Outcome of treatment in childhood acute lymphoblastic leukaemia with rearrangements of the 11q23 chromosomal region

S100A6 Regulates nucleus pulposus cell apoptosis via Wnt/β-catenin signaling pathway: an in vitro and in vivo study

BACKGROUND

Intervertebral disc degeneration (IDD) is a common musculoskeletal degenerative disease, which often leads to low back pain and even disability, resulting in loss of labor ability and decreased quality of life. Although many progresses have been made in the current research, the underlying mechanism of IDD remains unclear. The apoptosis of nucleus pulposus (NP) cells (NPCs) is an important pathological mechanism in intervertebral disc degeneration (IDD). This study evaluated the relationship between S100A6 and NPCs and its underlying mechanism.

METHODS

Mass spectrometry, bioinformatics, and quantitative real-time polymerase chain reaction (qRT-PCR) analyses were used to screen and verify hub genes for IDD in human IVD specimens with different degeneration degrees. Western blotting, immunohistochemistry (IHC), and/or immunofluorescence (IF) were used to detect the expression level of S100A6 in human NP tissues and NPCs. The apoptotic phenotype of NPCs and Wnt/β-catenin signaling pathway were evaluated using flow cytometry, western blotting, and IF. S100A6 was overexpressed or knocked down in NPCs to determine its impact on apoptosis and Wnt/β-catenin signaling pathway activity. Moreover, we used the XAV-939 to inhibit and SKL2001 to activate the Wnt/β-catenin signaling pathway. The therapeutic effect of S100A6 inhibition on IDD was also evaluated.

RESULTS

S100A6 expression increased in IDD. In vitro, increased S100A6 expression promoted apoptosis in interleukin (IL)-1β-induced NPCs. In contrast, the inhibition of S100A6 expression partially alleviated the progression of annulus fibrosus (AF) puncture-induced IDD in rats. Mechanistic studies revealed that S100A6 regulates NPC apoptosis via Wnt/β-catenin signaling pathway.

CONCLUSIONS

This study showed that S100A6 expression increased during IDD and promoted NPCs apoptosis by regulating the Wnt/β-catenin signaling pathway, suggesting that S100A6 is a promising new therapeutic target for IDD.

The RORɣ/SREBP2 pathway is a master regulator of cholesterol metabolism and serves as potential therapeutic target in t(4;11) leukemia

Dysregulated cholesterol homeostasis promotes tumorigenesis and progression. Therefore, metabolic reprogramming constitutes a new hallmark of cancer. However, until today, only few therapeutic approaches exist to target this pathway due to the often-observed negative feedback induced by agents like statins leading to controversially increased cholesterol synthesis upon inhibition. Sterol regulatory element-binding proteins (SREBPs) are key transcription factors regulating the synthesis of cholesterol and fatty acids. Since SREBP2 is difficult to target, we performed pharmacological inhibition of retinoic acid receptor (RAR)-related orphan receptor gamma (RORγ), which acts upstream of SREBP2 and serves as master regulator of the cholesterol metabolism. This resulted in an inactivated cholesterol-related gene program with significant downregulation of cholesterol biosynthesis. Strikingly, these effects were more pronounced than the effects of fatostatin, a direct SREBP2 inhibitor. Upon RORγ inhibition, RNA sequencing showed strongly increased cholesterol efflux genes leading to leukemic cell death and cell cycle changes in a dose- and time-dependent manner. Combinatorial treatment of t(4;11) cells with the RORγ inhibitor showed additive effects with cytarabine and even strong anti-leukemia synergism with atorvastatin by circumventing the statin-induced feedback. Our results suggest a novel therapeutic strategy to inhibit tumor-specific cholesterol metabolism for the treatment of t(4;11) leukemia.

Discovery, Structure-Activity Relationship and In Vitro Anticancer Activity of Small-Molecule Inhibitors of the Protein-Protein Interactions between AF9/ENL and AF4 or DOT1L

Chromosomal translocations involving the mixed lineage leukemia (MLL) gene cause 5-10% acute leukemias with poor clinical outcomes. Protein-protein interactions (PPI) between the most frequent MLL fusion partner proteins AF9/ENL and AF4 or histone methyltransferase DOT1L are drug targets for MLL-rearranged (MLL-r) leukemia. Several benzothiophene-carboxamide compounds were identified as novel inhibitors of these PPIs with IC50 values as low as 1.6 μM. Structure-activity relationship studies of 77 benzothiophene and related indole and benzofuran compounds show that a 4-piperidin-1-ylphenyl or 4-pyrrolidin-1-ylphenyl substituent is essential for the activity. The inhibitors suppressed expression of MLL target genes HoxA9, Meis1 and Myc, and selectively inhibited proliferation of MLL-r and other acute myeloid leukemia cells with EC50 values as low as 4.7 μM. These inhibitors are useful chemical probes for biological studies of AF9/ENL, as well as pharmacological leads for further drug development against MLL-r and other leukemias.

The Role of S100A6 in Human Diseases: Molecular Mechanisms and Therapeutic Potential

S100A6, also known as calcyclin, is a low-molecular-weight Ca2+-binding protein from the S100 family that contains two EF-hands. S100A6 is expressed in a variety of mammalian cells and tissues. It is also expressed in lung, colorectal, pancreatic, and liver cancers, as well as other cancers such as melanoma. S100A6 has many molecular functions related to cell proliferation, the cell cycle, cell differentiation, and the cytoskeleton. It is not only involved in tumor invasion, proliferation, and migration, but also the pathogenesis of other non-neoplastic diseases. In this review, we focus on the molecular mechanisms and potential therapeutic targets of S100A6 in tumors, nervous system diseases, leukemia, endometriosis, cardiovascular disease, osteoarthritis, and other related diseases.

The KMT2A recombinome of acute leukemias in 2023

Chromosomal rearrangements of the human KMT2A/MLL gene are associated with de novo as well as therapy-induced infant, pediatric, and adult acute leukemias. Here, we present the data obtained from 3401 acute leukemia patients that have been analyzed between 2003 and 2022. Genomic breakpoints within the KMT2A gene and the involved translocation partner genes (TPGs) and KMT2A-partial tandem duplications (PTDs) were determined. Including the published data from the literature, a total of 107 in-frame KMT2A gene fusions have been identified so far. Further 16 rearrangements were out-of-frame fusions, 18 patients had no partner gene fused to 5'-KMT2A, two patients had a 5'-KMT2A deletion, and one ETV6::RUNX1 patient had an KMT2A insertion at the breakpoint. The seven most frequent TPGs and PTDs account for more than 90% of all recombinations of the KMT2A, 37 occur recurrently and 63 were identified so far only once. This study provides a comprehensive analysis of the KMT2A recombinome in acute leukemia patients. Besides the scientific gain of information, genomic breakpoint sequences of these patients were used to monitor minimal residual disease (MRD). Thus, this work may be directly translated from the bench to the bedside of patients and meet the clinical needs to improve patient survival.

Targeting FLT3-specific chimeric antigen receptor T cells for acute lymphoblastic leukemia with KMT2A rearrangement

CD19-specific chimeric antigen receptor T (CAR T) immunotherapy is used to treat B-cell malignancies. However, antigen-escape mediated relapse following CAR T therapy has emerged as a major concern. In some relapsed cases, especially KMT2A rearrangement-positive B-acute lymphoblastic leukemia (KMT2A-r B-ALL), most of the B-cell antigens are lost via lineage conversion to the myeloid phenotype, rendering multi-B-cell-antigen-targeted CAR T cell therapy ineffective. Fms-related tyrosine kinase-3 (FLT3) is highly expressed in KMT2A-r B-ALL; therefore, in this study, we aimed to evaluate the antitumor efficacy of CAR T cells targeting both CD19 and FLT3 in KMT2A-r B-ALL cells. We developed piggyBac transposon-mediated CAR T cells targeting CD19, FLT3, or both (dual) and generated CD19-negative KMT2A-r B-ALL models through CRISPR-induced CD19 gene-knockout (KO). FLT3 CAR T cells showed antitumor efficacy against CD19-KO KMT2A-r B-ALL cells both in vitro and in vivo; dual-targeted CAR T cells showed cytotoxicity against wild-type (WT) and CD19-KO KMT2A-r B-ALL cells, whereas CD19 CAR T cells demonstrated cytotoxicity only against WT KMT2A-r B-ALL cells in vitro. Therefore, targeting FLT3-specific CAR T cells would be a promising strategy for KMT2A-r B-ALL cells even with CD19-negative relapsed cases.

Outcomes of Childhood Noninfant Acute Lymphoblastic Leukemia With 11q23/KMT2A Rearrangements in a Modern Therapy Era: A Retrospective International Study

PURPOSE

We aimed to study prognostic factors and efficacy of allogeneic hematopoietic stem-cell transplantation (allo-HSCT) in first remission of patients with noninfant childhood acute lymphoblastic leukemia (ALL) with 11q23/KMT2A rearrangements treated with chemotherapy regimens between 1995 and 2010.

PATIENTS AND METHODS

Data were retrospectively retrieved from 629 patients with 11q23/KMT2A-rearranged ALL from 17 members of the Ponte-di-Legno Childhood ALL Working Group. Clinical and biologic characteristics, early response assessed by minimal residual disease at the end of induction (EOI) therapy, and allo-HSCT were analyzed for their impact on outcomes.

RESULTS

A specific 11q23/KMT2A translocation partner gene was identified in 84.3% of patients, with the most frequent translocations being t(4;11)(q21;q23) (n = 273; 51.5%), t(11;19)(q23;p13.3) (n = 106; 20.0%), t(9;11)(p21_22;q23) (n = 76; 14.3%), t(6;11)(q27;q23) (n = 20; 3.8%), and t(10;11)(p12;q23) (n = 14; 2.6%); 41 patients (7.7%) had less frequently identified translocation partner genes. Patient characteristics and early response varied among subgroups, indicating large biologic heterogeneity and diversity in therapy sensitivity among 11q23/KMT2A-rearranged ALL. The EOI remission rate was 93.2%, and the 5-year event-free survival (EFS) for the entire cohort was 69.1% ± 1.9%, with a range from 41.7% ± 17.3% for patients with t(9;11)-positive T-ALL (n = 9) and 64.8% ± 3.0% for patients with t(4;11)-positive B-ALL (n = 266) to 91.2% ± 4.9% for patients with t(11;19)-positive T-ALL (n = 34). Low EOI minimal residual disease was associated with favorable EFS, and induction failure was particularly predictive of nonresponse to further therapy and relapse and poor EFS. In addition, EFS was not improved by allo-HSCT compared with chemotherapy only in patients with both t(4;11)-positive B-ALL (n = 64 v 51; P = .10) and 11q23/KMT2A-rearranged T-ALL (n = 16 v 10; P = .69).

CONCLUSION

Compared with historical data, prognosis of patients with noninfant 11q23/KMT2A-rearranged ALL has improved, but allo-HSCT failed to affect outcome. Targeted therapies are needed to reduce relapse and treatment-related mortality rates.

Clinical and Cytogenetic Characteristics of Children With Leukemia 20-Year Retrospective Study

Acute leukemias are the most common malignant diseases in childhood. The aims of this retrospective cohort study were to investigate the frequency of cytogenetic abnormalities in acute pediatric leukemia; the correlation between cytogenetic abnormalities and 5-year survival; and the correlation between cytogenetic abnormalities and clinical and laboratory features. We included 105 patients; acute lymphoblastic leukemia (ALL) had 80.9% patients, B-cell lineage ALL (B-ALL) 84.7% of them, and T-cell lineage (T-ALL) 15.3%. The overall 5-year survival for B-ALL was 85.9% and for T-ALL was 84.6%. The most common cytogenetic abnormalities in patients with B-ALL were t(12;21)(p13.2;q22.1); ETV6-RUNX1 with 22.2% and hyperdiploidy with 19.4%. Our survival analysis showed that t(12;21)(p13.2;q22.1); ETV6-RUNX1 and t(1;19)(q23;p13.3); TCF3-PBX1 had the best 5-year survival with 100% of patients surviving, whereas t(v;11q23.3); KMT2A rearranged had the worst 5-year survival of just 33.3% of patients surviving after 5 years. We found no difference in 5-year survival in B-ALL when comparing clinical features. Acute myelogenous leukemia had 20 patients with 70.6% 5-year survival. The most common cytogenetic abnormality in acute myelogenous leukemia was t(8;21)(q21;q22.1); RUNX1-RUNX1T1 (20%). In conclusion, this study showed the correlation of different cytogenetic abnormalities with 5-year survival in B-ALL patients. Such correlation was not found when comparing clinical features and 5-year survival of patients with B-ALL. This emphasized the significance of cytogenetic analysis in pediatric leukemia.

Targeted Treatment and Immunotherapy in High-risk and Relapsed/ Refractory Pediatric Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia is the most frequent pediatric malignancy in children, comprising 30% of all pediatric malignancies; adult ALL comprises 5% of all ALL cases, which have a 186.6 per 1 million incidence. In pediatric ALL (pALL), on which this review focuses, approximately 1 in 285 children are diagnosed with cancer before the age of 20, and approximately 1 in 530 young adults between the ages of 20 and 39 years old is a childhood cancer survivor. The survival probability in pALL is now very high, approximately 80-90%. Thus, the most important is to improve supportive care and treatment based on relapse risk, optimally being based on the genetic feature of malignant cells. Improvements made by now are mainly the classifying of subgroups based on genetic characteristics such as aneuploidy or translocation and aligning them with treatment response. Relevant genetic changes in ALL pathogenesis are transcription regulators of lymphoid development (PAX5, IKZF1, EBF1, and LEF1) and/or coactivators (TBL1XR1 and ERG), lymphoid signaling (BTLA, and CD200 TOX), and tumor suppressor genes (CDKN2A, CDKN2B, RB1, and TP53). This review aims to summarize treatment strategies inhibiting tyrosine kinases, influencing different signaling pathways, BCL inhibitors, and anti-CD therapy (anti-cluster differentiation therapy) in pALL. CAR T-cell therapy (chimeric antigen receptors T-cell therapy) is under research and requires further development.

The Histone Deacetylase Inhibitor I1 Induces Differentiation of Acute Leukemia Cells With MLL Gene Rearrangements via Epigenetic Modification

Acute leukemia (AL) is characterized by excessive proliferation and impaired differentiation of leukemic cells. AL includes acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Previous studies have demonstrated that about 10% of AML and 22% of ALL are mixed lineage leukemia gene rearrangements (MLLr) leukemia. The prognosis of MLLr leukemia is poor and new therapeutics are urgently needed. Differentiation therapy with all-trans-retinoic acid (ATRA) has prolonged the 5-years disease-free survival rate in acute promyelocytic leukemia (APL), a subtype of AML. However, the differentiation therapy has not been effective in other acute leukemia. Here, we aim to explore the cell differentiation effect of the potent HDACs inhibitor, I1, and the possible mechanism on the MLLr-AML and MLLr-ALL cells (MOLM-13, THP-1, MV4-11 and SEM). It is shown that I1 can significantly inhibit the proliferation and the colony-forming ability of MOLM-13, THP-1, MV4-11 and SEM cells by promoting cell differentiation coupled with cell cycle block at G0/G1 phase. We show that the anti-proliferative effect of I1 attributed to cell differentiation is most likely associated with the HDAC inhibition activity, as assessed by the acetylation of histone H3 and H4, which may dictates the activation of hematopoietic cell lineage pathway in both MOLM-13 and THP-1 cell lines. Moreover, the activity of HDAC inhibition of I1 is stronger than that of SAHA in MOLM-13 and THP-1 cells. Our findings suggest that I1, as a chromatin-remodeling agent, could be a potent epigenetic drug to overcome differentiation block in MLLr-AL patients and would be promising for the treatment of AL.

Impact of high-risk cytogenetics on outcomes for children and young adults receiving CD19-directed CAR T-cell therapy

Chimeric antigen receptor (CAR) T-cell therapy can induce durable remissions of relapsed/refractory B-acute lymphoblastic leukemia (ALL). However, case reports suggested differential outcomes mediated by leukemia cytogenetics. We identified children and young adults with relapsed/refractory CD19+ ALL/lymphoblastic lymphoma treated on 5 CD19-directed CAR T-cell (CTL019 or humanized CART19) clinical trials or with commercial tisagenlecleucel from April 2012 to April 2019. Patients were hierarchically categorized according to leukemia cytogenetics: High-risk lesions were defined as KMT2A (MLL) rearrangements, Philadelphia chromosome (Ph+), Ph-like, hypodiploidy, or TCF3/HLF; favorable as hyperdiploidy or ETV6/RUNX1; and intermediate as iAMP21, IKZF1 deletion, or TCF3/PBX1. Of 231 patients aged 1 to 29, 74 (32%) were categorized as high risk, 28 (12%) as intermediate, 43 (19%) as favorable, and 86 (37%) as uninformative. Overall complete remission rate was 94%, with no difference between strata. There was no difference in relapse-free survival (RFS; P = .8112), with 2-year RFS for the high-risk group of 63% (95% confidence interval [CI], 52-77). There was similarly no difference seen in overall survival (OS) (P = .5488), with 2-year OS for the high-risk group of 70% (95% CI, 60-82). For patients with KMT2A-rearranged infant ALL (n = 13), 2-year RFS was 67% (95% CI, 45-99), and OS was 62% (95% CI, 40-95), with multivariable analysis demonstrating no increased risk of relapse (hazard ratio, 0.70; 95% CI, 0.21-2.90; P = .7040) but a higher proportion of relapses associated with myeloid lineage switch and a 3.6-fold increased risk of all-cause death (95% CI, 1.04-12.75; P = .0434). CTL019/huCART19/tisagenlecleucel are effective at achieving durable remissions across cytogenetic categories. Relapsed/refractory patients with high-risk cytogenetics, including KMT2A-rearranged infant ALL, demonstrated high RFS and OS probabilities at 2 years.

The Opportunity of Proteomics to Advance the Understanding of Intra- and Extracellular Regulation of Malignant Hematopoiesis

Fetal and adult hematopoiesis are regulated by largely distinct sets of cell-intrinsic gene regulatory networks as well as extracellular cues in their respective microenvironment. These ontogeny-specific programs drive hematopoietic stem and progenitor cells (HSPCs) in fetus and adult to divergent susceptibility to initiation and progression of hematological malignancies, such as leukemia. Elucidating how leukemogenic hits disturb the intra- and extracellular programs in HSPCs along ontogeny will provide a better understanding of the causes for age-associated differences in malignant hematopoiesis and facilitate the improvement of strategies for prevention and treatment of pediatric and adult acute leukemia. Here, we review current knowledge of the intrinsic and extrinsic programs regulating normal and malignant hematopoiesis, with a particular focus on the differences between infant and adult acute leukemia. We discuss the recent advances in mass spectrometry-based proteomics and its opportunity for resolving the interplay of cell-intrinsic and niche-associated factors in regulating malignant hematopoiesis.

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.

Acute lymphoblastic leukemia in infants: A quarter century of nationwide efforts in Japan

Acute lymphoblastic leukemia (ALL) with KMT2A gene rearrangement (KMT2A-r) in infants is a biologically and clinically unique disease and one of the most difficult to cure forms of pediatric leukemia. Multicenter clinical trials have been carried out in Japan since the mid-1990s by introducing allogeneic hematopoietic stem cell transplantation (HSCT) in first remission, which led to a modest improvement in outcome of infants with KMT2A-r ALL. Because of the emerging evidence that HSCT does not benefit every infant with KMT2A-r ALL, the Japanese Pediatric Leukemia/Lymphoma Study Group trial MLL-10 introduced risk stratification using age and presence of central nervous system leukemia, and introduced intensive chemotherapy, including high-dose cytarabine in early consolidation; indication of HSCT was restricted to the patients with high-risk features. The trial resulted in excellent 3-year event-free survival of 66.2% (standard error, 5.6%) and overall survival of 83.9% (standard error, 4.3%) for 75 patients with KMT2A-r ALL recruited between 2011 and 2015. This Japanese experience and the results of the infant ALL trials worldwide suggest the importance of introducing effective therapy in the early phase of therapy, thus clearing minimal residual disease as rapidly as possible. However, further improvement in outcome is unlikely with conventional treatment approaches. Introduction of biology-driven novel agents and/or immunotherapies through international collaboration would be key solutions to overcome the disease.

A human fetal liver-derived infant MLL-AF4 acute lymphoblastic leukemia model reveals a distinct fetal gene expression program

Although 90% of children with acute lymphoblastic leukemia (ALL) are now cured, the prognosis for infant-ALL remains dismal. Infant-ALL is usually caused by a single genetic hit that arises in utero: an MLL/KMT2A gene rearrangement (MLL-r). This is sufficient to induce a uniquely aggressive and treatment-refractory leukemia compared to older children. The reasons for disparate outcomes in patients of different ages with identical driver mutations are unknown. Using the most common MLL-r in infant-ALL, MLL-AF4, as a disease model, we show that fetal-specific gene expression programs are maintained in MLL-AF4 infant-ALL but not in MLL-AF4 childhood-ALL. We use CRISPR-Cas9 gene editing of primary human fetal liver hematopoietic cells to produce a t(4;11)/MLL-AF4 translocation, which replicates the clinical features of infant-ALL and drives infant-ALL-specific and fetal-specific gene expression programs. These data support the hypothesis that fetal-specific gene expression programs cooperate with MLL-AF4 to initiate and maintain the distinct biology of infant-ALL.

B-cell acute lymphoblastic leukaemia: recent discoveries in molecular pathology, their prognostic significance, and a review of the current classification

Acute lymphoblastic leukaemia (ALL) remains a leading cause of non-traumatic death in children, and the majority of adults diagnosed will succumb to the disease. Recent advances in molecular biology and bioinformatics have enabled more detailed genomic analysis and a better understanding of the molecular biology of ALL. A number of recurrent genomic drivers have recently been described, which not only aid in diagnosis and prognostication, but also may offer opportunities for specific therapeutic targeting. The present review summarises B-ALL genomic pathology at diagnosis, including lesions detectable using traditional cytogenetic methods as well as those detected only through advanced molecular techniques.

Hematopoietic stem cell transplantation for infants with high-risk KMT2A gene-rearranged acute lymphoblastic leukemia

The role of allogeneic hematopoietic stem cell transplantation (HSCT) for infants with acute lymphoblastic leukemia (ALL) and KMT2A gene rearrangement (KMT2A-r) is controversial in terms of both its efficacy and potential for acute and late toxicities. In Japanese Pediatric Leukemia/Lymphoma Study Group trial MLL-10, by introducing intensive chemotherapy, indication of HSCT was restricted to patients with high-risk (HR) features only (KMT2A-r and either age <180 days or presence of central nervous system leukemia). Of the 56 HR patients, 49 achieved complete remission. Forty-three patients received HSCT in first remission including 38 patients receiving protocol-specified HSCT with conditioning consisting of individualized targeted doses of busulfan, etoposide, and cyclophosphamide. Three-year event-free survival (EFS) of 56.8% (95% confidence interval [CI], 42.4% to 68.8%) and overall survival of 80.2% (95% CI, 67.1% to 88.5%) were accomplished. Univariable analysis showed that Interfant-HR criteria and flow cytometric minimal residual disease (MRD; ≥0.01%), both at the end of induction and at the end of consolidation (EOC), were significantly associated with poorer EFS. In the multivariable analysis, positive MRD at EOC was solely associated with poor EFS (P < .001). Rapid pretransplant MRD clearance and tailored HSCT strategy in the MLL-10 trial resulted in a favorable outcome for infants with HR KMT2A-r ALL. However, considering the high rate of potentially life-threatening toxicities and the risk of late effects, its indication should be further restricted or even eliminated in the future by introducing more effective therapeutic modalities with minimal toxicities. This trial was registered at the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) as #UMIN000004801.

Computational modeling reveals key molecular properties and dynamic behavior of disruptor of telomeric silencing 1-like (DOT1L) and partnering complexes involved in leukemogenesis

Disruptor of telomeric silencing 1‐like (DOT1L) is the only non‐SET domain histone lysine methyltransferase (KMT) and writer of H3K79 methylation on nucleosomes marked by H2B ubiquitination. DOT1L has elicited significant attention because of its interaction or fusion with members of the AF protein family in blood cell biology and leukemogenic transformation. Here, our goal was to extend previous structural information by performing a robust molecular dynamic study of DOT1L and its leukemogenic partners combined with mutational analysis. We show that statically and dynamically, D161, G163, E186, and F223 make frequent time‐dependent interactions with SAM, while additional residues T139, K187, and N241 interact with SAM only under dynamics. Dynamics models reveal DOT1L, SAM, and H4 moving as one and show that more than twice the number of DOT1L residues interacts with these partners, relative to the static structure. Mutational analyses indicate that six of these residues are intolerant to substitution. We describe the dynamic behavior of DOT1L interacting with AF10 and AF9. Studies on the dynamics of a heterotrimeric complex of DOT1L1‐AF10 illuminated describe coordinated motions that impact the relative position of the DOT1L HMT domain to the nucleosome. The molecular motions of the DOT1L–AF9 complex are less extensive and highly dynamic, resembling a swivel‐like mechanics. Through molecular dynamics and mutational analysis, we extend the knowledge previous provided by static measurements. These results are important to consider when describing the biochemical properties of DOT1L, under normal and in disease conditions, as well as for the development of novel therapeutic agents.

Genetic Alterations in Childhood Acute Lymphoblastic Leukemia: Interactions with Clinical Features and Treatment Response

Acute lymphoblastic leukemia (ALL) is the most common cancer among children. This aggressive cancer comprises multiple molecular subtypes, each harboring a distinct constellation of somatic, and to a lesser extent, inherited genetic alterations. With recent advances in genomic analyses such as next-generation sequencing techniques, we can now clearly identify >20 different genetic subtypes in ALL. Clinically, identifying these genetic subtypes will better refine risk stratification and determine the optimal intensity of therapy for each patient. Underpinning each genetic subtype are unique clinical and therapeutic characteristics, such as age and presenting white blood cell (WBC) count. More importantly, within each genetic subtype, there is much less variability in treatment response and survival outcomes compared with current risk factors such as National Cancer Institute (NCI) criteria. We review how this new taxonomy of genetic subtypes in childhood ALL interacts with clinical risk factors used widely, i.e., age, presenting WBC, IKZF1del, treatment response, and outcomes.

Identification and characterization of relapse-initiating cells in MLL-rearranged infant ALL by single-cell transcriptomics

Infants with MLL-rearranged infant acute lymphoblastic leukemia (MLL-r iALL) undergo intense therapy to counter a highly aggressive malignancy with survival rates of only 30–40%. The majority of patients initially show therapy response, but in two-thirds of cases the leukemia returns, typically during treatment. The glucocorticoid drug prednisone is established as a major player in the treatment of leukemia and the in vivo response to prednisone monotreatment is currently the best indicator of risk for MLL-r iALL. We used two different single-cell RNA sequencing technologies to analyze the expression of a prednisone-dependent signature, derived from an independent study, in diagnostic bone marrow and peripheral blood biopsies. This allowed us to classify individual leukemic cells as either resistant or sensitive to treatment and show that quantification of these two groups can be used to better predict the occurrence of future relapse in individual patients. This work also sheds light on the nature of the therapy-resistant subpopulation of relapse-initiating cells. Leukemic cells associated with high relapse risk are characterized by basal activation of glucocorticoid response, smaller size, and a quiescent gene expression program with cell stemness properties. These results improve current risk stratification and elucidate leukemic therapy-resistant subpopulations at diagnosis.

Epigenetic Modification of Death Receptor Genes for TRAIL and TRAIL Resistance in Childhood B-Cell Precursor Acute Lymphoblastic Leukemia

Immunotherapies specific for B-cell precursor acute lymphoblastic leukemia (BCP-ALL), such as anti-CD19 chimeric antigen receptor (CAR) T-cells and blinatumomab, have dramatically improved the therapeutic outcome in refractory cases. In the anti-leukemic activity of those immunotherapies, TNF-related apoptosis-inducing ligand (TRAIL) on cytotoxic T-cells plays an essential role by inducing apoptosis of the target leukemia cells through its death receptors (DR4 and DR5). Since there are CpG islands in the promoter regions, hypermethylation of the DR4 and DR5 genes may be involved in resistance of leukemia cells to immunotherapies due to TRAIL-resistance. We analyzed the DR4 and DR5 methylation status in 32 BCP-ALL cell lines by sequencing their bisulfite PCR products with a next-generation sequencer. The DR4 and DR5 methylation status was significantly associated with the gene and cell-surface expression levels and the TRAIL-sensitivities. In the clinical samples at diagnosis (459 cases in the NOPHO study), both DR4 and DR5 genes were unmethylated in the majority of cases, whereas methylated in several cases with dic(9;20), MLL-rearrangement, and hypodiploidy, suggesting that evaluation of methylation status of the DR4 and DR5 genes might be clinically informative to predict efficacy of immunotherapy in certain cases with such unfavorable karyotypes. These observations provide an epigenetic rational for clinical efficacy of immunotherapy in the vast majority of BCP-ALL cases.

Discovery of first-in-class inhibitors of ASH1L histone methyltransferase with anti-leukemic activity

ASH1L histone methyltransferase plays a crucial role in the pathogenesis of different diseases, including acute leukemia. While ASH1L represents an attractive drug target, developing ASH1L inhibitors is challenging, as the catalytic SET domain adapts an inactive conformation with autoinhibitory loop blocking the access to the active site. Here, by applying fragment-based screening followed by medicinal chemistry and a structure-based design, we developed first-in-class small molecule inhibitors of the ASH1L SET domain. The crystal structures of ASH1L-inhibitor complexes reveal compound binding to the autoinhibitory loop region in the SET domain. When tested in MLL leukemia models, our lead compound, AS-99, blocks cell proliferation, induces apoptosis and differentiation, downregulates MLL fusion target genes, and reduces the leukemia burden in vivo. This work validates the ASH1L SET domain as a druggable target and provides a chemical probe to further study the biological functions of ASH1L as well as to develop therapeutic agents.

Identification of co-expressed genes associated with MLL rearrangement in pediatric acute lymphoblastic leukemia

Rearrangements involving the mixed lineage leukemia (MLL) gene are common adverse prognostic factors of pediatric acute lymphoblastic leukemia (ALL). Even allogeneic hematopoietic stem cell transplantation does not improve the outcome of ALL cases with some types of MLL rearrangements. The aim of the present study was to identify the co-expressed genes that related to MLL rearrangement (MLL-r) and elucidate the potential mechanisms of how MLL-r and their partner genes lead to leukemogenesis. Gene co-expression networks were constructed using the gene expression data and sample traits of 204 pretreated pediatric ALL patients, and co-expression modules significantly related to the MLL-r were screened out. Gene ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway analysis of the module genes were performed. Hub genes were identified and their expression levels were analyzed in samples with or without MLL-r and the results were validated by an independent investigation. Furthermore, the relationships between the hub genes and sample traits were analyzed. In total, 21 co-expression modules were identified. The green module was positively correlated with MLL-r. PROM1, LGALS1, CD44, FUT4 and HOXA10 were identified as hub genes, which were involved in focal adhesion, calcium-dependent phospholipid binding, connective tissue development and transcriptional misregulation in cancer. The expression levels of the five hub genes were significantly increased in MLL-r samples, and the results were further validated. PROM1, LGALS1, CD44 and HOXA10 were positively related to the leukocyte count. These findings might provide novel insight regarding the mechanisms and potential therapeutic targets for pediatric ALL with MLL-r.

Pediatric Acute Lymphoblastic Leukemia, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Advancements in technology that enhance our understanding of the biology of the disease, risk-adapted therapy, and enhanced supportive care have contributed to improved survival rates. However, additional clinical management is needed to improve outcomes for patients classified as high risk at presentation (eg, T-ALL, infant ALL) and who experience relapse. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric ALL provide recommendations on the workup, diagnostic evaluation, and treatment of the disease, including guidance on supportive care, hematopoietic stem cell transplantation, and pharmacogenomics. This portion of the NCCN Guidelines focuses on the frontline and relapsed/refractory management of pediatric ALL.

MLL-Rearranged Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

Rearrangements of the histone lysine [K]-MethylTransferase 2A gene (KMT2A) gene on chromosome 11q23, formerly known as the mixed-lineage leukemia (MLL) gene, are found in 10% and 5% of adult and children ALL cases, respectively. The most common translocated genes are AFF1 (formerly AF4), MLLT3 (formerly AF9), and MLLT1 (formerly ENL). The bimodal incidence of MLL-r-ALL usually peaks in infants in their first 2 years of life and then declines thereafter during the pediatric/young adult phase until it increases again with age. MLL-rearranged ALL (MLL-r-ALL) is characterized by hyperleukocytosis, aggressive behavior with early relapse, relatively high incidence of central nervous system (CNS) involvement, and poor prognosis.

RECENT FINDINGS

MLL-r-ALL cells are characterized by relative resistance to corticosteroids (due to Src kinase-induced phosphorylation of annexin A2) and L-asparaginase therapy, but they are sensitive to cytarabine chemotherapy (due to increased levels of hENT1 expression). Potential therapeutic targets include FLT3 inhibitors, MEK inhibitors, HDAC inhibitors, BCL-2 inhibitors, MCL-1 inhibitors, proteasome inhibitors, hypomethylating agents, Dot1L inhibitors, and CDK inhibitors. In this review, we discuss MLL-r-ALL focusing on clinical presentation, risk stratification, drug resistance, and treatment strategies, including potential novel therapeutic targets.

Helpful Criteria When Implementing NGS Panels in Childhood Lymphoblastic Leukemia

The development of Next-Generation Sequencing (NGS) has provided useful diagnostic, prognostic, and therapeutic strategies for individualized management of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) patients. Consequently, NGS is rapidly being established in clinical practice. However, the technology’s complexity, bioinformatics analysis, and the different available options difficult a broad consensus between different laboratories in its daily routine introduction. This collaborative study among Spanish centers was aimed to assess the feasibility, pros, and cons of our customized panel and other commercial alternatives of NGS-targeted approaches. The custom panel was tested in three different sequencing centers. We used the same samples to assess other commercial panels (Oncomine^TM Childhood Cancer Research Assay; Archer^®FusionPlex^® ALL, and Human Comprehensive Cancer Panel GeneRead Panel v2^®). Overall, the panels showed a good performance in different centers and platforms, but each NGS approach presented some issues, as well as pros and cons. Moreover, a previous consensus on the analysis and reporting following international guidelines would be preferable to improve the concordance in results among centers. Our study shows the challenges posed by NGS methodology and the need to consider several aspects of the chosen NGS-targeted approach and reach a consensus before implementing it in daily practice.

Novel therapeutic strategies for MLL-rearranged leukemias

MLL rearrangement is one of the key drivers and generally regarded as an independent poor prognostic marker in acute leukemias. The standard of care for MLL-rearranged (MLL-r) leukemias has remained largely unchanged for the past 50 years despite unsatisfying clinical outcomes, so there is an urgent need for novel therapeutic strategies. An increasing body of evidence demonstrates that a vast number of epigenetic regulators are directly or indirectly involved in MLL-r leukemia, and they are responsible for supporting the aberrant gene expression program mediated by MLL-fusions. Unlike genetic mutations, epigenetic modifications can be reversed by pharmacologic targeting of the responsible epigenetic regulators. This leads to significant interest in developing epigenetic therapies for MLL-r leukemia. Intriguingly, many of the epigenetic enzymes also involve in DNA damage response (DDR), which can be potential targets for synthetic lethality-induced therapies. In this review, we will summarize some of the recent advances in the development of epigenetic and DDR therapeutics by targeting epigenetic regulators or protein complexes that mediate MLL-r leukemia gene expression program and key players in DDR that safeguard essential genome integrity. The rationale and molecular mechanisms underpinning the therapeutic effects will also be discussed with a focus on how these treatments can disrupt MLL-fusion mediated transcriptional programs and impair DDR, which may help overcome treatment resistance.

Prognostic impact of Philadelphia chromosome in mixed phenotype acute leukemia (MPAL): A cancer registry analysis on real-world outcome

Mixed phenotype acute leukemia (MPAL) is thought to have poor outcome, and presence of the Philadelphia chromosome (Ph+) has been considered to be an adverse prognostic marker. However, most of these reports were in the pre-tyrosine kinase inhibitors (TKIs) era. Recent limited reports indicate improved outcomes for MPAL with the addition of TKIs. We examined the outcomes of 241 cases of MPAL according to the 2008 WHO classification from the Surveillance, Epidemiology, and End Results registry. The MLL+ patients had a median age of 6 years while other subtypes occurred mostly in adults and had comparable age. On multivariate analyses and after adjustment for age, year of diagnosis and chemotherapy status, Ph+ MPAL patients had reduced risk of death in comparison to Ph(-) MPAL patients (hazard ratio [HR] = 0.28, P = .002). So, MLL+ MPAL had the worst outcome with a 10-fold increased risk of death in comparison to Ph+ MPAL patients (HR = 10.2, P < .001). Importantly, the outcome of Ph+ MPAL was comparable to Ph+ acute lymphoblastic leukemia in a 1:1 matched case-control analysis. In conclusion, this is the largest registry study which examines the outcomes of MPAL subtypes. We confirm that MPAL is a heterogenous disease. Note, Ph+ MPAL nowadays has a better OS in comparison to other subtypes and is comparable to Ph+ ALL patients. This is most likely secondary to changes in practice and more utilization of TKIs. On the other hand, MLL rearrangement is associated with infantile MPAL and has a dismal prognosis.

Only Hematopoietic Stem and Progenitor Cells from Cord Blood Are Susceptible to Malignant Transformation by MLL-AF4 Translocations

Mixed lineage leukemia (MLL) (KMT2A) rearrangements (KMT2Ar) play a crucial role in leukemogenesis. Dependent on age, major differences exist regarding disease frequency, main fusion partners and prognosis. In infants, up to 80% of acute lymphoid leukemia (ALL) bear a MLL translocation and half of them are t(4;11), resulting in a poor prognosis. In contrast, in adults only 10% of acute myeloid leukemia (AML) bear t(9;11) with an intermediate prognosis. The reasons for these differences are poorly understood. Recently, we established an efficient CRISPR/Cas9-based KMT2Ar model in hematopoietic stem and progenitor cells (HSPCs) derived from human cord blood (huCB) and faithfully mimicked the underlying biology of the disease. Here, we applied this model to HSPCs from adult bone marrow (huBM) to investigate the impact of the cell of origin and fusion partner on disease development. Both genome-edited infant and adult KMT2Ar cells showed monoclonal outgrowth with an immature morphology, myelomonocytic phenotype and elevated KMT2Ar target gene expression comparable to patient cells. Strikingly, all KMT2Ar cells presented with indefinite growth potential except for MLL-AF4 huBM cells ceasing proliferation after 80 days. We uncovered FFAR2, an epigenetic tumor suppressor, as potentially responsible for the inability of MLL-AF4 to immortalize adult cells under myeloid conditions.

Personalized therapy in pediatric high-risk B-cell acute lymphoblastic leukemia

Although cure rates for pediatric acute lymphoblastic leukemia (ALL) have now risen to more than 90%, subsets of patients with high-risk features continue to experience high rates of treatment failure and relapse. Recent work in minimal residual disease stratification and leukemia genomics have increased the ability to identify and classify these high-risk patients. In this review, we discuss this work to identify and classify patients with high-risk ALL. Novel therapeutics, which may have the potential to improve outcomes for these patients, are also discussed.

MLL-rearranged infant leukaemia: A 'thorn in the side' of a remarkable success story

Advances in treatment of childhood leukaemia has led to vastly improved survival rates, however some subtypes such as those characterised by MLL gene rearrangement (MLL-r), especially in infants, continue to have high relapse rates and poor survival. Natural history and molecular studies indicate that infant acute lymphoblastic leukaemia (ALL) originates in utero, is distinct from childhood ALL, and most cases are caused by MLL-r resulting in an oncogenic MLL fusion protein. Unlike childhood ALL, only a very small number of additional mutations are present in infant ALL, indicating that MLL-r alone may be sufficient to give rise to this rapid onset, aggressive leukaemia in an appropriate fetal cell context. Despite modifications in treatment approaches, the outcome of MLL-r infant ALL has remained dismal and a clear understanding of the underlying biology of the disease is required in order to develop appropriate disease models and more effective therapeutic strategies.

Prognosis of haploidentical hematopoietic stem cell transplantation in non-infant children with t(v;11q23)/MLL-rearranged B-cell acute lymphoblastic leukemia

B-cell acute lymphoblastic leukemia (B-ALL) with MLL-rearrangements (MLL-r) is rare in pediatric patients (aged >1 year), and optimal treatment strategies remain unclear. This study aimed to retrospectively evaluate the clinical characteristics, outcomes, and effects of allogeneic hematopoietic stem cell transplantation (allo-HSCT) of 37 non-infant children with t(v;11q23)/MLL-r B-ALL. Their 4-year overall survival (OS), event-free survival (EFS), and cumulative incidence of relapse (CIR) were 69.8 %, 58.2 %, and 39.1 %, respectively, and differed significantly between patients receiving allo-HSCT (18/19 cases received haploidentical [haplo]-HSCT) at the first complete remission (HSCT at CR1, n = 19; 87.4 %, 89.5 % and 5.3 %) and those continuing consolidation therapy (Non-HSCT at CR1, n = 18; 52.2 %, 25.9 %, and 74.1 %, respectively), and the p values were 0.022, <0.001 and <0.001, respectively. Of the 13 patients experiencing relapse during consolidation chemotherapy, the five continuing with chemotherapy only died within 44 months, and the eight patients opting for allo-HSCT after CR2 had a 4-year OS of 57.1 %. Multivariate analysis revealed HSCT at CR1 as the only independent protective factor for OS, EFS, and CIR. The present results indicate that allo-HSCT (especially haplo-HSCT) at CR1 may decrease the relapse rate and improve the prognosis of non-infant children with t(v;11q23)/MLL-r B-ALL.

MLL-Rearranged Acute Leukemia with t(4;11)(q21;q23)-Current Treatment Options. Is There a Role for CAR-T Cell Therapy?

The MLL (mixed-lineage leukemia) gene, located on chromosome 11q23, is involved in chromosomal translocations in a subtype of acute leukemia, which represents approximately 10% of acute lymphoblastic leukemia and 2.8% of acute myeloid leukemia cases. These translocations form fusions with various genes, of which more than 80 partner genes for MLL have been identified. The most recurrent fusion partner in MLL rearrangements (MLL-r) is AF4, mapping at chromosome 4q21, accounting for approximately 36% of MLL-r leukemia and particularly prevalent in MLL-r acute lymphoblastic leukemia (ALL) cases (57%). MLL-r leukemia is associated with a sudden onset, aggressive progression, and notoriously poor prognosis in comparison to non-MLL-r leukemias. Despite modern chemotherapeutic interventions and the use of hematopoietic stem cell transplantations, infants, children, and adults with MLL-r leukemia generally have poor prognosis and response to these treatments. Based on the frequency of patients who relapse, do not achieve complete remission, or have brief event-free survival, there is a clear clinical need for a new effective therapy. In this review, we outline the current therapy options for MLL-r patients and the potential application of CAR-T therapy.

Outcome of Infants Younger Than 1 Year With Acute Lymphoblastic Leukemia Treated With the Interfant-06 Protocol: Results From an International Phase III Randomized Study

PURPOSE

Infant acute lymphoblastic leukemia (ALL) is characterized by KMT2A (MLL) gene rearrangements and coexpression of myeloid markers. The Interfant-06 study, comprising 18 national and international study groups, tested whether myeloid-style consolidation chemotherapy is superior to lymphoid style, the role of stem-cell transplantation (SCT), and which factors had independent prognostic value.

MATERIALS AND METHODS

Three risk groups were defined: low risk (LR): KMT2A germline; high risk (HR): KMT2A-rearranged and older than 6 months with WBC count 300 × 10⁹/L or more or a poor prednisone response; and medium risk (MR): all other KMT2A-rearranged cases. Patients in the MR and HR groups were randomly assigned to receive the lymphoid course low-dose cytosine arabinoside [araC], 6-mercaptopurine, cyclophosphamide (IB) or experimental myeloid courses, namely araC, daunorubicin, etoposide (ADE) and mitoxantrone, araC, etoposide (MAE).

RESULTS

A total of 651 infants were included, with 6-year event-free survival (EFS) and overall survival of 46.1% (SE, 2.1) and 58.2% (SE, 2.0). In West European/North American groups, 6-year EFS and overall survival were 49.4% (SE, 2.5) and 62.1% (SE, 2.4), which were 10% to 12% higher than in other countries. The 6-year probability of disease-free survival was comparable for the randomized arms (ADE+MAE 39.3% [SE 4.0; n = 169] v IB 36.8% [SE, 3.9; n = 161]; log-rank P = .47). The 6-year EFS rate of patients in the HR group was 20.9% (SE, 3.4) with the intention to undergo SCT; only 46% of them received SCT, because many had early events. KMT2A rearrangement was the strongest prognostic factor for EFS, followed by age, WBC count, and prednisone response.

CONCLUSION

Early intensification with postinduction myeloid-type chemotherapy courses did not significantly improve outcome for infant ALL compared with the lymphoid-type course IB. Outcome for infant ALL in Interfant-06 did not improve compared with that in Interfant-99.

Evaluation of Cytogenetic Abnormalities in Patients with Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) accounts for 20% of all adult leukemias and is the most common leukemia during childhood (80%). We present data on cytogenetics of ALL from a tertiary centre in India correlating it with clinical factors. Karyotyping of bone marrow samples of 204 patients with newly diagnosed ALL was performed with standard G-banding technique. Clinical data of patients was obtained from case records. Survival was estimated using Kaplan-Meir curves and compared by the log-rank test. Univariate and multivariate analysis was done for survival with age, sex, immunophenotype, hyperleukocytosis, risk type, remission status and cytogenetics. The most common karyotypes observed were normal in 39.7% (N = 81), hyperdiploidy in 12.7% (N = 26), t(9;22) in 4.4% (N = 9), t(1;19) in 3.9% (N = 8). Adults with ALL had worse survival compared with pediatric patients (HR 3.62; 2.03-6.45 95% CI, p < 0.001). Patients not in morphologic remission after induction chemotherapy fared poorly (HR 4.86; 2.67-8.84 95% CI, p < 0.001). Patients with favourable cytogenetics had better overall survival (HR 0.36; 0.12-1.05 95% CI, p < 0.05). On multivariate analysis, achievement of morphologic remission emerged as single most significant predictor of survival (p < 0.001). MLL gene rearrangement and t(12;21) were seen less commonly as compared to Western data. However, incidence rates of various cytogenetic abnormalities were similar to that reported from other centres from India. Age, morphologic remission at end of induction chemotherapy and favourable cytogenetics correlated significantly with survival.

Whole transcriptome sequencing reveals a KMT2A-USP2 fusion in infant acute myeloid leukemia

Infant acute lymphoblastic leukemia with lysine (K)-specific methyltransferase 2A (KMT2A) rearrangements usually has a poor prognosis regardless of the fusion partners of KMT2A. However, the prognosis of pediatric acute myeloid leukemia (AML) with KMT2A rearrangements depends on its translocation partners. We herein report the case of a 9-month-old boy with a KMT2A-USP2 fusion, which required diagnosis by whole transcriptome sequencing after the failure of detection of known translocation partners by conventional screening approaches. As this first report of a patient with AML with a KMT2A-USP2 fusion illustrates, identification of the partners in all patients with KMT2A-rearranged AML is critical to elucidate the outcomes associated with specific rearrangements and to develop appropriate treatment strategies. Moreover, development of additional methods to detect specific translocation partners of KMT2A and leukemia-specific targeting drugs is important to improve further the outcomes of KMT2A-rearranged AML.

Hematopoietic Stem-Cell Transplantation Does Not Improve the Poor Outcome of Children With Hypodiploid Acute Lymphoblastic Leukemia: A Report From Children's Oncology Group

PURPOSE

Children and young adults with hypodiploid B-lymphoblastic leukemia (B-ALL) fare poorly and hematopoietic stem-cell transplantation (HSCT) is often pursued in first complete remission (CR1). We retrospectively reviewed the outcomes of children and young adults with hypodiploid B-ALL who were enrolled in recent Children's Oncology Group (COG) trials to evaluate the impact of HSCT on outcome.

PATIENTS AND METHODS

Cytogenetic analyses and DNA index were performed at COG-approved laboratories, and hypodiploidy was defined as modal chromosome number less than 44 and/or DNA index less than 0.81. Minimal residual disease (MRD) was determined centrally using flow cytometry at two reference laboratories. Patients with hypodiploid ALL came off protocol therapy postinduction and we retrospectively collected details on their subsequent therapy and outcomes. Event-free survival (EFS) and overall survival (OS) were estimated for the cohort.

RESULTS

Between 2003 and 2011, 8,522 patients with National Cancer Institute standard-risk and high-risk B-ALL were enrolled in COG AALL03B1 ( ClinicalTrials.gov identifier: NCT00482352). Hypodiploidy occurred in 1.5% of patients (n = 131), 98.3% of whom achieved CR after induction therapy. Five-year EFS and OS were 52.2% ± 4.9% and 58.9% ± 4.8%, respectively. Outcomes for patients undergoing CR1 HSCT were not significantly improved: 5-year EFS and OS were 57.4% ± 7.0% and 66.2% ± 6.6% compared with 47.8% ± 7.5% and 53.8% ± 7.6%, respectively ( P = .49 and .34, respectively) for those who did not undergo transplantation. Patients with MRD of 0.01% or greater at the end of induction had 5-year EFS and OS of 26.7% ± 9.3% and 29.3% ± 10.1%, respectively, and HSCT had no significant impact on outcomes.

CONCLUSION

Children and young adults with hypodiploid B-ALL continue to fare poorly and do not seem to benefit from CR1 HSCT. This is especially true for patients with MRD of 0.01% or greater at the end of induction. New treatment strategies are urgently needed for these patients.

Insights of Acute Lymphoblastic Leukemia with Development of Genomic Investigation

Treatment outcomes for acute lymphoblastic leukemia (ALL), especially pediatric ALL, have greatly improved due to the risk-adapted therapy. Combination of drug development, clinical practice, as well as basic genetic researches has brought the survival rate of ALL from less than 10% to more than 90% today, not only increasing the treatment efficacy but also limiting adverse drug reactions (ADRs). In this review, we summarized the landscape identification of ALL genetic alterations, which provided the opportunity to increase the survival rate and especially minimize the relapse risk of ALL, and highlighted the importance of the development of new technologies of genomic investigation for translational medicine.

PRMT5-mediated H4R3sme2 Confers Cell Differentiation in Pediatric B-cell Precursor Acute Lymphoblastic Leukemia

PURPOSE

Little is known about the function of histone arginine methylation in acute lymphoblastic leukemia (ALL). The objective was to evaluate whether protein arginine methyltransferase 5 (PRMT5) plays a role in pediatric ALL and to determine the possible mechanism of epigenetic regulation.

EXPERIMENTAL DESIGN

We used bone marrow samples from patients with pediatric ALL, the Nalm6 cell line, mature B-cell lines, and mouse xenograft models to evaluate the function of PRMT5 in ALL tumorigenesis.

RESULTS

This study showed that PRMT5 and the symmetric dimethylation of H4R3 (H4R3sme2) were upregulated in most initially diagnosed (n = 15; 100%) and relapsed (n = 4; 75%) bone marrow leukemia cells from patients with pediatric B-cell precursor ALL (BCP-ALL) and were decreased when the disease was in remission (n = 15; 6.7%). Downregulation of H4R3sme2 by PRMT5 silencing induced BCP-ALL cell differentiation from the pre-B to immature B stage, whereas overexpressed PRMT5 with enhanced H4R3sme2 promoted human mature B cells to dedifferentiate back to the pre-B II/immature B stages in vitro. High PRMT5 expression enhanced the proportion of CD43⁺/B220⁺/sIgM^- B leukocytes in recipient mice. CLC and CTSB were identified as potential target genes of PRMT5 in BCP-ALL cells and were inhibited by H4R3sme2 in gene promoters.

CONCLUSIONS

We demonstrate that enhanced PRMT5 promotes BCP-ALL leukemogenesis partially by the dysregulation of B-cell lineage differentiation. H4R3sme2 and PRMT5 may serve as potential sensitive biomarkers of pediatric BCP-ALL. Suppression of the activation of PRMT5 may offer a promising therapeutic strategy against pediatric BCP-ALL.

Replacing cyclophosphamide/cytarabine/mercaptopurine with cyclophosphamide/etoposide during consolidation/delayed intensification does not improve outcome for pediatric B-cell acute lymphoblastic leukemia: a report from the COG

With modern chemotherapy, approximately 90% of patients with pediatric acute lymphoblastic leukemia are now cured. However, subsets of patients can be identified who remain at very high risk of relapse with expected 4-year disease-free survival rates <80%; such patients are appropriate candidates for intensive therapeutic strategies designed to improve survival. The AALL1131 trial was designed to determine, in a randomized fashion, whether substitution with cyclophosphamide/etoposide (experimental arm 1) would improve the 4-year disease-free survival of children, adolescents, and young adults with very high-risk B-cell acute lymphoblastic leukemia compared to a modified Berlin-Frankfurt-Münster regimen (control arm). Patients 1-30 years of age with newly diagnosed very high-risk B-cell acute lymphoblastic leukemia were randomized after induction in a 1:2 fashion to the control arm or experimental arm 1 in which they were given cyclophosphamide (440 mg/m² days 1-5)/etoposide (100 mg/m² days 1-5) during part 2 of consolidation and delayed intensification. Prospective interim monitoring rules for efficacy and futility were included where futility would be determined for a one-sided P-value ≥0.7664. The study was stopped for futility as the interim monitoring boundary was crossed [hazard ratio 0.606 (95% confidence interval: 0.297 - 1.237)] and the very high-risk arm of AALL1131 was closed in February 2017. Using data current as of December 31, 2017, 4-year disease-free survival rates were 85.5±6.8% (control arm) versus 72.3±6.3% (experimental arm 1) (P-value = 0.76). There were no significant differences in grade 3/4 adverse events between the two arms. Substitution of this therapy for very high-risk B-cell acute lymphoblastic leukemia patients on the Children’s Oncology Group AALL1131 trial (NCT02883049) randomized to cyclophosphamide/etoposide during part 2 of consolidation and delayed intensification did not improve disease-free survival.

Relatively favorable prognosis for MLL-rearranged childhood acute leukemia with reciprocal translocations

BACKGROUND

Mixed-lineage leukemia (MLL) with multifarious partner genes leads to aggressive leukemia with dismal outcomes.

METHODS

Using panel-based targeted sequencing, we examined 90 cases with MLL-rearranged (MLL-r) childhood acute leukemia, including 55 with acute lymphoblastic leukemia (ALL) and 35 with acute myeloid leukemia (AML).

RESULTS

MLL breakpoints and complete rearrangements were identified. A total of 37.8% (34/90) of patients displayed a single direct MLL fusion gene, 15.6% (14/90) carried a single reciprocal fusion, and 27.8% (25/90) had both reciprocal MLL fusion alleles. The remaining 17 MLL-r cases exhibited complex translocations with homozygous disruptions on chromosome 11 or two breakpoints on the same MLL allele with a deletion of functional regions. A total of 77 patients (45 ALL and 32 AML) received chemotherapy with a median follow-up of 2.5 years. Unexpectedly, we identified children with reciprocal MLL fusions who exhibited relatively favorable outcomes compared with those in children with complex translocations or a single direct MLL fusion allele (66.1% vs. 24.6% and 27.6%, P = 0.001). Reciprocal MLL fusion may be functionally rescued by a partially truncated MLL protein.

CONCLUSION

Comprehensive MLL-r analysis by targeted next-generation sequencing can provide detailed molecular information and is helpful for precise stratified treatment and clinical prognosis determination.

Structure and significance of cytogenetic abnormalities in adult patients with Ph-negative acute lymphoblastic leukemia

Objective. To evaluate occurrence, variety, structural peculiarities and prognostic meaning of cytogenetic abnormalities in adult patients with Ph-negative acute lymphoblastic leukemia (ALL) receiving therapy according to ALL-2009 protocol. Materials and methods. The study included 115 adult patients with firstly diagnosed Ph-negative ALL: 58 male and 57 female aged from 15 to 61 years (mean age 26.5 years), who underwent treatment from September 2009 to September 2015 in National Medical Research Center for Hematology MH RF (n=101) and in hematology departments of regional hospitals (n=14). All patients received therapy of ALL-2009 protocol (ClinicalTrials.gov, NCT01193933). The median follow-up was 24.5 months (0.2-94.4 months). As a part of the study results of a standard cytogenetic assay (SCA) were analyzed and fluorescence hybridization in situ (FISH) with the use of DNA-probes was performed on archived biological material for structural changes in gene locuses MLL/t(11q23), с-MYC/t(8q24), TP53/ deletion 17p13, CDKN2A/ deletion 9p21, translocation t(1;19)/E2A-PBX1 и t(12;21)/ETV6-RUNX1; iAMP21 identification. Results. Karyotype was defined using SCA in 86% of patients. Normal karyotype was found in 48.5% of them, chromosome aberrations in 51.5% (structural changes were found in 19.2%, hyperploidy in 27.2%, and hypoploidy in 5.1%). In 17.2% of patients complex karyotype abnormalities were found. With the use of FISH technique aberrations were found in 67% of patients: 9p21/CDKN2A deletion in 24.3%, MLL/t(11q23) gene abnormalities in 7.8%, 17p13/TP53 deletion in 5.2%, abnormalities of c-MYC/t(8q24) in 1.7%, t(1;19)/E2A-PBX1 in 0.8%, and iAMP21 in 0.8%, other abnormalities (additional signals/absence of signals from gene locuses) in 26.4%, t(12;21)/ETV6-RUNX1 was not found. FISH technique use in addition to SCA allows to increase aberrant karyotype location from 51.5 to 67%. A statistically significant correlation of 9p21/CDKN2A deletion with high serum lactate dehydrogenase activity (p=0.02); MLL/t(11q23) gene abnormalities - with leucocytosis and high blast cells level in blood (p=0.0016), hyperploidy - with normal leukocyte count (p=0.02) was shown. In groups with different cytogenetic abnormalities no statistically significant differences of treatment with ALL-2009 protocol were found (in terms of complete remission, early mortality and treatment resistance). When connection of cytogenetic abnormalities and their combinations with long-term results were analyzed according to ALL-2009 protocol, only two characteristics - MLL/t(11q23) and c MYC/t(8q24) gene abnormalities had a statistically significant influence on disease-free survival (HR - 176.9; p

Allogeneic hematopoietic cell transplantation in adult acute myeloid leukemia with 11q23 abnormality: a retrospective study of the Adult Acute Myeloid Leukemia Working Group of the Japan Society for Hematopoietic Cell Transplantation (JSHCT)

An 11q23 abnormality presents in approximately 5% of adults with acute myeloid leukemia (AML) and is associated with adverse outcomes even after allogeneic hematopoietic cell transplantation (allo-HCT). To evaluate the outcomes and prognostic factors following allo-HCT for adult AML with 11q23 abnormality, we retrospectively analyzed the Japanese registration data of 322 adult AML patients with 11q23 abnormality who had received allo-HCT between 1990 and 2014. In total, the disease status at HCT was first complete remission (CR1) in 159 (49%) patients. The probability of overall survival and the cumulative incidence of relapse at 3 years were 44 and 44%, respectively. In the multivariate analysis, disease status beyond CR1 at the time of HCT was significantly associated with a higher overall mortality and relapse. The 11q23 fusion partner did not have a significant impact on survival. We also evaluated the prognostic value of minimal residual disease (MRD) status at HCT on transplant outcomes among hematological CR patients. MRD status at HCT was the significant prognostic indicator for hematological relapse and survival. These data suggested that allo-HCT offered a curative option for adult AML with 11q23 abnormality. Pretransplant MRD status was the significant prognostic indicator for relapse and survival in CR patients.

Effect of allogeneic blood transfusion on levels of IL-6 and sIL-R2 in peripheral blood of children with acute lymphocytic leukemia

Effect of allogeneic blood transfusion on the expression of interleukin-6 (IL-6) and soluble interleukin-2 receptor (sIL-2R) in peripheral blood of children with acute lymphoblastic leukemia (ALL) was investigated. A total of 91 ALL children admitted to Nanfang Hospital from June 2014 to January 2017 were selected as the study group. Patients were randomly divided into allogeneic blood transfusion group (n=38) and non-transfusion group (n=53). In addition, a total of 64 healthy children were also selected from June 2014 to January 2017 as the control group. Patients in allogeneic blood transfusion group were transfused with red blood cell suspension and machine-collected platelets, while patients in non-transfusion group were not treated with blood transfusion. Peripheral venous blood was collected before and at 4, 8 and 12 weeks after blood transfusion to prepare serum. Serum IL-6 and sIL-2R levels were measured by enzyme-linked immunosorbent assay (ELISA). Before transfusion, serum levels of IL-6 and sIL-2R were significantly lower in the study group than those in control group (p<0.05), and no significant differences in serum levels of IL-6 and sIL-2R were found between the allogeneic blood transfusion and non-transfusion group. After transfusion, serum levels of IL-6 and sIL-2R were stable for 12 weeks in the non-transfusion group, while IL-6 and sIL-2R levels were significantly increased in the allogeneic blood transfusion group. The results showed that serum level of IL-6 and sIL-2R was increased in ALL patients with allogeneic blood transfusion, which resulted in reduced antibody production and decreased cellular immunity. The patients had low immunity, and attention should be paid on the pathogen infection prevention.

Global efforts toward the cure of childhood acute lymphoblastic leukaemia

Improvements in risk-directed treatment and supportive care, together with increased reliance on both national and international collaborative studies, have made childhood acute lymphoblastic leukaemia (ALL) one of the most curable human cancers. Next-generation sequencing studies of leukaemia cells and the host germline provide new opportunities for precision medicine and thus potential improvements in the cure rate and quality of life of patients. Efforts are underway to assess the global impact of childhood ALL and develop initiatives that can meet the long-term challenge of providing quality care to children with this disease worldwide and improving cure rates globally. This ambitious task will rely on increased collaborative research and international networking so that the therapeutic gains in high-income countries can be translated to patients in low-income and middle-income countries. Ultimately, the greatest obstacle to overcome will be to fully understand leukaemogenesis, enabling measures to decrease the risk of leukaemia development and thus close the last major gap in offering a cure to any child who might have the disease.

Simultaneous involvement of 11q23 translocation resulting in chimeric MLL-AFF1 and a second translocation [t (9;21) (p13; p11.2)] in an infant acute lymphoblastic leukemia patient at relapse: A case report

RATIONALE

Three-way translocations occasionally occur in MLL-AFF1 fusion and other fusion gene. However, the complex chromosomal rearrangements in the study were the first report.

PATIENT CONCERNS

We present novel cryptic and complex chromosomal rearrangements [der (21) t (9; 21) (p13; p11.2)] in an infant patient with relapsed acute lymphoblastic leukemia (ALL).

DIAGNOSES

The diagnosis was based on morphologic, cytochemical, and immunophenotypic criteria proposed by the French-American-British Committee, and karyotype, fluorescence in situ hybridization, array comparative genomic hybridization.

INTERVENTIONS

The patient was given chemotherapy with standard protocol for ALL.

OUTCOMES

The patient had unfavorable prognostic outcome based on the cytogenetic and molecular cytogenetic markers. After short remission, the patient relapsed.

LESSONS

MLL-AFF1, resulting from t(4;11)(q21;q23), is regarded as the hallmark of infant t(4;11) pre-B/mixed B-ALL. It is associated with a dismal prognosis and the multiple-way translocation involving chromosomes 4, 11 and 11 may function as an enhancer.