New and Emerging Targeted Therapies for Pediatric Acute Myeloid Leukemia (AML)

ARMH1 is a novel marker associated with poor pediatric AML outcomes that affect the fatty acid synthesis and cell cycle pathways

Introduction

Despite remarkable progress in Pediatric Acute Myeloid Leukemia (pAML) treatments, the relapsed disease remains difficult to treat, making it pertinent to identify novel biomarkers of prognostic/therapeutic significance.

Material and methods

Bone marrow samples from 21 pAML patients were analyzed using single cell RNA sequencing, functional assays with ARMH1 knockdown and overexpression were performed in leukemia cell lines to evaluate impact on proliferation and migration, and chemotherapy sensitivity. Mitochondrial function was assessed via Seahorse assay, ARMH1 interacting proteins were studied using co-immunoprecipitation. Bulk RNA-seq was performed on ARMH1knockdown and over expressing cell lines to evaluate the pathways and networks impacted by ARMH1.

Results

Our data shows that ARMH1, a novel cancer-associated gene, is highly expressed in the malignant blast cells of multiple pediatric hematologic malignancies, including AML, T/B-ALL, and T/B-MPAL. Notably, ARMH1 expression is significantly elevated in blast cells of patients who relapsed or have a high-risk cytogenetic profile (MLL) compared to standard-risk (RUNX1, inv (16)). ARMH1 expression is also significantly correlated with the pediatric leukemia stem cell score of 6 genes (LSC6) associated with poor outcomes. Perturbation of ARMH1 (knockdown and overexpression) in leukemia cell lines significantly impacted cell proliferation and migration. The RNA-sequencing analysis on multiple ARMH1 knockdown and overexpressing cell lines established an association with mitochondrial fatty acid synthesis and cell cycle pathways.The investigation of the mitochondrial matrix shows that pharmacological inhibition of a key enzyme in fatty acid synthesis regulation, CPT1A, resulted in ARMH1 downregulation. ARMH1 knockdown also led to a significant reduction in CPT1A and ATP production as well as Oxygen Consumption Rate. Our data indicates that downregulating ARMH1 impacts cell proliferation by reducing key cell cycle regulators such as CDCA7 and EZH2. Further, we also established that ARMH1 is a key physical interactant of EZH2, associated with multiple cancers.

Conclusion

Our findings underscore further evaluation of ARMH1 as a potential candidate for targeted therapies and stratification of aggressive pAML to improve outcomes.

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

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

Single-cell analysis reveals altered tumor microenvironments of relapse- and remission-associated pediatric acute myeloid leukemia

Acute myeloid leukemia (AML) microenvironment exhibits cellular and molecular differences among various subtypes. Here, we utilize single-cell RNA sequencing (scRNA-seq) to analyze pediatric AML bone marrow (BM) samples from diagnosis (Dx), end of induction (EOI), and relapse timepoints. Analysis of Dx, EOI scRNA-seq, and TARGET AML RNA-seq datasets reveals an AML blasts-associated 7-gene signature (CLEC11A, PRAME, AZU1, NREP, ARMH1, C1QBP, TRH), which we validate on independent datasets. The analysis reveals distinct clusters of Dx relapse- and continuous complete remission (CCR)-associated AML-blasts with differential expression of genes associated with survival. At Dx, relapse-associated samples have more exhausted T cells while CCR-associated samples have more inflammatory M1 macrophages. Post-therapy EOI residual blasts overexpress fatty acid oxidation, tumor growth, and stemness genes. Also, a post-therapy T-cell cluster associated with relapse samples exhibits downregulation of MHC Class I and T-cell regulatory genes. Altogether, this study deeply characterizes pediatric AML relapse- and CCR-associated samples to provide insights into the BM microenvironment landscape.

Mechanisms associated with t(7;12) acute myeloid leukaemia: from genetics to potential treatment targets

Acute myeloid leukaemia (AML), typically a disease of elderly adults, affects 8 children per million each year, with the highest paediatric incidence in infants aged 0-2 of 18 per million. Recurrent cytogenetic abnormalities contribute to leukaemia pathogenesis and are an important determinant of leukaemia classification. The t(7;12)(q36;p13) translocation is a high-risk AML subtype exclusively associated with infants and represents the second most common abnormality in this age group. Mechanisms of t(7;12) leukaemogenesis remain poorly understood. The translocation relocates the entire MNX1 gene within the ETV6 locus, but a fusion transcript is present in only half of the patients and its significance is unclear. Instead, research has focused on ectopic MNX1 expression, a defining feature of t(7;12) leukaemia, which has nevertheless failed to produce transformation in conventional disease models. Recently, advances in genome editing technologies have made it possible to recreate the t(7;12) rearrangement at the chromosomal level. Together with recent studies of MNX1 involvement using murine in vivo, in vitro, and organoid-based leukaemia models, specific investigation on the biology of t(7;12) can provide new insights into this AML subtype. In this review, we provide a comprehensive up-to-date analysis of the biological features of t(7;12), and discuss recent advances in mechanistic understanding of the disease which may deliver much-needed therapeutic opportunities to a leukaemia of notoriously poor prognosis.

Pharmacogenomic Profiling of Pediatric Acute Myeloid Leukemia to Identify Therapeutic Vulnerabilities and Inform Functional Precision Medicine

Despite the expanding portfolio of targeted therapies for adults with acute myeloid leukemia (AML), direct implementation in children is challenging due to inherent differences in underlying genetics. Here we established the pharmacologic profile of pediatric AML by screening myeloblast sensitivity to approved and investigational agents, revealing candidates of immediate clinical relevance. Drug responses ex vivo correlated with patient characteristics, exhibited age-specific alterations, and concorded with activities in xenograft models. Integration with genomic data uncovered new gene-drug associations, suggesting actionable therapeutic vulnerabilities. Transcriptome profiling further identified gene-expression signatures associated with on- and off-target drug responses. We also demonstrated the feasibility of drug screening-guided treatment for children with high-risk AML, with two evaluable cases achieving remission. Collectively, this study offers a high-dimensional gene-drug clinical data set that could be leveraged to research the unique biology of pediatric AML and sets the stage for realizing functional precision medicine for the clinical management of the disease.

SIGNIFICANCE

We conducted integrated drug and genomic profiling of patient biopsies to build the functional genomic landscape of pediatric AML. Age-specific differences in drug response and new gene-drug interactions were identified. The feasibility of functional precision medicine-guided management of children with high-risk AML was successfully demonstrated in two evaluable clinical cases. This article is highlighted in the In This Issue feature, p. 476.

Hemophagocytic Lymphohistiocytosis in the Setting of Therapy-Induced Acute Myeloid Leukemia: An Autopsy Report

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyper-inflammatory disorder that occurs due to immunologic dysregulation. HLH can be primary (hereditary) or secondary to infections, autoimmune diseases, immune deficiencies, metabolic diseases, drugs, or malignancies. Lymphoid neoplasms mostly accompany malignancy-associated HLH. We present a case of a 12-year-old boy with a history of precursor B lymphoblastic leukemia (B-ALL), who subsequently developed chemotherapy-induced acute myeloid leukemia (t-AML). The patient was admitted for febrile neutropenia and initial laboratory tests revealed hemophagocytic lymphohistiocytosis (HLH). The hospital course was complicated by multiple infections and septic shock. The patient received several broad-spectrum antimicrobials, dexamethasone, as well as a pericardial drain to drain the hemorrhagic pericardial effusion. Despite intervention, the patient expired, and an autopsy was performed. We provide a synopsis of the main autopsy findings.

The contributing factors of resistance or sensitivity to epigenetic drugs in the treatment of AML

Drug resistance is the drug-effectiveness reduction in treatment and is a serious problem in oncology and infections. In oncology, drug resistance is a complicated process resulting from enhancing the function of a pump that transports drugs out of tumor cells, or acquiring mutations in drug target. Surprisingly, most drugs are very effective in the early stages, but the response to the drug wears off over time and resistance eventually develops. Drug resistance is caused by genetic and epigenetic changes that affect cancer cells and the tumor environment. The study of inherited changes in the phenotype without changes in the DNA sequence is called epigenetics. Because of reversible changes in epigenetics, they are an attractive target for therapy. Some of these epigenetic drugs are effective in treating cancers like acute myeloid leukemia (AML), which is characterized by the accumulation and proliferation of immature hematopoietic cells in the blood and bone marrow. In this article, we outlined the various contributing factors involved in resistance or sensitivity to epigenetic drugs in the treatment of AML.

Mesothelin: An Immunotherapeutic Target beyond Solid Tumors

Simple Summary

This review summarizes the current knowledge on mesothelin’s function, its role in cancer, and opportunities for immunotherapeutic targeting of mesothelin. Immunotherapies including monoclonal antibodies, antibody–drug conjugates, chimeric antigen receptor T and NK-cells, targeted alpha therapies, and bispecific T cell engaging molecules are reviewed. We show future directions for mesothelin targeting in hematological malignancies, including acute myeloid leukemia.

Abstract

Modern targeted cancer therapies rely on the overexpression of tumor associated antigens with very little to no expression in normal cell types. Mesothelin is a glycosylphosphatidylinositol-anchored cell surface protein that has been identified in many different tumor types, including lung adenocarcinomas, ovarian carcinomas, and most recently in hematological malignancies, including acute myeloid leukemia (AML). Although the function of mesothelin is widely unknown, interactions with MUC16/CA125 indicate that mesothelin plays a role in the regulation of proliferation, growth, and adhesion signaling. Most research on mesothelin currently focuses on utilizing mesothelin to design targeted cancer therapies such as monoclonal antibodies, antibody–drug conjugates, chimeric antigen receptor T and NK cells, bispecific T cell engaging molecules, and targeted alpha therapies, amongst others. Both in vitro and in vivo studies using different immunotherapeutic modalities in mesothelin-positive AML models highlight the potential impact of this approach as a unique opportunity to treat hard-to-cure AML.

A Summary of the Inaugural WHO Classification of Pediatric Tumors: Transitioning from the Optical into the Molecular Era

Pediatric tumors are uncommon, yet are the leading cause of cancer-related death in childhood. Tumor types, molecular characteristics, and pathogenesis are unique, often originating from a single genetic driver event. The specific diagnostic challenges of childhood tumors led to the development of the first World Health Organization (WHO) Classification of Pediatric Tumors. The classification is rooted in a multilayered approach, incorporating morphology, IHC, and molecular characteristics. The volume is organized according to organ sites and provides a single, state-of-the-art compendium of pediatric tumor types. A special emphasis was placed on "blastomas," which variably recapitulate the morphologic maturation of organs from which they originate. SIGNIFICANCE: In this review, we briefly summarize the main features and updates of each chapter of the inaugural WHO Classification of Pediatric Tumors, including its rapid transition from a mostly microscopic into a molecularly driven classification systematically taking recent discoveries in pediatric tumor genomics into account.

Advances in the First Line Treatment of Pediatric Acute Myeloid Leukemia in the Polish Pediatric Leukemia and Lymphoma Study Group from 1983 to 2019

Simple Summary

We retrospectively analyzed the results of the five consecutive treatment protocols for pediatric acute myeloid leukemia (AML) used in Poland from 1983 to 2019 (excluding promyelocytic, secondary, biphenotypic, and Down syndrome AML). The study included 899 children. The probability of three-year overall, event-free, and relapse-free survival increased from 0.34 ± 0.03 to 0.75 ± 0.05, 0.31 ± 0.03 to 0.67 ± 0.05, and 0.52 ± 0.03 to 0.78 ± 0.05, respectively. A systematic reduction of early deaths and deaths in remission was achieved, while the percentage of relapses decreased only in the last therapeutic period. Surprisingly good results were obtained in the group of patients with unfavorable genetic abnormalities like KMT2A-MLLT10/t(10;11)(p12;q23) and DEK-NUP214/t(6;9)(p23;q24) who were treated in the AML-BFM 2012 Registry, while an unsatisfactory outcome was found in patients with FLT3-ITD. The use of standardized therapeutic protocols with the successive consideration of genetic prognostic factors and advances in supportive care led to a significant improvement in AML treatment outcomes over the last 40 years.

Abstract

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

Targeted Therapy in Pediatric AML: An Evolving Landscape

The outcomes associated with pediatric acute myeloid leukemia (AML) have improved over the last few decades, with the implementation of intensive chemotherapy, hematopoietic stem cell transplant, and improved supportive care. However, even with intensive therapy and the use of HSCT, both of which carry significant risks of short- and long-term side effects, approximately 30% of children are not able to be cured. The characterization of AML in pediatrics has evolved over time and it currently involves use of a variety of diagnostic tools, including flow cytometry and comprehensive genomic sequencing. Given the adverse effects of chemotherapy and the need for additional therapeutic options to improve outcomes in these patients, the genomic and molecular architecture is being utilized to inform selection of targeted therapies in pediatric AML. This review provides a summary of current, targeted therapy options in pediatric AML.

Antibody-Drug Conjugates for the Treatment of Acute Pediatric Leukemia

The clinical development of antibody-drug conjugates (ADCs) has gained momentum in recent years and these agents are gradually moving into frontline regimens for pediatric acute leukemias. ADCs consist of a monoclonal antibody attached to a cytotoxic payload by a cleavable linker. This structure allows for highly cytotoxic agents to be directly delivered to leukemia cells leading to cell death and avoids excessive off-tumor toxicity. Near universal expression on B-cell acute lymphoblastic leukemia (ALL) blasts and the ability of rapid internalization has rendered CD22 an ideal target for ADC in B-ALL. Inotuzumab ozogamicin, the anti-CD22 antibody linked to calicheamicin led to complete remission rates of 60-80% in patients with relapsed/refractory B-ALL. In acute myeloid leukemia (AML), the CD33 targeting gemtuzumab ozogamicin has demonstrated modest improvements in survival and is the only ADC currently licensed in the United States for pediatric patients with de novo AML. Several other ADCs have been developed and tested clinically for leukemia but have achieved limited success to date. The search for additional leukemia-specific targets and optimization of ADC structure and specificity are ongoing efforts to improve their therapeutic window. This review provides a comprehensive overview of ADCs in acute leukemias, with a focus on pediatric ALL and AML.

Cytogenetic risk groups for childhood acute myeloid leukemia based on survival analysis in a cancer referral hospital from Perú

Introduction: Acute myeloid leukemia is a heterogeneous disorder characterized by immature myeloid cell proliferation. Cytogenetic analysis has revealed the presence of chromosomal aberrations important to patient prognosis. Objective: To determine cytogenetic risk groups of pediatric patients with acute myeloid leukemia according to overall survival. Materials and methods: In this cross-sectional observational study, the clinical records of pediatric patients diagnosed with de novo acute myeloid leukemia admitted to the Instituto Nacional de Enfermedades Neoplásicas between 2001 and 2011 with cytogenetic analysis of bone marrow were included. Cytogenetic risk groups were established according to the criteria of the Medical Research Council. Overall survival curves were generated with the Kaplan-Meier method and compared using the Mantel-Cox test and Cox regression with the software R, version 3.3.2. Results: A total of 130 patients were included, 68 males (52.3%) and 62 females (47.7%), most of them with subtype M2 (33%). The average age was 7.7 years (range: 0-15 years). Chromosomal aberrations were observed in 60.8% of the patients, the most frequent of which was the translocation t(8;21). According to the overall survival analysis, two cytogenetic risk groups were established: favorable and unfavorable. Conclusion: Two groups of cytogenetic risk were determined: high (or unfavorable) and standard (favorable).

The application effect analysis of personalized health education in acute leukemia nursing

OBJECTIVE

To analyze the effectiveness of personalized health education care in the nursing of patients with acute leukemia.

METHODS

A total of 108 patients with leukemia who were admitted to our hospital were randomly selected as research subjects. A random number table was used to allocate the patients into the observation group and the control group, with 54 patients in each group. The control group had routine health education care and the observation group received personalized health education care in addition to treatment given to the control group. The knowledge of leukemia, bad moods, adverse reaction and nursing satisfaction were compared between the two groups.

RESULTS

The observation group had better knowledge of leukemia and nursing satisfaction than the control group, and the incidence of bad moods (anxiety, depression) and adverse reactions were lower than that in the control group (all P<0.05).

CONCLUSION

The application of personalized health education in the nursing of acute leukemia patients was significant, which improved the knowledge of acute leukemia, reduced the incidence of bad moods and adverse reactions, and improved nursing satisfaction.

Narrative review of targetable features of pediatric acute myeloid leukemia from molecular and metabolic perspectives

Background and Objective

Unlike the majority of pediatric leukemia patients, young patients with acute myeloid leukemia (AML) have not seen significant improvement in treatment outcomes. This is frequently attributed to the heterogeneity of this malignancy in terms of its mutations and molecularly defined categories. In adult versus pediatric cases of AML, the heterogeneity is preserved, although there are key differences in the incidence of gene mutations, chromosomal translocations, and other molecular features. Current treatment strategies consider broader cellular features of AML, such as altered metabolic and anti-apoptotic properties, and many of these are common across pediatric and adult AML.

Methods

A narrative review was conducted to compile literature regarding molecular and metabolic features of AML and new treatment modalities in the adult and pediatric population. Articles published in PubMed were gathered and studied over 6 months for review and comparison. Studies published in English over a ten-year period from 2000-2020 were included. Keywords used for the searches included acute myeloid leukemia, cytogenetics, pediatric acute myeloid leukemia, and treatment of acute myeloid leukemia.

Key Content and Findings

Molecular characteristics of adult-onset myeloid leukemia as compared to those in the pediatric population are detailed. We highlight unique features of pediatric AML biology and potential ties to metabolism, as well as recent advances in therapy.

Conclusions

Differences in adult and pediatric AML cytogenetics, metabolism, and molecular features should be further characterized in order to individualize treatment, develop new therapeutic options, and improve patient outcome.

Phase 2 Clinical Trial of Infusing Haploidentical K562-mb15-41BBL-Activated and Expanded Natural Killer Cells as Consolidation Therapy for Pediatric Acute Myeloblastic Leukemia

BACKGROUND

Acute myeloid leukemia (AML) accounts for approximately 20% of pediatric leukemia cases; 30% of these patients experience relapse. The antileukemia properties of natural killer (NK) cells and their safety profile have been reported in AML therapy. We proposed a phase 2, open, prospective, multicenter, nonrandomized clinical trial for the adoptive infusion of haploidentical K562-mb15-41BBL-activated and expanded NK (NKAE) cells as a consolidation strategy for children with favorable and intermediate risk AML in first complete remission after chemotherapy (NCT02763475).

PATIENTS AND METHODS

Before the NKAE cell infusion, patients underwent a lymphodepleting regimen. After the NKAE cell infusion, patients were administered low doses (1 × 10⁶/IU/m²) of subcutaneous interleukin-2. The primary study endpoint was AML relapse-free survival. We needed to include 35 patients to demonstrate a 50% reduction in relapses.

RESULTS

Seven patients (median age, 7.4 years; range, 0.78-15.98 years) were administered 13 infusions of NKAE cells, with a median of 36.44 × 10⁶ cells/kg (range, 6.92 × 10⁶ to 193.2 × 10⁶ cells/kg). We observed chimerism in 4 patients (median chimerism, 0.065%; range, 0.05-0.27%). After a median follow-up of 33 months, the disease of 6 patients (85.7%) remained in complete remission. The 3-year overall survival was 83.3% (95% confidence interval, 68.1-98.5), and the cumulative 3-year relapse rate was 28.6% (95% confidence interval, 11.5-45.7). The study was terminated early because of low patient recruitment.

CONCLUSION

This study emphasizes the difficulties in recruiting patients for cell therapy trials, though NKAE cell infusion is safe and feasible. However, we cannot draw any conclusions regarding efficacy because of the small number of included patients and insufficient biological markers.