Response-guided induction therapy in pediatric acute myeloid leukemia with excellent remission rate

Leaving the parental home, cohabitation, and marriage after a hematologic malignancy in childhood-A register-based cohort study from the SALiCCS research program

INTRODUCTION

Transitioning to adulthood often involves achieving independence from the parental home. We assessed whether the likelihood of leaving the parental home, cohabitation, and marriage was similar between patients who experienced a hematologic malignancy at a young age and their peers.

METHODS

We identified 11,575 patients diagnosed with a hematologic malignancy under the age of 20 years between 1971 and 2011 in Denmark, Finland, and Sweden, 57,727 country-, age-, and sex-matched population comparisons and 11,803 sibling comparisons and obtained annual information on family and marital status by linking to the statistical institute databases. Hazard ratios (HR) for leaving the parental home, cohabitation and marriage were estimated using Cox proportional hazards modeling.

RESULTS

Young adults with a history of a hematologic malignancy were slightly less likely to leave the parental home (HR 0.89; 95% confidence interval [CI] 0.86-0.92; HR 0.87 [95% CI 0.82-0.92]), cohabit with a nonmarital partner (HR 0.83 [95%CI 0.78-0.87]; HR 0.84 [95% CI 0.77-0.92]) and be married (HR 0.87 [95% CI 0.82-0.91]; HR 0.86 [95% CI 0.79-0.93]), compared with population comparisons and siblings, respectively.

CONCLUSIONS

Our findings provide reassurance that young adults with a history of a hematologic malignancy show only a slight decrease in their likelihood of gaining independence from their childhood family and forming close interpersonal relationships compared to peers. While most patients are coping well in the long term, integrating structured psychosocial support into long-term follow-up is recommended to facilitate a timely and adequate transition into adulthood.

Mitoxantrone Versus Liposomal Daunorubicin in Induction of Pediatric AML With Risk Stratification Based on Flow Cytometry Measurement of Residual Disease

PURPOSE

Measurable residual disease (MRD) by using flow cytometry after induction therapy is strongly prognostic in pediatric AML, and hematopoietic stem-cell transplant (hSCT) may counteract a poor response. We designed a phase III study with intensified response-guided induction and MRD-based risk stratification and treated poor induction response with hSCT. The efficacy of liposomal daunorubicin (DNX) in induction was compared with mitoxantrone.

METHODS

The study planned to randomly assign 300 patients, but the production of DNX ceased in 2017. One hundred ninety-four patients were randomly assigned to mitoxantrone or experimental DNX in induction 1. Ninety-three non-randomly assigned patients served as an observation cohort. Primary end point was fraction of patients with MRD <0.1% on day 22 after induction 1. Patients with MRD ≥15% after induction 1 or ≥0.1% after induction 2 or FLT3-ITD with NPM1 wildtype were stratified to high-risk therapy, including hSCT.

RESULTS

Outcome for all 287 children was good with 5-year event-free survival (EFS5y) 66.7% (CI, 61.4 to 72.4) and 5-year overall survival (OS5y) 79.6% (CI, 75.0 to 84.4). Overall, 75% were stratified to standard-risk and 19% to high-risk. There was no difference in the proportion of patients with MRD <0.1% on day 22 after induction 1 (34% mitoxantrone, etoposide, araC [MEC], 30% DNX, P = .65), but the proportion increased to 61% for MEC versus 47% for DNX (P = .061) at the last evaluation before induction 2. EFS5y was significantly lower, 56.6% (CI, 46.7 to 66.5) versus 71.9% (CI, 63.0 to 80.9), and cumulative incidence of relapse (CIR) was higher, 35.1% (CI, 25.7 to 44.7) versus 18.8% (CI, 11.6 to 27.2) for DNX. The inferior outcome for DNX was only in standard-risk patients with EFS5y 55.3% (CI, 45.1 to 67.7) versus 79.9% (CI, 71.1 to 89.9), CIR 39.5% (CI, 28.4 to 50.3) versus 18.7% (CI, 10.5 to 28.7), and OS5y 76.2% (CI, 67.2 to 86.4) versus 88.6% (CI, 81.4 to 96.3). As-treated analyses, including the observation cohort, supported these results. For all high-risk patients, 85% received hSCT, and EFS5y was 77.7 (CI, 67.3 to 89.7) and OS5y was 83.0 (CI, 73.5 to 93.8).

CONCLUSION

The intensification of induction therapy with risk stratification on the basis of response to induction and hSCT for high-risk patients led to improved outcomes. Mitoxantrone had a superior anti-leukemic effect than liposomal daunorubicin.

Intensive chemotherapy with dual induction and ALL-like consolidation for childhood acute myeloid leukemia: a respective report from multiple centers in China

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 × 109/L, 11 of whom ⩾100 × 109/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 × 109/L (n = 59) and ⩾100 × 109/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 × 109/L was the only independent risk factor in this cohort.

Trial registration

It is a retrospective study, and no registration on ClinicalTrials.gov.

Prognostic significance of multiparametric flow cytometry minimal residual disease at two time points after induction in pediatric acute myeloid leukemia

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.

Treatment outcome and prognostic factors in relapsed pediatric acute myeloid leukemia

Background

Despite improved outcomes for pediatric patients with acute myeloid leukemia (AML), the prognosis for relapse remains poor. This study aimed to examine the clinical factors associated with prognosis in relapsed pediatric AML.

Methods

We conducted a chart review of pediatric patients with AML who experienced their first relapse and received treatment at our institution between 2008 and 2019. Risk stratification at diagnosis was performed according to the definition suggested by the ongoing AML 2012 study in Korea, and the clinical factors associated with prognosis were analyzed.

Results

A total of 27 pediatric patients with relapsed AML were identified. The 5-year overall survival (OS) and event-free survival (EFS) rates were 32.9% and 32.9%, respectively. A duration ≥12 months from diagnosis to relapse had a favorable impact on survival outcomes (5-yr OS, 64.0% vs. 15.7%; P=0.007). Patients who achieved complete remission (CR) after 1 course of chemotherapy following relapse (N=15) had a 5-year OS rate of 59.3%, while none of the other patients survived (P＜0.0001). Additionally, the 5-year OS differed significantly based on the risk group at initial diagnosis (62.3% [favorable and intermediate prognosis groups, N=11] vs. 13.3% [poor prognosis group, N=15]; P=0.014).

Conclusion

Patients with a longer duration of CR before relapse, who achieved CR following 1 course of reinduction chemotherapy, and were in the favorable or intermediate prognosis group at diagnosis demonstrated better outcomes. These findings emphasize the importance of tailoring treatment strategies based on the expected prognosis at relapse in pediatric patients with AML.

Right femoral vein and right dorsal artery thrombosis in childhood acute myeloid leukemia: A case report

BACKGROUND

It is rare for newly diagnosed (de novo) or newly treated acute myeloid leukemia (AML) complicated with thrombotic complications, especially combined arterial and venous thrombosis.

METHODS

We reported a 13-year-old boy diagnosed with AML and leukocytosis, who developed right femoral vein and right dorsal artery thrombosis during chemotherapy. After treatment with low molecular weight heparin, diosmin, and alprostadil, symptoms were relieved. Unfortunately, the child suffered from coagulopathy afterward, which was unexpectedly caused by vitamin K deficiency.

RESULTS

After supplementation with vitamin K and prothrombin complex concentrate, coagulation function recovered.

CONCLUSION

For childhood AML patients with high thrombotic risks, close monitoring during anticoagulant treatment was necessary. Concomitantly, we should be alert to past medication history and combined medication use, especially those that may lead to vitamin K deficiency, secondary bleeding, and coagulation disorders. Rational use of antibiotics, anticoagulants, and antitumor drugs must be guaranteed.

Risk-Stratified Therapy for Pediatric Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) is the second most common type of leukemia in children. Recent advances in high-resolution genomic profiling techniques have uncovered the mutational landscape of pediatric AML as distinct from adult AML. Overall survival rates of children with AML have dramatically improved in the past 40 years, currently reaching 70% to 80% in developed countries. This was accomplished by the intensification of conventional chemotherapy, improvement in risk stratification using leukemia-specific cytogenetics/molecular genetics and measurable residual disease, appropriate use of allogeneic hematopoietic stem cell transplantation, and improvement in supportive care. However, the principle therapeutic approach for pediatric AML has not changed substantially for decades and improvement in event-free survival is rather modest. Further refinements in risk stratification and the introduction of emerging novel therapies to contemporary therapy, through international collaboration, would be key solutions for further improvements in outcomes.

Characteristics and outcome of primary resistant disease in paediatric acute myeloid leukaemia

A significant proportion of events in paediatric acute myeloid leukaemia (AML) are caused by resistant disease (RD). We investigated clinical and biological characteristics in 66 patients with RD from 1013 children with AML registered and treated according to the NOPHO-AML 93, NOPHO-AML 2004, DB AML-01 and NOPHO-DBH AML 2012 protocols. Risk factors for RD were age10 years or older and a white-blood-cell count (WBC) of 100 × 10⁹ /L or more at diagnosis. The five-year overall survival (OS) was 38% (95% confidence interval [CI]: 28%-52%). Of the 63 children that received salvage therapy with chemotherapy, 59% (N = 37) achieved complete remission (CR) with OS 57% (95% CI: 42%-75%) compared to 12% (95% CI: 4%-35%) for children that did not achieve CR. Giving more than two salvage chemotherapy courses did not increase CR rates. OS for all 43 patients receiving allogeneic haematopoietic stem cell transplantation (HSCT) was 49% (95% CI: 36%-66%). Those achieving CR and proceeding to HSCT had an OS of 56% (95% CI: 41%-77%, N = 30). This study showed that almost 40% of children with primary resistant AML can be cured with salvage therapy followed by HSCT. Children that did not achieve CR after two salvage courses with chemotherapy did not benefit from additional chemotherapy.

Fusion transcript analysis reveals slower response kinetics than multiparameter flow cytometry in childhood acute myeloid leukaemia

INTRODUCTION

Analysis of measurable residual disease (MRD) is increasingly being implemented in the clinical care of children and adults with acute myeloid leukaemia (AML). However, MRD methodologies differ and discordances in results lead to difficulties in interpretation and clinical decision-making. The aim of this study was to compare results from reverse transcription quantitative polymerase chain reaction (RT-qPCR) and multiparameter flow cytometry (MFC) in childhood AML and describe the kinetics of residual leukaemic burden during induction treatment.

METHODS

In 15 children who were treated in the NOPHO-AML 2004 trial and had fusion transcripts quantified by RT-qPCR, we compared MFC with RT-qPCR for analysis of MRD during (day 15) and after induction therapy. Eight children had RUNX1::RUNX1T1, one CBFB::MYH11 and six KMT2A::MLLT3.

RESULTS

When ≥0.1% was used as cut-off for positivity, 10 of 22 samples were discordant. The majority (9/10) were MRD positive with RT-qPCR but MRD negative with MFC, and several such cases showed the presence of mature myeloid cells. Fusion transcript expression was verified in mature cells as well as in CD34 expressing cells sorted from diagnostic samples.

CONCLUSIONS

Measurement with RT-qPCR suggests slower response kinetics than indicated from MFC, presumably due to the presence of mature cells expressing fusion transcript. The prognostic impact of early measurements with RT-qPCR remains to be determined.

Abdominal Complications During Treatment for Pediatric Acute Myeloid Leukemia

Acute myeloid leukemia (AML) accounts for 15% to 20% of childhood leukemias. Because of high-intensive therapy, up to 5% of patients suffer from treatment-related mortality (TRM). Abdominal complications are frequent, however, literature on this subject is sparse. We aimed to characterize severe abdominal pain (AP) and hyperbilirubinemia experienced by pediatric AML patients treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO)-AML 2004 protocol (n=313). Patients were censored at hematopoietic stem cell transplantation and relapse. Toxicity information was collected prospectively. Additional information was requested retrospectively from the treating centers. Sixteen episodes of hyperbilirubinemia and 107 episodes of AP were reported. The treating centers deemed infection (30%) and typhlitis (18%) as the most frequent causes of AP. Six patients developed appendicitis (2%). Patients experiencing concurrent AP and sepsis had a high risk of TRM (36%, n=4). Eighty percent of episodes with hyperbilirubinemia fulfilled the European Society for Bone and Marrow Transplantation criteria for sinusoidal obstruction syndrome. In conclusion, abdominal complications were frequent with infection considered the predominate cause. Most patients with hyperbilirubinemia fulfilled the criteria for sinusoidal obstruction syndrome. AML treatment might be associated with appendicitis. Patients suffering from concurrent AP and sepsis had a high risk of TRM indicating that high awareness of abdominal complications is essential to reduce mortality, especially during sepsis.

Early vascular toxicity after pediatric allogeneic hematopoietic stem cell transplantation

Treatment-related mortality and morbidity remain a challenge in hematopoietic stem cell transplantation (HSCT). In this retrospective, single-center study, we analyzed endothelial damage as a potential, common denominator and mechanism for the adverse effects. We evaluated the prevalence of key vascular complications and graft-versus-host disease among 122 pediatric patients with an allogeneic HSCT between 2001 and 2013. The spectrum and frequency of acute adverse events emerging ≤100 days post transplant were graded according to the CTCAE 4.03 and analyzed. We identified a total of 19/122 (15.6%) patients with vascular complications, fulfilling the criteria of capillary leak syndrome, veno-occlusive disease/sinusoidal obstruction syndrome or thrombotic microangiopathy. The patients had a poorer overall survival (77% versus 26%, p < 0.001). Nearly one half (56/122, 45.9%) had at least one, severe (grade 3 or 4) adverse event. Patients with vascular complications had more often edema/effusions (p = 0.023), thrombocytopenia (p = 0.001), gastrointestinal bleeding (p < 0.001), acute kidney injury (p < 0.001), ascites (p < 0.001) or bilirubin increase (p = 0.027). These endotheliopathy-related adverse events appeared early post HSCT, varied in their clinical phenotype and predicted a poor outcome. An unrelated donor but not previous exposure to leukemia or irradiation-based conditioning was identified as a risk factor for vascular complications and endotheliopathy.

Immunophenotypically defined stem cell subsets in paediatric AML are highly heterogeneous and demonstrate differences in BCL-2 expression by cytogenetic subgroups

In adult acute myeloid leukaemia (AML), immunophenotypic differences enable discrimination of leukaemic stem cells (LSCs) from healthy haematopoietic stem cells (HSCs). However, immunophenotypic stem cell characteristics are less explored in paediatric AML. Employing a 15-colour flow cytometry assay, we analysed the expression of eight aberrant surface markers together with BCL-2 on CD34⁺ CD38^- bone marrow stem cells from 38 paediatric AML patients and seven non-leukaemic, age-matched controls. Furthermore, clonality was investigated by genetic analyses of sorted immunophenotypically abnormal stem cells from six patients. A total of 50 aberrant marker positive (non-HSC-like) subsets with 41 different immunophenotypic profiles were detected. CD123, CLEC12A, and IL1RAP were the most frequently expressed markers. IL1RAP, CD93, and CD25 expression were not restricted to stem cells harbouring leukaemia-associated mutations. Differential BCL-2 expression was found among defined cytogenetic subgroups. Interestingly, only immunophenotypically abnormal non-HSC-like subsets demonstrated BCL-2 overexpression. Collectively, we observed pronounced immunophenotypic heterogeneity within the stem cell compartment of paediatric AML patients. Additionally, certain aberrant markers used in adults seemed to be ineligible for detection of leukaemia-representing stem cells in paediatric patients implying that inference from adult studies must be done with caution.

Blood Count Recovery Following Induction Therapy for Acute Myeloid Leukemia in Children Does Not Predict Survival

Simple Summary

International Working Group (IWG) and European LeukemiaNet (ELN) adult response definitions are currently used to evaluate the efficacy of new agents for childhood acute myeloid leukemia (AML); however, the criteria are not consistent with consensus definitions used in pediatric trials or the common practice of intensifying treatment prior to full hematopoietic recovery of ANC ≥ 1000 cells/μL and platelets ≥ 100 cells/μL. This retrospective analysis of the two most recent Phase 3 AML trials in the Children’s Oncology Group assesses the incidence, timing, and prognostic significance of count recovery following induction chemotherapy in children with AML. These data confirm that awaiting count recovery to meet adult criteria does not reflect standard practice in pediatric AML and IWG/ELN-defined CR does not have a significant impact on survival in children. Continuing to use adult IWG/ELN count recovery definitions limits childhood AML drug development by underestimating response, and therefore, updated response criteria are needed for pediatric AML patients.

Abstract

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.

Pediatric Acute Myeloid Leukemia—Past, Present, and Future

This review reports about the main steps of development in pediatric acute myeloid leukemia (AML) concerning diagnostics, treatment, risk groups, and outcomes. Finally, a short overview of present and future approaches is given.

Transcriptomic analysis reveals proinflammatory signatures associated with acute myeloid leukemia progression

Numerous studies have been performed over the last decade to exploit the complexity of genomic and transcriptomic lesions driving the initiation of acute myeloid leukemia (AML). These studies have helped improve risk classification and treatment options. Detailed molecular characterization of longitudinal AML samples is sparse, however; meanwhile, relapse and therapy resistance represent the main challenges in AML care. To this end, we performed transcriptome-wide RNA sequencing of longitudinal diagnosis, relapse, and/or primary resistant samples from 47 adult and 23 pediatric AML patients with known mutational background. Gene expression analysis revealed the association of short event-free survival with overexpression of GLI2 and IL1R1, as well as downregulation of ST18. Moreover, CR1 downregulation and DPEP1 upregulation were associated with AML relapse both in adults and children. Finally, machine learning-based and network-based analysis identified overexpressed CD6 and downregulated INSR as highly copredictive genes depicting important relapse-associated characteristics among adult patients with AML. Our findings highlight the importance of a tumor-promoting inflammatory environment in leukemia progression, as indicated by several of the herein identified differentially expressed genes. Together, this knowledge provides the foundation for novel personalized drug targets and has the potential to maximize the benefit of current treatments to improve cure rates in AML.

Measurable Residual Disease Monitoring of SPAG6, ST18, PRAME, and XAGE1A Expression in Peripheral Blood May Detect Imminent Relapse in Childhood Acute Myeloid Leukemia

Overexpressed genes may be useful for monitoring of measurable residual disease (MRD) in patients with childhood acute myeloid leukemia (AML) without a leukemia-specific target. The normal expression of five leukemia-associated genes (SPAG6, ST18, MSLN, PRAME, XAGE1A) was defined in children without hematologic disease (n = 53) and children with suspected infection (n = 90). Gene expression at AML diagnosis (n=50) and during follow-up (n = 21) was compared with child-specific reference values. At diagnosis, 34/50 children (68%) had high expression of at least one of the five genes, and so did 16/31 children (52%) without a leukemia-specific target. Gene expression was quantified in 110 peripheral blood (PB) samples (median, five samples/patient; range, 1 to 10) during follow-up in 21 patients with high expression at diagnosis. All nine patients with PB sampling performed within 100 days of disease recurrence displayed overexpression of SPAG6, ST18, PRAME, or XAGE1A at a median of 2 months (range, 0.6 to 9.6 months) before hematologic relapse, whereas MSLN did not reach expression above normal prior to hematologic relapse. Only 1 of 130 (0.8%) follow-up analyses performed in 10 patients in continuous complete remission had transient expression above normal. SPAG6, ST18, PRAME, and XAGE1A expression in PB may predict relapse in childhood AML patients and facilitate MRD monitoring in most patients without a leukemia-specific target.

Role of Minimal Residual Disease Testing in Acute Myeloid Leukemia

Minimal or measurable residual disease (MRD) after therapy is the most important independent prognostic factor in acute myeloid leukemia. MRD measured by multiparametric flow cytometry and real-time quantitative polymerase chain reaction has been integrated into risk stratification and used to guide future treatment strategies. Recent technological advances have allowed the application of the novel molecular method, high-throughput sequencing, in MRD detection in clinical practice to improve sensitivity and specificity. Randomized studies are needed to address outstanding issues, including the optimal methods and timing of MRD testing and interlaboratory standardization to facilitate comparisons, to further improve MRD-directed interventions.

Treatment of acute myeloid leukemia in children: A practical perspective

Pediatric acute myeloid leukemia (AML) is a heterogeneous disease that requires a multifaceted treatment approach. Although outcomes for low-risk AML have improved significantly over recent decades, high-risk AML continues to be associated with an adverse prognosis. Recent advances in molecular diagnostics, risk stratification, and supportive care have contributed to improvements in outcomes in pediatric AML. Targeted approaches, for example, the use of tyrosine kinase inhibitors to treat FLT3-ITD AML, offer promise and are currently undergoing clinical investigation in pediatric patients. New approaches to hematopoietic stem cell transplantation, including the use of haploidentical donors, are significantly expanding donor options for patients with high-risk AML. This review provides an overview of recent advances in the treatment of pediatric AML that are likely to have clinical impact and reshape the standard of care.

DNA Methylation Signatures Predict Cytogenetic Subtype and Outcome in Pediatric Acute Myeloid Leukemia (AML)

Pediatric acute myeloid leukemia (AML) is a heterogeneous disease composed of clinically relevant subtypes defined by recurrent cytogenetic aberrations. The majority of the aberrations used in risk grouping for treatment decisions are extensively studied, but still a large proportion of pediatric AML patients remain cytogenetically undefined and would therefore benefit from additional molecular investigation. As aberrant epigenetic regulation has been widely observed during leukemogenesis, we hypothesized that DNA methylation signatures could be used to predict molecular subtypes and identify signatures with prognostic impact in AML. To study genome-wide DNA methylation, we analyzed 123 diagnostic and 19 relapse AML samples on Illumina 450k DNA methylation arrays. We designed and validated DNA methylation-based classifiers for AML cytogenetic subtype, resulting in an overall test accuracy of 91%. Furthermore, we identified methylation signatures associated with outcome in t(8;21)/RUNX1-RUNX1T1, normal karyotype, and MLL/KMT2A-rearranged subgroups (p < 0.01). Overall, these results further underscore the clinical value of DNA methylation analysis in AML.

Genomic characterization of relapsed acute myeloid leukemia reveals novel putative therapeutic targets

Relapse is the leading cause of death of adult and pediatric patients with acute myeloid leukemia (AML). Numerous studies have helped to elucidate the complex mutational landscape at diagnosis of AML, leading to improved risk stratification and new therapeutic options. However, multi-whole-genome studies of adult and pediatric AML at relapse are necessary for further advances. To this end, we performed whole-genome and whole-exome sequencing analyses of longitudinal diagnosis, relapse, and/or primary resistant specimens from 48 adult and 25 pediatric patients with AML. We identified mutations recurrently gained at relapse in ARID1A and CSF1R, both of which represent potentially actionable therapeutic alternatives. Further, we report specific differences in the mutational spectrum between adult vs pediatric relapsed AML, with MGA and H3F3A p.Lys28Met mutations recurrently found at relapse in adults, whereas internal tandem duplications in UBTF were identified solely in children. Finally, our study revealed recurrent mutations in IKZF1, KANSL1, and NIPBL at relapse. All of the mentioned genes have either never been reported at diagnosis in de novo AML or have been reported at low frequency, suggesting important roles for these alterations predominantly in disease progression and/or resistance to therapy. Our findings shed further light on the complexity of relapsed AML and identified previously unappreciated alterations that may lead to improved outcomes through personalized medicine.

Survival Following Relapse in Children with Acute Myeloid Leukemia: A Report from AML-BFM and COG

Simple Summary

Acute myeloid leukemia in children remains a difficult disease to cure despite intensive therapies that push the limits of tolerability. Though the intent of initial therapy should be the prevention of relapse, about 30% of all patients experience a relapse. Hence, relapse therapy remains critically important for survival. This retrospective analysis of two large international study groups (COG and BFM) was undertaken to describe the current survival, response rates and clinical features that predict outcomes. We demonstrate that children with relapsed AML may be cured with cytotoxic therapy followed by HSCT. High-risk features at initial diagnosis and early relapse remain prognostic for post-relapse survival. Current response criteria are not aligned with the standards of care for children, nor are the count recovery thresholds meaningful for prognosis in children with relapsed AML. Our data provide a new baseline for future treatment planning and will allow an updated stratification in upcoming studies.

Abstract

Post-relapse therapy remains critical for survival in children with acute myeloid leukemia (AML). We evaluated survival, response and prognostic variables following relapse in independent cooperative group studies conducted by COG and the population-based AML-BFM study group. BFM included 197 patients who relapsed after closure of the last I-BFM relapse trial until 2017, while COG included 852 patients who relapsed on the last Phase 3 trials (AAML0531, AAML1031). Overall survival at 5 years (OS) was 42 ± 4% (BFM) and 35 ± 2% (COG). Initial high-risk features (BFM 32 ± 6%, COG 26 ± 4%) and short time to relapse (BFM 29 ± 4%, COG 25 ± 2%) predicted diminished survival. In the BFM dataset, there was no difference in OS for patients who had a complete remission with full hematopoietic recovery (CR) following post-relapse re-induction compared to those with partial neutrophil and platelet recovery (CRp and CRi) only (52 ± 7% vs. 63 ± 10%, p = 0.39). Among 90 patients alive at last follow-up, 87 had received a post-relapse hematopoietic stem cell transplant (HSCT). OS for patients with post-relapse HSCT was 54 ± 4%. In conclusion, initial high-risk features and early relapse remain prognostic. Response assessment with full hematopoietic recovery following initial relapse therapy does not predict survival. These data indicate the need for post-relapse risk stratification in future studies of relapse therapies.

Deciphering molecular heterogeneity in pediatric AML using a cancer vs. normal transcriptomic approach

BACKGROUND

Still 30-40% of pediatric acute myeloid leukemia (pedAML) patients relapse. Delineation of the transcriptomic profile of leukemic subpopulations could aid in a better understanding of molecular biology and provide novel biomarkers.

METHODS

Using microarray profiling and quantitative PCR validation, transcript expression was measured in leukemic stem cells (LSC, n = 24) and leukemic blasts (L-blast, n = 25) from pedAML patients in comparison to hematopoietic stem cells (HSCs, n = 19) and control myeloblasts (C-blast, n = 20) sorted from healthy subjects. Gene set enrichment analysis was performed to identify relevant gene set enrichment signatures, and functional protein associations were identified by STRING analysis.

RESULTS

Highly significantly overexpressed genes in LSC and L-blast were identified with a vast majority not studied in AML. CDKN1A, CFP, and CFD (LSC) and HOMER3, CTSA, and GADD45B (L-blast) represent potentially interesting biomarkers and therapeutic targets. Eleven LSC downregulated targets were identified that potentially qualify as tumor suppressor genes, with MYCT1, PBX1, and PTPRD of highest interest. Inflammatory and immune dysregulation appeared to be perturbed biological networks in LSC, whereas dysregulated metabolic profiles were observed in L-blast.

CONCLUSION

Our study illustrates the power of taking into account cell population heterogeneity and reveals novel targets eligible for functional evaluation and therapy in pedAML.

IMPACT

Novel transcriptional targets were discovered showing a significant differential expression in LSCs and blasts from pedAML patients compared to their normal counterparts from healthy controls. Deregulated pathways, including immune and metabolic dysregulation, were addressed for the first time in children, offering a deeper understanding of the molecular pathogenesis. These novel targets have the potential of acting as biomarkers for risk stratification, follow-up, and targeted therapy. Multiple LSC-downregulated targets endow tumor suppressor roles in other cancer entities, and further investigation whether hypomethylating therapy could result into LSC eradication in pedAML is warranted.

Treatment outcomes of pediatric acute myeloid leukemia: a retrospective analysis from 1996 to 2019 in Taiwan

Improvement in outcomes of children with acute myeloid leukemia (AML) is attributed to several refinements in clinical management. We evaluated treatment outcomes of Taiwanese pediatric AML patients in the past 20 years. Overall, 860 de novo AML patients aged 0-18 years and registered in the Childhood Cancer Foundation of R.O.C during January 1996-December 2019 were included. Survival analysis was performed to identify factors that improved treatment outcomes. Regardless of treatment modalities used, patients during 2008-2019 had better 5-year event-free survival (EFS) and overall survival (OS) rates than patients during 1996-2007. For patients received the TPOG-AML-97A treatment, only 5-year OS rates were significantly different between patients diagnosed before and after 2008. Patients with RUNX1-RUNX1T1 had similar relapse-free survival rates, but 5-year OS rates were better during 2008-2019. However, the survival of patients who received hematopoietic stem-cell transplantations (HSCT) did not differ significantly before and after 2008. For patients without relapse, the 5-year OS improved during 2008-2019. Non-relapse mortality decreased annually, and cumulative relapse rates were similar. In conclusion, 5-year EFS and OS rates improved during 2008-2019, though intensities of chemotherapy treatments were similar before and after 2008. Non-relapse mortality decreased gradually. Further treatment strategies including more intensive chemotherapy, novel agents' use, identification of high-risk patients using genotyping and minimal residual disease, early intervention of HSCT, and antibiotic prophylaxis can be considered for future clinical protocol designs in Taiwan.

Measurable residual disease in pediatric acute myeloid leukemia: a systematic review

Introduction: A systematic review was performed to assess the prognostic value of Measurable Residual Disease (MRD) during treatment, for relapse and overall survival in pediatric acute myeloid leukemia (AML).Areas covered: A systematic search of available literature was performed to identify original full-text articles concerning MRD as prognostic for relapse and survival in pediatric AML. Thirteen studies were included, and in all studies, MRD positivity during treatment was associated with worse clinical outcome. MRD positivity was significantly associated with a higher probability of relapse in eleven studies. However, MRD negativity does not exclude the possibility of relapse in pediatric AML, while positivity early during therapy does not exclude cure.Expert opinion: MRD positivity during treatment has emerged as the most powerful prognostic factor in pediatric AML concerning relapse and overall survival and is useful for risk-group adapted treatment. Future studies should identify the optimal time-point(s) for MRD measurements and the optimal technique, to further improve its prognostic significance.

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.

The efficacy and safety of a homoharringtonine-based protocol for children with acute myeloid leukemia: A retrospective study in China

The standard chemotherapy for acute myeloid leukemia (AML) is usually composed of anthracyclines and cytarabine. We previously reported that homoharringtonine (HHT) was incorporated into regimens for pediatric AML with acceptable efficacy and tolerable toxicity. We treated newly diagnosed AML patients aged 0-18 years on the AML-SCMC-2009 protocol. A total of 102 de novo newly diagnosed AML patients aged 0-18 years were enrolled. All patients were treated with ten courses of chemotherapy including double induction, high dose cytarabine consolidation, and maintenance. The cumulative dose of HHT was 165 mg/m² and the daunorubicin dose was 120 mg/m². Complete remission (CR), overall survival (OS) rate, event free survival (EFS) rate, adverse effect response and prognosis factors were retrospectively evaluated to investigate the long-term outcome and safety of this protocol. Eighty-two patients (80.4%) achieved complete remission with the first induction. The 5-year overall survival and event-free survival rates were 65.0% (SE, 4.9%) and 53.3% (SE, 5.2%), respectively. A first induction failure, age older than 2 years, and BCR-ABL translocation were associated with a significantly worse outcome (p < 0.05). No significant drug-related cardiac toxicity was observed. AML-SCMC-2009 protocol which use HHT as backbone drug is efficacious and tolerated. HHT could partially replace anthracycline to be an effective option for childhood AML.

Second Relapse of Pediatric Patients with Acute Myeloid Leukemia: A Report on Current Treatment Strategies and Outcome of the AML-BFM Study Group

Simple Summary

Children with acute myeloid leukemia (AML) experience high relapse rates of about 30%; still, survival rates following the first relapse are encouraging. Hence, it is critically important to examine the consequences of a second relapse; however, little is known about this subgroup of patients. This retrospective population-based analysis intends to describe response, survival and prognostic factors relevant for the survival of children with second relapse of AML. Treatment approaches include many different therapeutic regimens, including palliation and intensive treatment with curative intent (63% of the patients). Survival is poor; however, patients who respond to reinduction attempts can be rescued with subsequent hematopoietic stem cell transplantation. We deciphered risk factors, such as short time interval from first to second relapse below one year as being associated with a poor outcome. This analysis will help to improve future international treatment planning and patient care of children with advanced AML.

Abstract

Successful management of relapse is critical to improve outcomes of children with acute myeloid leukemia (AML). We evaluated response, survival and prognostic factors after a second relapse of AML. Among 1222 pediatric patients of the population-based AML-Berlin–Frankfurt–Munster (BFM) study group (2004 until 2017), 73 patients met the quality parameters for inclusion in this study. Central review of source documentation warranted the accuracy of reported data. Treatment approaches included palliation in 17 patients (23%), intensive therapy with curative intent (n = 46, 63%) and other regimens (n = 10). Twenty-five patients (35%) received hematopoietic stem cell transplantation (HSCT), 21 of whom (88%) had a prior HSCT. Survival was poor, with a five-year probability of overall survival (pOS) of 15 ± 4% and 31 ± 9% following HSCT (n = 25). Early second relapse (within one year after first relapse) was associated with dismal outcome (pOS 2 ± 2%, n = 44 vs. 33 ± 9%, n = 29; p < 0.0001). A third complete remission (CR) is required for survival: 31% (n = 14) of patients with intensive treatment achieved a third CR with a pOS of 36 ± 13%, while 28 patients (62%) were non-responders (pOS 7 ± 5%). In conclusion, survival is poor but possible, particularly after a late second relapse and an intensive chemotherapy followed by HSCT. This analysis provides a baseline for future treatment planning.

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.

OMIP 072: A 15-color panel for immunophenotypic identification, quantification, and characterization of leukemic stem cells in children with acute myeloid leukemia

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.

Attempts to optimize postinduction treatment in childhood acute myeloid leukemia without core-binding factors: A report from the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG)

We previously reported that risk-stratified therapy and intensive postremission chemotherapy (PRC) contributed to the improved survival of childhood acute myeloid leukemia (AML) in the AML99 study, which led us to consider a reduction in the number of PRC courses with more restrictive indications for stem cell transplantation (SCT) in the successor AML-05 study. We here report the outcome of AML patients without core-binding factor mutation (non-CBF AML) in the AML-05 study. Two-hundred eighty-nine children (age < 18 years old) with non-CBF AML were eligible. Patients with unfavorable cytogenetics and/or poor bone marrow response to the first induction course were candidates for SCT in the AML-05 study. After two courses of induction, a further three courses of PRC were given in AML-05, while four courses were given in the AML99 study. The 3-year event-free survival (EFS) rate in the AML-05 study (46.7%, 95% CI: 40.6-52.6%) was comparable to that of non-CBF AML in the AML99 study (51.5%, 95% CI: 42.7-59.6%) (P = .16). However, the 3-year overall survival (OS) rate in the AML-05 study (62.9%, 95% CI: 56.3-68.8%) was slightly lower than that in the AML99 study (71.6%, 95% CI: 63.2-78.5%) (P = .060), mainly due to decreased remission induction rate and increased nonrelapsed mortality. In conclusion, reductions in the number of PRC courses from four to three, together with repetitive cycles of high-dose cytarabine, were acceptable for non-CBF childhood AML.

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.

Paediatric Strategy Forum for medicinal product development for acute myeloid leukaemia in children and adolescents: ACCELERATE in collaboration with the European Medicines Agency with participation of the Food and Drug Administration

Purpose:

The current standard-of-care for front-line therapy for acute myeloid leukaemia (AML) results in short-term and long-term toxicity, but still approximately 40% of children relapse. Therefore, there is a major need to accelerate the evaluation of innovative medicines, yet drug development continues to be adult-focused. Furthermore, the large number of competing agents in rare patient populations requires coordinated prioritisation, within the global regulatory framework and cooperative group initiatives.

Methods:

The fourth multi-stakeholder Paediatric Strategy Forum focused on AML in children and adolescents.

Results:

CD123 is a high priority target and the paediatric development should be accelerated as a proof-of-concept. Efforts must be coordinated, however, as there are a limited number of studies that can be delivered. Studies of FLT3 inhibitors in agreed paediatric investigation plans present challenges to be completed because they require enrolment of a larger number of patients than actually exist. A consensus was developed by industry and academia of optimised clinical trials. For AML with rare mutations that are more frequent in adolescents than in children, adult trials should enrol adolescents and when scientifically justified, efficacy data could be extrapolated. Methodologies and definitions of minimal residual disease need to be standardised internationally and validated as a new response criterion. Industry supported, academic sponsored platform trials could identify products to be further developed. The Leukaemia and Lymphoma Society PedAL/EUpAL initiative has the potential to be a major advance in the field.

Conclusion:

These initiatives continue to accelerate drug development for children with AML and ultimately improve clinical outcomes.

A strategy to reduce cumulative anthracycline exposure in low-risk pediatric acute myeloid leukemia while maintaining favorable outcomes

BACKGROUND

Advances in risk stratification have improved the 3-year disease-free survival (DFS) and overall survival (OS) of low-risk pediatric acute myeloid leukemia (LR-AML) to approximately 70 % and 85 % respectively. LR-AML is defined by favorable cytogenetic/molecular features and/or optimal early response to therapy. However, cumulative anthracycline exposure in contemporary Children's Oncology Group (COG) regimens approach a doxorubicin equivalent exposure of 540 mg/m²; with rates of non-infection related left ventricular systolic dysfunction (LVSD) approaching 15 %. This is a major cause of toxicity in these patients and precludes the further use of anthracyclines in the relapsed setting; therefore, strategies that reduce cardiotoxicity while maintaining excellent outcomes are needed.

PATIENTS AND METHODS

Twenty-seven pediatric patients with LR-AML were treated with an anthracycline-reduced approach (Aflac-AML regimen) between 2011 and 2016. Patients received four courses of therapy including three high-dose cytarabine containing courses and a cumulative doxorubicin equivalent exposure of 390 mg/m², a 28 % reduction in anthracycline dosing compared to current COG regimens.

RESULTS

The 3-year DFS and OS was 70.0 % and 85.5 % respectively, from end of Induction I (first chemotherapy cycle) with a median follow-up of 3.2 years. These survival outcomes are comparable to current LR-AML regimens. Only two patients developed non-infection related LVSD during therapy and more importantly, none developed LVSD after completion of therapy.

CONCLUSION

These findings suggest that LR-AML outcomes can be maintained using a reduced anthracycline chemotherapy regimen, resulting in lower cardiac toxicity. This new chemotherapy backbone is now being tested prospectively (NCT04326439) to further validate its use in pediatric LR-AML.

Measurable residual disease assessment by qPCR in peripheral blood is an informative tool for disease surveillance in childhood acute myeloid leukaemia

Serial assessments of measurable (or minimal) residual disease (MRD) by qPCR may identify nascent relapse in children with acute myeloid leukaemia (AML) and enable pre-emptive therapy. We investigated the kinetics and prognostic impact of recurrent fusion transcripts (RUNX1-RUNX1T1, CBFB-MYH11, KMT2A-MLLT3 or KMT2A-ELL) in 774 post-induction samples from bone marrow (BM, 347) and peripheral blood (PB, 427) from 75 children with AML. BM MRD persistence during consolidation did not increase the risk of relapse, and MRD at therapy completion did not correlate to outcome (HR = 0·64/MRD log reduction (CI: 0·32-1·26), P = 0·19). In contrast, 8/8 patients with detectable MRD in PB after first consolidation relapsed. Persistence (n = 4) and shifting from negative to positive (n = 10) in PB during follow-up predicted relapse in 14/14 patients. All 253 PB samples collected during follow-up from 36 patients in continuous complete remission were MRD negative. In core-binding factor AML, persistent low-level MRD positivity in BM during follow-up was frequent but an increment to above 5 × 10^-4 heralded subsequent haematological relapse in 12/12 patients. We demonstrate that MRD monitoring in PB after induction therapy is highly informative and propose an MRD increment above 5 × 10^-4 in PB and BM as a definition of molecular relapse since it always leads to haematological relapse.

Pediatric acute myeloid leukemia: updates on biology, risk stratification, and therapy

PURPOSE OF REVIEW

Despite advances in therapy over the past decades, overall survival for children with acute myeloid leukemia (AML) has not exceeded 70%. In this review, we highlight recent insights into risk stratification for patients with pediatric AML and discuss data driving current and developing therapeutic approaches.

RECENT FINDINGS

Advances in cytogenetics and molecular profiling, as well as improvements in detection of minimal residual disease after induction therapy, have informed risk stratification, which now relies heavily on these elements. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. However, recent trials focus on limiting treatment-related toxicity through the identification of low-risk subsets who can safely receive fewer cycles of chemotherapy, allocation of hematopoietic stem-cell transplant to only high-risk patients and optimization of infectious and cardioprotective supportive care.

SUMMARY

Further incorporation of genomic and molecular data in pediatric AML will allow for additional refinements in risk stratification to enable the tailoring of treatment intensity. These data will also dictate the incorporation of molecularly targeted therapeutics into frontline treatment in the hope of improving survival while decreasing treatment-related toxicity.

Associations between pretherapeutic body mass index, outcome, and cytogenetic abnormalities in pediatric acute myeloid leukemia

Background

Associations between body mass index (BMI), outcome, and leukemia‐related factors in children with acute myeloid leukemia (AML) remain unclear. We investigated associations between pretherapeutic BMI, cytogenetic abnormalities, and outcome in a large multinational cohort of children with AML.

Methods

We included patients, age 2‐17 years, diagnosed with de novo AML from the five Nordic countries (2004‐2016), Hong Kong (2007‐2016), the Netherlands and Belgium (2010‐2016), and Canada and USA (1995‐2012). BMI standard deviations score for age and sex was calculated and categorized according to the World Health Organization. Cumulative incidence functions, Kaplan‐Meier estimator, Cox regression, and logistic regression were used to investigate associations.

Results

In total, 867 patients were included. The median age was 10 years (range 2‐17 years). At diagnosis, 32 (4%) were underweight, 632 (73%) were healthy weight, 127 (15%) were overweight, and 76 (9%) were obese. There was no difference in relapse risk, treatment‐related mortality or overall mortality across BMI groups. The frequency of t(8;21) and inv(16) increased with increasing BMI. For obese patients, the sex, age, and country adjusted odds ratio of having t(8;21) or inv(16) were 1.9 (95% confidence interval (CI) 1.1‐3.4) and 2.8 (95% CI 1.3‐5.8), respectively, compared to healthy weight patients.

Conclusions

This study did not confirm previous reports of associations between overweight and increased treatment‐related or overall mortality in children. Obesity was associated with a higher frequency of t(8;21) and inv(16). AML cytogenetics appear to differ by BMI status.

Measurable residual disease monitoring using Wilms tumor gene 1 expression in childhood acute myeloid leukemia based on child-specific reference values

BACKGROUND

Measurable/minimal residual disease (MRD) monitoring can predict imminent hematological relapse in acute myeloid leukemia (AML). The majority of childhood AML patients do not harbor fusion genes or mutations applicable as MRD markers and overexpression of Wilms tumor gene 1 (WT1) may constitute a useful monitoring target. However, age-specific reference values in healthy hematopoiesis and standardization of WT1 assessment are prerequisites for clinical utility.

PROCEDURE

We investigated WT1 expression across age in hematologically healthy controls (n = 109), during suspected infection (n = 90) and bone marrow (BM) regeneration (n = 13). WT1 expression in AML at diagnosis (n = 91) and during follow-up (n = 30) was compared with age-specific reference values.

RESULTS

WT1 expression correlated with age and showed higher levels in both BM and peripheral blood (PB) in children compared with adults (P < 0.001 and P = 0.01). WT1 expression from healthy hematopoiesis was lower in PB compared with BM (WT1_BM /WT1_PB  = 8.6, 95% CI: 5.3-13.7) and not influenced by infection nor BM regeneration. At AML diagnosis, 66% had more than 20-fold WT1 overexpression in PB or BM (PB 74%; BM 45%). WT1 was quantified in 279 PB samples during follow-up. All 11 patients with PB sampling within 4 months of disease recurrence displayed WT1 overexpression by a median of 1.9 months (range, 0.7-9.7) before hematological relapse.

CONCLUSIONS

This study defines child-specific reference values for WT1 expression in healthy hematopoiesis and demonstrates that WT1 expression in PB is a useful post-treatment monitoring tool in childhood AML. Based on these observations, we propose definitions for childhood AML molecular relapse using WT1 overexpression.

Use of granulocyte colony-stimulating factor and risk of relapse in pediatric patients treated for acute myeloid leukemia according to NOPHO-AML 2004 and DB AML-01

BACKGROUND

Supportive-care use of granulocyte colony-stimulating factor (G-CSF) in pediatric acute myeloid leukemia (AML) remains controversial due to a theoretical increased risk of relapse and limited impact on neutropenic complications. We describe the use of G-CSF in patients treated according to NOPHO-AML 2004 and DB AML-01 and investigated associations with relapse.

PROCEDURE

Patients diagnosed with de novo AML completing the first week of therapy and not treated with hematopoietic stem cell transplantation in the first complete remission were included (n = 367). Information on G-CSF treatment after each course (yes/no) was registered prospectively in the study database and detailed information was gathered retrospectively from each center. Descriptive statistics were used to describe G-CSF use and Cox regression to assess the association between G-CSF and risk of relapse.

RESULTS

G-CSF as supportive care was given to 128 (35%) patients after 268 (39%) courses, with a large variation between centers (0-93%). The use decreased with time-the country-adjusted odds ratio was 0.8/diagnostic year (95% confidence interval [CI] 0.7-0.9). The median daily dose was 5 μg/kg (range 3-12 μg/kg) and the median cumulative dose was 75 μg/kg (range 7-1460 μg/kg). Filgrastim was used in 82% of G-CSF administrations and infection was the indication in 44% of G-CSF administrations. G-CSF was associated with increased risk of relapse-the adjusted hazard ratio was 1.5 (95% CI 1.1-2.2).

CONCLUSIONS

G-CSF as supportive care was used in a third of patients, and use decreased with time. Our results indicate that the use of G-CSF may be associated with an increased risk of relapse.

Response-guided chemotherapy for pediatric acute myeloid leukemia without hematopoietic stem cell transplantation in first complete remission: Results from protocol DB AML-01

BACKGROUND

Children with acute myeloid leukemia (AML) have a 70% survival rate with treatment regimens containing high doses of cytarabine and anthracyclines and, in some, hematopoietic stem cell transplantation (allo-HSCT).

PROCEDURE

In this multicenter Dutch-Belgian protocol (DB AML-01), 112 children with de novo AML were included. Treatment was stratified according to day 15 bone marrow response after the first induction course. Poor responders received a second course without delay while good responders awaited hematological recovery. Patients achieving CR after two induction courses continued with three consolidation courses without HSCT in CR1.

RESULTS

The overall remission rate was 93.5%. After a median follow-up of 4.1 years, three-year event-free survival (EFS) was 52.6% (95% CI, 42.9%-61.3%), three-year cumulative incidence of relapse 39.7% (95% CI, 30.1%-49.0%), and three-year overall survival (OS) 74.0% (95% CI, 64.8%-81.2%). Significantly more events occurred in patients with high WBC at diagnosis or FLT3-ITD/NPM1-WT, whereas core binding factor (CBF) leukemia had a significantly better EFS. KMT2A rearrangements and age > 10 years negatively impacted OS.

CONCLUSIONS

DB AML-01 response-guided therapy results in a favorable OS, particularly for children with CBF leukemia, children younger than 10 years or with initial WBC counts below 100 × 10⁹ /L. Outcome of patients with FLT3-ITD/NPM1-WT remains poor and warrants alternative treatment strategies.

Alternative splicing of the tumor suppressor ASPP2 results in a stress-inducible, oncogenic isoform prevalent in acute leukemia

Background

Apoptosis-stimulating Protein of TP53-2 (ASPP2) is a tumor suppressor enhancing TP53-mediated apoptosis via binding to the TP53 core domain. TP53 mutations found in cancers disrupt ASPP2 binding, arguing for an important role of ASPP2 in TP53-mediated tumor suppression. We now identify an oncogenic splicing variant, ASPP2κ, with high prevalence in acute leukemia.

Methods

An mRNA screen to detect ASPP2 splicing variants was performed and ASPP2κ was validated using isoform-specific PCR approaches. Translation into a genuine protein isoform was evaluated after establishing epitope-specific antibodies. For functional studies cell models with forced expression of ASPP2κ or isoform-specific ASPP2κ-interference were created to evaluate proliferative, apoptotic and oncogenic characteristics of ASPP2κ.

Findings

Exon skipping generates a premature stop codon, leading to a truncated C-terminus, omitting the TP53-binding sites. ASPP2κ translates into a dominant-negative protein variant impairing TP53-dependent induction of apoptosis. ASPP2κ is expressed in CD34+ leukemic progenitor cells and functional studies argue for a role in early oncogenesis, resulting in perturbed proliferation and impaired induction of apoptosis, mitotic failure and chromosomal instability (CIN) – similar to TP53 mutations.

Importantly, as expression of ASPP2κ is stress-inducible it defines a novel class of dynamic oncogenes not represented by genomic mutations.

Interpretation

Our data demonstrates that ASPP2κ plays a distinctive role as an antiapoptotic regulator of the TP53 checkpoint, rendering cells to a more aggressive phenotype as evidenced by proliferation and apoptosis rates – and ASPP2κ expression results in acquisition of genomic mutations, a first initiating step in leukemogenesis. We provide proof-of-concept to establish ASPP2κ as a clinically relevant biomarker and a target for molecule-defined therapy.

Fund

Unrestricted grant support from the Wilhelm Sander Foundation for Cancer Research, the IZKF Program of the Medical Faculty Tübingen, the Brigitte Schlieben-Lange Program and the Margarete von Wrangell Program of the State Ministry Baden-Wuerttemberg for Science, Research and Arts and the Athene Program of the excellence initiative of the Eberhard-Karls University, Tübingen.

Lnc-SOX6-1 upregulation correlates with poor risk stratification and worse treatment outcomes, and promotes cell proliferation while inhibits apoptosis in pediatric acute myeloid leukemia

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.

Comparison of conditioning regimens for autologous stem cell transplantation in children with acute myeloid leukemia: A nationwide retrospective study in Japan

BACKGROUND

Indications for hematopoietic stem cell transplantation (HSCT) have decreased with the improvement in chemotherapy for pediatric acute myeloid leukemia (AML) in the last decade. We conducted reevaluation of autologous HSCT (AHSCT) to compare myeloablative conditioning (MAC) regimens for pediatric AML without the need for consideration of toxicities caused by allogeneic immune reactions.

PROCEDURE

This retrospective study analyzed the clinical outcomes of 220 children with AML who underwent consecutive AHSCT between 1989 and 2002 in Japan by the national prospective registry. The transplantation outcomes of various conditioning regimens were compared.

RESULTS

The median follow-up period of the survivors was 160 months. The clinical outcomes of busulfan + cyclophosphamide ± etoposide or busulfan + melphalan regimens were significantly superior compared with other busulfan-based and total body irradiation-based regimens (leukemia-free survival [LFS]: 68% vs 42% and 55%, P = 0.001; overall survival [OS]: 74% vs 49% and 61%, P < 0.001). Multivariate analysis showed that busulfan + cyclophosphamide ± etoposide and busulfan + melphalan regimens were independent favorable factors for LFS (hazard ratio: 0.46; P < 0.001) and OS (hazard ratio: 0.40; P < 0.001) compared with the other busulfan-based regimen, and both age 2 years or older and advanced stage at AHSCT were independent poor predictors for LFS and OS, simultaneously.

CONCLUSION

Busulfan + cyclophosphamide ± etoposide and busulfan + melphalan regimens exhibited superior antileukemic effects compared with other BU-based myeloablative regimens.

Flow-Cytometric Monitoring of Minimal Residual Disease in Pediatric Patients With Acute Myeloid Leukemia: Recent Advances and Future Strategies

Minimal residual disease (MRD) by multiparametric flow cytometry (MFC) has been recently shown as a strong and independent prognostic marker of relapse in pediatric AML (pedAML) when measured at specific time points during Induction and/or Consolidation therapy. Hence, MFC-MRD has the potential to refine the current strategies of pedAML risk stratification, traditionally based on the cytogenetic and molecular genetic aberrations at diagnosis. Consequently, it may guide the modulation of therapy intensity and clinical decision making. However, the use of non-standardized protocols, including different staining panels, analysis, and gating strategies, may hamper a broad implementation of MFC-MRD monitoring in clinical routine. Besides, the thresholds of MRD positivity still need to be validated in large, prospective and multi-center clinical studies, as well as optimal time points of MRD assessment during therapy, to better discriminate patients with different prognosis. In the present review, we summarize the most relevant findings on MFC-MRD testing in pedAML. We examine the clinical significance of MFC-MRD and the recent advances in its standardization, including innovative approaches with an automated analysis of MFC-MRD data. We also touch upon other technologies for MRD assessment in AML, such as quantitative genomic breakpoint PCR, current challenges and future strategies to enable full incorporation of MFC-MRD into clinical practice.

Preconditioning with fludarabine, busulfan and cytarabine versus standard BuCy2 for patients with acute myeloid leukemia: a prospective, randomized phase II study

To compare the efficacy and toxicity of a novel regimen called FBA, consisting of fludarabine, busulfan, and cytarabine, with the standard BuCy2 regimen for younger adult patients with acute myeloid leukemia, we conducted a prospective randomized phase II study. Patients in complete remission were randomly assigned to receive either the FBA (n = 56) or the BuCy2 regimen (n = 55). The difference in 100-day transplant-related mortality (TRM) was not statistically significant between the two arms (1.79% for FBA versus 5.45% for BuCy2, P = 0.260), as were the cumulative incidences of relapse, TRM, overall survival (OS) and event-free survival (EFS) at 3 years. However, the 100-day cumulative incidences of grades II-IV and III-IV acute graft-versus-host disease (aGVHD) were lower in the FBA group [(8.93% versus 21.86%, P = 0.032) (1.79% versus 9.09%, P = 0.025)]. The 3-year GVHD and relapse-free survival (GRFS) was 31.20% for the FBA group and 14.96% for the BuCy2 group (P = 0.004). The incidences of diarrhea and severe oral mucositis within the first 30 days post-transplantation were lower in the FBA group [(28.57% versus 65.45%; P < 0.001) (51.79% versus 70.91%; P = 0.039)]. In conclusion, allogenic transplantation with the FBA regimen achieved similar TRM, relapse rate, OS and EFS, as that with the BuCy2 regimen but with less frequent and less severe complications in early stage after transplantation and a trend toward higher GRFS.

Associations between neutrophil recovery time, infections and relapse in pediatric acute myeloid leukemia

BACKGROUND

Children with acute myeloid leukemia (AML) treated similarly show different toxicity and leukemic responses. We investigated associations between neutrophil recovery time after the first induction course, infection and relapse in children treated according to NOPHO-AML 2004 and DB AML-01.

PROCEDURE

Newly diagnosed patients with AML with bone marrow blast <5% between day 15 after the start of the treatment and the start of second induction course, and in complete remission after the second induction course were included (n = 279). Neutrophil recovery time was defined as the time from the start of the course to the last day with absolute neutrophil count <0.5 × 10⁹ /l. Linear and Cox regressions were used to investigate associations.

RESULTS

Neutrophil recovery time after the first induction course was positively associated with neutrophil recovery time after the remaining courses, and longer neutrophil recovery time (≥25 days) was associated with increased risk of grade 3-4 infections (hazard ratio 1.4, 95% confidence interval [CI], 1.1-1.8). Longer neutrophil recovery time after the first induction (>30 days) was associated with the increased risk of relapse (5-year cumulative incidence: 48% vs. 42%, hazard ratio 1.7, 95% CI, 1.1-2.6) for cases not treated with hematopoietic stem cell transplantation in first complete remission.

CONCLUSION

Longer neutrophil recovery time after the first induction course was associated with grade 3-4 infections and relapse. If confirmed, this knowledge could be incorporated into risk stratification strategies in pediatric AML.

Antibacterial prophylaxis in pediatric patients with leukemia

BACKGROUND

Bacterial infections in pediatric patients with leukemia are associated with increased risks for morbidity and mortality. Few Recommendations have been made on the use of antibacterial prophylaxis in pediatrics with acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML).

OBJECTIVES

To determine the role of antibacterial prophylaxis in pediatric patients with leukemia and the most appropriate regimen that can be safely and effectively used.

METHODS

Literature search was conducted independently by 3 reviewers to find studies on the safety and effectiveness of antibacterial prophylactic regimens.

RESULTS

The search strategy resulted in 13 studies; most of them were observational studies. The available evidence recommends use of antibiotics with Gram-positive bacterial coverage in AML patients. In ALL patients, prophylaxis was used during the intensive phases of chemotherapy with ciprofloxacin being recommended most commonly.

CONCLUSION

Antibacterial prophylaxis mainly with coverage against Gram-positive bacteria is recommended in pediatric patients with AML. For ALL patients, prophylaxis may be considered for patients who are undergoing intensive chemotherapy phases and are at high risk for infections with ciprofloxacin being the most commonly used agent. In general more studies are needed to determine the role of antibacterial prophylaxis in pediatric patients with leukemia.

Acute myelogenous leukemia in adolescents and young adults

The incidence of acute myelogenous leukemia (AML) increases progressively with age. Favorable genetic mutations are most prevalent in children, and unfavorable profiles increase proportionately in adolescents and young adults (AYA) and into later adulthood. Survival rates of AYA have improved over recent decades to 50-60%, but their accrual to clinical trials remains poor. In contrast to AYA with acute lymphoblastic leukemia, the prognostic benefit for AYA with AML enrolled in pediatric compared with adult trials is minor and only seen when different protocols are used. The distinctive needs of AYA, including intensive psychological services, call for their treatment within specialized centers that offer complex supportive care.