Defining low-risk high hyperdiploidy in patients with paediatric acute lymphoblastic leukaemia: a retrospective analysis of data from the UKALL97/99 and UKALL2003 clinical trials

Outcomes in patients with ETV6::RUNX1 or high-hyperdiploid B-ALL treated in the St. Jude Total Therapy XV/XVI studies

ABSTRACT

Children with ETV6::RUNX1 or high-hyperdiploid B-cell acute lymphoblastic leukemia (B-ALL) have favorable outcomes. The St. Jude (SJ) classification considers these patients low risk, regardless of their National Cancer Institute (NCI) risk classification, except when there is slow minimal residual disease (MRD) response or central nervous system/testicular involvement. We analyzed outcomes in children (aged 1-18.99 years) with these genotypes in the SJ Total XV/XVI studies (2000-2017). Patients with ETV6::RUNX1 (n = 222) or high-hyperdiploid (n = 296) B-ALL had 5-year event-free survival (EFS) of 97.7% ± 1.1% and 94.7% ± 1.4%, respectively. For ETV6::RUNX1, EFS was comparable between NCI standard-risk and high-risk patients and between SJ low-risk and standard-risk patients. Of the 40 NCI high-risk patients, 37 who received SJ low-risk therapy had excellent EFS (97.3% ± 2.8%). For high-hyperdiploid B-ALL, NCI high-risk patients had worse EFS than standard-risk patients (87.6% ± 4.5% vs 96.4% ± 1.3%; P = .016). EFS was similar for NCI standard-risk and high-risk patients classified as SJ low risk (96.0% ± 1.5% and 96.9% ± 3.2%; P = .719). However, EFS was worse for NCI high-risk patients than for NCI standard-risk patients receiving SJ standard/high-risk therapy (77.4% ± 8.2% vs 98.0% ± 2.2%; P = .004). NCI high-risk patients with ETV6::RUNX1 or high-hyperdiploid B-ALL who received SJ low-risk therapy had lower incidences of thrombosis (P = .013) and pancreatitis (P = .011) than those who received SJ standard/high-risk therapy. MRD-directed therapy yielded excellent outcomes, except for NCI high-risk high-hyperdiploid B-ALL patients with slow MRD response, who require new treatment approaches. Among NCI high-risk patients, 93% with ETV6::RUNX1 and 54% with high-hyperdiploid B-ALL experienced excellent outcomes with a low-intensity regimen. These trials were registered at www.clinicaltrials.gov as #NCT00137111 and #NCT00549848.

Genomic Determinants of Outcome in Acute Lymphoblastic Leukemia

PURPOSE

Although cure rates for childhood acute lymphoblastic leukemia (ALL) exceed 90%, ALL remains a leading cause of cancer death in children. Half of relapses arise in children initially classified with standard-risk (SR) disease.

MATERIALS AND METHODS

To identify genomic determinants of relapse in children with SR ALL, we performed genome and transcriptome sequencing of diagnostic and remission samples of children with SR (n = 1,381) or high-risk B-ALL with favorable cytogenetic features (n = 115) enrolled on Children's Oncology Group trials. We used a case-control study design analyzing 439 patients who relapsed and 1,057 who remained in complete remission for at least 5 years.

RESULTS

Genomic subtype was associated with relapse, which occurred in approximately 50% of cases of PAX5-altered ALL (odds ratio [OR], 3.31 [95% CI, 2.17 to 5.03]; P = 3.18 × 10-8). Within high-hyperdiploid ALL, gain of chromosome 10 with disomy of chromosome 7 was associated with favorable outcome (OR, 0.27 [95% CI, 0.17 to 0.42]; P = 8.02 × 10-10; St Jude Children's Research Hospital validation cohort: OR, 0.22 [95% CI, 0.05 to 0.80]; P = .009), and disomy of chromosomes 10 and 17 with gain of chromosome 6 was associated with relapse (OR, 7.16 [95% CI, 2.63 to 21.51]; P = 2.19 × 10-5; validation cohort: OR, 21.32 [95% CI, 3.62 to 119.30]; P = .0004). Genomic alterations were associated with relapse in a subtype-dependent manner, including alterations of INO80 in ETV6::RUNX1 ALL, IKZF1, and CREBBP in high-hyperdiploid ALL and FHIT in BCR::ABL1-like ALL. Genomic alterations were also associated with the presence of minimal residual disease, including NRAS and CREBBP in high-hyperdiploid ALL.

CONCLUSION

Genetic subtype, patterns of aneuploidy, and secondary genomic alterations determine risk of relapse in childhood ALL. Comprehensive genomic analysis is required for optimal risk stratification.

Insights into the Clinical, Biological and Therapeutic Impact of Copy Number Alteration in Cancer

Copy number alterations (CNAs), resulting from the gain or loss of genetic material from as little as 50 base pairs or as big as entire chromosome(s), have been associated with many congenital diseases, de novo syndromes and cancer. It is established that CNAs disturb the dosage of genomic regions including enhancers/promoters, long non-coding RNA and gene(s) among others, ultimately leading to an altered balance of key cellular functions. In cancer, CNAs have been associated with almost all steps of the disease: predisposition, initiation, development, maintenance, response to treatment, resistance, and relapse. Therefore, understanding how specific CNAs contribute to tumourigenesis may provide prognostic insight and ultimately lead to the development of new therapeutic approaches to improve patient outcomes. In this review, we provide a snapshot of what is currently known about CNAs and cancer, incorporating topics regarding their detection, clinical impact, origin, and nature, and discuss the integration of innovative genetic engineering strategies, to highlight the potential for targeting CNAs using novel, dosage-sensitive and less toxic therapies for CNA-driven cancer.

Fifth Edition of the World Health Organization Classification of Tumors of the Hematopoietic and Lymphoid Tissues: Acute Lymphoblastic Leukemias, Mixed-Phenotype Acute Leukemias, Myeloid/Lymphoid Neoplasms With Eosinophilia, Dendritic/Histiocytic Neoplasms, and Genetic Tumor Syndromes

This manuscript represents a review of lymphoblastic leukemia/lymphoma (acute lymphoblastic leukemia/lymphoblastic lymphoma), acute leukemias of ambiguous lineage, mixed-phenotype acute leukemias, myeloid/lymphoid neoplasms with eosinophilia and defining gene rearrangements, histiocytic and dendritic neoplasms, and genetic tumor syndromes of the 5th edition of the World Health Organization Classification of Tumors of the Hematopoietic and Lymphoid Tissues. The diagnostic, clinicopathologic, cytogenetic, and molecular genetic features are discussed. The differences in comparison to the 4th revised edition of the World Health Organization classification of hematolymphoid neoplasms are highlighted.

The Eμ-Ret mouse is a novel model of hyperdiploid B-cell acute lymphoblastic leukemia

The presence of supernumerary chromosomes is the only abnormality shared by all patients diagnosed with high-hyperdiploid B cell acute lymphoblastic leukemia (HD-ALL). Despite being the most frequently diagnosed pediatric leukemia, the lack of clonal molecular lesions and complete absence of appropriate experimental models have impeded the elucidation of HD-ALL leukemogenesis. Here, we report that for 23 leukemia samples isolated from moribund Eμ-Ret mice, all were characterized by non-random chromosomal gains, involving combinations of trisomy 9, 12, 14, 15, and 17. With a median gain of three chromosomes, leukemia emerged after a prolonged latency from a preleukemic B cell precursor cell population displaying more diverse aneuploidy. Transition from preleukemia to overt disease in Eμ-Ret mice is associated with acquisition of heterogeneous genomic abnormalities affecting the expression of genes implicated in pediatric B-ALL. The development of abnormal centrosomes in parallel with aneuploidy renders both preleukemic and leukemic cells sensitive to inhibitors of centrosome clustering, enabling targeted in vivo depletion of leukemia-propagating cells. This study reveals the Eμ-Ret mouse to be a novel tool for investigating HD-ALL leukemogenesis, including supervision and selection of preleukemic aneuploid clones by the immune system and identification of vulnerabilities that could be targeted to prevent relapse.

Enhanced Risk Stratification for Children and Young Adults with B-Cell Acute Lymphoblastic Leukemia: A Children's Oncology Group Report

Current strategies to treat pediatric acute lymphoblastic leukemia rely on risk stratification algorithms using categorical data. We investigated whether using continuous variables assigned different weights would improve risk stratification. We developed and validated a multivariable Cox model for relapse-free survival (RFS) using information from 21199 patients. We constructed risk groups by identifying cutoffs of the COG Prognostic Index (PICOG) that maximized discrimination of the predictive model. Patients with higher PICOG have higher predicted relapse risk. The PICOG reliably discriminates patients with low vs. high relapse risk. For those with moderate relapse risk using current COG risk classification, the PICOG identifies subgroups with varying 5-year RFS. Among current COG standard-risk average patients, PICOG identifies low and intermediate risk groups with 96% and 90% RFS, respectively. Similarly, amongst current COG high-risk patients, PICOG identifies four groups ranging from 96% to 66% RFS, providing additional discrimination for future treatment stratification. When coupled with traditional algorithms, the novel PICOG can more accurately risk stratify patients, identifying groups with better outcomes who may benefit from less intensive therapy, and those who have high relapse risk needing innovative approaches for cure.

RNA-seq-based miRNA signature as an independent predictor of relapse in pediatric B-cell acute lymphoblastic leukemia

ABSTRACT

Aberrant micro-RNA (miRNA) expression profiles have been associated with disease progression and clinical outcome in pediatric cancers. However, few studies have analyzed genome-wide dysregulation of miRNAs and messenger RNAs (mRNAs) in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL). To identify novel prognostic factors, we comprehensively investigated miRNA and mRNA sequencing (miRNA-seq and mRNA-seq) data in pediatric BCP-ALL samples with poor outcome. We analyzed 180 patients, including 43 matched pairs at diagnosis and relapse. Consensus clustering of miRNA expression data revealed a distinct profile characterized by mainly downregulation of miRNAs (referred to as an miR-low cluster [MLC]). The MLC profile was not associated with any known genetic subgroups. Intriguingly, patients classified as MLC had significantly shorter event-free survival (median 21 vs 33 months; log-rank P = 3 ×10-5). Furthermore, this poor prognosis was retained even in hyperdiploid ALL. This poor prognostic MLC profiling was confirmed in the validation cohort. Notably, non-MLC profiling at diagnosis (n = 9 of 23; Fisher exact test, P = .039) often changed into MLC profiling at relapse for the same patient. Integrated analysis of miRNA-seq and mRNA-seq data revealed that the transcriptional profile of MLC was characterized by enrichment of MYC target and oxidative phosphorylation genes, reduced intron retention, and low expression of DICER1. Thus, our miRNA-mRNA integration approach yielded a truly unbiased molecular stratification of pediatric BCP-ALL cases based on a novel prognostic miRNA signature, which may lead to better clinical outcomes.

Association between Leukemic Evolution and Uncommon Chromosomal Alterations in Pediatric Myelodysplastic Syndrome

Background

Pediatric myelodysplastic syndrome (pMDS) is a group of rare clonal neoplasms with a difficult diagnosis and risk of progression to acute myeloid leukemia (AML). The early stratification in risk groups is essential to choose the treatment and indication for allogeneic hematopoietic stem cell transplantation (HSCT). According to the Revised International Prognostic Scoring System, cytogenetic analysis has demonstrated an essential role in diagnosis and prognosis. In pMDS, abnormal karyotypes are present in 30-50% of the cases. Monosomy 7 is the most common chromosomal alteration associated with poor prognosis. However, the rarity of specific cytogenetic alterations makes its prognosis uncertain. Thus, this study aimed to describe uncommon cytogenetic alterations in a cohort of 200 pMDS patients and their association with evolution to AML.

Methods

The cytogenetic analysis was performed in 200 pMDS patients by G-banding and fluorescence in situ hybridization between 2000 to 2022.

Results

Rare chromosome alterations were observed in 7.5% (15/200) of the cases. These chromosome alterations were divided into four cytogenetic groups: hyperdiploidy, biclonal chromosomal alterations, translocations, and uncommon deletions representing 33.3%, 33.3%, 20%, and 13.3%, respectively. Most of these patients (10/15) were classified with advanced MDS (MDS-EB and MDS/AML) and the initial subtype was present in five patients (RCC). The leukemic evolution was observed in 66.66% (10/15) of the patients. Most patients had poor clinical outcomes and they were indicated for HSCT.

Conclusion

The study of uncommon cytogenetic alterations in pMDS is important to improve the prognosis and guide early indication of HSCT.

Prognostic and Pharmacotypic Heterogeneity of Hyperdiploidy in Childhood ALL

PURPOSE

High hyperdiploidy, the largest and favorable subtype of childhood ALL, exhibits significant biological and prognostic heterogeneity. However, factors contributing to the varied treatment response and the optimal definition of hyperdiploidy remain uncertain.

METHODS

We analyzed outcomes of patients treated on two consecutive frontline ALL protocols, using six different definitions of hyperdiploidy: chromosome number 51-67 (Chr51-67); DNA index (DI; DI1.16-1.6); United Kingdom ALL study group low-risk hyperdiploid, either trisomy of chromosomes 17 and 18 or +17 or +18 in the absence of +5 and +20; single trisomy of chromosome 18; double trisomy of chromosomes 4 and 10; and triple trisomy (TT) of chromosomes 4, 10, and 17. Additionally, we characterized ALL ex vivo pharmacotypes across eight main cytotoxic drugs.

RESULTS

Among 1,096 patients analyzed, 915 had B-ALL and 634 had pharmacotyping performed. In univariate analysis, TT emerged as the most favorable criterion for event-free survival (EFS; 10-year EFS, 97.3% v 86.8%; P = .0003) and cumulative incidence of relapse (CIR; 10-year CIR, 1.4% v 8.8%; P = .002) compared with the remaining B-ALL. In multivariable analysis, accounting for patient numbers using the akaike information criterion (AIC), DI1.16-1.6 was the most favorable criterion, exhibiting the best AIC for both EFS (hazard ratio [HR], 0.45; 95% CI, 0.23 to 0.88) and CIR (HR, 0.45; 95% CI, 0.21 to 0.99). Hyperdiploidy and subgroups with favorable prognoses exhibited notable sensitivities to asparaginase and mercaptopurine. Specifically, asparaginase sensitivity was associated with trisomy of chromosomes 16 and 17, whereas mercaptopurine sensitivity was linked to gains of chromosomes 14 and 17.

CONCLUSION

Among different definitions of hyperdiploid ALL, DI is optimal based on independent prognostic impact and also the large proportion of low-risk patients identified. Hyperdiploid ALL exhibited particular sensitivities to asparaginase and mercaptopurine, with chromosome-specific associations.

Paediatric B lymphoblastic leukaemia with hyperdiploidy and a false-positive KMT2A fluorescence in situ hybridization result

The dramatic improvement in the event-free survival of paediatric B-lymphoblastic leukaemia (B-ALL) has led to risk-stratified treatment. Through a combination of clinical features, cytogenetic abnormalities and assessment of treatment response, patients are stratified to receive different intensities of therapy. The presence of high hyperdiploidy (>50 chromosomes) is considered a favourable genetic feature. Conversely, KMT2A fusion genes in B-ALL are associated with a poor prognosis, resulting in intensification of treatment. We present a seven-year-old female with B-ALL, a high hyperdiploid karyotype (56 chromosomes) and KMT2A rearrangement detected on FISH, but with no productive fusion identified. Single nucleotide polymorphism (SNP) array suggested the KMT2A rearrangement was due to chromosome 11 chromothripsis. Subsequent targeted RNA fusion panel and whole transcriptomic sequencing (mRNA-seq) did not detect an expressed KMT2A fusion. Differential expression analyses of the mRNA-seq data led to clustering of this case with other hyperdiploid cases, consistent with the hyperdiploid cytogenetic results. Given the additional intensity and potential toxicity of high-risk treatment, unusual findings by chromosome analysis, FISH and/or chromosomal microarray should prompt consideration of testing for a KMT2A fusion by another method to avoid misclassification.

Cytogenetics in the management of B-cell acute lymphoblastic leukemia: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Cytogenetic analysis is mandatory at initial assessment of B-cell acute lymphoblastic leukemia (B-ALL) due to its diagnostic and prognostic value. Results from chromosome banding analysis and complementary FISH are taken into account in therapeutic protocols and further completed by other techniques (RT-PCR, SNP-array, MLPA, NGS, OGM). Indeed, new genomic entities have been identified by NGS, mostly RNA sequencing, such as Ph-like ALL that can benefit from targeted therapy. Here, we have attempted to establish cytogenetic guidelines by reviewing the most recent published data including the novel 5th World Health Organization and International Consensus Classifications. We also focused on newly described cytogenomic entities and indicate alternative diagnostic tools such as NGS technology, as its importance is vastly increasing in the diagnostic setting.

Optical Genome Mapping Identifies Novel Recurrent Structural Alterations in Childhood ETV6::RUNX1+ and High Hyperdiploid Acute Lymphoblastic Leukemia

The mutational landscape of B-cell precursor acute lymphoblastic leukemia (BCP-ALL), the most common pediatric cancer, is not fully described partially because commonly applied short-read next generation sequencing has a limited ability to identify structural variations. By combining comprehensive analysis of structural variants (SVs), single-nucleotide variants (SNVs), and small insertions-deletions, new subtype-defining and therapeutic targets may be detected. We analyzed the landscape of somatic alterations in 60 pediatric patients diagnosed with the most common BCP-ALL subtypes, ETV6::RUNX1+ and classical hyperdiploid (HD), using conventional cytogenetics, single nucleotide polymorphism (SNP) array, whole exome sequencing (WES), and the novel optical genome mapping (OGM) technique. Ninety-five percent of SVs detected by cytogenetics and SNP-array were verified by OGM. OGM detected an additional 677 SVs not identified using the conventional methods, including (subclonal) IKZF1 deletions. Based on OGM, ETV6::RUNX1+ BCP-ALL harbored 2.7 times more SVs than HD BCP-ALL, mainly focal deletions. Besides SVs in known leukemia development genes (ETV6, PAX5, BTG1, CDKN2A), we identified 19 novel recurrently altered regions (in n ≥ 3) including 9p21.3 (FOCAD/HACD4), 8p11.21 (IKBKB), 1p34.3 (ZMYM1), 4q24 (MANBA), 8p23.1 (MSRA), and 10p14 (SFMBT2), as well as ETV6::RUNX1+ subtype-specific SVs (12p13.1 (GPRC5A), 12q24.21 (MED13L), 18q11.2 (MIB1), 20q11.22 (NCOA6)). We detected 3 novel fusion genes (SFMBT2::DGKD, PDS5B::STAG2, and TDRD5::LPCAT2), for which the sequence and expression were validated by long-read and whole transcriptome sequencing, respectively. OGM and WES identified double hits of SVs and SNVs (ETV6, BTG1, STAG2, MANBA, TBL1XR1, NSD2) in the same patient demonstrating the power of the combined approach to define the landscape of genomic alterations in BCP-ALL.

PersonALL: a genetic scoring guide for personalized risk assessment in pediatric B-cell precursor acute lymphoblastic leukemia

BACKGROUND

Recurrent genetic lesions provide basis for risk assessment in pediatric acute lymphoblastic leukemia (ALL). However, current prognostic classifiers rely on a limited number of predefined sets of alterations.

METHODS

Disease-relevant copy number aberrations (CNAs) were screened genome-wide in 260 children with B-cell precursor ALL. Results were integrated with cytogenetic data to improve risk assessment.

RESULTS

CNAs were detected in 93.8% (n = 244) of the patients. First, cytogenetic profiles were combined with IKZF1 status (IKZF1normal, IKZF1del and IKZF1plus) and three prognostic subgroups were distinguished with significantly different 5-year event-free survival (EFS) rates, IKAROS-low (n = 215): 86.3%, IKAROS-medium (n = 27): 57.4% and IKAROS-high (n = 18): 37.5%. Second, contribution of genetic aberrations to the clinical outcome was assessed and an aberration-specific score was assigned to each prognostically relevant alteration. By aggregating the scores of aberrations emerging in individual patients, personalized cumulative values were calculated and used for defining four prognostic subgroups with distinct clinical outcomes. Two favorable subgroups included 60% of patients (n = 157) with a 5-year EFS of 96.3% (excellent risk, n = 105) and 87.2% (good risk, n = 52), respectively; while 40% of patients (n = 103) showed high (n = 74) or ultra-poor (n = 29) risk profile (5-year EFS: 67.4% and 39.0%, respectively).

CONCLUSIONS

PersonALL, our conceptually novel prognostic classifier considers all combinations of co-segregating genetic alterations, providing a highly personalized patient stratification.

Overview on Aneuploidy in Childhood B-Cell Acute Lymphoblastic Leukemia

Recent years have brought significant progress in the treatment of B-cell acute lymphoblastic leukemia (ALL). This was influenced by both the improved schemes of conventionally used therapy, as well as the development of new forms of treatment. As a consequence, 5-year survival rates have increased and now exceed 90% in pediatric patients. For this reason, it would seem that everything has already been explored in the context of ALL. However, delving into its pathogenesis at the molecular level shows that there are many variations that still need to be analyzed in more detail. One of them is aneuploidy, which is among the most common genetic changes in B-cell ALL. It includes both hyperdiploidy and hypodiploidy. Knowledge of the genetic background is important already at the time of diagnosis, because the first of these forms of aneuploidy is characterized by a good prognosis, in contrast to the second, which is in favor of an unfavorable course. In our work, we will focus on summarizing the current state of knowledge on aneuploidy, along with an indication of all the consequences that may be correlated with it in the context of the treatment of patients with B-cell ALL.

Childhood Acute Lymphoblastic Leukemia: Results of the Randomized Acute Lymphoblastic Leukemia Intercontinental-Berlin-Frankfurt-Münster 2009 Trial

PURPOSE

The International Berlin-Frankfurt-Münster (BFM) study group conducted a study on pediatric acute lymphoblastic leukemia (ALL). Minimal residual disease (MRD) was assessed using flow cytometry (FCM), and the impact of early intensification and methotrexate (MTX) dose on survival was evaluated.

PATIENTS AND METHODS

We included 6,187 patients younger than 19 years. MRD by FCM refined the risk group definition previously used in the ALL intercontinental-BFM 2002 study on the basis of age, WBC count, unfavorable genetic aberrations, and treatment response measured morphologically. Patients at intermediate risk (IR) and high risk (HR) were randomly assigned to protocol augmented protocol I phase B (IB) versus IB regimen. MTX doses of 2 versus 5 g/m² every 2 weeks, four times, were evaluated in precursor B-cell-ALL (pcB-ALL) IR.

RESULTS

The 5-year event-free survival (EFS ± SE) and overall survival (OS ± SE) rates were 75.2% ± 0.6% and 82.6% ± 0.5%, respectively. Their values in risk groups were standard risk (n = 624), 90.7% ± 1.4% and 94.7% ± 1.1%; IR (n = 4,111), 77.9% ± 0.7% and 85.7% ± 0.6%; and HR (n = 1,452), 60.8% ± 1.5% and 68.4% ± 1.4%, respectively. MRD by FCM was available in 82.6% of cases. The 5-year EFS rates in patients randomly assigned to protocol IB (n = 1,669) and augmented IB (n = 1,620) were 73.6% ± 1.2% and 72.8% ± 1.2%, respectively (P = .55), while those in patients receiving MTX doses of 2 g/m² (n = 1,056) and MTX 5 g/m² (n = 1,027) were 78.8% ± 1.4% and 78.9% ± 1.4%, respectively (P = .84).

CONCLUSION

The MRDs were successfully assessed using FCM. An MTX dose of 2 g/m² was effective in preventing relapse in non-HR pcB-ALL. Augmented IB showed no advantages over the standard IB.

The Prognostic Effect of IKZF1 Deletions in ETV6::RUNX1 and High Hyperdiploid Childhood Acute Lymphoblastic Leukemia

IKZF1 deletions are an established prognostic factor in childhood acute lymphoblastic leukemia (ALL). However, their relevance in patients with good risk genetics, namely ETV6::RUNX1 and high hyperdiploid (HeH), ALL remains unclear. We assessed the prognostic impact of IKZF1 deletions in 939 ETV6::RUNX1 and 968 HeH ALL patients by evaluating data from 16 trials from 9 study groups. Only 3% of ETV6::RUNX1 cases (n = 26) were IKZF1-deleted; this adversely affected survival combining all trials (5-year event-free survival [EFS], 79% versus 92%; P = 0.02). No relapses occurred among the 14 patients with an IKZF1 deletion treated on a minimal residual disease (MRD)-guided protocols. Nine percent of HeH cases (n = 85) had an IKZF1 deletion; this adversely affected survival in all trials (5-year EFS, 76% versus 89%; P = 0.006) and in MRD-guided protocols (73% versus 88%; P = 0.004). HeH cases with an IKZF1 deletion had significantly higher end of induction MRD values (P = 0.03). Multivariate Cox regression showed that IKZF1 deletions negatively affected survival independent of sex, age, and white blood cell count at diagnosis in HeH ALL (hazard ratio of relapse rate [95% confidence interval]: 2.48 [1.32-4.66]). There was no evidence to suggest that IKZF1 deletions affected outcome in the small number of ETV6::RUNX1 cases in MRD-guided protocols but that they are related to higher MRD values, higher relapse, and lower survival rates in HeH ALL. Future trials are needed to study whether stratifying by MRD is adequate for HeH patients or additional risk stratification is necessary.

[Clinical features and prognosis of high hyperdiploid childhood acute lymphoblastic leukemia: a multicenter retrospective analysis in Fujian Province, China]

OBJECTIVES

To study the clinical features and prognosis of high hyperdiploid (HHD) childhood acute lymphoblastic leukemia (ALL).

METHODS

A retrospective analysis was performed on the medical data of 1 414 children who were newly diagnosed with ALL and were admitted to five hospitals in Fujian Province of China from April 2011 to December 2020. According to karyotype, they were divided into two groups: HHD (n=172) and non-HHD (n=1 242). The clinical features and treatment outcome were compared between the two groups, and the factors influencing the prognosis were further explored.

RESULTS

Among the 1 414 children with ALL, 172 (12.16%) had HHD. Compared with the non-HHD group, the HHD group had significantly lower proportions of children with risk factors for poor prognosis at diagnosis (age of onset ≥10 years or <1 year, white blood cell count ≥50×109/L, and T-cell phenotype) or positive fusion genes (TEL-AML1, BCR-ABL1, E2A-PBX1, and MLL gene rearrangement) (P<0.05). The HHD group had a significantly higher proportion of children with minimal residual disease (MRD) <0.01% at the end of induction chemotherapy (P<0.05). The 10-year event-free survival (EFS) rate and overall survival (OS) rate in the HHD group were significantly higher than those in the non-HHD group (P<0.05). The univariate analysis showed that the number of chromosomes of 58-66, trisomy of chromosome 10, trisomy of chromosome 17, bone marrow MRD <1% on day 15 or 19 of induction chemotherapy, and bone marrow MRD <0.01% on day 33 or 46 of induction chemotherapy were associated with a higher EFS rate (P<0.05), and trisomy of chromosome 10 was associated with a higher OS rate (P<0.05). The multivariate Cox analysis showed that trisomy of chromosome 17 was closely associated with a high EFS rate (P<0.05).

CONCLUSIONS

The ALL children with HHD have few risk factors for poor prognosis at diagnosis and often have good prognosis. The number of chromosomes and trisomy of specific chromosomes are associated with prognosis in these children.

Hyperdiploidy: the longest known, most prevalent, and most enigmatic form of acute lymphoblastic leukemia in children

Hyperdiploidy is the largest genetic entity B-cell precursor acute lymphoblastic leukemia in children. The diagnostic hallmark of its two variants that will be discussed in detail herein is a chromosome count between 52 and 67, respectively. The classical HD form consists of heterozygous di-, tri-, and tetrasomies, whereas the nonclassical one (usually viewed as "duplicated hyperhaploid") contains only disomies and tetrasomies. Despite their apparently different clinical behavior, we show that these two sub-forms can in principle be produced by the same chromosomal maldistribution mechanism. Moreover, their respective array, gene expression, and mutation patterns also indicate that they are biologically more similar than hitherto appreciated. Even though in-depth analyses of the genomic intricacies of classical HD leukemias are indispensable for the elucidation of the disease process, the ensuing results play at present surprisingly little role in treatment stratification, a fact that can be attributed to the overall good prognoses and low relapse rates of the concerned patients and, consequently, their excellent treatment outcome. Irrespective of this underutilization, however, the detailed genetic characterization of HD leukemias may, especially in planned treatment reduction trials, eventually become important for further treatment stratification, patient management, and the clinical elucidation of outcome data. It should therefore become an integral part of all upcoming treatment studies.

Real-World Cost of Pediatric Acute Lymphoblastic Leukemia Care Among Commercially Insured Individuals in the United States: Effect of Era and Age at Diagnosis

PURPOSE

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Five-year survival is approaching 90%. In efforts to further improve outcomes, it is critical to consider the cost of ALL care.

MATERIALS AND METHODS

Commercial insurance data from OptumLabs Data Warehouse were used to identify patients with ALL, age 1-30 years, diagnosed in 1993-2017 in the United States, with 36 months of continuous insurance coverage. Patients treated with hematopoietic cell transplantation were excluded. Inpatient and outpatient utilization and cumulative reimbursements (inflation-adjusted to December 2020) were computed 8 and 36 months from diagnosis and stratified by age (1-9, 10-12, and ≥ 13 years) as proxies for National Cancer Institute risk groups. Regression models were constructed to assess associations with demographic and clinical characteristics.

RESULTS

Among 927 patients (median age, 6 years; interquartile range, 3-12 years; 43% female), individuals age ≥ 10 years had 23-25 more inpatient days and 22 more outpatient encounters compared with younger patients. The 36-month median cost was $394,000 (USD) (interquartile range, $256,000-$695,000 [USD]), and 64% of the total cost was incurred during the initial 8 months. The 36-month cost was 1.5-fold higher for those age 10-12 years and 1.7-fold higher for those age ≥ 13 years compared with 1-9 years. The cost for those diagnosed in 2013-2017 was 70% higher compared with 1993-2002, and was not different on the basis of sex, race, or ethnicity.

CONCLUSION

Older age was associated with higher utilization and cost, and the cost of treatment increased significantly over time. These data provide valuable benchmarks for future studies examining the cost-benefit of ALL therapy modifications.

Increasing Complexity of Molecular Landscapes in Human Hematopoietic Stem and Progenitor Cells during Development and Aging

The past five decades have seen significant progress in our understanding of human hematopoiesis. This has in part been due to the unprecedented development of advanced technologies, which have allowed the identification and characterization of rare subsets of human hematopoietic stem and progenitor cells and their lineage trajectories from embryonic through to adult life. Additionally, surrogate in vitro and in vivo models, although not fully recapitulating human hematopoiesis, have spurred on these scientific advances. These approaches have heightened our knowledge of hematological disorders and diseases and have led to their improved diagnosis and therapies. Here, we review human hematopoiesis at each end of the age spectrum, during embryonic and fetal development and on aging, providing exemplars of recent progress in deciphering the increasingly complex cellular and molecular hematopoietic landscapes in health and disease. This review concludes by highlighting links between chronic inflammation and metabolic and epigenetic changes associated with aging and in the development of clonal hematopoiesis.

Resistance Mechanisms in Pediatric B-Cell Acute Lymphoblastic Leukemia

Despite the rapid development of medicine, even nowadays, acute lymphoblastic leukemia (ALL) is still a problem for pediatric clinicians. Modern medicine has reached a limit of curability even though the recovery rate exceeds 90%. Relapse occurs in around 20% of treated patients and, regrettably, 10% of diagnosed ALL patients are still incurable. In this article, we would like to focus on the treatment resistance and disease relapse of patients with B-cell leukemia in the context of prognostic factors of ALL. We demonstrate the mechanisms of the resistance to steroid therapy and Tyrosine Kinase Inhibitors and assess the impact of genetic factors on the treatment resistance, especially TCF3::HLF translocation. We compare therapeutic protocols and decipher how cancer cells become resistant to innovative treatments—including CAR-T-cell therapies and monoclonal antibodies. The comparisons made in our article help to bring closer the main factors of resistance in hematologic malignancies in the context of ALL.

Genetic Biomarkers and Their Clinical Implications in B-Cell Acute Lymphoblastic Leukemia in Children

Acute lymphoblastic leukemia (ALL) is a heterogeneous group of hematologic malignancies characterized by abnormal proliferation of immature lymphoid cells. It is the most commonly diagnosed childhood cancer with an almost 80% cure rate. Despite favorable survival rates in the pediatric population, a significant number of patients develop resistance to therapy, resulting in poor prognosis. ALL is a heterogeneous disease at the genetic level, but the intensive development of sequencing in the last decade has made it possible to broaden the study of genomic changes. New technologies allow us to detect molecular changes such as point mutations or to characterize epigenetic or proteomic profiles. This process made it possible to identify new subtypes of this disease characterized by constellations of genetic alterations, including chromosome changes, sequence mutations, and DNA copy number alterations. These genetic abnormalities are used as diagnostic, prognostic and predictive biomarkers that play an important role in earlier disease detection, more accurate risk stratification, and treatment. Identification of new ALL biomarkers, and thus a greater understanding of their molecular basis, will lead to better monitoring of the course of the disease. In this article, we provide an overview of the latest information on genomic alterations found in childhood ALL and discuss their impact on patients' clinical outcomes.