Prognostic factors in pediatric acute myeloid leukemia

Exploration of differentially expressed mRNAs and miRNAs for pediatric acute myeloid leukemia

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.

Prognostic Factors in Childhood Acute Myeloid Leukemia; Experience from A Developing Country

BACKGROUND

In the developed world, 5-years survival of childhood acute myeloid leukaemia (AML) has improved to 70%. However, the survival rates in the developing world are below 40%. The main contributing factors to these reduced survival rates are a late presentation, malnutrition and high treatment-related mortality.

AIM

To document the factors affecting treatment outcome of childhood AML at a tertiary care facility of Pakistan.

METHODS AND RESULTS

All newly registered cases of AML under 18 years of age from January 1, 2012 onwards who completed their treatment before November 30, 2019 were included. Data of 219 cases of AML containing 140 (63.9%) males and 79 (36.1%) females was analyzed. The mean age was 6.30 ± 3.66 years. Pallor was the commonest presenting features in 180 (82.2%) and M2 was the commonest French American-British (FAB) subtype in 103 (47.0%) cases. In univariate analysis, high white blood cells (WBC) count at presentation (P = .006), poor nutritional status (P = .005), unfavourable cytogenetics (P = .019), certain types of FAB AML subtype (P = .005), and use of etoposide in induction chemotherapy (P = .042) significantly adversely affected overall survival (OS). Neutropenic sepsis and bleeding were the major causes of treatment-related mortality. Response to induction chemotherapy was the most significant prognostic factor in the multivariate analysis (P = <.001). After a median follow-up of 40.96 ± 26.23 months, 5-year OS and DFS of the cohort were 40.6% and 38.3% respectively.

CONCLUSIONS

In this largest cohort of childhood AML from Pakistan, high WBC count at presentation, malnutrition, unfavourable cytogenetics and use of etoposide during induction chemotherapy were associated with decreased OS and DFS rates. Response to the induction chemotherapy was the most significant prognostic factor.

Outcome of Childhood Acute Myeloid Leukemia With FLT3-ITD Mutation: The Experience of Children's Cancer Hospital Egypt, 2007-17

INTRODUCTION

The presence of FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) mutation in pediatric acute myeloid leukemia (AML) is associated with high rates of induction failure and worse survival. Its presence places the patient into a high-risk group. We aimed to describe the outcome of pediatric AML with FLT3-ITD mutation.

PATIENTS AND METHODS

We performed a retrospective analysis of cases of AML from July 2007 till July 2017 at Children's Cancer Hospital Egypt.

RESULTS

Seventy-one patients had FLT3 gene mutation out of 687 patients with AML. Sixty-five patients had FLT3 gene mutation with allelic ratio > 0.4; 43 (66.1%) of 65 patients experienced complete remission (CR). Of the 43 patients, 16 patients maintained CR, 18 patients relapsed after first CR, 8 patients died, and 1 patient was lost to follow-up. Patients with relapsing disease died after salvage chemotherapy, except for one patient, who was alive after second CR. Allogeneic bone marrow transplantation (allo-BMT) was performed for 9 (13.8%) of 65 patients in first CR, of whom 8 were alive and in CR, and 1 patient experienced disease relapse and died. Seven patients (10.7%) were alive without allo-BMT. Three years' overall and event-free survival for patients with FLT3-ITD mutation with high allelic ratio was 26.9% and 22.8%, respectively. Three years' overall and event-free survival for patients treated with allo-BMT was 77.8% and 78.8%, respectively, versus patients treated without allo-BMT, 16.3% and 12.8%, respectively.

CONCLUSION

FLT3-ITD mutation in pediatric AML was associated with poor treatment outcomes, and the survival of relapsing patients was extremely poor. Allo-BMT in first remission was the best treatment option. Alternative donor transplants and FLT3 inhibitors are needed to improve outcome in developing countries.

A six-gene-based prognostic model predicts complete remission and overall survival in childhood acute myeloid leukemia

Objective

Acute myeloid leukemia (AML) is a malignant clonal disorder. Despite enormous progress in its diagnosis and treatment, the mortality rate of AML remains high. The aim of this study was to identify prognostic biomarkers by using the gene expression profile dataset from public database, and to improve the risk-stratification criteria of survival for patients with AML.

Materials and methods

The gene expression data and clinical parameter were acquired from the Therapeutically Applicable Research to Generate Effective Treatment (TARGET) database. A total of 856 differentially expressed genes (DEGs) were obtained from the childhood AML patients classified into first complete remission (CR1) group (n=791) and not CR group (n=249). We performed a series of bioinformatics analysis to screen key genes and pathways, further comprehending these DEGs through Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses.

Results

Six genes (SLC17A7, MSX2, CDC26, MSLN, CTSZ and DEFA3) identified by univariate, Kaplan-Meier survival and multivariate Cox regression analyses were used to develop the prognostic model. Further analysis showed that the survival estimations in the high-risk group had an increased risk of death compared with the low-risk group based on the model. The area under the curve of the receiver operator characteristic curve in the prognostic model for predicting the overall survival was 0.729, confirming good prognostic model. We also performed a nomogram to provide an individual patient with the overall probability, and internal validation in the TARGET cohort.

Conclusion

We identified a six-gene prognostic signature for risk-stratifying in patients with childhood AML. The risk classification model can be used to predict CR markers and may assist clinicians in providing realize the individualized treatment in this patient population.

Stage at diagnosis for children with blood cancers in Australia: Application of the Toronto Paediatric Cancer Stage Guidelines in a population-based national childhood cancer registry

BACKGROUND

Information on stage at diagnosis for childhood blood cancers is essential for surveillance but is not available on a population basis in most countries. Our aim was to apply the internationally endorsed Toronto Paediatric Cancer Stage Guidelines to children (<15 years) with acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), Hodgkin lymphoma (HL), or non-Hodgkin lymphoma (NHL) and to assess differences in survival by stage at diagnosis.

PROCEDURE

Stage was defined by extent of involvement of the central nervous system (CNS) for ALL and AML and using the Ann Arbor and St Jude-Murphy systems for HL and NHL, respectively. The study cohort was drawn from the population-based Australian Childhood Cancer Registry, consisting of children diagnosed with one of these four blood cancers between 2006 and 2014 with follow-up to 2015. Five-year observed survival was estimated from the Kaplan-Meier method.

RESULTS

Stage was assigned to 2201 of 2351 eligible patients (94%), ranging from 85% for AML to 95% for ALL, HL, and NHL. Survival following ALL varied from 94% (95% CI = 93%-95%) for CNS1 disease to 89% (95% CI = 79%-94%) for CNS2 (P = 0.07), whereas for AML there was essentially no difference in survival between CNS^- (77%) and CNS⁺ disease (78%; P = 0.94). Nearly all children with HL survived for five years. There was a trend (P = 0.04) toward worsening survival with higher stage for NHL.

CONCLUSIONS

These results provide the first population-wide picture of the distribution and outcomes for childhood blood cancers in Australia by extent of disease at diagnosis and provide a baseline for future comparisons.

Survival differences in childhood and young adult acute myeloid leukemia: A cross-national study using US and England data

BACKGROUND

Acute myeloid leukemia (AML) is a serious disease with complex etiology and marked variation in survival. Known prognostic factors include AML subtypes, age at diagnosis and sex. However, survival outcomes may vary across healthcare systems. In this study, we evaluated the survival patterns in individuals diagnosed with AML at ages 0-24 years in the US and England between prognostic features and across countries.

METHODS

We obtained data on 4387 and 2194 subjects from the US Surveillance Epidemiology and End Result registries and UK National Cancer Data Repository. Subjects were diagnosed and followed in 1995-2014. Kaplan-Meier curve and stratified Cox proportional hazards regression were used in the analysis.

RESULTS

Overall risk of mortality was 23% lower in English patients compared to that in the US patients (adjusted hazard ratio (aHR), 95% confidence Interval (CI): 0.77, 0.71-0.84). Survival difference of similar extent was observed in subgroups of sex and age at diagnosis. However, mortality risks between two countries varied substantially across AML subtypes, especially in AML inv(16) (1.81, 0.61-5.34), AML with minimal differentiation (0.54, 0.25-1.17), AML without maturation (0.38, 0.20-0.74) and AML with maturation (0.52, 0.31-0.86).

CONCLUSIONS

Similar to the population trend, mortality risk across sex, age at diagnosis, and most AML subtypes was lower in England. Survival outcome for AML with and without maturation in England was better than the population trend, while that for AML inv(16) was worse. Our findings suggest that future etiologic and policy research may uncover the underlying mechanisms and contribute to closing these morality gaps.

Gene Mutations as Emerging Biomarkers and Therapeutic Targets for Relapsed Acute Myeloid Leukemia

It is believed that there are key differences in the genomic profile between adult and childhood acute myeloid leukemia (AML). Relapse is the significant contributor of mortality in patients with AML and remains as the leading cause of cancer death among children, posing great challenges in the treatment of AML. The knowledge about the genomic lesions in childhood AML is still premature as most genomic events defined in children were derived from adult cohorts. However, the emerging technologies of next generation sequencing have narrowed the gap of knowledge in the biology of AML by the detection of gene mutations for each sub-type which have led to the improvement in terms of prognostication as well as the use of targeted therapies. In this review, we describe the recent understanding of the genomic landscape including the prevalence of mutation, prognostic impact, and targeted therapies that will provide an insight into the pathogenesis of AML relapse in both adult and childhood cases.

MicroRNA-181 as a prognostic biomarker for survival in acute myeloid leukemia: a meta-analysis

Accumulating evidence has indicated that microRNA-181 (miR-181) is dysregulated in hematological malignancies, and associates with the clinical outcomes. However, the association of miR-181 expression levels with acute myeloid leukemia (AML) remains inconclusive, as publications from different groups have reported contradictory results. In this manuscript, a meta-analysis was performed to assess the prognostic significance of miR-181 in AML patients. Eligible studies were retrieved from PubMed, Embase and Cochrane Library databases, and a total of 6 studies including 815 AML patients were included in the final analysis. Hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were extracted and pooled to investigate the correlation between miR-181 and the survival of AML patients. Our results showed that elevated miR-181 expression was associated with increased survival in 395 American patients, and reduced survival in 325 Chinese patients. Both subgroup analyses and meta-regression indicated that the origin of AML patients contributed to the heterogeneity in the datasets evaluating the correlation between overall survival (OS) and miR-181. These results indicate that miR-181 can be used as a promising prognostic biomarker in AML patients, which may depend on the origin of patient population.

Trisomy 8 in pediatric acute myeloid leukemia: A NOPHO-AML study

Trisomy 8 (+8) is a common cytogenetic aberration in acute myeloid leukemia (AML); however, the impact of +8 in pediatric AML is largely unknown. We retrospectively investigated 609 patients from the NOPHO-AML database to determine the clinical and cytogenetic characteristics of +8 in pediatric AML and to investigate its prognostic impact. Complete cytogenetic data were available in 596 patients (98%) aged 0-18 years, diagnosed from 1993 to 2012, and treated according to the NOPHO-AML 1993 and 2004 protocols in the Nordic countries and Hong Kong. We identified 86 patients (14%) with +8. Trisomy 8 was combined with other cytogenetic aberrations in 68 patients (11%) (+8 other) and in 18 patients (3%), it was the sole abnormality (+8 alone). Trisomy 8 was associated with FAB M5 (36%) but otherwise clinically comparable with non-trisomy 8 patients. Trisomy 8 was favorable in patients of young age and with t(9;11). Trisomy 8 alone was associated with older age (median age 10.1 years), FAB M2 (33%), and FLT3-ITD mutations (58%). The 5-year event-free survival for patients with +8 alone was 50% and 5-year overall survival was 75%. In conclusion, +8 is one of the most common cytogenetic aberrations in pediatric AML. Trisomy 8 positive AML is a heterogeneous group and the majority of cases have additional cytogenetic aberrations. Patients with +8 alone differed from patients with +8 other and were associated with older age, FAB M2, and FLT3-ITD aberrations. There were no differences in survival despite the more frequent occurrence of FLT3-ITD in +8 alone. © 2016 Wiley Periodicals, Inc.

Sex disparity in childhood and young adult acute myeloid leukemia (AML) survival: Evidence from US population data

Sex variation has been persistently investigated in studies concerning acute myeloid leukemia (AML) survival outcomes but has not been fully explored among pediatric and young adult AML patients. We detected sex difference in the survival of AML patients diagnosed at ages 0-24 years and explored distinct effects of sex across subgroups of age at diagnosis, race-ethnicity and AML subtypes utilizing the United States Surveillance Epidemiology and End Results (SEER) population based dataset of 4865 patients diagnosed with AML between 1973 and 2012. Kaplan-Meier survival function, propensity scores and stratified Cox proportional hazards regression were used for data analyses. After controlling for other prognostic factors, females showed a significant survival advantage over their male counterparts, adjusted hazard ratio (aHR, 95% confidence interval (CI): 1.09, 1.00-1.18). Compared to females, male patients had substantially increased risk of mortality in the following subgroups of: ages 20-24 years at diagnosis (aHR1.30), Caucasian (1.14), acute promyelocytic leukemia (APL) (1.35), acute erythroid leukemia (AEL) (1.39), AML with inv(16)(p13.1q22) (2.57), AML with minimum differentiation (1.47); and had substantially decreased aHR in AML t(9;11)(p22;q23) (0.57) and AML with maturation (0.82). Overall, females demonstrated increased survival over males and this disparity was considerably large in patients ages 20-24 years at diagnosis, Caucasians, and in AML subtypes of AML inv(16), APL and AEL. In contrast, males with AML t(9;11)(p22;q23), AML with maturation and age at diagnosis of 10-14 years showed survival benefit. Further investigations are needed to detect the biological processes influencing the mechanisms of these interactions.

Prognostic factors of childhood and adolescent acute myeloid leukemia (AML) survival: evidence from four decades of US population data

Growing insight into prognosis of pediatric acute myeloid leukemia (AML) survival has led to improved outcome over time and could be further enhanced through investigation using a large number of patients. To characterize the extent of the association of pediatric AML survival with its identified prognostic factors, we analyzed the United States population-based Surveillance Epidemiology and End Results (SEER) large dataset of 3442 pediatric AML patients diagnosed and followed between 1973 and 2011 using a Cox proportional hazards model stratified by year of diagnosis. Patients diagnosed between 10 and 19 years of age were at a higher risk of death compared to those diagnosed before age 10 (adjusted hazard ratio (aHR): 1.30, 95% confidence interval (CI): 1.17-1.44). African Americans (1.27, 1.09-1.48) and Hispanics (1.15, 1.00-1.32) had an elevated risk of mortality than Caucasians. Compared to the subtype acute promyelocytic leukemia, AML with minimal differentiation (2.44, 1.78-3.35); acute erythroid leukemia (2.34, 1.60-3.40); AML without maturation (1.87, 1.35-2.59); and most other AML subtypes had a higher risk of mortality, whereas AML with inv(16) had a substantially lower risk. Age at diagnosis, race-ethnicity, AML subtype, county level poverty and geographic region appeared as significant prognostic factors of pediatric AML survival in the US. Contrary to previous findings, the subtypes of AML with t(9;11)(p22;q23)MLLT3-MLL, AML without maturation and acute myelomonocytic leukemia emerged to be indicative of poor outcome.

Minimal residual disease of leukemia and the quality of cryopreserved human ovarian tissue in vitro

Auto-transplant of cryopreserved ovarian tissue in leukemia patients carries a risk to reintroduce malignant cells. Maturation of ovarian follicles in vitro is a promising strategy to overcome the leukemic cell contamination. The follicle development and survival in 14 cryopreserved ovarian tissues with leukemia-specific PCR marker was evaluated after 7 or 14 days culture. Minimal residual disease (MRD) quantification was assessed by real-time quantitative PCR in order to identify the MRD positive (n = 6) and negative (n = 8) samples and to monitor levels of MRD before and after culture. The morphology of ovarian follicles were studied by light microscopy. After culture, no statistical significant differences were detected in follicle densities between MRD positive- and negative samples. Ovarian MRD either decreased below undetectable or fluctuated near the baseline level after 7 and 14 days in culture. This study provides quantitative in vitro evidence that leukemia contamination does not affect the follicle survival in cryopreserved ovarian tissue.

Overview of therapy and strategies for optimizing outcomes in de novo pediatric acute myeloid leukemia

Although acute myelogenous leukemia (AML) accounts for <20 % of leukemia in children, it is responsible for over half of all pediatric leukemia deaths. Improvement in event-free survival rates, now over 50 %, are due largely to intensification of chemotherapy, aggressive supportive care, development of risk stratification based on cytogenetic and molecular markers, and improved salvage regimens. Despite this improvement over the past few decades, the survival rates have recently plateaued, and further improvement will need to take into account advances in molecular characterization of AML, development of novel agents, and better understanding of host factors influencing toxicity and response to chemotherapy. This article reviews the epidemiology and biology trends in diagnosis and treatment of pediatric acute myelogenous leukemia.

Molecular therapeutic approaches for pediatric acute myeloid leukemia

Approximately two-thirds of children with acute myeloid leukemia (AML) are cured with intensive multi-agent chemotherapy. However, refractory and relapsed AML remains a significant source of childhood cancer mortality, highlighting the need for new therapies. Further therapy intensification with traditional cytotoxic chemotherapy in pediatric AML is not feasible given the risks of both short-term and long-term organ dysfunction. Substantial emphasis has been placed upon the development of molecularly targeted therapeutic approaches for adults and children with high-risk subtypes of AML with the goal of improving remission induction and minimizing relapse. Several promising agents are currently in clinical testing or late preclinical development for AML, including monoclonal antibodies against leukemia cell surface proteins, kinase inhibitors, proteasome inhibitors, epigenetic agents, and chimeric antigen receptor engineered T cell immunotherapies. Many of these therapies have been specifically tested in children with relapsed/refractory AML in Phase 1 and 2 trials with a smaller number of new agents under Phase 3 evaluation for children with de novo AML. Although successful identification and implementation of new drugs for children with AML remain a formidable challenge, enthusiasm for novel molecular therapeutic approaches is great given the potential for significant clinical benefit for children who do not have other curative options.

High-resolution melting curve analysis, a rapid and affordable method for mutation analysis in childhood acute myeloid leukemia

BACKGROUND

Molecular genetic alterations with prognostic significance have been described in childhood acute myeloid leukemia (AML). The aim of this study was to establish cost-effective techniques to detect mutations of FMS-like tyrosine kinase 3 (FLT3), nucleophosmin 1 (NPM1), and a partial tandem duplication within the mixed-lineage leukemia (MLL-PTD) genes in childhood AML.

PROCEDURE

Ninety-nine children with newly diagnosed AML were included in this study. We developed a fluorescent dye SYTO-82 based high-resolution melting (HRM) curve analysis to detect FLT3 internal tandem duplication (FLT3-ITD), FLT3 tyrosine kinase domain (FLT3-TKD), and NPM1 mutations. MLL-PTD was screened by real-time quantitative PCR.

RESULTS

The HRM methodology correlated well with gold standard Sanger sequencing with less cost. Among the 99 patients studied, the FLT3-ITD mutation was associated with significantly worse event-free survival (EFS). Patients with the NPM1 mutation had significantly better EFS and overall survival. However, HRM was not sensitive enough for minimal residual disease monitoring.

CONCLUSION

High-resolution melting was a rapid and efficient method for screening of FLT3 and NPM1 gene mutations. It was both affordable and accurate, especially in resource underprivileged regions. Our results indicated that HRM could be a useful clinical tool for rapid and cost-effective screening of the FLT3 and NPM1 mutations in AML patients.

The adolescent and young adult with cancer: state of the art-- acute leukemias

Despite survival gains over the past several decades, adolescent and young adult (AYA) patients with both acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) demonstrate a consistent survival disadvantage. The AYA population exhibits unique disease and host characteristics, and further study is needed to improve their outcomes. This review will highlight distinctive aspects of disease biology in this population, as well as salient treatment-related toxicities including osteonecrosis, pancreatitis, thromboembolism, hyperglycemia, and infections. The impact of obesity and differences in drug metabolism and chemotherapy resistance will also be discussed, as well as optimal treatment considerations for the AYA population.

Detection of acquired hemoglobinopathy in children with hematological malignancies at disease onset: results form a national referral centre

Abnormal hemoglobin synthesis is usually inherited but may also arise as a secondary manifestation of a hematological neoplasia. The objective of this study is to identify the presence of acquired hemoglobinopathy in children diagnosed with hematological malignancies and compare these against healthy controls. Prospective matched case-control study held from 2010 to 2012. For each patient with hematological malignancy two healthy controls matched on gender, age and race were recruited. Patients with other co-morbidities were excluded. All samples underwent supravital staining and high-performance liquid chromatography (HPLC) electrophoresis. Following identification of abnormal results, molecular genetic testing for all α- and β-thalassemia mutations prevalent in the Greek population was performed. Other causes of anemia were ruled out based on specific testing. A total of 44 (32 males) patients with a mean age of 7.1 years were enrolled in the study. Hematological disorders included acute lymphocytic leukemia (24), acute myeloid leukemia (8), non-Hodgkin lymphoma (8), Hodgkin disease (3), and Langerhans cell histiocytosis (1). Following exclusion of congenital hemoglobinopathies, atypical HPLC electrophoretic findings persisted in 18.1 % of the patient group, compared to 0 % in the control group (p < 0.001). The patient group showed marked microcytic anemia (p < 0.01) and detection of small inclusions (p = 0.034) on supravital staining. Comparison of the HPLC findings between the groups demonstrated significantly lower percentages of HbA (p = 0.02), normal HbA2 and higher percentage of fast moving Hb bands (p = 0.04) in the patient group. Interestingly, the majority of these patients belonged to the high-risk group. Acquired hemoglobinopathy is recognized in adult patients. This is a novel study describing evidence of abnormal erythropoiesis in children with hematological malignancies and in particular those classified as high-risk cancer patients according to international criteria.

Children's Oncology Group's 2013 blueprint for research: acute myeloid leukemia

For the 365 children diagnosed with acute myeloid leukemia in the US annually, 5-year survival for patients on COG trials with low, intermediate, and high risk disease is 83%, 62%, and 23%, respectively. Recent advances include improved therapeutic stratification, improved survival with dose intensification, and further elucidation of the heterogeneity specific to childhood AML. These discoveries now guide current strategy incorporating targeted agents to pathways specific to childhood AML as well as evaluating methods to increase the sensitivity of the leukemic stem cell, first in Phase II feasibility trials followed by Phase III efficacy trials of the most promising agents. Acute myeloid leukemia in children, though with similar subgroups to adults, remains uniquely different based upon quite different prevalence of subtypes as well as overall response to therapy. The Children's Oncology Group's research agenda builds upon earlier efforts to better elucidate the leukemogenic steps distinct to childhood AML in order to more scientifically develop and test novel therapeutic approaches to the treatment and ultimate cure for children with this disorder. Pediatr Blood Cancer 2013; 60: 964-971. © 2012 Wiley Periodicals, Inc.

Immunologic consequences of chemotherapy for acute myeloid leukemia

There are few data characterizing the immunologic consequences of chemotherapy for acute myeloid leukemia (AML) and almost nothing is known about the effects of chemotherapy in a pediatric AML cohort. We identified T-cell subsets, B-cell subsets, and used Enzyme-linked immunosorbent spot analyses to define the function of T cells and B cells in 7 pediatric patients with AML on chemotherapy. The data show that the effects of chemotherapy disproportionately target the B cell and depletion of B cells is associated with impaired responses to the inactivated influenza vaccine. Diminished T-cell numbers were also observed although the magnitude of the effect was less than what was seen for B cells. Furthermore, measures of T-cell function were largely intact. We conclude that humoral immunity is significantly affected by chemotherapy for AML.

FCHSD2 predicts response to chemotherapy in acute myeloid leukemia patients

Acute myeloid leukemia (AML) is characterized by the growth and accumulation of cells blocked in their ability to differentiate, and blocks production of normal blood cells. The response to induction chemotherapy is heterogeneous, therefore biomarkers that predict for the outcome of such treatment are of potential value. FCHSD2 in a sensitized screen was identified as a potential chemo-protector (TW Mak, unpublished). In the present study, we found that FCHSD2 knockdown by shRNA could enhance chemosensitivity of U937 cells. This coincided with the increased expression of p21 and PUMA as well as the decreased expression of Bcl-2, c-myc and hTERT. In contrast, over-expression of FCHSD2 significantly increased cellular chemoresistance. To see if there was potential clinical relevance of FCHSD2 expression in leukemia we used qRT-PCR to assess FCHSD2 expression levels in peripheral blood or bone marrow blasts of 71 AML patients. There was an inverse correlation between the level of FCHSD2 with overall survival time (r=-0.7647, p<0.0001) and relapse free time (r=-0.8165, p<0.0001). By dividing patients into high and low expression groups using a FCHSD2 expression threshold value of 0.001, the median survival of the high expression group (72 days) was shorter than in the low expression group (2472 days). The average FCHSD2 expression level in 41 patients with complete remission was significantly lower than that in 30 non-responder patients (p<0.0001). Moreover, in 32 de novo AML patients receiving initial remission-induction chemotherapy, we confirmed that the patients with lower FCHSD2 expression prior to the treatment had an increased chance of attaining remission compared to patients with high level FCHSD2. In conclusion, our study, for the first time, demonstrates FCHSD2 as a predictor of outcome for AML patient. The determination of FCHSD2 expression at the time of diagnosis could help to identify the responses of AML patients to chemotherapy.

Lessons learned from the investigational device exemption review of Children's Oncology Group trial AAML1031

The U.S. Food and Drug Administration is now exerting its regulatory authority over the use of molecular diagnostics and related assays for medical decision making in clinical trials, by performing pre-Investigational Device Exemption reviews in all phases of clinical trials. In this review, we assess the analytical performance of the assay for the diagnostic, and consider how that performance affects the diagnostic and the patient and their risks and benefits from treatment. We also discuss the process involved in the first review of a new Children's Oncology Group phase III trial in acute myelogenous leukemia. The lessons learned and recommendations for how to prepare for and incorporate this new level of regulatory review into the protocol development process are presented.

Targeted indocyanine-green-loaded calcium phosphosilicate nanoparticles for in vivo photodynamic therapy of leukemia

Leukemia is one of the most common and aggressive adult cancers, as well as the most prevalent childhood cancer. Leukemia is a cancer of the hematological system and can be divided into a diversity of unique malignancies based on the onset of the disease as well as the specific cell lineages involved. Cancer stem cells, including recently identified leukemia stem cells (LSCs), are hypothesized to be responsible for cancer development, relapse, and resistance to treatment, and new therapeutics targeting these cellular populations are urgently needed. Nontoxic and nonaggregating calcium phosphosilicate nanoparticles (CPSNPs) encapsulating the near-infrared fluoroprobe indocyanine green (ICG) were recently developed for diagnostic imaging and drug delivery as well as for photodynamic therapy (PDT) of solid tumors. Prior studies revealed that specific targeting of CPSNPs allowed for enhanced accumulation within breast cancer tumors, via CD71 targeting, or pancreatic cancer tumors, via gastrin receptor targeting. In the present study, ICG-loaded CPSNPs were evaluated as photosensitizers for PDT of leukemia. Using a novel bioconjugation approach to specifically target CD117 or CD96, surface features enhanced on leukemia stem cells, in vitro ICG-CPSNP PDT of a murine leukemia cell line and human leukemia samples were dramatically improved. Furthermore, the in vivo efficacy of PDT was dramatically enhanced in a murine leukemia model by utilizing CD117-targeted ICG-CPSNPs, resulting in 29% disease-free survival. Altogether, this study demonstrates that leukemia-targeted ICG-loaded CPSNPs offer the promise to effectively treat relapsing and multidrug-resistant leukemia and to improve the life of leukemia patients.

Overexpression of IL-3Rα on CD34+CD38- stem cells defines leukemia-initiating cells in Fanconi anemia AML

Patients with Fanconi anemia (FA) have a high risk of developing acute myeloid leukemia (AML). In this study, we attempted to identify cell-surface markers for leukemia-initiating cells in FA-AML patients. We found that the IL-3 receptor-α (IL-3Rα) is a promising candidate as an leukemia-initiating cell-specific antigen for FA-AML. Whereas IL-3Rα expression is undetectable on normal CD34(+)CD38(-) HSCs, it is overexpressed on CD34(+)CD38(-) cells from FA patients with AML. We examined the leukemia-initiating cell activity of IL-3Rα-positive FA-AML cells in a "humanized" FA xenotransplant model in which we separated AML cells into IL-3Rα-positive and IL-3Rα-negative CD34 fractions and transplanted them into irradiated recipient mice. In all 3 FA-AML samples, only IL-3Rα-positive cells showed significant levels of engraftment and developed leukemia in the recipient mice. The FA CD34(+)IL-3Rα(+) blasts isolated from leukemic mice exhibited hypersensitivity to IL-3 deprivation and JAK2-STAT5 overactivation after IL-3 treatment. Finally, treatment of FA CD34(+)IL-3Rα(+) blasts with an IL-3Rα-neutralizing antibody inhibited IL-3-mediated proliferation and STAT5 activation. These results demonstrate that IL-3Rα is a cell-surface marker present on FA-AML leukemia-initiating cells and may be a valuable therapeutic target.