Mapping the cellular origin and early evolution of leukemia in Down syndrome

Children with Down syndrome have a 150-fold increased risk of developing myeloid leukemia, but the mechanism of predisposition is unclear. Because Down syndrome leukemogenesis initiates during fetal development, we characterized the cellular and developmental context of preleukemic initiation and leukemic progression using gene editing in human disomic and trisomic fetal hematopoietic cells and xenotransplantation. GATA binding protein 1 (GATA1) mutations caused transient preleukemia when introduced into trisomy 21 long-term hematopoietic stem cells, where a subset of chromosome 21 microRNAs affected predisposition to preleukemia. By contrast, progression to leukemia was independent of trisomy 21 and originated in various stem and progenitor cells through additional mutations in cohesin genes. CD117+/KIT proto-oncogene (KIT) cells mediated the propagation of preleukemia and leukemia, and KIT inhibition targeted preleukemic stem cells.

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Mapping the Cellular Origin and Early Evolution of Leukemia in Down Syndrome

10.1101/2020.11.29.402800 ◽

2020 ◽

Author(s):

Elvin Wagenblast ◽

Joana Araújo ◽

Olga I. Gan ◽

Sarah K. Cutting ◽

Alex Murison ◽

...

Keyword(s):

Stem Cells ◽

Down Syndrome ◽

Trisomy 21 ◽

Fetal Liver ◽

Chromosome 21 ◽

Hematopoietic Stem ◽

Cellular Origin ◽

Increased Risk ◽

Stem And Progenitor Cells ◽

Cellular Context

AbstractChildren with Down syndrome have a 150-fold increased risk of developing myeloid leukemia, but the mechanism of predisposition is unclear. As Down syndrome leukemogenesis initiates during fetal development, we characterized the cellular context of preleukemic initiation and leukemic progression using gene editing in human disomic and trisomic fetal liver hematopoietic cells and xenotransplantation. GATA1 mutations caused transient preleukemia only when introduced into trisomy 21 long-term hematopoietic stem cells, where a subset of chromosome 21 miRNAs triggers predisposition to preleukemia. By contrast, progression to leukemia was independent of trisomy 21 and originated in various stem and progenitor cells through additional mutations in cohesin genes. CD117+/KIT cells mediated the propagation of preleukemia and leukemia, and functional KIT inhibition targeted preleukemic stem cells, blocking progression to leukemia.

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Increased Mutagenesis during Fetal Hematopoietic Development in Down Syndrome

Blood ◽

10.1182/blood-2019-122855 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1186-1186

Author(s):

Karlijn Hasaart ◽

Freek Manders ◽

Susana Chuva de Sousa Lopes ◽

Ruben Van Boxtel

Keyword(s):

Stem Cells ◽

Down Syndrome ◽

Somatic Mutation ◽

Mutation Rate ◽

Fetal Development ◽

Chromosome 21 ◽

Mutational Signatures ◽

Hematopoietic Stem ◽

Fetal Stem Cells ◽

Increased Risk

Children with Down syndrome are predisposed to leukemia during the first years of their life. 5-10% of newborns with Down syndrome are born with transient myeloproliferative disorder (TMD), which often spontaneously disappears. The majority of these patients achieves complete remission. However, in 20-30% of all TMD patients the disease progress in acute megakaryoblastic leukemia. In addition, they have a 20 fold higher risk of developing B-lymphocyte acute leukemia (B-ALL). Leukemic development in Down syndrome is initiated during fetal development. However, it is unclear why fetuses with a trisomy of chromosome 21 have an increased risk of developing leukemia. Previously, we have developed a method to study somatic mutations in single cells using clonal cultures. Here, we applied this method to human fetal hematopoietic stem and progenitor cells (HSPCs) from liver and bone marrow of Down syndrome human fetuses and control fetuses with two copies of chromosome 21 (D21). In addition, we characterized somatic mutation accumulation in not affected small intestine stem cells. Subsequently, we performed in depth mutational analyses to characterize active processes using mutational signatures in fetal stem cells, which potentially can drive leukemic development during early life. Recently, we have shown that that healthy adult HSPCs gradually accumulate somatic mutations in a linear fashion with an annual mutation rate of 14.2 base substitutions per year. Whereas the somatic mutation rate is significantly higher during fetal development. Subsequently, in Down syndrome fetuses the overall somatic mutation rate of fetal stem cells is significantly increased compared to D21 fetal stem cells (P-value: 0,024). We performed phylogenetic analysis to study relatedness of the cells and observed an higher somatic mutation rate in the first cell divisions. This elevated mutation rate can be explained by increased contribution of mutational process signature 1 and 5, which are already present in fetal stem cells. Therefore, Down syndrome fetal stem cells show enhanced activity or increased sensitivity to mutational processes that are normally active during development. The same mutational signatures are present in TMD blast cells, indicating that these processes can cause cancer driver mutations and subsequently contribute to leukemic development. Interestingly, some Down syndrome fetal stem cells showed very high mutation numbers that could partly be attributed to mutational signature 18, which likely reflect oxidative-stress induced mutagenesis. These findings, show increased mutagenesis in Down syndrome during fetal development in hematopoietic stem cells and small intestine stem cells. This increased mutagenesis can potentially explain why children with Down syndrome have an increased risk of developing leukemia in early life. Disclosures No relevant conflicts of interest to declare.

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The AML1-ETO fusion protein promotes the expansion of human hematopoietic stem cells

Blood ◽

10.1182/blood.v99.1.15 ◽

2002 ◽

Vol 99 (1) ◽

pp. 15-23 ◽

Cited By ~ 141

Author(s):

James C. Mulloy ◽

Jörg Cammenga ◽

Karen L. MacKenzie ◽

Francisco J. Berguido ◽

Malcolm A. S. Moore ◽

...

Keyword(s):

Stem Cells ◽

Fusion Protein ◽

Progenitor Cells ◽

Protein Interactions ◽

Dominant Negative ◽

Myelogenous Leukemia ◽

Hematopoietic Stem ◽

Stem And Progenitor Cells

The acute myelogenous leukemia–1 (AML1)–ETO fusion protein is generated by the t(8;21), which is found in 40% of AMLs of the French-American-British M2 subtype. AML1-ETO interferes with the function of the AML1 (RUNX1, CBFA2) transcription factor in a dominant-negative fashion and represses transcription by binding its consensus DNA–binding site and via protein-protein interactions with other transcription factors. AML1 activity is critical for the development of definitive hematopoiesis, and haploinsufficiency of AML1 has been linked to a propensity to develop AML. Murine experiments suggest that AML1-ETO expression may not be sufficient for leukemogenesis; however, like the BCR-ABL isoforms, the cellular background in which these fusion proteins are expressed may be critical to the phenotype observed. Retroviral gene transfer was used to examine the effect of AML1-ETO on the in vitro behavior of human hematopoietic stem and progenitor cells. Following transduction of CD34+ cells, stem and progenitor cells were quantified in clonogenic assays, cytokine-driven expansion cultures, and long-term stromal cocultures. Expression of AML1-ETO inhibited colony formation by committed progenitors, but enhanced the growth of stem cells (cobblestone area-forming cells), resulting in a profound survival advantage of transduced over nontransduced cells. AML1-ETO–expressing cells retained progenitor activity and continued to express CD34 throughout the 5-week long-term culture. Thus, AML1-ETO enhances the self-renewal of pluripotent stem cells, the physiological target of many acute myeloid leukemias.

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Malignant Myeloma Cells Impair Phenotype and Function of stem and Progenitor Cells.

Blood ◽

10.1182/blood.v114.22.1799.1799 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1799-1799

Author(s):

Ingmar Bruns ◽

Sebastian Büst ◽

Akos G. Czibere ◽

Ron-Patrick Cadeddu ◽

Ines Brückmann ◽

...

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Hematopoietic Stem Cells ◽

Progenitor Cells ◽

Plasma Cells ◽

Self Renewal ◽

Hematopoietic Stem ◽

Healthy Donors ◽

Stem And Progenitor Cells

Abstract Abstract 1799 Poster Board I-825 Multiple myeloma (MM) patients often present with anemia at the time of initial diagnosis. This has so far only attributed to a physically marrow suppression by the invading malignant plasma cells and the overexpression of Fas-L and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) by malignant plasma cells triggering the death of immature erythroblasts. Still the impact of MM on hematopoietic stem cells and their niches is scarcely established. In this study we analyzed highly purified CD34+ hematopoietic stem and progenitor cell subsets from the bone marrow of newly diagnosed MM patients in comparison to normal donors. Quantitative flowcytometric analyses revealed a significant reduction of the megakaryocyte-erythrocyte progenitor (MEP) proportion in MM patients, whereas the percentage of granulocyte-macrophage progenitors (GMP) was significantly increased. Proportions of hematopoietic stem cells (HSC) and myeloid progenitors (CMP) were not significantly altered. We then asked if this is also reflected by clonogenic assays and found a significantly decreased percentage of erythroid precursors (BFU-E and CFU-E). Using Affymetrix HU133 2.0 gene arrays, we compared the gene expression signatures of stem cells and progenitor subsets in MM patients and healthy donors. The most striking findings so far reflect reduced adhesive and migratory potential, impaired self-renewal capacity and disturbed B-cell development in HSC whereas the MEP expression profile reflects decreased in cell cycle activity and enhanced apoptosis. In line we found a decreased expression of the adhesion molecule CD44 and a reduced actin polymerization in MM HSC by immunofluorescence analysis. Accordingly, in vitro adhesion and transwell migration assays showed reduced adhesive and migratory capacities. The impaired self-renewal capacity of MM HSC was functionally corroborated by a significantly decreased long-term culture initiating cell (LTC-IC) frequency in long term culture assays. Cell cycle analyses revealed a significantly larger proportion of MM MEP in G0-phase of the cell cycle. Furthermore, the proportion of apoptotic cells in MM MEP determined by the content of cleaved caspase 3 was increased as compared to MEP from healthy donors. Taken together, our findings indicate an impact of MM on the molecular phenotype and functional properties of stem and progenitor cells. Anemia in MM seems at least partially to originate already at the stem and progenitor level. Disclosures Off Label Use: AML with multikinase inhibitor sorafenib, which is approved by EMEA + FDA for renal cell carcinoma.

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Inactivation of PUMA Protects Hematopoietic Stem Cells and Confers Long Term Survival in Response to High Dose γ-Irradiation

Blood ◽

10.1182/blood.v112.11.612.612 ◽

2008 ◽

Vol 112 (11) ◽

pp. 612-612 ◽

Cited By ~ 1

Author(s):

Hui Yu ◽

Hongmei Shen ◽

Feng Xu ◽

Xiaoxia Hu ◽

Yanxin Li ◽

...

Keyword(s):

Stem Cells ◽

Hematopoietic Stem Cells ◽

Progenitor Cells ◽

Radiation Injury ◽

Γ Irradiation ◽

Hematopoietic Stem ◽

Cycle Arrest ◽

Stem And Progenitor Cells ◽

Radiation Induced

Abstract Radiation injury remains a significant health problem. New medical intervention to prevent or manage radiation damage is highly dependent on a deeper understanding of how radiation-induced cell death is accomplished in the irradiated tissue cells such as stem and progenitor cells. To date, relatively specific or untainted molecular mediators in apoptosis of tissue stem and progenitor cells upon radiation injury have not been clearly defined. The p53 pathway is known as a major molecular mechanism for cell apoptosis, upon the exposure of lethal radiation. Targeting p53 confers a radioprotective effect, but may increase tumorigenesis due to impaired cell cycle arrest for DNA repair. In our current study, we have examined the specific role of PUMA (p53 up-regulated mediator of apoptosis) in the radiosensitivity of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs). By quantitative RT PCR, we found that the level of PUMA mRNA was relatively low in the most primitive long-term repopulating hematopoietic stem cells (LT-HSC, isolated based on the immnunophenotype “CD34−LKS”) as compared to other hematopoietic cell populations from mice, but it was significantly elevated in response to γ-irradiation. In the mice lacking PUMA, while neither HSC number nor HSC function was altered under homeostatic conditions, the PUMA−/− HSCs appeared to be resistant to radiation damage in vivo as retrospectively quantified in a competitive HSC transplant model. Our further direct measurement with a single cell culture system for HSC growth in vitro, demonstrated that PUMA, but not p21 (the chief mediator of p53 in cell cycle arrest), is primarily responsible for the radiosensitivity of HSC in the p53 pathway (200 LT-HSCs analyzed for each cell type). Together, these data provide definitive evidence for PUMA as an essential mediator in radiation-induced apoptosis of tissue stem cells. We finally focused on the beneficial effects of targeting PUMA in HSCs and HPCs on the animal survival upon the exposure of lethal irradiation. Strikingly, the wild-type mice reconstituted with PUMA−/− hematopoietic cells exhibited a significant survival advantage after two rounds of 9-Gy γ-irradiation (18 Gy in total) as compared to the mice reconstituted with PUMA+/+ hematopoietic cells (95 % vs. 0 % survival in 20 days, n=21/each group; 50% vs. 0 % survival in 180 days, n=20 or 11/each group, respectively) as shown in the figure below. Moreover, unlike the p53−/− mice, those PUMA−/− reconstituted mice did not have an increased incidence of hematopoietic malignancies (n=20) within 180 days. Therefore, our current study establishes PUMA as an attractive molecular target for the development of therapeutic agents for the prevention and treatment of radiation injury.

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DNA Methyltransferase 1 Is Essential for and Uniquely Regulates Hematopoietic Stem and Progenitor Cells.

Blood ◽

10.1182/blood.v114.22.392.392 ◽

2009 ◽

Vol 114 (22) ◽

pp. 392-392 ◽

Cited By ~ 1

Author(s):

Jennifer J. Trowbridge ◽

Jonathan W. Snow ◽

Jonghwan Kim ◽

Stuart H. Orkin

Keyword(s):

Dna Methylation ◽

Stem Cells ◽

Progenitor Cells ◽

Dna Methyltransferase ◽

Adult Stem Cells ◽

Global Gene Expression ◽

Hematopoietic Stem ◽

Multipotent Progenitors ◽

Stem And Progenitor Cells

Abstract Abstract 392 DNA methylation is essential for development and plays crucial roles in a variety of biological processes. The DNA methyltransferase Dnmt1 serves to maintain parental cell methylation patterns on daughter DNA strands in mitotic cells, however, the precise role of Dnmt1 in regulation of quiescent adult stem cells is not known. To examine the role of Dnmt1 in adult hematopoietic stem cells (HSCs), we crossed Dnmt1fl/fl mice with Mx1-Cre transgenic mice, and by injection of poly(I)-poly(C) we selectively deleted Dnmt1 in the hematopoietic system (Dnmt1Δ/Δ). In Dnmt1Δ/Δ mice, peripheral blood counts and mature multilineage composition of the bone marrow was found to be normal. Interestingly, specific defects were observed in Dnmt1Δ/Δ HSC self-renewal as assessed by long-term and secondary competitive transplantation, in retention of Dnmt1Δ/Δ HSCs within the bone marrow niche, and in the ability of Dnmt1Δ/Δ HSCs to give rise to multilineage hematopoiesis. Loss of Dnmt1 also had unique impact on myeloid progenitor cells (including common myeloid progenitors, granulocyte-macrophage progenitors, and megakaryocyte-erythrocyte progenitors), regulating their cycling and transcriptional lineage fidelity. To determine the molecular mechanisms underlying these defects, we performed global gene expression microarray analysis and bisulfite sequencing of select loci (IAP, Car1, and Gata1) in purified populations of control and Dnmt1Δ/Δ long-term HSCs, short-term HSCs/multipotent progenitor cells, and myeloid restricted progenitor cells. Through this approach, we demonstrate that loss of Dnmt1 has cell type-specific molecular consequences. For example, demethylation of the Car1 and Gata1 loci in Dnmt1Δ/Δ long-term HSCs is not sufficient to activate gene transcription, whereas demethylation of these genes in Dnmt1Δ/Δ short-term HSCs is associated with activation of transcription. In Dnmt1Δ/Δ myeloid restricted progenitor cells, we observed increases in DNA methylation at specific gene loci such as Car1, indicating that methylation can be established by other methyltransferases in the absence of Dnmt1. Our global gene expression microarray analysis clearly demonstrates that Dnmt1 regulates expression of distinct gene families in these closely related, primitive hematopoietic populations. We were unable to attribute specific functional defects in Dnmt1Δ/Δ hematopoietic stem and progenitor cells to alterations in expression of previously characterized genes, supporting the existence of novel, uncharacterized regulators of HSC and progenitor cell function to be explored from candidates in our data set. We conclude that maintenance methylation induced by Dnmt1 appears to be especially important for HSC and progenitor cell state transitions, such as the stepwise differentiation of long-term HSCs to multipotent progenitors, multipotent progenitors to myeloid restricted progenitors, stem cell mobilization, and regulating cell cycle entry. These findings establish a unique and critical role for Dnmt1 in the primitive hematopoietic compartment. Furthermore, our evidence suggests that epigenetic regulation, at least with respect to DNA methylation, of adult stem cells is distinct from embryonic stem cells and other somatic cell types. Disclosures: No relevant conflicts of interest to declare.

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Single Cell Proteomics Reveals Novel Cytokine-Producing Function of Hematopoietic Stem and Progenitor Cells

Blood ◽

10.1182/blood.v120.21.26.26 ◽

2012 ◽

Vol 120 (21) ◽

pp. 26-26

Author(s):

Jimmy L. Zhao ◽

Chao Ma ◽

Ryan O'Connell ◽

Dinesh S. Rao ◽

James Heath ◽

...

Keyword(s):

Stem Cells ◽

Immune Response ◽

Single Cell ◽

Progenitor Cells ◽

Cytokine Production ◽

Conflicts Of Interest ◽

Severe Neutropenia ◽

Hematopoietic Stem ◽

Stem And Progenitor Cells

Abstract Abstract 26 During infection, hematopoietic stem and progenitor cells (HSPCs) are called upon to proliferate and differentiate to produce more innate and adaptive immune cells to combat infection. Traditionally, HSPCs are thought to respond to depletion of downstream hematopoietic cells during infection. More recent evidence suggests that HSPCs may respond directly to infection and pro-inflammatory cytokines. However, little is known about the direct immune response of HSPCs and the molecular signaling regulating this response upon sensing an infection. In this study, we have combined transgenic and genetic knockout mouse models with a novel single cell barcode proteomics microchip technology to tackle these questions. We show that although long-term hematopoietic stem cells (HSCs) (defined by Lineage-cKit+Sca1+CD150+CD48-) do not secrete cytokines upon toll-like receptor (TLR) stimulation, short-term HSCs and multipotent progenitor cells (MPPs) (defined by Lineage-cKit+Sca1+, referred to as LKS thereafter) can produce copious amounts of cytokines upon direct TLR-4 and TLR-2 stimulation, indicating that LKS cells can directly participate in an immune response by producing a myriad of cytokines, upon a bacterial infection. Within the population of LKS cells we detect multiple functional subsets of cells, specialized in producing myeloid-like, lymphoid-like or both types of cytokines. Moreover, we show that the cytokine production by LKS cells is regulated by the NF-κB activity, as p50-deficient LKS cells show reduced cytokine production while microRNA-146a (miR-146a)-deficient LKS cells show significantly increased cytokine production. As long-term HSCs differentiate, they start to gain effector immune function much earlier than we had originally anticipated. In light of this finding, we should start to view the stepwise differentiation scheme of HSCs, and perhaps all other stem cells, as a strategy to sequentially gain functional capacity, instead of simply losing stemness and self-renewal ability. The remarkable ability of LKS cells to produce copious amounts of cytokines in response to bacteria may provide some protective immunity during severe neutropenia and lymphopenia or in the early stage of HSC transplantation. This study further extends the functions of NF-κB to include the regulation of primitive hematopoietic stem and progenitor cells and provides direct evidence of the bacteria-responding ability of HSPCs through the TLR/NF-κB axis. The single cell barcode proteomics technology can be widely applied to study proteomics of other rare cells or heterogeneous cell population at a single cell level. Disclosures: No relevant conflicts of interest to declare.

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Highly penetrant myeloproliferative disease in the Ts65Dn mouse model of Down syndrome

Blood ◽

10.1182/blood-2007-04-085670 ◽

2008 ◽

Vol 111 (2) ◽

pp. 767-775 ◽

Cited By ~ 68

Author(s):

Gina Kirsammer ◽

Sarah Jilani ◽

Hui Liu ◽

Elizabeth Davis ◽

Sandeep Gurbuxani ◽

...

Keyword(s):

Down Syndrome ◽

Mouse Model ◽

Gene Dosage ◽

Hematologic Malignancies ◽

Chromosome 21 ◽

Myeloproliferative Disease ◽

Ts65dn Mouse ◽

Hematopoietic Stem ◽

Megakaryoblastic Leukemia ◽

Increased Risk

Children with Down syndrome (DS) display macrocytosis, thrombocytosis, and a 500-fold increased risk of developing megakaryocytic leukemia; however, the specific effects of trisomy 21 on hematopoiesis remain poorly defined. To study this question, we analyzed blood cell development in the Ts65Dn mouse model of DS. Ts65Dn mice are trisomic for 104 orthologs of Hsa21 genes and are the most widely used mouse model for DS. We discovered that Ts65Dn mice display persistent macrocytosis and develop a myeloproliferative disease (MPD) characterized by profound thrombocytosis, megakaryocyte hyperplasia, dysplastic megakaryocyte morphology, and myelofibrosis. In addition, these animals bear distorted hematopoietic stem and myeloid progenitor cell compartments compared with euploid control littermates. Of the 104 trisomic genes in Ts65Dn mice, Aml1/Runx1 attracts considerable attention as a candidate oncogene in DS–acute megakaryoblastic leukemia (DS-AMKL). To determine whether trisomy for Aml1/Runx1 is essential for MPD, we restored disomy at the Aml1/Runx1 locus in the Ts65Dn strain. Surprisingly, trisomy for Aml1/Runx1 is not required for megakaryocyte hyperplasia and myelofibrosis, suggesting that trisomy for one or more of the remaining genes can promote this disease. Our studies demonstrate the potential of DS mouse models to improve our understanding of chromosome 21 gene dosage effects in human hematologic malignancies.

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Identification of Lin–Sca1+kit+CD34+Flt3– short-term hematopoietic stem cells capable of rapidly reconstituting and rescuing myeloablated transplant recipients

Blood ◽

10.1182/blood-2004-06-2159 ◽

2005 ◽

Vol 105 (7) ◽

pp. 2717-2723 ◽

Cited By ~ 271

Author(s):

Liping Yang ◽

David Bryder ◽

Jörgen Adolfsson ◽

Jens Nygren ◽

Robert Månsson ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Hematopoietic Stem Cells ◽

Transplant Recipients ◽

Short Term ◽

Hematopoietic Stem ◽

Regulatory Pathways ◽

Stem And Progenitor Cells ◽

Bone Marrow Ablation

AbstractIn clinical bone marrow transplantation, the severe cytopenias induced by bone marrow ablation translate into high risks of developing fatal infections and bleedings, until transplanted hematopoietic stem and progenitor cells have replaced sufficient myeloerythroid offspring. Although adult long-term hematopoietic stem cells (LT-HSCs) are absolutely required and at the single-cell level sufficient for sustained reconstitution of all blood cell lineages, they have been suggested to be less efficient at rapidly reconstituting the hematopoietic system and rescuing myeloablated recipients. Such a function has been proposed to rather be mediated by less well-defined short-term hematopoietic stem cells (ST-HSCs). Herein, we demonstrate that Lin–Sca1+kithiCD34+ short-term reconstituting cells contain 2 phenotypically and functionally distinct subpopulations: Lin–Sca1+kithiCD34+flt3– cells fulfilling all criteria of ST-HSCs, capable of rapidly reconstituting myelopoiesis, rescuing myeloablated mice, and generating Lin–Sca1+kithiCD34+flt3+ cells, responsible primarily for rapid lymphoid reconstitution. Representing the first commitment steps from Lin–Sca1+kithi CD34–flt3– LT-HSCs, their identification will greatly facilitate delineation of regulatory pathways controlling HSC fate decisions and identification of human ST-HSCs responsible for rapid reconstitution following HSC transplantations.

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A Monocentric Clinical Observation of Haploidientical Transplantation in 27 Patients with Acute Megakaryocytic Leukemia

Blood ◽

10.1182/blood-2020-137374 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 15-16

Author(s):

Zhijie Wei ◽

Fei Pan ◽

Rong Yang ◽

Shuquan Ji ◽

Yue Guanlan ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Down Syndrome ◽

Stem Cell ◽

Hematopoietic Stem Cell Transplantation ◽

Clinical Observation ◽

Hematopoietic Stem ◽

Acute Megakaryocytic Leukemia

Background Acute Megakaryocytic Leukemia (AMKL) accounts for approximately 10% of childhood AML and 1% of adult AML cases. Although AMKL with Down syndrome has a good prognosis, the prognosis for non-DS-AMKL is quite poor with a 3-years survival rate of less than 40%. At present, only allogeneic HSCT is curative. In our study, we followed 27 patients with AMKL who received a modified Bu/Cy/Mel protocol and underwent hematopoietic stem cell transplantation. The patients were then followed up with monocentric clinical observation. Methods From August 2015 to July 2020, 27 AMKL patients (14 males, 13 females, all non-Down-AMKL) with a median age of 2 years (range: 1-9 years) were continuously treated in our hospital (Hebei Yanda Lu Daopei Hospital) including 18 cases of chromosome abnormality including 3 cases of CBFA2T3/GLIS2 gene fusion (11.1%). Gene mutation included WT1(8), EVI1(5), JAK2(5): 18.51%, TET2(4), ASXL1(4), PTPN11(4): 14.81%, GATA1(2), GATA2(2): 7.4%. Bone marrow status before transplantation: 19 complete remission (CR) cases, 3 partial response (PR) cases, and 5 no response (NR) cases. There were 24 haploidentical transplants (including one patient going through 3 transplants), one transplant from a HLA-identical sibling donor and two from matched unrelated donors. Source of donor stem cells: parents in 23 cases, brothers in 2 cases, non-blood relationship in 2 cases, and none from offspring. HLA matching between the donor and recipient: 21 cases with HLA 5/10, 6 cases with ≥HLA 6/10. Haplo stem cells all came from BM+PBSC, with a median MNC input of 20.32x108/kg (10.1-26.7), CD34+ 11.68106/kg (4.05-22.44), and CD3+ 4.66x108/kg (2.11-11.29). Pre-treatment protocol: 27 patients received a modified Bu/Cy/Mel and were treated with graft-versus-host disease (GVHD) to prevent CsA+MMF+sMTX. Results During a median follow-up period of 10 months (range: 2-48 months), the 27 patients remained alive, with a median of +13 days (range: 9-21 days) to leukocyte transplantation and a median of +9 days (range: 4-38 days) to platelet transplantation. One month following transplantation, the bone marrow of all patients was 100% donor type. The overall survival (OS) rate was 63.0%, event-free survival (EFS) was 59.3%. OS was 84.2%, 33.3%, and 0% in the CR, PR, and NR groups, respectively (P<0.001). There were 7 cases of relapse and 10 deaths, among which 4 were caused by GVHD and 5 due to relapse. Incidence of acute GVHD (aGVHD) was 59.25% Grade I-IV and 18.51% Grade III-IV. Incidence of chronic GVHD (cGVHD) was 56%, with cystitis accounting for 14.81% of cases, 29.62% cytomegalovirus (CMV), 3.7% EBV, 0% thrombotic microangiopathy (TMA) and 18.51% infection. Conclusion For high-risk AMKL patients with poor long-term prognosis, the application of a modified Bu/Cy/Mel pretreatment significantly improves the efficacy of haploid transplantation without increasing pretreat-related death. For non-Down syndrome AMKL, we conclude that it is feasible to perform hematopoietic stem cell transplantation in CR status patients. Additional studies and multicenter and large-scale clinical studies with long-term follow-up are still needed to confirm these results. Disclosures No relevant conflicts of interest to declare.

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