Clinical and Molecular Heterogeneity in the Myelodysplastic Syndromes

总结 MDS代表一组由造血干细胞引起的获得性骨髓衰竭综合征 （HSC）。虽然大多数MDS患者经历进行性血细胞减少，但显著少数（30%）患者将进展 急性髓细胞白血病（AML）;然而，决定患者是否经历 进行性血细胞减少症或白血病转化知之甚少。虽然MDS的无效性 这些疗法是由于它们不能有效地消除MDS克隆和/或恢复正常分化， 目前尚不清楚低甲基化剂（HMA）是否作用于HSC或定向祖细胞以诱导 血液学改善和/或原始细胞计数减少，或者HMA是否通过相似或独特的机制发挥作用 在这些不同的细胞群中。我们和其他人已经表明MDS HSC表现出明显不同的基因， CD 34+造血干/祖细胞（HSPCs）的表达谱，并且它们在遗传上也是 和转录异质性6 -10;然而，这些先前的研究并不是为了特异性地捕获 致力于祖细胞对疾病进展或对HMA的治疗反应的贡献。我们假设 来自经历进行性血细胞减少或 白血病转化在HMA之前和响应HMA时表现出独特转录特征 疗法其次，我们假设HMAs诱导独特的转录和功能变化 在MDS造血干细胞和定向祖细胞中， 程序确定患者是否响应血液学改善和/或急变 减少。我们建议阐明HSC和定向祖细胞反应的转录基础， 使用新的全长cDNA scRNA-seq技术在单细胞水平上对MDS患者进行研究， 同时表征转录组和突变数据在个别细胞内从配对的前， 来自具有不同类型疾病进展和对HMA的应答的MDS患者的治疗后样品 疗法我们还将通过评估MDS相关的RNA特征来评估我们研究结果的临床相关性。 在转录组数据和临床结果数据可用的较大MDS患者队列中。 失调转录物对MDS进展的贡献的评估将使用小鼠骨髓瘤模型进行评估。 MDS模型以及原代MDS患者细胞。总的来说，我们希望我们的研究：1）确定基因 以及决定MDS患者是否会经历进行性血细胞减少的生物学途径， 白血病转化; 2）阐明不同HSPC群体在确定临床应答中的作用 3）鉴定新的生物标志物，用于说明HMA治疗的临床结果和治疗反应， MDS; 4）为新途径或遗传靶向的MDS的未来临床研究提供生物学原理 与HMA组合的药剂。

SUMMARY MDS represents a group of acquired bone marrow failure syndromes arising from hematopoietic stem cells (HSCs). While most MDS patients experience progressive cytopenias, a significant minority (30%) will progress to acute myeloid leukemia (AML); however, the mechanisms that determine whether patients experience progressive cytopenias or leukemia transformation are poorly understood. While the ineffectiveness of MDS therapies is due to their inability to effectively eliminate MDS clones and/or restore normal differentiation, it remains unclear whether hypomethylating agents (HMAs) act on HSCs or committed progenitors to induce hematologic improvement and/or reductions in blast count, or if HMAs act through similar or unique mechanisms in these distinct cell populations. We and others have shown that MDS HSCs exhibit markedly different gene expression profiles than CD34+ hematopoietic stem/progenitor cells (HSPCs) and that they are also genetically and transcriptionally heterogeneous6-10; however, these prior studies were not designed to specifically capture committed progenitor contributions to disease progression or therapeutic responses to HMAs. We hypothesize that HSCs and committed progenitors from MDS patients who experience progressive cytopenias or leukemic transformation exhibit unique transcriptional signatures prior to, and in response to, HMA therapy. Secondarily, we hypothesize that HMAs induce unique transcriptional and functional changes in MDS HSCs and committed progenitors, and that their ability to induce specific transcriptional programs determines whether or not patients respond with hematologic improvements and/or blast reductions. We propose to elucidate the transcriptional basis of HSC and committed progenitor responses from MDS patients at the single cell level using novel full-length cDNA scRNA-seq technologies that will allow simultaneous characterization of the transcriptome and mutational data within individual cells from paired pre- and post-therapy samples from MDS patients with different types of disease progression and responses to HMA therapy. We also will evaluate the clinical relevance of our findings by evaluating MDS-associated RNA features in larger cohorts of MDS patients for whom transcriptome data and clinical outcome data are available. Assessments of the contribution of dysregulated transcripts to MDS progression will be evaluated using mouse models of MDS as well as primary MDS patient cells. Overall, we expect our studies to: 1) Identify the genes and biological pathways that determine whether MDS patients will experience progressive cytopenia versus leukemic transformation; 2) Elucidate the roles of different HSPC populations in determining clinical responses to HMA therapy; 3) Identify novel biomarkers for prognostication of clinical outcomes and therapy responses in MDS; 4) Provide the biological rationale for future clinical studies of novel pathway- or genetically-targeted agents in combination with HMAs.