Pediatric Leukemia Research Articles

Comparative study of posaconazole and voriconazole for primary antifungal prophylaxis in patients with pediatric acute leukemia

Posaconazole and voriconazole are commonly used for preventing invasive fungal disease (IFD), but few studies compared posaconazole with voriconazole for primary antifungal prophylaxis (PAP) in pediatric acute leukemia. To compare posaconazole with voriconazole for PAP in pediatric acute leukemia. This retrospective observational study enrolled pediatric patients with non-M3 acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) between December 2017 and November 2019 in the Second Affiliated Hospital of Anhui Medical University. The patients received voriconazole or posaconazole for PAP. The primary outcome was the breakthrough of IFD. The secondary outcome was the overall survival (OS) and IFD-free survival of patients. A total of the 275 patients were enrolled, of which 120 patients taking voriconazole (43.6%) and 155 patients taking posaconazole (56.4%). The breakthrough of IFD occurred in 19 (15.8%) patients taking voriconazole and in 12 (7.7%) patients taking posaconazole (P = 0.035). There was no significant differences in IFD-free survival (P = 0.336) or OS (P = 0.069) between the patients taking voriconazole and posaconazole. In the subgroup of AML patients, the OS of patients taking posaconazole was better than those receiving voriconazole (P = 0.017). Posaconazole and voriconazole were comparable for PAP in patients with pediatric acute leukemia regarding the OS and IFD-free survival, but posaconazole might achieve a lower IFD breakthrough rate.

Acute myeloid leukemias with UBTF tandem duplications are sensitive to menin inhibitors

AbstractUBTF tandem duplications (UBTF-TDs) have recently emerged as a recurrent alteration in pediatric and adult acute myeloid leukemia (AML). UBTF-TD leukemias are characterized by a poor response to conventional chemotherapy and a transcriptional signature that mirrors NUP98-rearranged and NPM1-mutant AMLs, including HOX-gene dysregulation. However, the mechanism by which UBTF-TD drives leukemogenesis remains unknown. In this study, we investigated the genomic occupancy of UBTF-TD in transformed cord blood CD34+ cells and patient-derived xenograft models. We found that UBTF-TD protein maintained genomic occupancy at ribosomal DNA loci while also occupying genomic targets commonly dysregulated in UBTF-TD myeloid malignancies, such as the HOXA/HOXB gene clusters and MEIS1. These data suggest that UBTF-TD is a gain-of-function alteration that results in mislocalization to genomic loci dysregulated in UBTF-TD leukemias. UBTF-TD also co-occupies key genomic loci with KMT2A and menin, which are known to be key partners involved in HOX-dysregulated leukemias. Using a protein degradation system, we showed that stemness, proliferation, and transcriptional signatures are dependent on sustained UBTF-TD localization to chromatin. Finally, we demonstrate that primary cells from UBTF-TD leukemias are sensitive to the menin inhibitor SNDX-5613, resulting in markedly reduced in vitro and in vivo tumor growth, myeloid differentiation, and abrogation of the UBTF-TD leukemic expression signature. These findings provide a viable therapeutic strategy for patients with this high-risk AML subtype.

66. Screening for genetic predisposition to pediatric leukemia in a Peruvian population

66. Screening for genetic predisposition to pediatric leukemia in a Peruvian population

Agricultural intensification and childhood cancer in Brazil.

Over the last several decades, Brazil has become both the world's leading soy producer and the world's leading consumer of hazardous pesticides. Despite identified links between pesticide exposure and carcinogenesis, there has been little population-level research on the effects of pesticide intensification on broader human health in Brazil. We estimate the relationship between expanded soy production-and related community exposure to pesticides-on childhood cancer incidence using 15 y of data on disease mortality. We find a statistically significant increase in pediatric leukemia following expanded local soy production, but timely access to treatment mitigates this relationship. We show that pesticide exposure likely occurs via water supply penetration. Our findings represent only the tip of the iceberg for substantial health externalities of high-input crop production and land use change. Our results are of particular interest in developing contexts with demand for intensified food production systems and underscore the need for stronger regulation of pesticides and increased public health attention to exposure in the broader community.

Therapeutic targeting in pediatric acute myeloid leukemia with aberrant HOX/MEIS1 expression

Despite advances in the clinical management of childhood acute myeloid leukemia (AML) during the last decades, outcome remains fatal in approximately one third of patients. Primary chemoresistance, relapse and acute and long-term toxicities to conventional myelosuppressive therapies still constitute significant challenges and emphasize the unmet need for effective targeted therapies. Years of scientific efforts have translated into extensive insights on the heterogeneous spectrum of genetics and oncogenic signaling pathways of AML and identified a subset of patients characterized by upregulation of HOXA and HOXB homeobox genes and myeloid ecotropic virus insertion site 1 (MEIS1). Aberrant HOXA/MEIS1 expression is associated with genotypes such as rearrangements in Histone-lysine N-methyltransferase 2A (KMT2A-r), nucleoporin 98 (NUP98-r) and mutated nucleophosmin (NPM1c) that are found in approximately one third of children with AML. AML with upregulated HOXA/MEIS1 shares a number of molecular vulnerabilities amenable to recently developed molecules targeting the assembly of protein complexes or transcriptional regulators. The interaction between the nuclear scaffold protein menin and KMT2A has gained particular interest and constitutes a molecular dependency for maintenance of the HOXA/MEIS1 transcription program. Menin inhibitors disrupt the menin-KMT2A complex in preclinical models of KMT2A-r, NUP98-r and NPM1c acute leukemias and its occupancy at target genes leading to leukemic cell differentiation and apoptosis. Early-phase clinical trials are either ongoing or in development and preliminary data suggests tolerable toxicities and encouraging efficacy of menin inhibitors in adults with relapsed or refractory KMT2A-r and NPM1c AML. The Pediatric Acute Leukemia/European Pediatric Acute Leukemia (PedAL/EUPAL) project is focused to advance and coordinate informative clinical trials with new agents and constitute an ideal framework for testing of menin inhibitors in pediatric study populations. Menin inhibitors in combination with standard chemotherapy or other targeting agents may enhance anti-leukemic effects and constitute rational treatment strategies for select genotypes of childhood AML, and provide enhanced safety to avoid differentiation syndrome. In this review, we discuss the pathophysiological mechanisms in KMT2A-r, NUP98-r and NPM1c AML, emerging molecules targeting the HOXA/MEIS1 transcription program with menin inhibitors as the most prominent examples and future therapeutic implications of these agents in childhood AML.

Epigenetic Profiling of PTPN11 Mutant JMML Hematopoietic Stem and Progenitor Cells Reveals an Aberrant Histone Landscape.

Juvenile myelomonocytic leukemia (JMML) is a deadly pediatric leukemia driven by RAS pathway mutations, of which >35% are gain-of-function in PTPN11. Although DNA hypermethylation portends severe clinical phenotypes, the landscape of histone modifications and chromatin profiles in JMML patient cells have not been explored. Using global mass cytometry, Epigenetic Time of Flight (EpiTOF), we analyzed hematopoietic stem and progenitor cells (HSPCs) from five JMML patients with PTPN11 mutations. These data revealed statistically significant changes in histone methylation, phosphorylation, and acetylation marks that were unique to JMML HSPCs when compared with healthy controls. Consistent with these data, assay for transposase-accessible chromatin with sequencing (ATAC-seq) analysis revealed significant alterations in chromatin profiles at loci encoding post-translational modification enzymes, strongly suggesting their mis-regulated expression. Collectively, this study reveals histone modification pathways as an additional epigenetic abnormality in JMML patient HSPCs, thereby uncovering a new family of potential druggable targets for the treatment of JMML.

CD72 is a pan-tumor antigen associated to pediatric acute leukemia.

In the development of novel immunotherapeutic approaches, the step of target identification is a challenging process, because it aims at identifying robust tumor-associated antigens (TAAs) specific for the pathological population and causing no off-target effects. Here we propose CD72 as a novel and robust TAA for pediatric acute leukemias. We provided an outline of CD72 expression assessed by flow cytometry on a variety of cancer cell lines and primary samples, including normal bone marrow (BM) samples and hematopoietic stem and progenitor cells. We analyzed CD 72 expression on a cohort of 495 pathological pediatric BM aspirates, including: 215 B-cell precursor acute lymphoblastic leukemias (BCP-ALL), 156 acute myeloid leukemias (AMLs), 88 T-lineage ALLs or lymphoblastic lymphomas with BM infiltration, 13 B-lineage lymphoblastic lymphomas with BM infiltration, 9 myelodysplastic syndromes with increased blasts (5%-9% blasts on BM: MDS-IB1) and 14 non-hematopoietic solid tumors infiltrating BM. Results showed that CD72 is highly expressed in almost all BCP-ALL and the majority of AML at diagnosis, including BCP-ALL cases characterized by CD19 loss. These findings support a potential role for advanced diagnostics and novel immunotherapy approaches, providing a pan-ALL and AML target.

A scoring system based on fusion genes to predict treatment outcomes of the non-acute promyelocytic leukemia pediatric acute myeloid leukemia

BackgroundFusion genes are considered to be one of the major drivers behind cancer initiation and progression. Meanwhile, non-acute promyelocytic leukemia (APL) pediatric patients with acute myeloid leukemia (AML) in children had limited treatment efficacy. Hence, we developed and validated a simple clinical scoring system for predicting outcomes in non-APL pediatric patients with AML.MethodA total of 184 non-APL pediatric patients with AML who were admitted to our hospital and an independent dataset (318 patients) from the TARGET database were included. Least absolute shrinkage and selection operation (LASSO) and Cox regression analysis were used to identify prognostic factors. Then, a nomogram score was developed to predict the 1, 3, and 5 years overall survival (OS) based on their clinical characteristics and fusion genes. The accuracy of the nomogram score was determined by calibration curves and receiver operating characteristic (ROC) curves. Additionally, an internal verification cohort was used to assess its applicability.ResultsBased on Cox and LASSO regression analyses, a nomogram score was constructed using clinical characteristics and OS-related fusion genes (CBFβ::MYH11, RUNX1::RUNX1T1, KMT2A::ELL, and KMT2A::MLLT10), yielded good calibration and concordance for predicting OS of non-APL pediatric patients with AML. Furthermore, patients with higher scores exhibited worse outcomes. The nomogram score also demonstrated good discrimination and calibration in the whole cohort and internal validation. Furthermore, artificial neural networks demonstrated that this nomogram score exhibits good predictive performance.ConclusionOur model based on the fusion gene is a prognostic biomarker for non-APL pediatric patients with AML. The nomogram score can provide personalized prognosis prediction, thereby benefiting clinical decision-making.

Continuous therapy response references for BCR::ABL1 monitoring in pediatric chronic myeloid leukemia

Response to tyrosine kinase inhibitor (TKI) therapy in patients with chronic myeloid leukemia (CML) is monitored by quantification of BCR::ABL1 transcript levels. Milestones for assessing optimal treatment response have been defined in adult CML patients and are applied to children and adolescents although it is questionable whether transferability to pediatric patients is appropriate regarding genetic and clinical differences. Therefore, we analyzed the molecular response kinetics to TKI therapy in 129 pediatric CML patients and investigated whether response assessment based on continuous references can support an early individual therapy adjustment. We applied a moving quantiles approach to establish a high-resolution response target curve and contrasted the median responses in all patients with the median of the ideal target curve obtained from a subgroup of optimal responders. The high-resolution response target curve of the optimal responder group presents a valuable tool for continuous therapy monitoring of individual pediatric CML patients in addition to the fixed milestones. By further comparing BCR::ABL1 transcript levels with BCR::ABL1 fusion gene copy numbers, it is also possible to model the differential dynamics of BCR::ABL1 expression and cell number under therapy. The developed methodology can be transferred to other biomarkers for continuous therapy monitoring.

Persistence of UBTF tandem duplications in remission in acute myeloid leukaemia.

UBTF tandem duplications are recurrent in adult and paediatric acute myeloid leukaemia and have been reported to be associated with a poor prognosis. Co-mutations in WT1 and FLT3 are common while morphological dysplasia is frequent. The role of UBTF-TDs in leukemogenesis is yet to be elucidated; however they have been proposed as early initiating events, making them attractive for assessment of MRD and a potential therapeutic target. We present two cases where the UBTF-TD was observed in remission and discuss the implications of these findings in the clinicobiological understanding of this emerging entity.

NKG2D-CAR memory T cells target pediatric T-cell acute lymphoblastic leukemia in vitro and in vivo but fail to eliminate leukemia initiating cells

IntroductionRefractory/relapsed pediatric acute leukemia are still clinically challenging and new therapeutic strategies are needed. Interactions between Natural Killer Group 2D (NKG2D) receptor, expressed in cytotoxic immune cells, and its ligands (NKG2DL), which are upregulated in leukemic blasts, are important for anti-leukemia immunosurveillance. Nevertheless, leukemia cells may develop immunoescape strategies as NKG2DL shedding and/or downregulation.MethodsIn this report, we analyzed the anti-leukemia activity of NKG2D chimeric antigen receptor (CAR) redirected memory (CD45RA-) T cells in vitro and in a murine model of T-cell acute lymphoblastic leukemia (T-ALL). We also explored in vitro how soluble NKG2DL (sNKG2DL) affected NKG2D-CAR T cells’ cytotoxicity and the impact of NKG2D-CAR T cells on Jurkat cells gene expression and in vivo functionality.ResultsIn vitro, we found NKG2D-CAR T cells targeted leukemia cells and showed resistance to the immunosuppressive effects exerted by sNKG2DL. In vivo, NKG2D-CAR T cells controlled T cell leukemia burden and increased survival of the treated mice but failed to cure the animals. After CAR T cell treatment, Jurkat cells upregulated genes related to proliferation, survival and stemness, and in vivo, they exhibited functional properties of leukemia initiating cells.DiscussionThe data here presented suggest, that, in combination with other therapeutic approaches, NKG2D-CAR T cells could be a novel treatment for pediatric T-ALL.

An implementation of Hurdle models for spatial count data. Study case: civil war as a risk factor for the development of childhood leukemia in Colombia

We propose a novel, efficient, and powerful methodology to deal with overdispersion, excess zeros, heterogeneity, and spatial correlation. It is based on the combination of Hurdle models and Spatial filtering Moran eigenvectors. Hurdle models are the best option to manage the presence of overdispersion and excess of zeros, separating the model into two parts: the first part models the probability of the zero value, and the second part models the probability of the non-zero values. Finally, gathering the spatial information in new covariates through a spatial filtering Moran vector method involves spatial correlation and spatial heterogeneity to improve the model fitting and explain spatial effects of variables that were not possible to measure. Thus, our proposal adapts usual regression models for count data so that it is possible to deal with phenomena where the usual theoretical assumptions, such as constant variance, independence, and unique distribution are not fulfilled. In addition, this research shows how a prolonged armed conflict can impact the health of children. The data includes children exposed to armed conflict in Colombia, a country enduring a non-international armed conflict lasting over 60 years. The findings indicate that children exposed to high levels of violence, as measured by the armed conflict index, demonstrate a significant association with the incidence and mortality rate of LAP in children. This fact is illustrated here using one of the most catastrophic conditions in childhood, as is Pediatric Acute Leukemia (LAP). The association between armed conflict and LAP has its conceptual basis in the epidemiology literature, given that, the incidence and mortality rates of neoplastic diseases increase with exposure to toxic and chronic stress during gestation and childhood. Our methodology provides a valuable framework for complex data analysis and contributes to understanding the health implications in conflict-affected regions.

Single-cell RNA sequencing distinctly characterizes the wide heterogeneity in pediatric mixed phenotype acute leukemia

BackgroundMixed phenotype acute leukemia (MPAL), a rare subgroup of leukemia characterized by blast cells with myeloid and lymphoid lineage features, is difficult to diagnose and treat. A better characterization of MPAL is essential to understand the subtype heterogeneity and how it compares with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Therefore, we performed single-cell RNA sequencing (scRNAseq) on pediatric MPAL bone marrow (BM) samples to develop a granular map of the MPAL blasts and microenvironment landscape.MethodsWe analyzed over 40,000 cells from nine pediatric MPAL BM samples to generate a single-cell transcriptomic landscape of B/myeloid (B/My) and T/myeloid (T/My) MPAL. Cells were clustered using unsupervised single-cell methods, and malignant blast and immune clusters were annotated. Differential expression analysis was performed to identify B/My and T/My MPAL blast-specific signatures by comparing transcriptome profiles of MPAL with normal BM, AML, and ALL. Gene set enrichment analysis (GSEA) was performed, and significantly enriched pathways were compared in MPAL subtypes.ResultsB/My and T/My MPAL blasts displayed distinct blast signatures. Transcriptomic analysis revealed that B/My MPAL profile overlaps with B-ALL and AML samples. Similarly, T/My MPAL exhibited overlap with T-ALL and AML samples. Genes overexpressed in both MPAL subtypes’ blast cells compared to AML, ALL, and healthy BM included MAP2K2 and CD81. Subtype-specific genes included HBEGF for B/My and PTEN for T/My. These marker sets segregated bulk RNA-seq AML, ALL, and MPAL samples based on expression profiles. Analysis comparing T/My MPAL to ETP, near-ETP, and non-ETP T-ALL, showed that T/My MPAL had greater overlap with ETP-ALL cases. Comparisons among MPAL subtypes between adult and pediatric samples showed analogous transcriptomic landscapes of corresponding subtypes. Transcriptomic differences were observed in the MPAL samples based on response to induction chemotherapy, including selective upregulation of the IL-16 pathway in relapsed samples.ConclusionsWe have for the first time described the single-cell transcriptomic landscape of pediatric MPAL and demonstrated that B/My and T/My MPAL have distinct scRNAseq profiles from each other, AML, and ALL. Differences in transcriptomic profiles were seen based on response to therapy, but larger studies will be needed to validate these findings.

Outcomes and challenges treating pediatric acute myeloid leukemia: a retrospective analysis of patients treated at the Fundación Valle del Lili between 2011 and 2020

IntroductionAcute myeloid leukemia is a challenging disease, due to a poor prognosis in developing countries. Herein, we aim to describe the clinical characteristics and outcomes after chemotherapy and transplantation. MethodsA retrospective analytic observational study was performed with patients under 18 years of age with newly diagnosed acute myeloid leukemia treated at a referral center in Colombia. Two groups were compared: induction therapy (IT) and induction therapy plus consolidation (IT + C). The survival analysis was performed using the Kaplan–Meier method. ResultsWe analyzed 34 patients diagnosed with acute myeloid leukemia; 20 received hematopoietic stem cell transplantation. Most were French-American-British (FAB) classification types M1, M5 and M0. The transplantation was haploidentical in 65%, conditioning was myeloablative in 67% and graft-versus-host disease prophylaxis was performed with post-transplant cyclophosphamide in 70%. Overall, the 5-year survival was 52% and the overall 5-year survival in the transplanted group was 80%. There were 16 deaths; in the IT group, n = 12, and in the IT + C group, n = 4. In the former, the main cause of death was septic shock and in the latter, it was relapse. ConclusionTransplantation is a safe option. Receiving treatment and supportive measures in hematopoietic stem cell transplantation units is necessary to avoid infections, especially during induction cycles.

Comprehensive characterization of patient-derived xenograft models of pediatric leukemia

Patient-derived xenografts (PDX) remain valuable models for understanding the biology and for developing novel therapeutics. To expand current PDX models of childhood leukemia, we have developed new PDX models from Hispanic patients, a subgroup with a poorer overall outcome. Of 117 primary leukemia samples obtained, successful engraftment and serial passage in mice were achieved in 82 samples (70%). Hispanic patient samples engrafted at a rate (51/73, 70%) that was similar to non-Hispanic patient samples (31/45, 70%). With a new algorithm to remove mouse contamination in multi-omics datasets including methylation data, we found PDX models faithfully reflected somatic mutations, copy-number alterations, RNA expression, gene fusions, whole-genome methylation patterns, and immunophenotypes found in primary tumor (PT) samples in the first 50 reported here. This cohort of characterized PDX childhood leukemias represents a valuable resource in that germline DNA sequencing has allowed the unambiguous determination of somatic mutations in both PT and PDX.

B - 09 Neuropsychological Impacts and Cognitive Effects of Pediatric Leukemia Treatment.

The current study seeks to investigate the neuropsychological and cognitive late effects of pediatric Acute Lymphoblastic Leukemia (ALL) treatment. A search for peer-reviewed articles was conducted. Google Scholar was searched using keywords including neuropsychology, neuro-cognitive, neuropsychological effects, neuropsychological battery, neuropsychological impacts, cognitive effects, cognitive impacts, pediatric, pediatric leukemia, acute lymphoblastic leukemia treatment, bone marrow transplant, whole brain radiation, whole-body radiation, chemotherapy, cranial radiotherapy, health psychology, and neuropsychological testing. Articles were included if they discussed neuropsychology and ALL. Articles with non-human subjects and case studies were excluded from the study. Fifty-nine studies were included in the study. Treatments for ALL result in impairments in working memory, reduced processing speed, attention deficits, executive functioning deficits, visual-spatial and visuomotor weakness, fine motor weakness, deficits in delayed memory, an initial decline in performance IQ, and a delayed decline in verbal abilities such as attention and reading. The initial decline in performance abilities following a late decline in verbal abilities seen in patients who have undergone CRT may be due to structural changes in the white and gray matter following CRT treatment. Healthcare providers should attend to patients' cognitive complaints, particularly as they pertain to patients' ability to adhere to treatment recommendations and subsequently to their ability to resume attending school or social roles. As patient and parent complaints of cognitive compromise are associated with psychological distress and functional decline, cognitive complaints could justify further in-depth neuropsychological assessment to mobilize comprehensive supportive care or rehabilitative services.

The Small-Molecule E26-Transformation-Specific Inhibitor TK216 Attenuates the Oncogenic Properties of Pediatric Leukemia.

The E26-transformation-specific (ETS) transcription factors regulate multiple aspects of the normal hematopoietic system. There is an increasing body of evidence suggesting aberrant ETS activity and its contribution to leukemia initiation and progression. In this study, we evaluated the small-molecule ETS inhibitor TK216 and demonstrated its anti-tumor activity in pediatric leukemia. We found TK216 induced growth inhibition, cell cycle arrest and apoptosis and inhibited the migratory capability of leukemic cells, without significantly inhibiting the cell viability of normal blood mononuclear cells. Priming the leukemic cells with 5-Azacitidine enhanced the cytotoxic effects of TK216 on pediatric leukemia cells. Importantly, we found purine-rich box1 (PU.1) to be a potential target of TK216 in myeloid and B-lymphoid leukemic cells. In addition, TK216 sharply decreased Mcl-1 protein levels in a dose-dependent manner. Consistent with this, TK216 also potentiated the cytotoxic effects of Bcl-2 inhibition in venetoclax-resistant cells. The sustained survival benefit provided to leukemic cells in the presence of bone-marrow-derived conditioned media is also found to be modulated by TK216. Taken together, our data indicates that TK216 could be a promising targeted therapeutic agent for the treatment of acute myeloid and B-lymphoid leukemia.

Overexpression of CHK1 and CHK2 in pediatric patients of B-acute lymphoblastic leukemia

Background: Despite breakthroughs in the development of chemotherapy drugs to treat pediatric B-acute lymphoblastic leukemia (B-ALL), the relapse rate remains a major therapeutic challenge, requiring more detailed characterization of molecular elements underlying disease development and resistance to treatment. Checkpoint kinase 1 (CHK1) and checkpoint kinase 2 (CHK2) are two critical mediators of the DNA damage response (DDR) mechanism that activate the downstream components responsible for DNA repair, cell cycle regulation, and apoptosis. It has been shown that altered expression of CHK1 and CHK2 in various tumor entities promotes tumorigenesis and disease progression.
 Materials and Methods: In this case-control study, we evaluated the relative expression status of CHK1 and CHK2 genes in pediatric B-ALL patients at diagnosis (n=20), during complete remission (n=23) and relapse phase (n=10), as well as 20 peripheral blood samples from healthy children as a normal control group. The mRNA expression levels of CHK1 and CHK2 were determined by the Real-time PCR method. Data were compared using the Mann–Whitney U test for the relative expression level of target mRNA in different phases of B-ALL. Data were presented as median and statistical significance was described as a P-value less than 0.05.
 Results: Our results revealed that CHK1 expression increased in newly diagnosed patients than in healthy individuals (p ≤ 0.001). Relapsed patients had higher CHK1 expression than the newly diagnosed (p ≤ 0.05) and complete remission (p ≤ 0.001) counterparts. CHK2 was overexpressed in all phases of the diseases (p ≤ 0.001) without any significant alteration among the studied groups.
 Conclusion: Given the CHK1 ability to endow cancer cells with a survival advantage upon chemotherapy, the present study suggests it as a potentially promising target in the fight against B-ALL.

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.

SAT146 Recurrent Hypoglycemia Following Asparaginase Therapy For Childhood Cancer: Institutional Experience

Abstract Disclosure: M. Tantoush: None. Background: Asparaginase (ASP) is a cornerstone pediatric leukemia and lymphoma therapy. Hyperglycemia following ASP is described, but hypoglycemia is infrequently identified as a complication. Following hypoglycemic events in children receiving ASP therapy, evaluation of associations and outcomes was undertaken. Aim: Evaluate and describe the risk factors, prevalence, duration, severity, recurrence and outcomes of children developing ASP-induced hypoglycemia. Method: Retrospective cohort study using electronic medical records to identify all patients who received ASP (PEGylated or non-PEGylated), and had diagnosis of hypoglycemia between 6/1/2017 and 6/30/22 at Texas Children's Hospital. We defined ASP-induced hypoglycemia as blood glucose (BG) <70 mg/dl 2-8 weeks from ASP administration, without alternative causes. If hypoglycemia evaluation was completed, hyperinsulinism was defined by: BG < 50 mg/dL; insulin > 2 mIU/mL; β-hydroxybutyrate < 1.8 mmol/L; free fatty acids < 1.7 mmol/L; or a post-glucagon BG > 30 mg/dL. Demographic and clinically relevant data were collected. Descriptive analysis was completed. Univariate regression models using Stata16 were analyzed. A p-value <0.05 was statistically significant. Results: Patients receiving ASP totaled 722, with 56 (7.6%) having ASP-induced hypoglycemia. Cancer diagnosis included acute lymphoblastic leukemia (n=50), lymphoblastic lymphoma (n=5) or acute myeloid leukemia (n=1). Median age was 4.4 years (IQR: 2.6 - 8.1), with 46% Hispanic and 59% male. Median BMI z-score was +0.4 (IQR: -0.3 - 1.2). Initial hypoglycemia event was during Induction therapy in 86% (n=48), with median time from ASP to hypoglycemia diagnosis 11 days (IQR: 6-15). Median lowest BG was 51 mg/dL (IQR: 43-57) with median duration 11 days (IQR: 7-19). Treatment included dietary change (52%, n=29), cornstarch (29%, n=16), and continuous feedings (13%, n=7). Continuous BG monitoring was utilized in 9 (16%). A critical sample was obtained in 18 (32%) with all evaluations consistent with hyperinsulinism. Recurrent hypoglycemia with subsequent ASP doses occurred in 42 (74%), with a median duration 14 days (IQR: 8-21; max: 56 days). Overall cancer survival following ASP-induced hypoglycemia was 80% (85% if excluding relapse disease), with 3 years’ median follow up. Severity of hypoglycemia (lowest BG, number of events, or length of events) was not associated with age, sex, ethnicity, or BMI z-score in univariate analysis. Conclusion: ASP-induced hypoglycemia is relatively common, often recurs with subsequent dosing, and may become severe requiring intensive therapy. Prospective screening of patients receiving ASP may be appropriate to prevent and manage events. Patients completed chemotherapy without change in survival at 3 years’ follow-up. Further studies to elucidate prognostic factors of ASP-induced hypoglycemia are needed. Presentation: Saturday, June 17, 2023