Novel therapies for bone marrow failure and Diamond-Blackfan Anemia

骨髓衰竭和戴蒙德-布莱克范贫血的新疗法

基本信息

批准号：
10929163
负责人：
CYNTHIA E DUNBAR
金额：
$ 68.6万
依托单位：
NATIONAL HEART, LUNG, AND BLOOD INSTITUTE
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10929163
关键词：
Agonist Anemia Annual Reports Aplastic Anemia Binding Blood Bone Marrow Bone marrow failure Cells Chelating Activity Clinical Clinical Research Clinical Trials Clonal Evolution Cohort Studies Collaborations Cyclosporine Cytogenetics Data Development Diamond-Blackfan anemia Disease Dose Dysmyelopoietic Syndromes Effectiveness Erythroid Erythroid Cells Erythropoiesis Failure Functional disorder Gene Proteins Genes Genotype Globin Glycine Hematology Hematopoiesis Hematopoietic Hematopoietic Neoplasms Hematopoietic Stem Cell Transplantation Heme Immunosuppression In Vitro Inherited Iron Iron Chelating Agents Iron Chelation Island Knowledge Laboratory Study Link Marrow Modeling Molecular Morbidity - disease rate Mosaicism Mus Mutation New Agents Oral Outcome Output Pathway interactions Patients Pharmaceutical Preparations Population Production Property Protein Biosynthesis Publishing Reactive Oxygen Species Refractory Refractory anemias Regimen Relapse Report (document)Reporting Research Residual state Ribosomal Proteins Role Safety Sampling Therapeutic immunosuppression Thrombopoietin Time Toxic effect Transfusion Translational Research Transplantation Chimera Universities Washington Work cell type clinically relevant clinically significant cytopenia design follow-up gene therapy heme biosynthesis imaging study improved in vivo inhibitor iron deficiency iron supplementation mosaic mouse model mutant novel therapeutics participant enrollment patient response predicting response progenitor programs receptor response ribosomopathy single-cell RNA sequencing small molecule stem stem cells thrombocytosis transport inhibitor

项目摘要

We developed a translational and clinical research program investigating the efficacy and safety of in vivo stimulation of hematopoiesis via the drug eltrombopag (EPAG), a small molecular that binds to the c-mpl receptor on hematopoetic stem and progenitor cells, demonstrating efficacy in refractory severe aplastic anemia, de novo severe aplastic anemia, moderate aplastic anemia, and myelodysplasia. During the current reporting period, we focused on predictors for response and molecular/cytogenetic progression and outcomes, participating in collaborative research with the group of Dr Neal Young on these topics. A major focus that resulted from our initial program studying the role of EPAG in marrow failure was the striking response to the drug in a patient with Diamond-Blackfan anemia, an inherited severe hypoproliferative anemia shown to result from mutations resulting in haploinsufficiency of one of a a group of ribosomal protein genes. This response was surprising, and led us to investigate the mechanism and pursue EPAG as a possible new therapy for DBA. Based on data generated in all of our EPAG bone marrow failure trials, we observed that EPAG is a potent iron chelator. In our large cohort study, we found that EPAG treatment results in rapid and clinically-significant iron unloading. Response rates and relapse rates were not impacted by initial iron status, suggesting that in aplastic anemia the activity of EPAG is linked to HSC stimulation not iron unloading. However, several patients have required oral iron supplementation while on long-term EPAG to avoid clinically-relevant iron deficiency (Young et al, 2022) The observation that EPAG reversed anemia in the inherited ribosomopathy DBA in the single DBA patient enrolled in the moderate AA/cytopenia trial along with new knowledge regarding possible DBA pathophysiology led us to hypothesize that the possible effectiveness of EPAG in DBA may be due to the potent intracellular chelating activity of EPAG. Recent laboratory studies suggest that erythroid development is inhibited in DBA due to slowed protein synthesis in erythroid progenitors, with a resulting imbalance in global chain production versus heme biosynthesis, leading to free heme/increased intracellular iron and toxic accumulation of reactive oxygen species. We have designed and now completed accrual and follow-up for a clinical trial to investigate the safety and activity of EPAG in DBA (20-H-0021). Only 1/15 patients responded, however the majority of patients required dose reductions or drug discontinuation due to thrombocytosis. The now two total patient responses is encouraging regarding the underlying hypothesis regarding how heme depletion might improve erythroid output in DBA. We are now focusing on a new drug that can slow heme synthesis without inducing thrombocytosis. Bitopterin in an oral Gly1T glycine transport inhibitor, It slows heme synthesis in erythroid precursors that are dependent on glycine for the first step in producing heme. We have shown that this drug is active in improving DBA erythroid progenitor maturation in vitro and in vivo in murine models. This trial has now begun enrolling patients. We are carrying out correlative laboratory and imaging studies to assess iron status and mechanism of EPAG and bitopertin action on samples from patients enrolled in the initial DBA trial. We have also noted that the initial DBA patient responding to EPAG in our prior trial was a mosaic, with somatic reversion in an early HSC, resulting in a fraction of wild type HSC hematopoietic output. Despite this mosaicism, the patient remained severely anemic and transfusion-dependent prior to EPAG, suggesting that mutant developing erythroid cells could inhibit wild-type cells within erythroblastic islands. We have explored this hypothesis in analyzing the lineage properties of the mosaicism and impact of EPAG, as well as a murine competitive repopulation model collaboratively with Janis Abkowitz at the University of Washington, documenting a marked inhibitory effect of mutant DBA cells on WT cells in experimental murine transplant chimeras, and this work has now been published (Doty et al, Blood, 2022). We are carrying out single cell RNASeq and genotyping of developing erythroid cells from both DBA patients (including the mosaic patient) and mosaic mice to investigate the likely mechanism and pathways that are involved. These studies have great relevance for the development of gene therapies for DBA, which would not be effective if residual mutant cells can inhibit wild type erythropoiesis

我们开发了一项转化和临床研究计划，研究通过药物艾曲波帕 (EPAG) 体内刺激造血的功效和安全性，艾曲波帕是一种与造血干细胞和祖细胞上的 c-mpl 受体结合的小分子，证明了其对难治性重症患者的疗效。再生障碍性贫血、重度再生障碍性贫血、中度再生障碍性贫血和骨髓增生异常。在当前报告期间，我们重点关注反应以及分子/细胞遗传学进展和结果的预测因素，并与 Neal Young 博士小组就这些主题进行合作研究。我们最初研究 EPAG 在骨髓衰竭中的作用的一个主要焦点是一名患有 Diamond-Blackfan 贫血的患者对该药物的惊人反应，这是一种遗传性严重低增殖性贫血，显示是由导致 a 之一的单倍体不足的突变引起的。一组核糖体蛋白基因。这种反应令人惊讶，促使我们研究其机制并寻求 EPAG 作为 DBA 的可能新疗法。根据我们所有 EPAG 骨髓衰竭试验中产生的数据，我们观察到 EPAG 是一种有效的铁螯合剂。在我们的大型队列研究中，我们发现 EPAG 治疗可实现快速且具有临床意义的铁卸载。缓解率和复发率不受初始铁状态的影响，这表明在再生障碍性贫血中，EPAG 的活性与 HSC 刺激有关，而不是与铁卸载有关。然而，一些患者在长期 EPAG 治疗期间需要口服补铁，以避免临床相关的铁缺乏（Young 等人，2022） EPAG 逆转了参加中度 AA/血细胞减少症试验的单个 DBA 患者的遗传性核糖体病 DBA 贫血的观察结果，以及有关可能的 DBA 病理生理学的新知识，使我们推测 EPAG 对 DBA 的可能有效性可能是由于EPAG 的细胞内螯合活性。最近的实验室研究表明，由于红系祖细胞中蛋白质合成减慢，DBA 中红系发育受到抑制，从而导致全链生产与血红素生物合成不平衡，导致游离血红素/细胞内铁增加和活性氧物质的有毒积累。我们已经设计并现已完成一项临床试验的应计和随访，以调查 EPAG 在 DBA 中的安全性和活性 (20-H-0021)。只有 1/15 的患者有反应，但大多数患者由于血小板增多需要减少剂量或停药。关于血红素消耗如何改善 DBA 中红细胞输出的基本假设，目前两名患者的总反应令人鼓舞。我们现在专注于一种可以减缓血红素合成而不诱导血小板增多的新药。双蝶呤是一种口服 Gly1T 甘氨酸转运抑制剂，它可以减缓红系前体中血红素的合成，而红系前体在生成血红素的第一步中依赖于甘氨酸。我们已经证明，该药物在体外和体内小鼠模型中可有效促进 DBA 红系祖细胞成熟。该试验现已开始招募患者。我们正在开展相关的实验室和影像学研究，以评估铁状态以及 EPAG 和 bitopertin 对初始 DBA 试验患者样本的作用机制。我们还注意到，在我们之前的试验中，最初对 EPAG 做出反应的 DBA 患者是嵌合体，早期 HSC 出现体细胞逆转，导致野生型 HSC 造血输出的一小部分。尽管存在这种镶嵌现象，患者在 EPAG 之前仍然存在严重贫血和输血依赖性，这表明正在发育的突变红系细胞可以抑制成红细胞岛内的野生型细胞。我们通过分析嵌合体的谱系特性和 EPAG 的影响，以及与华盛顿大学的 Janis Abkowitz 合作的小鼠竞争性再增殖模型，探索了这一假设，记录了实验中突变 DBA 细胞对 WT 细胞的显着抑制作用。小鼠移植嵌合体，这项工作现已发表（Doty 等人，Blood，2022）。我们正在对来自 DBA 患者（包括嵌合体患者）和嵌合体小鼠的正在发育的红细胞进行单细胞 RNASeq 和基因分型，以研究所涉及的可能机制和途径。这些研究对于 DBA 基因疗法的开发具有很大的相关性，如果残留的突变细胞能够抑制野生型红细胞生成，那么 DBA 基因疗法将不会有效