotoxicity and the impacts of cardiotoxicity on event-free survival (EFS) and overall survival (OS).

METHODS

Cardiotoxicity was ascertained through adverse event monitoring over the course of follow-up among 1,022 pediatric patients with acute myeloid leukemia treated in the Children's Oncology Group trial AAML0531. It was defined as grade 2 or higher left ventricular systolic dysfunction on the basis of Common Terminology Criteria for Adverse Events (version 3) definitions.

RESULTS

Approximately 12% of patients experienced cardiotoxicity over a 5-year follow-up, with more than 70% of incident events occurring during on-protocol therapy. Documented cardiotoxicity during on-protocol therapy was significantly associated with subsequent off-protocol toxicity. Overall, the incidence was higher among noninfants and black patients, and in the setting of a bloodstream infection. Both EFS (hazard ratio [HR], 1.6; 95% CI, 1.2 to 2.1; P = .004) and OS (HR, 1.6; 95% CI, 1.2 to 2.2, P = .005) were significantly worse in patients with documented cardiotoxicity. Impacts on EFS were equivalent whether the incident cardiotoxicity event occurred in the absence (HR, 1.6; 95% CI, 1.1 to 2.2; P = .017) or presence of infection (HR, 1.6; 95% CI, 1.0 to 2.7; P = .069) compared with patients without documented cardiotoxicity. However, the reduction in OS was more pronounced for cardiotoxicity not associated with infection (HR, 1.7; 95% CI, 1.2 to 2.5; P = .004) than for infection-associated cardiotoxicity (HR, 1.3; 95% CI, 0.7 to 2.4; P = .387).

CONCLUSION

Early treatment-related cardiotoxicity may be associated with decreased EFS and OS. Cardioprotective strategies are urgently needed to improve relapse risk and both short- and long-term mortality outcomes.