Myeloid Leukemia Of Down Syndrome Research Articles

Down Syndrome with Acute Myeloid Leukemia in an Adolescent Male Successfully Treated with Low Dose Ara-C in Combination with Hypomethylating Agent

Introduction Patients with Down syndrome (DS) are prone to developing hematological malignancies, with risk of acute myeloid leukemia (AML) being 150 -fold higher compared to the general population. DS patients with leukemia are likely to experience significant chemotherapy related toxicities, hence require dose modifications. The myeloid leukemia of Down Syndrome (ML-DS) typically reflects acute megakaryoblastic leukemia (AMKL) a rare subtype of AML. ML-DS typically evolves from transient aberrant/abnormal myelopoiesis (TAM), aka transient myeloproliferative disorder (TMD), a pre-leukemic syndrome that almost always precedes myeloid leukemia in Down syndrome. GATA1, the hallmark driver mutation of TAM, is found in all TMD/TAM cases. AML in DS can occur de-novo which represents a different entity, appears immunophenotypically as (non-AMKL) AML, but differs morphologically from the classical ML-DS. The de-novo type AML in DS is reported to have worse prognosis. Poor outcomes are due to increased chemosensitivity and resulting chemotherapy-related toxicities when treated on standard high dose Ara-C based AML regimens. There is currently a lack of consensus on standard-of-care AML therapy applicable to this population. Methods Case report, retrospective electronic medical record review with institutional board review exemption Results We report a case of a 25-year-old male with trisomy 21, presenting with a one-month history of low-grade fevers, fatigue, and upper back pain. Initial laboratories showed a white cell count of 6.6 K/uL, hemoglobin 11.9 gm/dL, platelets 352 K/uL. CT chest showed a large right-sided pleural effusion, pleural thickening and multiple sclerotic bone lesions concerning for malignancy. Positron emission tomography (PET) CT revealed multiple hypermetabolic foci in the pelvis, spine, ribs, and cervical lymph nodes. Thoracocentesis was completed and pleural fluid pathology revealed atypical cells, flow cytometry showed 18% blasts positive for CD38, CD45, CD117 and negative for CD34 and HLA DR indicative of a myeloid neoplasm. Bone marrow aspirate and biopsy showed 10% CD117 positive immature myeloid cells. Morphology was not megakaryoblastic. Bone marrow flow cytometry results were consistent with that of pleural fluid with CD117 and myeloperoxidase (MPO) positive blasts. Fluorescent in-situ hybridization was negative for fusions/rearrangements. Next generation sequencing (NGS) detected NPM1 mutation and also a low level (variant allelic frequency <3%) FLT3 p.Y599C mutation (not internal tandem duplication or tyrosine kinase domain). GATA1 mutation was absent. A diagnosis of AML with NPM1 mutation and staging CNS1 was confirmed. Our patient was defined as DS and AML. Given innate fragility and higher chemo sensitivity in patients with DS, we elected to treat him off protocol with Cladribine and low dose Ara-C alternating with Decitabine. This regime was derived from an adult leukemia protocol. Cycle 1 was complicated by central line related occlusive thrombus requiring anticoagulation, slow count recovery, and a brief episode of febrile neutropenia managed with antibiotics. End of induction marrow evaluation was negative for minimal residual disease (MRD). Flow cytometry on pleural fluid was also negative for abnormal blasts that were previously detected. Repeat molecular testing with NGS was negative for NPM1, DNMT3A, and FLT3 mutations. The patient received a total of 8 cycles of chemotherapy. On subsequent bone marrow evaluations, blasts remained <5% and MRD was negative. Interval PET scan showed significant improvement. Patient is currently more than a year off therapy and remains in remission. Conclusion Patients with DS and AML have a higher mortality due to increased risk of cardiotoxicity and infection from chemotherapy. There is a risk of either undertreatment or less commonly overtreatment leading to early mortality. Our case describes an adolescent male with DS and AML with pulmonary comorbidity who was successfully treated with a low-dose Ara-C regimen adapted from an adult protocol and had great clinical outcome. AML treatment in DS remains a challenge and further research is warranted to develop tailored regimens effectively balancing curative intent and reduced toxicity. This regimen could be considered in pediatric patients with Down Syndrome and other comorbidities.

APAL2020SC Pediatric Acute Leukemia (PedAL) Screening Trial - Developing New Therapies for Relapsed Leukemias

Background: Outcomes for children with relapsed acute myeloid leukemia (AML) and subgroups with relapsed acute lymphoblastic leukemia (ALL) remain poor, and therapeutic options are limited. There is no standard of care for relapsed disease, and data collection after relapse is lacking. In recent years, extensive molecular studies of pediatric leukemias have advanced target identification and clinical trial development. Such studies have shown that pediatric leukemias are biologically distinct from adult leukemias. The current paradigm of requiring new agent studies in adults prior to conducting pediatric trials is thus not appropriate. However, the rarity of relapsed leukemia in children makes the conduct of randomized registration trials for new agents infeasible. Recognizing that impactful progress requires international collaboration, the Leukemia & Lymphoma Society is sponsoring the Pediatric Acute Leukemia (PedAL) Initiative in North America, Australia and New Zealand. In parallel, the European Pediatric Acute Leukemia (EuPAL) Foundation has established a registry for pediatric relapsed leukemia. The principal goal of this international PedAL/EuPAL collaboration is to establish a data-driven developmental therapeutics program for children with relapsed/refractory leukemias. Trial Summary: A central component of the PedAL Initiative is the screening protocol APAL2020SC (NCT04726241), which serves as the entry point for associated therapeutic sub-trials. The primary aims of APAL2020SC are (1) to use clinical and biological characteristics to screen for eligibility for therapeutic sub-trials; and (2) to maintain a longitudinal data registry and biobank for relapsed leukemia. Eligible patients are <22 years old and have one of the following leukemias in first or greater relapse, or primary refractory: AML, myeloid leukemia of Down syndrome, T-ALL, mixed phenotype acute leukemia, and KMT2A-rearranged B-ALL. Additional eligible diagnoses include any B-ALL in second or greater relapse, and de novo or relapsed treatment-related AML. All leukemia specimens are profiled by multiparameter flow cytometry (MFC) at a central lab (Hematologics). Families have the option to submit biospecimens for banking. Patients with myeloid leukemia also have molecular testing through Foundation Medicine. Clinical data collected include demographics, cytomolecular features at diagnosis, prior treatment and post-relapse treatment. Patients are encouraged to submit follow-up bone marrow samples for central MFC. The MFC assay determines lineage and blast percent and quantifies expression of markers relevant to therapeutic sub-trials. Trial Progress: APAL2020SC opened in April 2022. As of July 25, 2023, 148 patients have enrolled and 97 have had leukemia confirmed centrally. The distribution of diagnoses is shown in Table 1. All patients had blast enumeration and target expression assessed by MFC at study entry and when follow-up samples were provided. Of the patients with myeloid leukemia (n=71), targeted DNA/RNA sequencing was successful for 69%. The distribution of AML-associated alterations is shown in Table 2. Of the patients with confirmed leukemia at enrollment, 79% submitted at least 1 follow-up sample, and 77% submitted a sample for biobanking. To date, two therapeutic trials have opened that require enrollment to the screening trial. APAL2020D/ITCC101 is a randomized phase III study comparing fludarabine-cytarabine (FLA) to FLA-venetoclax. APAL2020E/PEPN2113 is a phase 1 study of the E-selectin inhibitor uproleselan in combination with FLA. Pediatric-specific therapeutic trials for menin inhibitors and other new agents are in development. The study is collecting treatment information for children who do not enroll on a subtrial, with the goal of describing current practices and outcomes (Table 2). Conclusion: APAL2020SC will accrue patients with relapsed acute leukemias and treatment-related AML for 5 years. This protocol will promote clinical trial development by engaging industry partners and providing a single entry point to therapeutic studies with biological rationale. APAL2020SC and the EuPAL Foundation registry will generate a large, comprehensive and longitudinal dataset that will inform future trials. The biobank component will support innovative translational research to feed the pipeline of new agents.

Myeloid Leukemia of Down Syndrome.

Myeloid leukemia of Down syndrome (ML-DS) is characterized by a distinct natural history and is classified by the World Health Organization (WHO) as an independent entity, occurring with unique clinical and molecular features. The presence of a long preleukemic, myelodysplastic phase, called transient abnormal myelopoiesis (TAM), precedes the initiation of ML-DS and is defined by unusual chromosomal findings. Individuals with constitutional trisomy 21 have a profound dosage imbalance in the hematopoiesis-governing genes located on chromosome 21 and thus are subject to impaired fetal as well as to neonatal erythro-megakaryopoiesis. Almost all neonates with DS develop quantitative and morphological hematological abnormalities, yet still only 5-10% of them present with one of the preleukemic or leukemic conditions of DS. The acquired mutations in the key hematopoietic transcription factor gene GATA1, found solely in cells trisomic for chromosome 21, are considered to be the essential step for the selective growth advantage of leukemic cells. While the majority of cases of TAM remain clinically 'silent' or undergo spontaneous remission, the remaining 20% to 30% of them progress into ML-DS until the age of 4 years. The hypersensitivity of ML-DS blasts to chemotherapeutic agents, including but not limited to cytarabine, and drugs' increased infectious and cardiac toxicity have necessitated the development of risk-adapted treatment protocols for children with ML-DS. Recent advances in cytogenetics and specific molecular mechanisms involved in the evolution of TAM and ML-DS are reviewed here, as well as their integration in the improvement of risk stratification and targeted management of ML-DS.

Treatment results of children with the diagnosis of acute myeloid leukemia. Is trisomy 21 an important cause of mortality?

Background: Acute myeloid leukemia (AML) is the second most common leukemia accounts for 20% of childhood leukemia. Intensive chemotherapy and hematopoietic stem cell transplantation (HSCT) improve outcomes. In this study, it was aimed to present the clinical features and treatment results of patients diagnosed with pediatric AML in the last three years. Methods: It is an observational clinical study, patients who received chemotherapy and HSCT with the diagnosis of AML between 2018 and 2020 were retrospectively evaluated. Age, gender, AML subtype, genetic characteristics, laboratory findings, treatment responses, febrile neutropenia and fungal infection frequencies of the patients were evaluated. HSCT indications, pre-transplant bone marrow aspiration results, transplant type, donor characteristics, and post-transplant complications of patients who underwent HSCT were recorded. Post-treatment status and treatment success rates of the patients were evaluated. Results: Of the 46 patients included in the study, 26 were female and 20 were male. The mean age was 8.2 ± 5.75 years. The most common subtypes were AML M4 and M5 with 9 patients. Total of 201 febrile neutropenia attacks were observed. Suspicious or definite proven Aspergillus infection was detected in 20 of the patients. HSCT was applied to 27 of the patients. Four patients were Down syndrome-myeloid leukemia (DS-ML) and FLT3-ITD mutation was detecetd in 5 patients. Conclusions: FLT3-ITD mutation, relapse disease, and pre-HSCT M2 bone marrow were found to be highly correlated with progressive disease and mortality. In addition, patients with Down syndrome had a high mortality due to additional comorbidity and drug adverse effects.

Layered immunity and layered leukemogenicity: Developmentally restricted mechanisms of pediatric leukemia initiation.

Hematopoietic stem cells (HSCs) and multipotent progenitor cells (MPPs) arise in successive waves during ontogeny, and their properties change significantly throughout life. Ontological changes in HSCs/MPPs underlie corresponding changes in mechanisms of pediatric leukemia initiation. As HSCs and MPPs progress from fetal to neonatal, juvenile and adult stages of life, they undergo transcriptional and epigenetic reprogramming that modifies immune output to meet age-specific pathogenic challenges. Some immune cells arise exclusively from fetal HSCs/MPPs. We propose that this layered immunity instructs cell fates that underlie a parallel layered leukemogenicity. Indeed, some pediatric leukemias, such as juvenile myelomonocytic leukemia, myeloid leukemia of Down syndrome, and infant pre-B-cell acute lymphoblastic leukemia, are age-restricted. They only present during infancy or early childhood. These leukemias likely arise from fetal progenitors that lose competence for transformation as they age. Other childhood leukemias, such as non-infant pre-B-cell acute lymphoblastic leukemia and acute myeloid leukemia, have mutation profiles that are common in childhood but rare in morphologically similar adult leukemias. These differences could reflect temporal changes in mechanisms of mutagenesis or changes in how progenitors respond to a given mutation at different ages. Interactions between leukemogenic mutations and normal developmental switches offer potential targets for therapy.

Acute Kidney Injury in Myeloid Leukemia of Down Syndrome: Risk Factors and Outcomes

Objective: To identify the risk factors and describe the outcomes of patients who developed acute kidney injury (AKI)during treatment for myeloid leukemia of Down syndrome (ML-DS).Material and Methods: The medical records of 23 Down syndrome patients under the age of 15 who had been diagnosedwith acute myeloid leukemia (AML) and were being treated at a major tertiary care referral facility in Southern Thailandwere reviewed. The identification of factors associated with AKI was done using logistic regression. The Kaplan-Meiermethod was used to calculate survival probabilities.Results: Eight (34.8%) patients developed AKI during their course of chemotherapy with a median time from the firstvisit to the AKI event of 1.1 (IQR 0.7, 3.1) months. Higher levels of blast cells (OR: 1.19, 95% CI: 1.05-1.98) and septicshock during the course of chemotherapy (OR: 621.1, 95% CI: 2.40-Inf.) were independently associated with AKI. The1-year overall survival rate was 26.1%. The median survival times among those who developed AKI and those who didnot were 1.94 and 10.7 months, respectively.Conclusion: About one-third of the cases with ML-DS in our cohort developed AKI during the course of chemotherapy.The risk factors of AKI were higher peripheral blast count and septic shock during chemotherapy.

Mechanism of KIT gene regulation by GATA1 lacking the N-terminal domain in Down syndrome–related myeloid disorders

Children with Down syndrome (DS) are at high risk of transient abnormal myelopoiesis (TAM) and myeloid leukemia of DS (ML-DS). GATA1 mutations are detected in almost all TAM and ML-DS samples, with exclusive expression of short GATA1 protein (GATA1s) lacking the N-terminal domain (NTD). However, it remains to be clarified how GATA1s is involved with both disorders. Here, we established the K562 GATA1s (K562-G1s) clones expressing only GATA1s by CRISPR/Cas9 genome editing. The K562-G1s clones expressed KIT at significantly higher levels compared to the wild type of K562 (K562-WT). Chromatin immunoprecipitation studies identified the GATA1-bound regulatory sites upstream of KIT in K562-WT, K562-G1s clones and two ML-DS cell lines; KPAM1 and CMK11-5. Sonication-based chromosome conformation capture (3C) assay demonstrated that in K562-WT, the − 87 kb enhancer region of KIT was proximal to the − 115 kb, − 109 kb and + 1 kb region, while in a K562-G1s clone, CMK11-5 and primary TAM cells, the − 87 kb region was more proximal to the KIT transcriptional start site. These results suggest that the NTD of GATA1 is essential for proper genomic conformation and regulation of KIT gene expression, and that perturbation of this function might be involved in the pathogenesis of TAM and ML-DS.

Selinexor Prolongs Survival in Patient-Derived Xenograft Models of Down Syndrome Myeloid Leukemia

Background: Selinexor, an inhibitor of the nuclear exportin protein XPO1, has been shown to promote cell cycle arrest and induce apoptosis in acute myeloid leukemia (AML) cells. By inhibiting protein export from the nucleus to the cytoplasm, Selinexor causes nuclear accumulation of proteins including tumor suppressors and translation initiation factor eIF4E, resulting in reduced translation of anti-apoptotic proteins BCL2 and MCL1. Venetoclax, a BCL2 inhibitor, has been considered to synergize with Selinexor in preclinical studies of multiple myeloma (Nguyen et a., Blood, 138:2270, 2021), lymphoma and AML (Fischer et al., Blood Adv, 4:586, 2020). A clinical trial evaluating the combination of Selinexor and venetoclax in relapsed/refractory pediatric AML is currently underway (NCT04898894). However, children with Down syndrome, who have a 500-fold increased risk of developing acute leukemia are excluded from this trial. Methods: The viability of mouse passaged Down syndrome myeloid leukemia (DS-ML) samples following exposure to Selinexor and/or venetoclax was evaluated ex vivo by flow cytometry using annexin V and propidium iodide staining. BLISS synergy scores were calculated using SynergyFinder. For the PDX models, 2-3 million cells were injected intravenously in NSG-SGM3 mice. The percentage of human cells in mouse peripheral blood was determined at periodic intervals by flow cytometry. Mice were randomly recruited to treatment groups (n=5 each) when the percentage of human CD45+ cells were first detected in blood. Selinexor (10 mg/Kg) and venetoclax (100 mg/Kg) were administered by oral gavage for 2 weeks and 4 weeks respectively. Mice were carefully monitored and euthanized at the first instance of pre-determined experimental endpoints. Kaplan-Meier survival estimates were generated using GraphPad Prism. Results: We have generated and extensively characterized patient-derived xenograft models of DS-ML, and used for preclinical evaluation of epigenetic drug combination (azacitidine and panobinostat) (Barwe et al., Blood, 134:2683, 2019), and a combination of azacitidine and venetoclax (Barwe et al., Blood, 138:3452, 2021). Ex vivo studies showed a dose-dependent decrease in the viability of mouse passaged DS-ML cells treated with Selinexor or venetoclax. The estimated EC50 concentrations for Selinexor were 0.31 uM (NTPL-60), 0.53 uM (NTPL-386), and 1.01 uM (15384-029). Venetoclax reduced cell viability at EC50 concentrations ranging from 0.37 uM to 1.54 uM. A combination of these drugs was either additive (NTPL-60), mildly synergistic (NTPL-386) or antagonistic (15384-029) (Figure 1A). We tested the efficacy of Selinexor and venetoclax alone or in combination in vivo in three distinct DS-ML PDX models. Selinexor treatment significantly increased median survival in all three models, while venetoclax was effective in two of three models (Figure 1B, *P<0.05, **P<0.01). However, unlike prior reports in multiple myeloma and AML, addition of venetoclax to the treatment regimen did not provide any survival advantage compared to Selinexor alone. This effect was also observed in the percentage of human CD45+ in blood over time, where human CD45+ blood counts were significantly higher in the combination than Selinexor treatment alone, indicating that Selinexor monotherapy was much more efficient in reducing leukemia burden. Conclusion: We evaluated a combination of Selinexor and venetoclax in DS-ML PDX models ex vivo and in vivo. The combination did not show significant synergy in any of the models ex vivo. Selinexor showed significant improvement in median survival in each of the models and performed better than venetoclax alone. Selinexor venetoclax combination was not beneficial than Selinexor alone in DS-ML PDX models. Studies are in progress to identify the determinants of combinatorial response to Selinexor and venetoclax in DS-ML. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

DDB1 and CUL4 Associated Factor 7 (DCAF7) Is Essential for Hematopoiesis

Mutations in DDB1 And CUL4 Associated Factor 7 (DCAF7) have been detected in a subset of patients with Myeloid Leukemia in Down syndrome. DCAF7 is a highly conserved WD40 domain protein with 100% homology among vertebrates and is a prominent binding partner of DYRK1A, a kinase located on chromosome 21. Analysis of the DepMap database revealed that hematopoietic cell lines are highly dependent on DCAF7 compared to cell lines from other tumors. However, the function of DCAF7 during normal hematopoiesis is currently unknown. Thus, we aimed to study its function in hematopoietic cell lines and in a conditional knockout mouse model. We first deleted DCAF7 from a panel of hematopoietic cell lines by CRISPR/Cas9 editing and observed its absence led to cell cycle arrest and decreased proliferation. Rescue experiments in which a CRISPR resistant DCAF7 allele was expressed in the targeted clones restored proliferation and cell cycling. A comparison of RNA-seq data between parental HEL cells and those without DCAF7 showed decreased expression of genes involved in differentiation, TNF signaling and the IFN pathway, indicating that DCAF7 is important for cell differentiation. Next, we created a Dcaf7 conditionally targeted mouse strain (Dcaf7F/F Mx-1 Cre) and assessed its role in hematopoiesis in vivo. Following Cre induction by pIpC, we observed a decrease in white blood cells, hemoglobin and platelet counts in KO mice. Analysis of the bone marrow showed an accumulation of LT-HSCs and multipotent progenitors. In addition, we observed a defect in the generation of B-cells, reminiscent of the phenotype observed upon Dyr1ka deletion. We then tested the recovery of Dcaf7 KO hematopoietic cells after different types of stress, which included ex-vivo culture, transplantation, and myelosuppression. Dcaf7 deficient HSCs showed defective expansion in PVA-containing media and poor differentiation in single cell colony assays in methylcellulose. In non-competitive transplants, KO cells reconstituted hematopoiesis although the number of mature myeloid and lymphoid cells was dramatically decreased. In competitive transplants, Dcaf7 KO cells were outcompeted by wild-type cells. Lastly, upon myelosuppression with 5-FU, Dcaf7 deficient mice were not able to recover and died acutely. Overall, these results indicate that DCAF7 plays a critical role in HSCs during homeostasis and regeneration. To uncover the mechanisms by which DCAF7 contributes to hematopoiesis, we performed IP-MS using tagged DCAF7 as bait in a hematopoietic cell line. In addition to DYRK1A, we found that DCAF7 interacts with multiple components of the polycomb repressive complex1 (PRC1), specifically the non-canonical PRC1.5 complex, which has been previously implicated in gene activation and transcription. We confirmed that DCAF7 engages in the PRC1.5 complex by glycerol gradient centrifugation. Upon DCAF7 absence the size the PRC1 complex shifts towards a lower molecular weight, indicating that DCAF7 is a core subunit of the complex. We then performed RNASeq analysis in sorted LT-HSCs (Lin-cKit+Sca1+CD48-CD150+) and found that 70% of the differentially expressed genes were downregulated in KO cells. These downregulated genes were associated with diminished activation of GATA1, GATA2, RUNX1 and SP1 target genes, in agreement with the functional role of the PRC1.5 complex in gene activation and cell differentiation. Together our results reveal that DCAF7 regulates hematopoiesis by participating in transcriptional regulatory complexes, and we predict that DCAF7 mutations contribute to leukemia by cooperating with DYRK1A and altering the activity of the PRC1 complex.

A sensitive and inexpensive high-resolution melting-based testing algorithm for diagnosis of transient abnormal myelopoiesis and myeloid leukemia of Down syndrome.

Patients with Down syndrome (DS) are commonly affected by a pre-leukemic disorder known as transient abnormal myelopoiesis (TAM). This condition usually undergoes spontaneous remission within the first 2months after birth; however, in children under 5, 20%-30% of cases evolve to myeloid leukemia of Down syndrome (ML-DS). TAM and ML-DS are caused by co-operation between trisomy 21 and acquired mutations in the GATA1 gene. Currently, only next-generation sequencing (NGS)-based methodologies are sufficiently sensitive for diagnosis in samples with small GATA1 mutant clones (≤10% blasts). Alternatively, this study presents research on a new, fast, sensitive, and inexpensive high-resolution melting (HRM)-based diagnostic approach that allows the detection of most cases of GATA1 mutations, including silent TAM. The algorithm first uses flow cytometry for blast count, followed by HRM and Sanger sequencing to search for mutations on exons 2 and 3 of GATA1. We analyzed 138 samples of DS patients: 110 of asymptomatic neonates, 10 suspected of having TAM, and 18 suspected of having ML-DS. Our algorithm enabled the identification of 33 mutant samples, among them five cases of silent TAM (5/110) and seven cases of ML-DS (7/18) with blast count ≤10%, in which GATA1 alterations were easily detected by HRM. Depending on the type of genetic variation and its location, our methodology reached sensitivity similar to that obtained by NGS (0.3%) at a considerably reduced time and cost, thus making it accessible worldwide.

Non-Infectious Morbidity during Pediatric Acute Myeloid Leukemia Chemotherapy in the Netherlands: A 15-Year Overview

IntroductionTogether with considerable improvement in diagnostics and supportive care measures, treatment intensification has contributed to the improvement of pediatric acute myeloid leukemia (AML) survival outcomes. However, treatment-related toxicity is a consequence of intensified chemotherapy regimens, which has profound implications for both morbidity and mortality. Despite the known devastating impact of all types of toxicity on quality of life (QoL), studies presenting the different forms of non-infectious toxicity prevalent during the most recent Dutch pediatric AML protocols are lacking given that only prior protocols have been evaluated in this manner as of yet. Furthermore, the literature on non-infectious toxicity incidence in pediatric AML patients is relatively scarce. Therefore, the objectives of this study were to: 1) evaluate the cumulative incidence (C.I.) of severe, but non-lethal, non-infectious toxicity during AML treatment according to the last three consecutive protocols of the Dutch Childhood Oncology Group (DCOG), and 2) compare treatment-related toxicity frequencies between protocols.MethodsA retrospective chart review was performed on 245 Dutch patients diagnosed with de novo AML (acute promyelocytic leukemia, myeloid leukemia of Down Syndrome, and secondary AML were excluded) and treated according to ANLL-97/AML-12 (1998-2005) n=118, AML-15 (2005-2010) n=60, or DB-AML-01 (2010-2013) n=67. Table 1 details protocol specifics, including drug dosages per course. Grade 3-4 toxicities, including hematological toxicity, cardiotoxicity, respiratory toxicity, mucositis, typhlitis, nephrotoxicity, hepatotoxicity, neurotoxicity, pain, allergic anaphylactic reaction, and elevation of alanineaminotransferase or bilirubin were defined according to Common Terminology Criteria for Adverse Event version 4.0, excluding infectious toxicity. Grade 5 toxicity (treatment-related mortality) was beyond the scope of this study. Intensive care unit (ICU) admission data was additionally assessed. Toxicity C.I.s were determined via competing events analyses. Relapse and death were considered competing events. Patients were censored at time of stem cell transplantation. Per-protocol comparisons were conducted via Chi-square test, due to lack of sufficient power required to calculate C.I.s.ResultsMedian age at diagnosis was 6.0 years [interquartile range (IQR) 1.0-12.0], 58% were male. Mucositis was the most frequent form of non-hematological toxicity with a C.I. of 86.1% (standard error (S.E.) 3.5%), followed by hepatotoxicity (C.I. 27.4%, S.E. 2.9%), and respiratory toxicity (C.I. 24.6%, S.E. 3.0%) (Table 2). Eighty-three patients (C.I. 33.9%, S.E. 3.0%) were admitted to the ICU at least once, for a median of 6.0 days [IQR 2.0-15.0] (Table 2).Relatively more blood transfusions (both erythrocyte and thrombocyte) were administered to patients treated according to AML-15 (98.3%) and DB-AML-01 (97.0%) compared to AML-12 (86.4%) (p=0.01 and p=0.02, respectively). Relatively more patients suffered from severe mucositis during DB-AML-01 compared to AML-12 (43.4% vs. 25.4%, p=0.01). More patients treated according to AML-15 had bilirubin levels >3x upper limit of normal (ULN) compared to those treated according to AML-12 (13.3% vs. 3.4%, p=0.01). There were no differences in non-infectious toxicity frequency between AML-15 and DB-AML-01. Other forms of toxicity did not differ significantly between protocols. The percentage of patients admitted to the ICU at least once during treatment was 33.9% in AML-12, 26.7% in AML-15, and 40.3% in DB-AML-01.ConclusionsThe high incidence of severe short- and long-term toxicities during pediatric AML therapy poses substantial challenges for patients, families, and care providers. Mucositis was the most common form of non-hematological, non-infectious toxicity in the whole cohort and across all Dutch protocols. Toxicities were more prevalent during the more recent protocols (AML-15 and DB-AML-01) compared to AML-12. Therefore, our findings are important in that they substantiate the need to optimize pediatric AML care in a manner which decreases treatment-related toxicity and QoL impairment. High treatment-related morbidity rates stress the urge to improve supportive care and develop less toxic treatment, while maintaining efficacy. [Display omitted] DisclosuresZwaan: Sanofi: Consultancy.

Clinical and biological aspects of myeloid leukemia in Down syndrome.

Children with Down syndrome are at an elevated risk of leukemia, especially myeloid leukemia (ML-DS). This malignancy is frequently preceded by transient abnormal myelopoiesis (TAM), which is self-limited expansion of fetal liver-derived megakaryocyte progenitors. An array of international studies has led to consensus in treating ML-DS with reduced-intensity chemotherapy, leading to excellent outcomes. In addition, studies performed in the past 20 years have revealed many of the genetic and epigenetic features of the tumors, including GATA1 mutations that are arguably associated with all cases of both TAM and ML-DS. Despite these advances in understanding the clinical and biological aspects of ML-DS, little is known about the mechanisms of relapse. Upon relapse, patients face a poor outcome, and there is no consensus on treatment. Future studies need to be focused on this challenging aspect of leukemia in children with DS.

Recommendations for Diagnosis and Treatment of Children with Transient Abnormal Myelopoiesis (TAM) and Myeloid Leukemia in Down Syndrome (ML-DS).

Children with Down syndrome are at a high risk of developing transient abnormal myelopoiesis (TAM; synonym: TMD) or myeloid leukemia (ML-DS). While most patients with TAM are asymptomatic and go into spontaneous remission without a need for therapy, around 20% of patients die within the first six months due to TAM-related complications. Another 20-30% of patients progress from TAM to ML-DS. ML-DS patients are particularly vulnerable to therapy-associated toxicity, but the prognosis of relapsed ML-DS is extremely poor - thus, ML-DS therapy schemata must strive for a balance between appropriate efficacy (to avoid relapses) and treatment-related toxicity. This guideline presents diagnostic and therapeutic strategies for TAM and ML-DS based on the experience and results of previous clinical studies from the BFM working group, which have helped reduce the risk of early death in symptomatic TAM patients using low-dose cytarabine, and which have achieved excellent cure rates for ML-DS using intensity-reduced treatment protocols.

The Mutational Landscape of Myeloid Leukaemia in Down Syndrome

Simple SummaryLeukaemia occurs when specific mutations promote aberrant transcriptional and proliferation programs, which drive uncontrolled cell division and inhibit the cell’s capacity to differentiate. In this review, we summarize the most frequent genetic lesions found in myeloid leukaemia of Down syndrome, a rare paediatric leukaemia specific to individuals with trisomy 21. The evolution of this disease follows a well-defined sequence of events and represents a unique model to understand how the ordered acquisition of mutations drives malignancy.Children with Down syndrome (DS) are particularly prone to haematopoietic disorders. Paediatric myeloid malignancies in DS occur at an unusually high frequency and generally follow a well-defined stepwise clinical evolution. First, the acquisition of mutations in the GATA1 transcription factor gives rise to a transient myeloproliferative disorder (TMD) in DS newborns. While this condition spontaneously resolves in most cases, some clones can acquire additional mutations, which trigger myeloid leukaemia of Down syndrome (ML-DS). These secondary mutations are predominantly found in chromatin and epigenetic regulators—such as cohesin, CTCF or EZH2—and in signalling mediators of the JAK/STAT and RAS pathways. Most of them are also found in non-DS myeloid malignancies, albeit at extremely different frequencies. Intriguingly, mutations in proteins involved in the three-dimensional organization of the genome are found in nearly 50% of cases. How the resulting mutant proteins cooperate with trisomy 21 and mutant GATA1 to promote ML-DS is not fully understood. In this review, we summarize and discuss current knowledge about the sequential acquisition of genomic alterations in ML-DS.

Genome Editing: the Fetal Origins of Acute Myeloid Leukemia in Down Syndrome

Genome Editing: the Fetal Origins of Acute Myeloid Leukemia in Down Syndrome

Mature Analysis of the Prospective Oxford Down Syndrome (DS) Cohort Study: Timing and Clinical Impact of Preleukemic GATA1 Mutations and Lessons for Management of Newborns with DS

Children with Down syndrome (DS) have a high risk of developing a unique form of AML known as myeloid leukaemia of DS (ML-DS) defined by the presence of one or more acquired N-terminal truncating mutations in the hematopoietic transcription factor gene GATA1 . ML-DS is confined to children <4 y of age and preceded by a neonatal preleukemic syndrome, Transient Abnormal Myelopoiesis (TAM). Although the same GATA1 mutations are present in ML-DS and TAM, indicating they are clonally-linked disorders, chemotherapy is essential to cure ML-DS whereas most cases of TAM spontaneously resolve without treatment.To determine the natural history of GATA1 mutations in DS and the true risk of subsequent leukemia conferred by GATA1 mutations we established the Oxford DS Cohort Study that prospectively analyses serial clinical, hematological and GATA1 mutational data from children with DS from birth to age 4y. All children had serial blood counts and smears and mutation analysis of exon 2/3 of GATA1 by next-generation-sequencing (NGS). A diagnosis of TAM was made if peripheral blood (PB) blasts were >10% and a GATA1 mutation was detected. DS neonates with PB blasts <10% and a GATA1 mutation were designated Silent TAM as our previous data on 18/80 DS neonates with blasts <10% showed that small mutant GATA1 clones were clinically and hematologically undetectable [Roberts et al, Blood 2013].We have now studied 471 neonates (gestational age [GA] at birth 29-42 wks) with karyotypically-confirmed DS. 130/471 (27.6%) had >1 GATA1 mutation confirming the high frequency of GATA1 mutations in DS neonates. Multiple GATA1 clones (2-7) were detected in 19% of TAM and 21% of Silent TAM (p=ns). A diagnosis of TAM was made in 55/471 (11.7%). 75/471 (15.9%) had Silent TAM and 341/471 had no GATA1 mutations. Typical clinical findings of TAM (hepatomegaly, splenomegaly, skin rash and effusions) were uncommon in Silent TAM, affecting 7%, 1.3%, 1.3% and 3% neonates respectively compared to 40%, 29%, 17% and 10% of neonates with TAM (p<0.0001). There were no specific hematological abnormalities in Silent TAM: median WBC and blasts were not increased: 13.1x109/L v 14.5x109/L and 4% v 4% (Silent TAM v no GATA1 mutation) and no neonates with Silent TAM had leucocytosis (WBC >35x109/L) or anemia. There was a strong correlation (r=0.753; p<0.0001) between PB blast% and mutant GATA1 clone size (assessed by VAF) with a greater mutant clone size in TAM v Silent TAM (median VAF 17.1% v 1.2%; p<0.0001).Unexpectedly, clone size was inversely proportional to GA (r=-0.2569; p=0.004). Despite similar median GA at delivery for all 3 groups, no GATA1 mutations were detected before 31 wks GA and no cases of TAM before 33 wks; the highest frequency of GATA1 mutations was seen at 34-35 wks GA (40%) reducing to 7% at >40 wks. This suggests GATA1 mutations are likely to be acquired and expand during a narrow time window early in the 3rd trimester of fetal life. Consistent with this, GATA1 mutations were not detected in 16 DS fetal liver samples (GA 8-19 wks) analysed over the same period. Similarly, in a case of TAM presenting in utero with fetal pericardial effusion and 96% PB blasts at 27 wks GA, the blast% and mutant GATA1 VAF spontaneously fell progressively (blasts 19%; VAF 23% at birth at 34 wks GA; undetectable at 4 wks postnatal age).Outcome: 7 neonates developed ML-DS: 6/52 survivors with TAM; 1/71 survivors with Silent TAM and 0/328 survivors without neonatal GATA1 mutations; 2/451 survivors developed ALL (1 Silent TAM, 1 no GATA1 mutation). 5 yr overall survival was the same in all 3 groups (95.1%, 95.8%, 95.1% for TAM, Silent TAM and no GATA1 mutations; Plog-rank 0.8994) while 5 yr event-free survival was lower in TAM (89.2%, 92.8%, 95.1% in TAM, Silent TAM and neonates with no GATA1 mutations; Plog-rank=0.0262). ML-DS was diagnosed at a median age of 14 m (range 3-18 m) preceded in all cases by a fall in platelet count. No single risk factor at birth specifically predicted for ML-DS although all 6 neonates with TAM who developed ML-DS had a mutant GATA1 VAF of >15% and blasts >20% at birth. The DS neonate with Silent TAM had a VAF of 2.5% and 4% blasts; this neonate was the only one of the cohort with a partial trisomy 21. Conclusion: Acquired N-terminal mutations in GATA1 are very frequent in neonates with DS and most probably occur or expand in the 3rd trimester; in the majority of cases mutant GATA1 clones are very small, clinically silent, resolve spontaneously and confer an extremely low risk of ML-DS. DisclosuresVyas:Jazz Pharmaceuticals: Speakers Bureau; Celgene Corporation: Speakers Bureau.

Post-induction MRD by FCM and GATA1-PCR are significant prognostic factors for myeloid leukemia of Down syndrome.

Myeloid leukemia of Down syndrome (ML-DS) is associated with good response to chemotherapy, resulting in favorable outcomes. However, no universal prognostic factors have been identified to date. To clarify a subgroup with high risk of relapse, the role of minimal residual disease (MRD) was explored in the AML-D11 trial by the Japanese Pediatric Leukemia/Lymphoma Study Group. MRD was prospectively evaluated at after induction therapy and at the end of all chemotherapy, using flow cytometry (FCM-MRD) and GATA1-targeted deep sequencing (GATA1-MRD). A total of 78 patients were eligible and 76 patients were stratified to the standard risk (SR) group by morphology. In SR patients, FCM-MRD and GATA1-MRD after induction were positive in 5/65 and 7/59 patients, respectively. Three-year event-free survival (EFS) and overall survival (OS) rates were 95.0% and 96.7% in the FCM-MRD-negative population, and 60.0% and 80.0% in the positive population. Three-year EFS and OS rates were both 98.1% in the GATA1-MRD-negative population, and 57.1% and 71.4% in the positive population. Adjusted hazard ratios for associations of FCM-MRD with EFS were 14.67 (p = 0.01). Detection of MRD by either FCM or GATA1 after initial induction therapy represents a significant prognostic factor for predicting ML-DS relapse.

Exposure of Patient-Derived Mesenchymal Stromal Cells to TGFB1 Supports Fibrosis Induction in a Pediatric Acute Megakaryoblastic Leukemia Model.

Bone marrow fibrosis (BMF) is a rare complication in acute leukemia. In pediatrics, it predominantly occurs in acute megakaryoblastic leukemia (AMKL) and especially in patients with trisomy 21, called myeloid leukemia in Down syndrome (ML-DS). Defects in mesenchymal stromal cells (MSC) and cytokines specifically released by the myeloid blasts are thought to be the main drivers of fibrosis in the bone marrow niche (BMN). To model the BMN of pediatric patients with AMKL in mice, we first established MSCs from pediatric patients with AMKL (n = 5) and ML-DS (n = 9). Healthy donor control MSCs (n = 6) were generated from unaffected children and adolescents ≤18 years of age. Steady-state analyses of the MSCs revealed that patient-derived MSCs exhibited decreased adipogenic differentiation potential and enrichment of proliferation-associated genes. Importantly, TGFB1 exposure in vitro promoted early profibrotic changes in all three MSC entities. To study BMF induction for longer periods of time, we created an in vivo humanized artificial BMN subcutaneously in immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice, using a mixture of MSCs, human umbilical vein endothelial cell, and Matrigel. Injection of AMKL blasts as producers of TGFB1 into this BMN after 8 weeks induced fibrosis grade I/II in a dose-dependent fashion over a time period of 4 weeks. Thus, our study developed a humanized mouse model that will be instrumental to specifically examine leukemogenesis and therapeutic targets for AMKL blasts in future. IMPLICATIONS: TGFB1 supports fibrosis induction in a pediatric AMKL model generated with patient-derived MSCs. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/18/10/1603/F1.large.jpg.

Complete blood count differences in a cohort of Down syndrome neonates with transient abnormal myelopoiesis screened for GATA1 pathogenic variants.

Transient abnormal myelopoiesis (TAM) raises the risk for acute myeloid leukemia of Down syndrome (DS) (ML-DS), and both are related to GATA1 pathogenic variants. Here, we analyzed which findings on complete blood count (CBC) are associated with TAM in a cohort of neonates with DS screened for GATA1 pathogenic variants. The CBCs were compared among 70 newborns with DS, including 16 patients (22.9%) with TAM (cases), and 54 patients (77.1%) without TAM (controls). TAM was defined as peripheral circulating blasts (PCBs) ≥ 1%. PCR and direct sequencing were used to screen DNA samples from peripheral blood for GATA1 exon 2 mutations. Multivariate logistic regression analyses determined that the mean count of lymphocytes was significantly higher in DS infants with TAM (p = .035) and that lymphocytosis confers a risk for TAM (adjusted odds ratio = 7.23, 95% confidence intervals: 2.02-25.92). Pathogenic variants of GATA1 were identified in 2 of 70 analyzed DS neonates (2.9%), of which one had ML-DS and another had an asymptomatic TAM. Among those DS infants with TAM, the GATA1 pathogenic variant detection was 12.5%. Our results indicated that lymphocytosis is associated with TAM in neonates with DS. However, since not all infants with an abnormal CBC had TAM, and not all infants with TAM had GATA1 pathogenic variants, we emphasize that only the search for GATA1 pathogenic variants allows the proper identification of the subgroup of DS infants with a real increasing in risk for ML-DS.

Retrospective Analysis of the Treatment Outcome in Myeloid Leukemia of Down Syndrome in Polish Pediatric Leukemia and Lymphoma Study Group From 2005 to 2019.

Background: Children with Down syndrome (DS) have increased risk of myeloid leukemia (ML), but specific treatment protocols ensure excellent outcome. This study was a retrospective analysis of the treatment results and genetic characteristics of ML of DS (ML-DS) in Poland from 2005 to 2019.Methods: All 54 patients with ML-DS registered in the Polish Pediatric Leukemia and Lymphoma Study Group in analyzed period were enrolled to the study. There were 34 children treated with Acute Myeloid Leukemia–Berlin-Frankfurt-Munster 2004 Interim Protocol (group I) and 20 patients treated with ML-DS 2006 Protocol (group II). In the first protocol, there was reduction of the antracyclines doses and intrathecal treatment for ML-DS compared to non-DS patients. In the second protocol, further reduction of the treatment was introduced (omission of etoposide in the last cycle, no maintenance therapy).Results: Probabilities of 5-year overall survival (OS), event-free survival (EFS), and relapse-free survival in the whole analyzed group were 0.85 ± 0.05, 0.83 ± 0.05, and 0.97 ± 0.03, respectively. No significant differences were found between two protocols in the terms of OS and EFS (0.79 ± 0.07 vs. 0.95 ± 0.05, p = 0.14, and 0.76 ± 0.07 vs. 0.95 ± 0.05, p = 0.12, respectively). All deaths were caused by the treatment-related toxicities. Reduction of the treatment-related mortality was noticed (20% in group I and 5% in group II). The only one relapse in the whole cohort occurred in the patient from group I, older than 4 years, without GATA1 gene mutation. He was treated successfully with IdaFLA cycle followed by hematopoietic stem cell transplantation from matched sibling donor. No significant prognostic factor was found in the study group probably due to low number of patients in the subgroups.Conclusions: The study confirms that the reduced intensity protocols are very effective in ML-DS patients. The only cause of deaths was toxicities; however, systematic decrease of the treatment-related mortality was noticed.