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The AML-05 study aimed to examine the efficacy and safety of a therapeutic strategy based on risk stratification for low-, intermediate-, or high-risk acute myeloid leukemia (AML) pediatric patients. Allogeneic hematopoietic cell transplantation (allo-HCT) was not indicated for low- or intermediate-risk AML patients in first complete remission (CR1). The present retrospective study for the AML-05 study aimed to identify prognostic factors for survival and to determine optimal allo-HCT according to multivariate analysis on overall survival (OS), event-free survival (EFS), cumulative incidence of relapse (CIR), and cumulative incidence of nonrelapse mortality (NRM) for and between low- and intermediate-risk AML group patients in the AML-05 study who had undergone allo-HCT after its completion and relapse. The unique patient numbers (UPNs) of the AML-05 study were matched with the Transplant Registry Unified Management Program (TRUMP)-registered numbers, and the tied data on the AML-05 study's UPNs and the TRUMP-registered numbers were analyzed. The primary endpoint was 3-yr OS. Among 443 AML patients in the AML-05 study, 79 (32 low-risk AML and 47 intermediate-risk AML) were analyzed. The following statistically favorable prognostic factors were identified by multivariate analysis on the low- and intermediate-risk AML groups, respectively: UCB (OS-hazard ratio [HR], 0.105; 95% CI, 0.011 to 0.941; P = .004 and EFS-HR, .065, 95% CI, .007 to .577, P = .014) and late relapse (OS-HR, .212; 95% CI, .072 to .626; P = .005 and EFS-HR, .236; 95% CI, .088 to .630; P = .004). Three-year OS, 3-yr EFS, and 3-yr CIR were significantly different between the low- and intermediate-risk AML groups. UCB may be a safe and beneficial donor source for low-risk AML patients, while late relapse was a favorable prognostic factor for intermediate-risk AML patients. Intermediate-risk AML patients with late relapse and low-risk AML patients may benefit from allo-HCT after relapse., (Copyright © 2024. Published by Elsevier Inc.)

Background: The outcome of extramedullary infiltration (EMI) in pediatric acute myeloid leukemia (AML) is controversial, and little is known about the implications of stem cell transplantation (SCT) and gemtuzumab ozogamicin (GO) treatment on patients with EMI., Methods: We retrieved the clinical data of 713 pediatric patients with AML from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) dataset, and analyzed the clinical and prognostic characteristics of patients with EMI at diagnosis and relapse., Results: A total of 123 patients were identified to have EMI at diagnosis and 64 presented with EMI at relapse. The presence of EMI was associated with age ≤2 years, M5 morphology, abnormal karyotype, and KMT2A rearrangements. Hyperleukocytosis and complex karyotype were more prevalent in patients with EMI at relapse. Additionally, patients with EMI at diagnosis had a reduced incidence of FLT3 ITD - /NPM1 + , whereas those with EMI at relapse displayed a lower frequency of FLT3 ITD + . Patients with EMI at diagnosis exhibited a lower complete remission (CR) rate at the end of Induction Course 1 and higher relapse incidence. Importantly, EMI at diagnosis independently predicted both shorter event-free survival (EFS) and overall survival (OS). Regarding relapse patients, the occurrence of EMI at relapse showed no impact on OS. However, relapse patients with myeloid sarcoma (MS)/no central nervous system (CNS) exhibited poorer OS compared to those with CNS/no MS. Furthermore, regarding patients with EMI at diagnosis, SCT failed to improve the survival, whereas GO treatment potentially enhanced OS., Conclusion: EMI at diagnosis is an independent adverse prognostic risk factor for pediatric AML, and GO treatment potentially improves survival for patients with EMI at diagnosis., (© 2024 Wiley Periodicals LLC.)

Objectives: Cognitive-behavioral stress management (CBSM) is an effective psychological intervention to relieve psychological and symptomatic distress. This study aimed to investigate the effect of CBSM in anxiety, depression, and post-traumatic stress disorder (PTSD) in parents of pediatric acute myeloid leukemia (AML) patients., Methods: Totally, 56 pediatric AML patients and 100 parents were randomized into the CBSM group (28 patients and 49 parents) and the normal control (NC) group (28 patients and 51 parents) to receive corresponding interventions for 10 weeks. The questionnaire scores were assessed at month M0, M1, M3, and M6., Results: In parents of pediatric AML patients, self-rating anxiety scale score at M1 ( p  = 0.034), M3 ( p  = 0.010), and M6 ( p  = 0.003), as well as anxiety at M3 ( p  = 0.036) and M6 ( p  = 0.012) were decreased in the CBSM group versus the NC group. Self-rating depression scale score at M3 ( p  = 0.022) and M6 ( p  = 0.002), as well as depression at M6 ( p  = 0.019) were declined in the CBSM group versus the NC group. Symptom checklist-90 (a psychotic status questionnaire) score at M3 ( p  = 0.031) and M6 ( p  = 0.019) were declined in the CBSM group versus the NC group. Regarding PTSD, the impact of the events scale-revised score at M3 ( p  = 0.044) and M6 ( p  = 0.010) were decreased in the CBSM group versus the NC group. By subgroup analyses CBSM (versus NC) improved all outcomes in parents with anxiety at M0 and depression at M0 (all p  < 0.050), but could not affect the outcomes in parents without anxiety or depression at M0 (all p  > 0.050)., Conclusion: CBSM reduces anxiety, depression, and PTSD in parents of pediatric AML patients.

Circular RNAs (circRNAs) arise from precursor mRNA processing through back-splicing and have been increasingly recognized for their functions in various cancers including acute myeloid leukemia (AML). However, the prognostic implications of circRNA in AML remain unclear. We conducted a comprehensive genome-wide analysis of circRNAs using RNA-seq data in pediatric AML. We revealed a group of circRNAs associated with inferior outcomes, exerting effects on cancer-related pathways. Several of these circRNAs were transcribed directly from genes with established functions in AML, such as circRUNX1, circWHSC1, and circFLT3. Further investigations indicated the increased number of circRNAs and linear RNAs splicing were significantly correlated with inferior clinical outcomes, highlighting the pivotal role of splicing dysregulation. Subsequent analysis identified a group of upregulated RNA binding proteins in AMLs associated with high number of circRNAs, with TROVE2 being a prominent candidate, suggesting their involvement in circRNA associated prognosis. Through the integration of drug sensitivity data, we pinpointed 25 drugs that could target high-risk AMLs characterized by aberrant circRNA transcription. These findings underscore prognostic significance of circRNAs in pediatric AML and offer an alternative perspective for treating high-risk cases in this malignancy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Pediatric acute myeloid leukemia (AML) has poor prognosis and high rate of relapse and mortality, and exploration of new treatment options is still critically needed., Objectives: To summarize the outcome of our new treatment strategies for pediatric AML, which is characterized by dual induction and acute lymphoblastic leukemia (ALL) elements consolidation., Design: Retrospective, single-arm study., Methods: From July 2012 to December 2019, an intensive chemotherapy protocol was used for newly diagnosed children with AML, which contains dual induction, three courses of consolidations based on high-dose cytarabine, and two courses of consolidations composed of high-dose methotrexate, vincristine, asparaginase, and mercaptopurine (ALL-like elements). Blasts were monitored by bone marrow smears at intervals, and two lumbar punctures were performed during chemotherapy. We retrospectively analyzed the efficacy and safety of this study. The last follow-up was on 26 May 2023., Results: A total of 70 pediatric AMLs were included. The median age at diagnosis was 6.7 (0.5-16.0) years. The median initial WBC count was 23.74 × 10 9 /L, 11 of whom ⩾100 × 10 9 /L. After dual induction, there were 62 cases of complete remission (CR), 5 cases of partial remission, and 3 cases of nonremission. The CR rate was 88.57%. The median follow-up time was 5.8 (0.2-9.4) years, the 5-year overall survival was 78.2% ± 5%, the event-free survival (EFS) was 71.2% ± 5.6%, and the cumulative recurrence rate was 27.75%. The 5-year EFS of patients with initial WBC < 100 × 10 9 /L ( n  = 59) and ⩾100 × 10 9 /L ( n  = 11) were 76.4% ± 5.7% and 45.5% ± 15% ( p  = 0.013), respectively. A total of 650 hospital infections occurred. The main causes of infection were respiratory tract infection (26.92%), septicemia (18.46%), stomatitis (11.85%), and skin and soft-tissue infection (10.46%)., Conclusion: This intensive treatment protocol with dual induction and ALL-like elements is effective and safe for childhood AML. Initial WBC ⩾ 100 × 10 9 /L was the only independent risk factor in this cohort., Trial Registration: It is a retrospective study, and no registration on ClinicalTrials.gov., Competing Interests: The authors declare that there is no conflict of interest., (© The Author(s), 2024.)

This retrospective study aimed to analyze the treatment effect and prognostic factors of pediatric acute myeloid leukemia (AML) patients with t(8;21). A total of 268 newly diagnosed pediatric AML (pAML) enrolled from 1 January 2005 to 31 December 2022 were retrospectively reviewed, and 50 (18.7%) patients harbored t(8;21) translocation. CR rate, OS, EFS, and RFS were assessed by multivariate Logistic and Cox regression models in these patients. Of the 50 patients, 2 patients abandoned treatment during the first induction course. Of the remaining 48 patients who received double-induction therapy and were included in the final analyses, CR1 and CR2 were 75.0% (36/48) and 95.8% (46/48), respectively. The overall three-year OS, EFS, and RFS were 68.4% (95% CI, 55.0-85.1), 64.2% (95% CI, 50.7-81.4), and 65.5% (95% CI, 51.9-82.8), respectively. The presence of loss of sex chromosome (LOS) at diagnosis (n = 21) was associated with a better 3-year OS [87.5% (95% CI, 72.7-100) vs. 52.7% (95% CI, 35.1-79.3), p = 0.0089], 3-year EFS [81.6% (95% CI, 64.7-100) vs. 49.7% (95% CI, 32.4-76.4), p = 0.023], and 3-year RFS [81.6% (95% CI, 64.7-100) vs. 51.7% (95% CI, 33.9-78.9), p = 0.036] than those without LOS (n = 27), and it was also an independent good prognostic factor of OS (HR, 0.08 [95% CI, 0.01-0.48], p = 0.005), EFS (HR, 0.22 [95% CI, 0.05-0.85], p = 0.029), and RFS (HR, 0.21 [95% CI, 0.05-0.90], p = 0.035). However, extramedullary leukemia (EML) featured the independent risk factors of inferior OS (HR, 10.99 [95% CI, 2.08-58.12], p = 0.005), EFS (HR, 4.75 [95% CI, 1.10-20.61], p = 0.037), and RFS (HR, 6.55 [95% CI, 1.40-30.63], p = 0.017) in pediatric individuals with t(8;21) AML. Further analysis of combining LOS with EML indicated that the EML+LOS- subgroup had significantly inferior OS (92.9%, [95% CI, 80.3-100]), EFS (86.2%, [95% CI, 70.0-100]), and RFS (86.2%, [95% CI, 80.3-100]) compared to the other three subgroups (all p < 0.001). LOS and EML are independent prognostic factors of OS, EFS, and RFS with t(8;21) pAML patients. LOS combined with EML may help improve risk stratification.

The addition of the proteasome inhibitor bortezomib to standard chemotherapy did not improve survival in pediatric acute myeloid leukemia (AML) when all patients were analyzed as a group in the Children's Oncology Group phase 3 trial AAML1031 (NCT01371981). Proteasome inhibition influences the chromatin landscape and proteostasis, and we hypothesized that baseline proteomic analysis of histone- and chromatin-modifying enzymes (HMEs) would identify AML subgroups that benefitted from bortezomib addition. A proteomic profile of 483 patients treated with AAML1031 chemotherapy was generated using a reverse-phase protein array. A relatively high expression of 16 HME was associated with lower EFS and higher 3-year relapse risk after AML standard treatment compared to low expressions (52% vs. 29%, p = 0.005). The high-HME profile correlated with more transposase-accessible chromatin, as demonstrated via ATAC-sequencing, and the bortezomib addition improved the 3-year overall survival compared with standard therapy (62% vs. 75%, p = 0.033). These data suggest that there are pediatric AML populations that respond well to bortezomib-containing chemotherapy.

Background: Prompt response to induction chemotherapy is a prognostic factor in pediatric acute myeloid leukemia. In this study, we aimed to evaluate the prognostic significance of multiparametric flow cytometry-minimal residual disease (MFC-MRD), assessed at the end of the first and second induction courses., Methods: MFC-MRD was performed at the end of the first induction (TP1) in 524 patients and second induction (TP2) in 467 patients who were treated according to the modified Medical Research Council (UK) acute myeloid leukemia 15 protocol., Results: Using a 0.1% cutoff level, patients with MFC-MRD at the two time points had lower event-free survival and overall survival. Only the TP2 MFC-MRD level could predict the outcome in a separate analysis of high and intermediate risks based on European LeukemiaNet risk stratification and KMT2A rearrangement. The TP2 MFC-MRD level could further differentiate the prognosis of patients into complete remission or non-complete remission based on morphological evaluation. Multivariate analysis indicated the TP2 MFC-MRD level as an independent adverse prognostic factor for event-free survival and overall survival. When comparing patients with MFC-MRD ≥ 0.1%, those who underwent hematopoietic stem cell transplant during the first complete remission had significantly higher 5-year event-free survival and overall survival and lower cumulative incidence of relapse than those who only received consolidation chemotherapy., Conclusions: The TP2 MFC-MRD level can predict the outcomes in pediatric patients with acute myeloid leukemia and help stratify post-remission treatment., (© 2024. The Author(s).)

Risk classification in pediatric acute myeloid leukemia (P-AML) is crucial for personalizing treatments. Thus, we aimed to establish a risk-stratification tool for P-AML patients and eventually guide individual treatment. A total of 256 P-AML patients with accredited mRNA-seq data from the TARGET database were divided into training and internal validation datasets. A gene-expression-based prognostic score was constructed for overall survival (OS), by using univariate Cox analysis, LASSO regression analysis, Kaplan-Meier (K-M) survival, and multivariate Cox analysis. A P-AML-5G prognostic score bioinformatically derived from expression levels of 5 genes (ZNF775, RNFT1, CRNDE, COL23A1, and TTC38), clustered P-AML patients in training dataset into high-risk group (above optimal cut-off) with shorter OS, and low-risk group (below optimal cut-off) with longer OS (p < 0.0001). Meanwhile, similar results were obtained in internal validation dataset (p = 0.005), combination dataset (p < 0.001), two treatment sub-groups (p < 0.05), intermediate-risk group defined with the Children's Oncology Group (COG) (p < 0.05) and an external Japanese P-AML dataset (p = 0.005). The model was further validated in the COG study AAML1031(p = 0.001), and based on transcriptomic analysis of 943 pediatric patients and 70 normal bone marrow samples from this dataset, two genes in the model demonstrated significant differential expression between the groups [all log2(foldchange) > 3, p < 0.001]. Independent of other prognostic factors, the P-AML-5G groups presented the highest concordance-index values in training dataset, chemo-therapy only treatment subgroups of the training and internal validation datasets, and whole genome-sequencing subgroup of the combined dataset, outperforming two Children's Oncology Group (COG) risk stratification systems, 2022 European LeukemiaNet (ELN) risk classification tool and two leukemic stem cell expression-based models. The 5-gene prognostic model generated by a single assay can further refine the current COG risk stratification system that relies on numerous tests and may have the potential for the risk judgment and identification of the high-risk pediatric AML patients receiving chemo-therapy only treatment., (© 2024. The Author(s).)

Purpose: Circular RNA (circRNA) is a type of novel non-coding RNA with close involvement in the tumorigenesis and treatment response of leukemias. This study aimed to screen and validate candidate circRNAs that estimate disease risk and response to induction therapy of pediatric acute myeloid leukemia (AML)., Methods: Bone marrow samples were obtained from 4 complete response (CR) pediatric AML patients, 4 non-CR pediatric AML patients, and 4 controls to screen differentially expressed circRNAs (DECs) through microarray analyses. Ten candidate circRNAs were selected and validated in 40 pediatric AML patients and 10 controls through reverse transcription-quantitative polymerase chain reaction., Results: Microarray assay discovered 378 upregulated DECs and 688 downregulated DECs in pediatric AML patients vs. controls; 832 upregulated DECs and 950 downregulated DECs in CR AML patients vs. non-CR AML patients. Then cross-analysis identified 441 DECs that both related to pediatric AML risk and CR achievement. Further validation of ten candidate circRNAs in larger sample-sized populations showed that circ&#95;0032891, circ&#95;0076995, circ&#95;0014352, circ&#95;0047663, circ&#95;0007444, circ&#95;0001684, circ&#95;0000544, and circ&#95;0005354 were related to pediatric AML risk; circ&#95;0032891, circ&#95;0076995, circ&#95;0014352, circ&#95;0047663, circ&#95;0007444, circ&#95;0001684, and circ&#95;0000544 were related to CR achievement in pediatric AML patients. Regarding the correlation of candidate circRNAs with survival profile, only circ&#95;0032891, circ&#95;0076995, and circ&#95;0000544 forecasted event-free survival; circ&#95;0076995 and circ&#95;0001684 estimated overall survival in pediatric AML patients., Conclusion: CircRNA profile is intensively implicated in the disease risk and treatment response of pediatric AML, especially that circ&#95;0032891, circ&#95;0000544, circ&#95;0076995, and circ&#95;0001684 are related to pediatric AML risk, CR achievement, and survival., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: The Pediatric Oncology in Developing Countries (PODC) committee of the International Society of Pediatric Oncology (SIOP) published a pediatric acute myeloid leukemia (AML)-specific adapted treatment guideline for low- and middle-income countries. We evaluated the outcomes of children with AML at a large Kenyan academic hospital before (period 1) and after (period 2) implementing this guideline., Patients and Methods: Records of children (≤17 years) newly diagnosed with AML between 2010 and 2021 were retrospectively studied. In period 1, induction therapy comprised two courses with doxorubicin and cytarabine, and consolidation comprised two courses with etoposide and cytarabine. In period 2, a prephase with intravenous low-dose etoposide was administered prior to induction therapy, induction course I was intensified, and consolidation was adapted to two high-dose cytarabine courses. Probabilities of event-free survival (pEFS) and overall survival (pOS) were estimated using the Kaplan-Meier method., Results: One-hundred twenty-two children with AML were included - 83 in period 1 and 39 in period 2. Overall, 95 patients received chemotherapy. The abandonment rate was 19% (16/83) in period 1 and 3% (1/39) in period 2. The early death, treatment-related mortality, complete remission, and relapse rates in periods 1 and 2 were 46% (29/63) versus 44% (14/32), 36% (12/33) versus 47% (8/17), 33% (21/63) versus 38% (12/32), and 57% (12/21) versus 17% (2/12), respectively. The 2-year pEFS and pOS in periods 1 and 2 were 5% versus 15% (p = .53), and 8% versus 16% (p = .93), respectively., Conclusion: The implementation of the SIOP PODC guideline did not result in improved outcomes of Kenyan children with AML. Survival of these children remains dismal, mainly attributable to early mortality., (© 2023 The Authors. Cancer Reports published by Wiley Periodicals LLC.)

Background: Acute myeloid leukemia (AML) with megakaryocytic differentiation (AMkL) is a rare subtype of AML more common in children. Recent literature has identified multiple fusions associated with this type of leukemia., Methods: Morphology, cytogenetics, and genomic sequencing were assessed in patients from Children's Oncology Group trials AAML0531 and AAML1031 with central-pathology review confirmed non-Down syndrome AMkL. The 5-year event-free survival (EFS), overall survival (OS), and RR were evaluated in these AMkL subcategories., Results: A total of 107 cases of AMkL (5.5%) were included. Distinct fusions were identified in the majority: RBM15::MRTFA (20%), CBFA2T3::GLIS2 (16%), NUP98 (10%), KMT2A (7%), TEC::MLLT10 (2%), MECOM (1%), and FUS::ERG (1%); many of the remaining cases were classified as AMkL with (other) myelodysplasia-related changes (MRC). Very few cases had AML-associated somatic mutations. Cases with CBFA2T3::GLIS2 were enriched in trisomy 3 (p = .015) and the RAM phenotype, with associated high CD56 expression (p < .001). Cases with NUP98 fusions were enriched in trisomy 6 (p < .001), monosomy 13/del(13q) (p < .001), trisomy 21 (p = .026), and/or complex karyotypes (p = .026). While different 5-year EFS and OS were observed in AMkL in each trial, in general, those with CBFA2T3::GLIS2 or KMT2A rearrangements had worse outcomes compared to other AMkL, while those with RBM15::MRTFA or classified as AMkl-MRC fared better. AMkL with NUP98 fusions also had poor outcomes in the AAML1031 trial., Conclusion: Given the differences in outcomes, AMkL classification by fusions, cytogenetics, and morphology may be warranted to help in risk stratification and therapeutic options., (© 2023 Wiley Periodicals LLC.)

MicroRNA (miR)-381-3p is the newly discovered tumor-associated miRNA, which is frequently associated with diverse human malignancies; but, it is still unknown about its effect on acute myeloid leukemia (AML) in children. This work focused on exploring miR-381-3p's effect on childhood AML and identifying the possible mechanisms facilitating new treatment development. Using qRT-PCR analysis, miR-381-3p expression remarkably reduced in pediatric AML patients and AML cell lines (HL-60 and U937). Following transfection of miR-381-3p mimic or inhibitor into HL-60 and U937 cells, we conducted MTT assay to evaluate cell proliferation, flow cytometry (FCM) to measured cell apoptosis and cell cycle, whereas Transwell assays to detect cell invasion and migration. Our results demonstrated that miR-381-3p overexpression remarkably repressed cell growth, invasion and migration; additionally, miR-381-3p overexpression resulted in arrest of cell cycle and enhanced cell apoptosis. In contrast, miR-381-3p knockdown led to an opposite effect. Moreover, we predicted miR-381's target gene and validated it by luciferase reporter assay and TargetScan, separately. We identified miR-381-3p's binding site in ROCK1 3'-UTR. As revealed by Western-blot (WB) assay, miR-381-3p overexpression notably suppressed ROCK1 level. Moreover, restoring ROCK1 expression abolished miR-381-3p's inhibition on cell proliferation, invasion and migration. Data in this work indicated the role of miR-381-3p as the tumor suppressor within pediatric AML by targeting ROCK1. Therefore, miR-381-3p might serve as a potential therapeutic target for the treatment of pediatric AML., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Alterations of 11q23/KMT2A are the most prevalent cytogenetic abnormalities in acute myeloid leukemia (AML) and the prognostic significance of 11q23/KMT2A-rearranged AML based on various translocation partners varies among different studies. However, few studies evaluated the molecular characteristics of 11q23/KMT2A-rearranged pediatric AML. We aim to analyze the mutational landscape of 11q23/KMT2A-rearranged AML and assess their prognostic value in outcomes., Methods: The mutational landscape and clinical prognosis of 105 children with 11q23/KMT2A-rearranged AML in comparison with 277 children with non-11q23/KMT2A-rearranged AML were analyzed using publicly accessible next-generation sequencing data from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) dataset., Results: Pediatric AML patients with 11q23/KMT2A-rearrangements harbored a low number of mutations (Median, 1 mutation/patient, range, 1-22), 58% of which involved in RAS pathway mutations (KRAS, NRAS, and PTPN11) and 10.5% of which comprised of SETD2 mutations. Compared with non-11q23/KMT2A-rearranged AML, the incidence of KRAS (32.4% vs. 10.1%, P〈0.001) and SETD2 (10.5% vs. 1.4%, P=0.001) gene mutations in 11q23/KMT2A-rearranged AML was significantly higher. Both KRAS and SETD2 mutations occurred more often in t(10;11)(p12;q23). KRAS mutations were correlated with worse 5-year event-free survival [EFS] (Plog-rank = 0.001) and 5-year overall survival [OS] (Plog-rank = 0.009) and the presence of SETD2 mutations increases the 5-year relapse rate (PGray = 0.004). Multivariate analyses confirmed KRAS mutations in 11q23/KMT2A-rearranged AML as an independent predictor for poor EFS (hazard ratio [HR] = 2.10, P=0.05) and OS (HR = 2.39, P=0.054)., Conclusion: Our findings show that pediatric patients with 11q23/KMT2A rearrangements have characteristic mutation patterns and varying clinical outcomes depending on different translocation partners, which could be utilized to develop more accurate risk stratification and tailored therapies., (© 2022 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Acute myeloid leukemia (AML) is a heterogeneous disease that accounts for ~20% of all childhood leukemias, and more than 40% of children with AML relapse within three years of diagnosis. Although recent efforts have focused on developing a precise medicine-based approach towards treating AML in adults, there remains a critical gap in therapies designed specifically for children. Here, we present ex vivo drug sensitivity profiles for children with de novo AML using an automated flow cytometry platform. Fresh diagnostic blood or bone marrow aspirate samples were screened for sensitivity in response to 78 dose conditions by measuring the reduction in leukemic blasts relative to the control. In pediatric patients treated with conventional chemotherapy, comprising cytarabine, daunorubicin and etoposide (ADE), ex vivo drug sensitivity results correlated with minimal residual disease (r = 0.63) and one year relapse-free survival (r = 0.70; AUROC = 0.94). In the de novo ADE analysis cohort of 13 patients, AML cells showed greater sensitivity to bortezomib/panobinostat compared with ADE, and comparable sensitivity between venetoclax/azacitidine and ADE ex vivo. Two patients showed a differential response between ADE and bortezomib/panobinostat, thus supporting the incorporation of ex vivo drug sensitivity testing in clinical trials to further evaluate the predictive utility of this platform in children with AML.

Background: Pediatric acute myeloid leukemia (AML) is a challenging disease to treat in low- and middle-income countries (LMICs). Literature suggests that survival in LMICs is poorer compared with survival in high-income countries (HICs)., Aims: This study evaluates the outcomes of Kenyan children with AML and the impact of sociodemographic and clinical characteristics on outcome., Methods and Results: A retrospective medical records study was performed at Moi Teaching and Referral Hospital (MTRH) in Eldoret, Kenya, between January 2010 and December 2018. Sociodemographic and clinical characteristics, and treatment outcomes were evaluated. Chemotherapy included two "3 + 7" induction courses with doxorubicin and cytarabine and two "3 + 5" consolidation courses with etoposide and cytarabine. Supportive care included antimicrobial prophylaxis with cotrimoxazole and fluconazole, and blood products, if available. Seventy-three children with AML were included. The median duration of symptoms before admission at MTRH was 1 month. The median time from admission at MTRH to diagnosis was 6 days and to the start of AML treatment 16 days. Out of the 55 children who were started on chemotherapy, 18 (33%) achieved complete remission, of whom 10 (56%) relapsed. The abandonment rate was 22% and the early death rate was 46%. The 2-year probabilities of event-free survival and overall survival were 4% and 7%, respectively. None of the sociodemographic and clinical characteristics were significantly associated with outcome., Conclusion: Survival of Kenyan children with AML is dismal and considerably lower compared with survival in HICs. Strategies to improve survival should be put in place including better supportive care, optimization of the treatment protocol, and reduction of the abandonment rate and time lag to diagnosis with sooner start of treatment., (© 2021 The Authors. Cancer Reports published by Wiley Periodicals LLC.)

Background: To establish a comprehensive differential gene profile for pediatric acute myeloid leukemia patients (pAML) based on two independent databases and verify the differentially expressed genes using in vitro and in vivo analyses. Methods: The mRNA and miRNA sequencing information of GSE2191 and GSE35320, clinically recruited pAML individuals, and human AML cell line (NB4 cells) were utilized in the study. Results: Compared with the control sample, pAML patients demonstrated a total of 778 differentially expressed genes, including 565 upregulated genes and 213 downregulated genes. The genes including ZC3H15 , BCLAF1 , PPIG , DNTTIP2 , SRSF11 , KTN1 , UBE3A , PRPF40A , TMED5 , and GNL2 were the top 10 potential hub genes. At the same time, 12 miRNAs demonstrated remarkable differential expressions in pAML individuals compared with control individuals, as five upregulated and seven downregulated miRNAs. The hsa-miR-133 , hsa-miR-181 , and hsa-miR-195 were significantly downregulated. Building a miRNA-mRNA regulatory network, hsa-miR-133 regulated ZC3H15 , BCLAF1 , SRSF11 , KTN1 , PRPF40A , and GNL2 . Using the NB4 cell model, hsa-miR-133 treatment inhibited cell proliferation capacity, which could be attenuated by a single mRNA transfection or a combination of ZC3H15 and BCLAF1 . At the same time, hsa-miR-133 mimic treatment could significantly accelerate cell apoptosis in NB4 cells, which was also ZC3H15 - and BCLAF1 -dependent. The concentrations of ZC3H15 and BCLAF1 were investigated in peripheral blood using the ELISA method for the clinical control and pAML samples. In pAML samples, the expression levels of ZC3H15 and BCLAF1 were significantly enhanced ( p < 0.01), regardless of the classification. Conclusion: Collectively, this study hypothesized several promising candidates for pAML formation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wang, Yue, Liu and Che.)

MicroRNA-199a (miR-199a) inhibits the progression of several hematological malignancies and enhances the sensitivity to chemotherapy in acute myeloid leukemia (AML), but its clinical role in AML needs further investigation. This study aimed to explore the correlation of miR-199a with clinical features and prognosis in pediatric AML patients. Totally, 71 pediatric AML patients were enrolled. Their bone marrows (BMs) before and after one course of treatment were collected. Besides, 30 pediatric patients with nonmalignant hematological disease who underwent BM examination were enrolled with their BMs collected. miR-199a expression was detected by reverse transcription-quantitative polymerase chain reaction. miR-199a expression was lower in pediatric AML patients than in controls ( p  < 0.001). Meanwhile, downregulated miR-199a expression was correlated with the occurrence of FLT3-ITD mutation ( p  = 0.023), higher BM blasts ( p  = 0.037), poor NCCN risk stratification ( p  = 0.012) and unfavorable Chinese Medical Association risk stratification ( p  = 0.002) but not associated with other clinical features. Additionally, downregulated miR-199a expression was correlated with lower complete response (CR) rate after one course of treatment ( p  = 0.036). Interestingly, after treatment, miR-199a expression was increased in patients who achieved CR ( p  < 0.001), but remained unchanged in those who didn't achieve CR ( p  = 0.163). Moreover, downregulated miR-199a expression was correlated with shorter event-free survival ( p  = 0.021); meanwhile, it showed a trend of associating with poor OS ( p  = 0.055), which was not statistically significant. In this series, decreased expression of miR199a was associated with inadequate treatment response and worse OS in pediatric AML patients, indicating its potential as a prognostic biomarker for pediatric AML.Supplemental data for this article is available online at https://doi.org/10.1080/08880018.2021.2022045.

Background: The prognostic roles of ferroptosis-related mRNAs (FG) and lncRNAs (FL) in pediatric acute myeloid leukemia (P-AML) patients remain unclear. Methods: RNA-seq and clinical data of P-AML patients were downloaded from the TARGET project. Cox and LASSO regression analyses were performed to identify FG, FL, and FGL (combination of FG and FL) prognostic models, and their performances were compared. Tumor microenvironment, functional enrichment, mutation landscape, and anticancer drug sensitivity were analyzed. Results: An FGL model of 22 ferroptosis-related signatures was identified as an independent parameter, and it showed performance better than FG, FL, and four additional public prognostic models. The FGL model divided patients in the discovery cohort ( N = 145), validation cohort ( N = 111), combination cohort ( N = 256), and intermediate-risk group ( N = 103) defined by the 2017 European LeukemiaNet (ELN) classification system into two groups with distinct survival. The high-risk group was enriched in apoptosis, hypoxia, TNFA signaling via NFKB, reactive oxygen species pathway, oxidative phosphorylation, and p53 pathway and associated with low immunity, while patients in the low-risk group may benefit from anti-TIM3 antibodies. In addition, patients within the FGL high-risk group might benefit from treatment using SB505124&#95;1194 and JAK&#95;8517&#95;1739. Conclusion: Our established FGL model may refine and provide a reference for clinical prognosis judgment and immunotherapies for P-AML patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Tao, Wei and You.)

Non-relapse mortality due to GVHD and infections represents a major source of morbidity and mortality in pediatric HSCT recipients. Post-transplant cyclophosphamide (PTCy) has emerged as an effective and safe GVHD prophylaxis strategy, with improved GVHD and relapse-free survival in matched (related and unrelated) and mismatched haploidentical HSCT adult recipients. However, there are no published data in pediatric patients with acute myeloid leukemia who received matched-donor HSCT with PTCy. We demonstrate, in this case series, that the use of PTCy in this population is potentially safe, effective in preventing acute GVHD, does not impair engraftment, is associated with reduced non-relapse mortality, and does not hinder immune reconstitution post HSCT.

Novel therapeutic tools are warranted to improve outcomes for children with acute myeloid leukemia (AML). Differences in the proteome of leukemic blasts and stem cells (AML-SCs) in AML compared with normal hematopoietic stem cells (HSCs) may facilitate the identification of potential targets for future treatment strategies. In this explorative study, we used mass spectrometry to compare the proteome of AML-SCs and CLEC12A+ blasts from five pediatric AML patients with HSCs and hematopoietic progenitor cells from hematologically healthy, age-matched controls. A total of 456 shared proteins were identified in both leukemic and control samples. Varying protein expression profiles were observed in AML-SCs and leukemic blasts, none having any overall resemblance to healthy counterpart cell populations. Thirty-four proteins were differentially expressed between AML-SCs and HSCs, including the upregulation of HSPE1, SRSF1, and NUP210, and the enrichment of proteins suggestive of protein synthesis perturbations through the downregulation of EIF2 signaling was found. Among others, NUP210 and calreticulin were upregulated in CLEC12A+ blasts compared with HSCs. In conclusion, the observed differences in protein expression between pediatric patients with AML and pediatric controls, in particular when comparing stem cell subsets, encourages the extended exploration of leukemia and AML-SC-specific biomarkers of potential relevance in the development of future therapeutic options in pediatric AML.

Bloodstream infections (BSIs), especially those caused by Gram-negative rods (GNR) and viridans group streptococci (VGS), are common and potentially life-threatening complications of pediatric acute myeloid leukemia (AML) treatment. Limited literature is available on prophylactic regimens. We retrospectively evaluated the effect of different antibacterial prophylaxis regimens on the incidence of febrile neutropenic (FN) episodes and bacterial BSIs. Medical records of children (0−18 years) diagnosed with de novo AML and treated at two Dutch centers from May 1998 to March 2021 were studied. Data were analyzed per chemotherapy course and consecutive neutropenic period. A total of 82 patients had 316 evaluable courses: 92 were given with single-agent ciprofloxacin, 138 with penicillin plus ciprofloxacin, and 51 with teicoplanin plus ciprofloxacin. The remaining 35 courses with various other prophylaxis regimens were not statistically compared. During courses with teicoplanin plus ciprofloxacin, significantly fewer FN episodes (43 vs. 90% and 75%; p < 0.0001) and bacterial BSIs (4 vs. 63% and 33%; p < 0.0001) occurred than with single-agent ciprofloxacin and penicillin plus ciprofloxacin, respectively. GNR and VGS BSIs did not occur with teicoplanin plus ciprofloxacin and no bacterial BSI-related pediatric intensive care unit (PICU) admissions were required, whereas, with single-agent ciprofloxacin and penicillin plus ciprofloxacin, GNR BSIs occurred in 8 and 1% (p = 0.004), VGS BSIs in 24 and 14% (p = 0.0005), and BSI-related PICU admissions were required in 8 and 2% of the courses (p = 0.029), respectively. Teicoplanin plus ciprofloxacin as antibacterial prophylaxis is associated with a lower incidence of FN episodes and bacterial BSIs. This may be a good prophylactic regimen for pediatric AML patients during treatment.

Acute myeloid leukemia (AML) in children remains deadly, despite the use of maximally intensive therapy. Because leukemia stem cells (LSCs) significantly contribute to chemoresistance and relapse, therapies that specifically target the LSCs are likely to be more beneficial in improving outcome. LSCs are known to have high telomerase activity and telomerase activity is negatively correlated with survival in pediatric AML. We evaluated the preclinical efficacy of imetelstat, an oligonucleotide inhibitor of telomerase activity in patient-derived xenograft (PDX) lines of pediatric AML. Imetelstat treatment significantly increased apoptosis/death of the LSC population in a dose-dependent manner in six pediatric AML PDX lines ex vivo, while it had limited activity on the stem cell population in normal bone marrow specimens. These results were validated in vivo in two distinct PDX models wherein imetelstat as single agent or in combination with chemotherapy greatly reduced the LSC percentage and prolonged median survival. Imetelstat combination with DNA hypomethylating agent azacitidine was also beneficial in extending survival. Secondary transplantation experiments showed delayed engraftment and improved survival of mice receiving imetelstat-treated cells, confirming the diminished LSC population. Thus, our data suggest that imetelstat represents an effective therapeutic strategy for pediatric AML.

International Working Group (IWG) and European LeukemiaNet (ELN) response definitions are utilized to evaluate the efficacy of new agents for childhood acute myeloid leukemia (AML) for regulatory purposes. However, these criteria are not consistent with definitions used in pediatric AML trials or with standard pediatric practice to proceed with subsequent therapy cycles prior to IWG/ELN-defined count recovery. We retrospectively analyzed data from the two most recent Phase 3 pediatric AML clinical trials conducted by the Children's Oncology Group (COG) to assess the incidence, timing, and prognostic significance of count recovery following induction chemotherapy. Of the patients with fewer than 5% bone marrow blasts at the end of first induction, 21.5% of patients proceeded to a second induction cycle prior to achieving ANC ≥ 500 cells/μL and platelets ≥ 50,000 cells/μL, both well below the IWG/ELN thresholds of ANC > 1000 cells/μL and platelets > 100,000 cells/μL. In these two sequential childhood AML Phase 3 trials, neither ANC nor platelet recovery predicted survival. Intensification of treatment through the initiation of subsequent therapy cycles prior to attainment of IWG/ELN-defined CR is common practice in clinical trials for children with AML, suggesting that updated response definitions are needed for pediatric AML.

Background: The optimal number of chemotherapy courses for low-risk (LR) pediatric acute myeloid leukemia (AML) is not known., Objective: To compare outcomes for four (21.6 g/m 2 cytarabine) versus five (45.6 g/m 2 cytarabine) chemotherapy courses for LR-AML using data from Children's Oncology Group (COG) AAML0531 and AAML1031., Methods: We compared relapse risk (RR), disease-free survival (DFS), and overall survival (OS), and the differential impact in LR subgroups for patients receiving four versus five chemotherapy courses. Cox (OS and DFS) and risk (RR) regressions were used to estimate hazard ratios (HR) to compare outcomes., Results: A total of 923 LR-AML patients were included; 21% received five courses. Overall, LR-AML patients who received four courses had higher RR (40.9% vs. 31.4%; HR = 1.40, 95% confidence interval [CI]: 1.06-1.85), and worse DFS (56.0% vs. 67.0%; HR = 1.45, 95% CI: 1.10-1.91). There was a similar decrement in OS though it was not statistically significant (77.0% vs. 83.5%; HR = 1.45, 95% CI: 0.97-2.17). Stratified analyses revealed the detrimental effects of cytarabine dose de-escalation to be most pronounced in the LR-AML subgroup with uninformative cytogenetic/molecular features who were minimal residual disease (MRD) negative after the first induction course (EOI1). The absolute decrease in DFS with four courses for patients with favorable cytogenetic/molecular features and positive MRD was similar to that observed for patients with uninformative cytogenetic/molecular features and negative MRD at EOI1, though not statistically significant., Conclusions: Our results support de-escalation of cytarabine exposure through the elimination of a fifth chemotherapy course only for LR-AML patients who have both favorable cytogenetic/molecular features and negative MRD after the first induction cycle., (© 2021 Wiley Periodicals LLC.)

Advances in the treatment of pediatric AML have been modest over the past four decades. Despite maximally intensive therapy, approximately 40% of patients will relapse. Novel targeted therapies are needed to improve outcomes. We identified mesothelin (MSLN), a well-validated target overexpressed in some adult malignancies, to be highly expressed on the leukemic cell surface in a subset of pediatric AML patients. The lack of expression on normal bone marrow cells makes MSLN a viable target for immunotherapies such as T-cell engaging bispecific antibodies (BsAbs) that combine two distinct antibody-variable regions into a single molecule targeting a cancer-specific antigen and the T-cell co-receptor CD3. Using antibody single-chain variable region (scFv) sequences derived from amatuximab-recognizing MSLN, and from either blinatumomab or AMG330 targeting CD3, we engineered and expressed two MSLN/CD3-targeting BsAbs: MSLN AMA -CD3 L2K and MSLN AMA -CD3 AMG , respectively. Both BsAbs promoted T-cell activation and reduced leukemic burden in MV4;11:MSLN xenografted mice, but not in those transplanted with MSLN-negative parental MV4;11 cells. MSLN AMA -CD3 AMG induced complete remission in NTPL-146 and DF-5 patient-derived xenograft models. These data validate the in vivo efficacy and specificity of MSLN-targeting BsAbs. Because prior MSLN-directed therapies appeared safe in humans, MSLN-targeting BsAbs could be ideal immunotherapies for MSLN-positive pediatric AML patients.

Background: From 1983, standardized therapeutic protocols for pediatric acute myeloid leukemia (AML) based on the BFM group experience were introduced in Poland. We retrospectively analyzed the results of pediatric AML treatment in Poland from 1983 to 2019 (excluding promyelocytic, therapy-related, biphenotypic, and Down syndrome AML)., Methods: The study included 899 children suffering from AML treated with the following: AML-PPPLBC 83 (1983-1993, n = 187), AML-PPGLBC 94 (1994-1997, n = 74), AML-PPGLBC 98 (1998-2004, n = 151), AML-BFM 2004 Interim (2004-2015, n = 356), and AML-BFM 2012 (2015-2019, n = 131)., Results: The probability of three-year overall survival was 0.34 ± 0.03, 0.37 ± 0.05, 0.54 ± 0.04, 0.67 ± 0.03, and 0.75 ± 0.05; event-free survival was 0.31 ± 0.03, 0.34 ± 0.05, 0.44 ± 0.04, 0.53 ± 0.03, and 0.67 ± 0.05; and relapse-free survival was 0.52 ± 0.03, 0.65 ± 0.05, 0.58 ± 0.04, 0.66 ± 0.03, and 0.78 ± 0.05, respectively, in the subsequent periods. A systematic reduction of early deaths and deaths in remission was achieved, while the percentage of relapses decreased only in the last therapeutic period. Surprisingly good results were obtained in the group of patients treated with AML-BFM 2012 with unfavorable genetic abnormalities like KMT2A-MLLT10/t(10;11)(p12;q23) and DEK-NUP214/t(6;9)(p23;q24), while unsatisfactory outcomes were found in the patients with FLT3-ITD., Conclusions: The use of standardized, systematically modified therapeutic protocols, with the successive consideration of genetic prognostic factors, and advances in supportive care led to a significant improvement in AML treatment outcomes over the last 40 years.

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.

Detection of somatic genetic drivers is important for risk stratification and treatment selection in pediatric leukemias; however, newly recognized genetic markers may not be detected by routine karyotyping and fluorescence in situ hybridization (FISH). To identify the combination of assays that provides the highest detection rate for clinically significant molecular abnormalities, we tested 160 B- lymphoblastic leukemia (B-ALL) by karyotyping, FISH, chromosomal microarray analysis (CMA) and the custom next-generation sequencing (NGS) panel, OncoKids Ⓡ . In addition, we tested 40 myeloid malignancies with karyotyping, chromosomal microarray analysis (CMA), and OncoKids Ⓡ ; 36/40 myeloid malignancies were also tested with FISH. In B-ALL, individual testing methods had the following diagnostic yields for the key genetic drivers: karyotype 34%; basic FISH panel 45%; FISH panel with IGH and CRLF2 probes 65%; CMA 48%; OncoKids Ⓡ 39%. CMA and OncoKids Ⓡ testing allowed detection of key genetic drivers in 42% of the samples that remained unknown upon testing by conventional methods. In myeloid malignancies, OncoKids Ⓡ had the highest yield for detection of both primary and secondary DNA mutations and RNA fusions. Our data highlights the complementarity between CMA and NGS and conventional cytogenetics/FISH in pediatric leukemia diagnostics. Due to rapid turn-around-time, FISH may be useful as an initial screening method in B-ALL. Our data also suggests NGS testing with a comprehensive panel, despite a longer turnaround time, is a good alternative to karyotyping and FISH in pediatric AML due to its superior detection rate., Competing Interests: Declaration of Competing Interest Matthew C. Hiemenz is an employee of Foundation Medicine, Inc., a wholly owned subsidiary of Roche Holdings Inc. and Roche Finance Ltd., and has an equity interest in an affiliate of these Roche entities., (Copyright © 2021. Published by Elsevier Inc.)

Normal karyotype acute myeloid leukemia (NK-AML) constitutes 20-25% of pediatric AML and detailed molecular analysis is essential to unravel the genetic background of this group. Using publicly available sequencing data from the TARGET-AML initiative, we investigated the mutational landscape of NK-AML in comparison with abnormal karyotype AML (AK-AML). In 164 (97.6%) of 168 independent NK-AML samples, at least one somatic protein-coding mutation was identified using whole-genome or targeted capture sequencing. We identified a unique mutational landscape of NK-AML characterized by a higher prevalence of mutated CEBPA , FLT3 , GATA2 , NPM1 , PTPN11 , TET2 , and WT1 and a lower prevalence of mutated KIT , KRAS , and NRAS compared with AK-AML. Mutated CEBPA often co-occurred with mutated GATA2 , whereas mutated FLT3 co-occurred with mutated WT1 and NPM1 . In multivariate regression analysis, we identified younger age, WBC count ≥50 × 10 9 /L, FLT3 -internal tandem duplications, and mutated WT1 as independent predictors of adverse prognosis and mutated NPM1 and GATA2 as independent predictors of favorable prognosis in NK-AML. In conclusion, NK-AML in children is characterized by a unique mutational landscape which impacts the disease outcome.

There is paucity of data on outcomes of MSD-HSCT in children with relapsed or high-risk AML from developing countries, which have unique challenges including adverse host factors and resource constraints. We retrospectively reviewed records of children (age ≤ 18 years) who underwent MSD-HSCT for AML at our center from 2009 to 2019 to evaluate clinical outcome and its predictors using Cox proportional hazards model. There were 46 children (36 boys and 10 girls) with mean age 10.7 ± 4.8 years. Indication for HSCT was relapsed AML in CR2 (n = 37), primary refractory (n = 3), or relapsed refractory disease (n = 3); high-risk (n = 1) or secondary (n = 2) AML in CR1. Five-year EFS and OS were 33.3 ± 7.2% and 36.3 ± 7.6%, respectively. On multivariate analysis, CR1 duration less than 12 months, presence of active disease at transplant, and use of bone marrow stem cell graft were associated with poorer EFS and OS. There was one (2.2%) TRM, while disease relapse occurred in 20/40 patients who underwent HSCT in remission. Though the 5-year EFS and OS were inferior to results reported from high-income countries, relapse (and not TRM) was the major cause of treatment failure. A well-sustained CR1, achievement of disease remission, and use of peripheral blood allograft seem imperative to a successful transplant. Targeted therapy along with HSCT may be the option for those with early relapse., (© 2020 Wiley Periodicals LLC.)

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 IC 50 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., Competing Interests: Declaration of Competing Interest None., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Polo-like kinase 1 (Plk1) is an important regulator of the cell cycle and it is frequently overexpressed in cancer cells. Several small molecule inhibitors have been developed to target Plk1 and some of them have reached clinical trials in adults with acute myeloid leukemia (AML). Pediatric AML patients have a poor prognosis and survivors suffer from long-term side effects. As adult AML cells have an elevated expression of Plk1, AML is a disease candidate for Plk1 inhibition. However, the relative success of clinical trials have been hampered by adverse reactions. Herein, PLK1-targeting RNA interference (RNAi) prodrugs that enter cells without a transfection reagent are used to target PLK1 selectively in primary cells from pediatric AML patients. We show that PLK1 and PLK4 mRNA expression are significantly higher in pediatric AML patients when compared to healthy donors and that PLK1 is downregulated by on average 50% using RNAi prodrugs without a significant effect on other PLK family members. In addition, the RNAi prodrug-induced decrease in PLK1 can be used to potentiate the effect of cytarabine. In summary, PLK1-targeting RNAi prodrugs can decrease the elevated levels of PLK1 in primary cells from pediatric AML patients and sensitize pediatric AML cells to chemotherapeutics., (© 2021 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

This panel was designed to identify, quantify and phenotypically characterize putative leukemic stem cells (LSCs) in bone marrow (BM) samples from individual pediatric patients diagnosed with acute myeloid leukemia (AML). Based on an aberrant expression on immunophenotypically defined hematopoietic stem cells (HSCs), several antigens have been proposed as LSC markers in AML research, using healthy adult BM samples as reference material. Generally, these antigens have been evaluated individually in smaller panels (e.g. 8-color panels). This necessitates several tubes to characterize the LSC phenotype and compromises the ability to evaluate LSC heterogeneity. The present 15-color OMIP incorporates nine suggested LSC markers to comprehensively capture LSC immunophenotypes and to explore heterogenic marker-patterns within LSC populations in a single tube. Importantly, this single tube approach requires less input material, which is essential when sampling BM aspirates from pediatric patients where sample volumes often are sparse. As knowledge on normal expression levels of the included LSC markers in HSCs from hematologically healthy children are a prerequisite for labelling a phenotype as abnormal, we have evaluated the applicability of the panel on cryopreserved mononuclear cells (MNCs) isolated from BM samples from pediatric patients without hematological disorders as well as pediatric AML patients. The panel is optimized for cryopreserved BM MNCs, but could in principle, be utilized for LSC detection in any biological material containing human hematopoietic cells., (© 2020 International Society for Advancement of Cytometry.)

Background: The prognosis of children with acute myeloid leukemia (AML) has improved with the efficacy of hematopoietic cell transplantation (HCT) as a second-line therapy and improvements in supportive care following anthracycline- and cytarabine-based chemotherapy; however, the outcomes of children with relapsed AML still remain unsatisfactory., Procedure: In order to identify prognostic factors and improve their prognosis, we analyzed 111 patients who relapsed after treatment with the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-05 protocol and who were registered in the retrospective JPLSG AML-05R study., Results: The 5-year overall survival rate was 36.1%. The major determinant of survival was duration from the diagnosis to relapse. The mean duration in the nonsurviving group (10.1 ± 4.1 months) was shorter than that in the surviving group (16.3 ± 8.3 months) (P < .01). Moreover, achieving a second complete remission (CR2) prior to HCT was associated with a good prognosis (P < .01). Etoposide, cytarabine, and mitoxantrone (ECM)- or fludarabine, cytarabine, and granulocyte colony-stimulating factor (FLAG)-based regimens were therefore recommended for reinduction therapy (P < .01). A genetic analysis also revealed the prognostic significance of FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication as a poor prognostic marker (P = .04) and core binding factor-AML, t(8;21), and inv(16) as good prognostic markers (P < .01)., Conclusions: Achieving a CR2 prior to HCT is important in order to improve the prognosis of relapsed pediatric AML. Recent molecular targeted therapies, such as FLT3 inhibitors, may contribute to overcome their prognoses. Larger prospective investigations are necessary to establish individualized treatment strategies for patients with relapsed childhood AML., (© 2020 Wiley Periodicals LLC.)

Pediatric acute myeloid leukemia (AML) is an aggressive malignancy with poor prognosis for which there are few effective targeted approaches, despite the numerous genetic alterations, including MLL gene rearrangements ( MLL -r). The histone methyltransferase DOT1L is involved in supporting the proliferation of MLL -r cells, for which a target inhibitor, Pinometostat, has been evaluated in a clinical trial recruiting pediatric MLL -r leukemic patients. However, modest clinical effects have been observed. Recent studies have reported that additional leukemia subtypes lacking MLL -r are sensitive to DOT1L inhibition. Here, we report that targeting DOT1L with Pinometostat sensitizes pediatric AML cells to further treatment with the multi-kinase inhibitor Sorafenib, irrespectively of MLL -r. DOT1L pharmacologic inhibition induces AML cell differentiation and modulates the expression of genes with relevant roles in cancer development. Such modifications in the transcriptional program increase the apoptosis and growth suppression of both AML cell lines and primary pediatric AML cells with diverse genotypes. Through ChIP-seq analysis, we identified the genes regulated by DOT1L irrespective of MLL -r, including the Sorafenib target BRAF , providing mechanistic insights into the drug combination activity. Our results highlight a novel therapeutic strategy for pediatric AML patients.

Novel treatment strategies are of paramount importance to improve clinical outcomes in pediatric AML. Since chemotherapy is likely to remain the cornerstone of curative treatment of AML, insights in the molecular mechanisms that determine its cytotoxic effects could aid further treatment optimization. To assess which genes and pathways are implicated in tumor drug resistance, we correlated ex vivo drug response data to genome-wide gene expression profiles of 73 primary pediatric AML samples obtained at initial diagnosis. Ex vivo response of primary AML blasts towards cytarabine (Ara C), daunorubicin (DNR), etoposide (VP16), and cladribine (2-CdA) was associated with the expression of 101, 345, 206, and 599 genes, respectively ( p < 0.001, FDR 0.004-0.416). Microarray based expression of multiple genes was technically validated using qRT-PCR for a selection of genes. Moreover, expression levels of BRE , HIF1A , and CLEC7A were confirmed to be significantly ( p < 0.05) associated with ex vivo drug response in an independent set of 48 primary pediatric AML patients. We present unique data that addresses transcriptomic analyses of the mechanisms underlying ex vivo drug response of primary tumor samples. Our data suggest that distinct gene expression profiles are associated with ex vivo drug response, and may confer a priori drug resistance in leukemic cells. The described associations represent a fundament for the development of interventions to overcome drug resistance in AML, and maximize the benefits of current chemotherapy for sensitive patients.

The long noncoding RNA urothelial carcinoma-associated 1 (UCA1) has been reported to sustain the proliferation of acute myeloid leukemia (AML) cells through downregulating cell cycle regulators p27 kip1 . Yet, the foundational mechanism of UCA1 in AML pathologies remains unclear. Herein, we found an escalation of UCA1 expression and suppression of miR-204 expression in pediatric AML patients and cells. UCA1 silencing suppressed cell proliferative abilities, promoted apoptotic rates, decreased Ki67, and increased cleaved caspase-3 in AML cells. Moreover, UCA1 sponged miR-204 and suppressed its expression. UCA1 overexpression inversed the miR-204 suppressed proliferation and promoted apoptosis. UCA1 also boosted the expression of SIRT1, a miR-204 target, via the sponging interaction. Furthermore, miR-204 inhibited inducible nitric oxide synthase and cyclooxygenase-2 expression, while UCA1 overexpression inversed the inhibitory effects in AML cells. Our findings concluded that UCA1 downregulation repressed cell proliferation and promoted apoptosis through inactivating SIRT1 signals by upregulating miR-204 in pediatric AML., (© 2020 Wiley Periodicals, Inc.)

Objectives: Treatment outcome in children with acute myeloid leukemia (AML) has improved in the developed world but remains poor in developing countries. We assessed the role of etoposide in induction chemotherapy in pediatric AML., Methods: This analysis retrospectively compared 2 induction chemotherapy regimens consisting of daunorubicin and cytarabine with etoposide (ADE) and without etoposide (AD). All newly diagnosed cases of AML younger than 18 years from January 1, 2012, onwards who completed their treatment before January 31, 2019, were included. Data of 186 cases, including 117 males (62.9%) and 69 females (37.1%), were analyzed. Demographic, initial presentation blood counts, and AML subtypes were almost identical in both groups., Results: Complete remission rates were almost identical for the ADE versus the AD group (78.8% vs 80.0%, p = 0.980). Treatment-related mortality was higher, albeit not significantly, in the ADE (25 of 105; 23.8%) versus the AD (16 of 81; 19.8%) group (p = 0.508). Overall survival was 32 of 105 (30.5%) in the ADE and 43 of 81 (53.1%) in the AD group (p = 0.079), and disease-free survival was 29 of 105 (27.6%) and 39 of 81 (48.1%) in ADE and AD groups (p = 0.056), respectively., Conclusions: Etoposide in induction treatment of pediatric AML is associated with increased episodes of bacterial and fungal infections and high treatment-related mortality. Moreover, it does not offer any survival benefit. In low- and middle-income countries like Pakistan, it should not be used in the induction treatment protocol., Competing Interests: Disclosure The authors declare no conflicts or financial interest in any product or service mentioned in the manuscript, including grants, equipment, medications, employment, gifts, and honoraria. All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis., (Copyright Pediatric Pharmacy Association. All rights reserved. For permissions, email: mhelms@pediatricpharmacy.org 2020.)

In Japan, acute myeloid leukemia (AML) accounts for approximately 25% of all pediatric leukemias, with approximately 150 cases of newly diagnosed AML occurring annually. Approximately 10% of patients have primary induction failure and 30% of patients, who initially achieve remission in primary treatments, subsequently relapse. Novel treatment modalities need to be developed to further improve the prognosis of pediatric AML patients. AML is a heterogeneous genetic disease characterized by changes in the genome of hematopoietic progenitor cells. Recent studies that have made progress in research related to the pathogenesis of AML have suggested that genotype-specific treatment strategies are associated with increased efficacy. Potential new therapeutic alternatives for pediatric AML include: tyrosine kinase inhibitors, monoclonal or bispecific T-cell engager antibodies, chimeric antigen receptor T-cell therapy, and metabolic agents. This review highlights the current landscape of novel therapeutic approaches for childhood AML, including the results of both preclinical and clinical trials, as well as introducing the results of several preceding adult clinical studies, which could potentially be translated into pediatric AML patients.

Background: Background">Rare subgroups of pediatric patients with acute myeloid leukemia (AML), such as t(16:21) (p11;q22), require international cooperation to establish a proper stratification system to assign clinical risk., Case Report: Here, we report a 13-year-old female who was admitted for asthenia, fatigue, and intermittent fever. The hematological data showed thrombocytopenia and anemia, and the bone marrow test showed 82.5% blast cells, which were positive for CD13, CD33, CD38, and CD117. Blast cells showed negative myeloperoxidase staining and positive periodic acid-Schiff staining. A diagnosis of AML M6 was made. Cells were positive for the fusion transcript FUS-ERG t(16;21)(p11;q22). The patient achieved morphological remission. However, molecular remission was not achieved, and she died 11 months after diagnosis., Conclusions: It is essential to report this sporadic case of AML to provide clinicians with data for clinical decision-making, such as for risk-group stratification. To the best of our knowledge, this is the first association between this translocation and this morphological subtype., (Copyright: © 2020 Permanyer.)

Gilteritinib is an FMS-like tyrosine kinase 3 (FLT3) inhibitor that has shown efficacy in patients with refractory or recurrent adult acute myeloid leukemia (AML) with FLT3 mutations. However, there are limited data for pediatric patients treated with this drug. Herein, we report the clinical courses of two children with FLT3-mutated recurrent AML who received gilteritinib. Case 1: An 11-year-old boy with secondary relapsed AML presented with an FLT3 internal tandem duplication (ITD) since the first recurrence. One week after gilteritinib initiation, blasts, which had comprised 90% of the white blood cells before treatment, almost disappeared from the peripheral blood without tumor lysis syndrome. The patient developed multiple adverse effects and died from the disease 2.5 months after gilteritinib initiation. Case 2: A 12-year-old girl diagnosed with AML was positive for FLT3 ITD. She received gilteritinib during her first relapse post-stem cell transplantation. After the drug was administered, the recipient cell counts increased, as determined by molecular tests (i.e., FISH), whereas microscopically, there was a complete response for 5 months with good performance status. Gilteritinib treatment in children with FLT3-mutated recurrent AML is feasible and effective. As a patient experienced several adverse effects with gilteritinib treatment, clinical trials are required to determine the appropriate pediatric dose of this medication.

Pediatric acute myeloid leukemia (AML) is a complex and heterogeneous disease. Several studies have shown the regulatory functions of microRNAs (miRNAs) in pediatric AML progression, and in this study, we aimed to evaluate the biological role of miR-206 in pediatric AML. The results demonstrated that miR-206 expression levels in the bone marrow and serum of pediatric AML patients were remarkably decreased than those in normal controls, and low serum miR-206 expression was closely associated with the unfavorable clinicopathological characteristics and prognosis of pediatric AML patients. In addition, in vitro functional experiments revealed that overexpression of miR-206 significantly inhibited AML cell proliferation partly through induction of cell cycle arrest. Further studies showed that Cyclin D1 might be a direct target of miR-206 in AML cells, and the impaired proliferation ability of miR-206-overexpressing AML cells was notably rescued by Cyclin D1 restoration. Accordingly, the findings of our study suggested that miR-206 might serve as a promising prognostic marker and a potential therapy target for patients with pediatric AML., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

Introduction: To investigate the correlation of long noncoding RNA-SOX6-1 (lnc-SOX6-1) with clinicopathological features and treatment outcomes in pediatric acute myeloid leukemia (AML) patients, and further explore its function in AML cell proliferation and apoptosis., Methods: A total of 146 de novo pediatric AML patients and 73 nonhematologic malignancy patients/donors were recruited. Bone marrow samples were obtained, followed by measurement of lnc-SOX6-1 expression by qPCR. Besides, lnc-SOX6-1 expression in various AML cells and control cells was detected. Blank overexpression (NC (+)), lnc-SOX6-1 overexpression (Lnc RNA (+)), blank shRNA (NC (-)), and lnc-SOX6-1 shRNA plasmids (Lnc RNA (-)) were transferred into KG-1 cells and THP-1 cells. Cell proliferation rate and cell apoptosis rate were detected by CCK-8 assay and AV/PI assay, respectively., Results: Lnc-SOX6-1 expression was upregulated in pediatric AML patients compared to controls, and its high expression correlated with the presence of monosomal karyotype, severer risk stratification, lower possibility of complete response achievement, shorter event-free survival, and poor overall survival. Furthermore, lnc-SOX6-1 expression was elevated in various AML cells compared to normal cells. In KG-1 cells and THP-1 cells, cell proliferation rate was elevated in Lnc RNA (+) group but reduced in Lnc RNA (-) group at 48 and 72 hours, and cell apoptosis rate was decreased in Lnc RNA (+) group but increased in Lnc RNA (-) group at 72 hours compared to the corresponding control groups., Conclusion: Lnc-SOX6-1 is highly expressed and correlates with worse risk stratification and poor treatment outcomes, and promotes cell proliferation while represses apoptosis in pediatric AML., (© 2019 John Wiley & Sons Ltd.)

Cytarabine has been an integral part of acute myeloid leukemia (AML) chemotherapy for over four decades. However, development of resistance and high rates of relapse is a significant impediment in successfully treating AML. We performed a genome-wide association analysis (GWAS) and identified 113 (83 after adjusting for Linkage Disequilibrium) SNPs associated with in vitro cytarabine chemosensitivity of diagnostic leukemic cells from a cohort of 50 pediatric AML patients (p<10 -4 ). Further evaluation of diagnostic leukemic cell gene-expression identified 19 SNP-gene pairs with a concordant triad of associations: i)SNP genotype with cytarabine sensitivity (p<0.0001), ii) gene-expression with cytarabine sensitivity (p<0.05), and iii) genotype with gene-expression (p<0.1). Two genes from SNP-gene pairs, rs1376041- GPR56 and rs75400242- IGF1R , were functionally validated by siRNA knockdown in AML cell lines. Consistent with association of rs1376041 and gene-expression in AML patients siRNA mediated knock-down of GPR56 increased cytarabine sensitivity of AML cell lines. Similarly for IGF1R , knockdown increased the cytarabine sensitivity of AML cell lines consistent with results in AML patients. Given both IGF1R and GPR56 are promising drug-targets in AML, our results on SNPs driving the expression/function of these genes will not only enhance our understanding of cytarabine resistance but also hold promise in personalizing AML for targeted therapies., Competing Interests: CONFLICTS OF INTEREST The authors declare no conflicts of interest.

Background: MicroRNA-195 acts as a tumor suppressor in a variety of cancers. However, its clinical significance in pediatric acute myeloid leukemia (AML) remains largely undefined., Objective: To investigate the diagnostic and prognostic relevance of miR-195 in this malignancy., Methods: Expression levels of miR-195 in peripheral blood and bone marrow samples of patients with pediatric AML and normal controls were detected by real-time quantitative PCR. Then, receiver-operating characteristic (ROC) curve analysis, Kaplan-Meier method, and Cox regression analysis were performed to evaluate the diagnostic and prognostic relevance of serum miR-195 in pediatric AML., Results: Compared to normal controls, the expression levels of miR-195 in both bone marrow and patients' sera were significantly decreased (both P< 0.001). In addition, serum miR-195 had an optimal diagnostic cut-off point (2.09) for pediatric AML with sensitivity of 68.87% and specificity of 96.23%. The area under the ROC curve (AUC) based on serum miR-195 was 0.910. Moreover, patients with low serum miR-195 level more often had French-American-British classification subtype M7 (P= 0.02), unfavorable karyotypes (P= 0.01), and shorter relapse-free and overall survivals (both P= 0.001) than those with high serum miR-195 level. Furthermore, the multivariate analysis identified serum miR-195 level as an independent prognostic factor for both relapse-free and overall survivals., Conclusion: The findings of this study suggest that the aberrant expression of miR-195 may play crucial roles in the development and progression of pediatric AML patients. Serum miR-195 may serve as a promising marker for monitoring the occurrence of this disease and predicting the clinical outcome of patients.

Objectives: The purpose of this study was to identify featured microRNAs and their regulated network between adult and pediatric acute myeloid leukemia (AML) and find potential utility as biomarkers for diagnosis and treatment of pediatric AML., Methods: We downloaded the microRNA expression dataset GSE35320 from Gene Expression Omnibus database and selected expression chips from bone marrow of 71 pediatric AML samples and 6 adulthood AML samples. Differentially expressed microRNAs were identified by Wilcox test. The target genes of these microRNAs were predicted using an integrative method and their functional enrichment analysis was performed using DAVID. Finally, STRING database and Cytoscape software was used to construct and analyze the interaction network., Results: A total of 7 differentially expressed microRNAs were identified and the remarkably up-regulated and down-regulated microRNAs were miR-16 and miR-142-5p which included 323 and 22 predicted target genes, respectively. The target genes of 7 microRNAs were most associated with regulation of cell cycle, p53 signaling pathway, Wnt signaling pathway and neurotrophin signaling pathway. The interaction network of miR-16 target genes was constructed among 354 high confidence interaction pairs. The core genes of the network, such as TP53, BCL2, VEGFA, had a role in prognosis of children with AML., Conclusions: The featured microRNAs and their target genes are significant in the occurrence and development of pediatric AML, which is likely to be important for the identification of therapeutic targets and biomarkers for these patients., Competing Interests: None., (IJCEP Copyright © 2017.)

Purpose: The aim of this study was to investigate roles of microRNA (miR)-183 in pediatric acute myeloid leukemia (AML)., Methods: miR-183 expression in bone marrow and patients' sera of childhood AML was detected by real-time quantitative PCR. Functions of miR-183 in malignant phenotypes of two leukemia cell lines were then evaluated. Additionally, putative targets of miR-183 were predicted using three miRNA target prediction algorithms and validated by luciferase reporter assay. Clinical relevance of miR-183 and its target gene were further determined., Results: miR-183 expression in bone marrow and patients' sera of childhood AML was both significantly higher than those in the corresponding normal controls (both P < 0.001). Enforced expression of miR-183 dramatically enhanced cell proliferation and G1/S transition, but inhibited cell apoptosis of leukemia cells. Bioinformatics prediction and luciferase reporter assay identified programmed cell death 6 (PDCD6) as a direct target gene of miR-183. Moreover, high serum miR-183 combined with low serum PDCD6 mRNA was significantly associated with French-American-British classification subtype M7 (P = 0.01) and unfavorable karyotypes (P = 0.006). Further multivariate analysis identified the combination of serum miR-183 and PDCD6 levels as an independent prognostic factor for both relapse-free and overall survivals. Functionally, re-introduction of PDCD6 markedly reversed the effects of miR-183 in cell cycle, proliferation and apoptosis of two leukemia cell lines., Conclusion: Combined serum miR-183 and PDCD6 mRNA may serve as a novel prognostic biomarker for pediatric AML. Interestingly, miR-183 may function as an oncogene and may enhance cell proliferation by targeting PDCD6, implying a potential therapeutic target for this malignancy.