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

我们制定了一项翻译和临床研究计划，研究了通过药物Eltrombopag（EPAG）（EPAG）对体内刺激造血的功效和安全性，这是一种与血小质干细胞和祖细胞上C-MPL受体结合的小分子，表明在质量严重的疾病中，表现出疗效骨髓增生。在当前的报告期间，我们专注于预测因子，以进行反应和分子/细胞遗传学进展和结果，并与Neal Young博士一起就这些主题进行了协作研究。我们最初研究EPAG在骨髓衰竭中的作用而产生的主要重点是对钻石黑粉血症患者对药物的惊人反应，这是一种遗传性的严重的低增生性贫血，该突变导致突变导致一组核糖体蛋白质基因的单倍不足。这种反应令人惊讶，并使我们研究了该机制，并追求EPAG作为DBA的新疗法。基于我们所有EPAG骨髓衰竭试验中产生的数据，我们观察到EPAG是有效的铁螯合剂。在我们的大型队列研究中，我们发现EPAG治疗可导致快速且临床上的铁卸载。反应率和复发率不受初始铁状态的影响，这表明在性贫血中，EPAG的活性与HSC刺激而不是铁卸载有关。但是，在长期EPAG上，有几名患者需要口服铁，以避免临床上的铁缺乏症（Young等，2022） EPAG在中度AA/细胞质试验中入选的单个DBA患者中EPAG逆转遗传性核糖体病DBA的贫血的观察结果以及有关可能DBA病理生理学的新知识导致我们假设EPAG在DBA中的可能有效性可能是由于EPAG的强大细胞内脑浮动活性而引起的。最近的实验室研究表明，由于红细胞祖细胞中蛋白质的合成缓慢，DBA抑制了红细胞发育，导致全球链产生与血红素生物合成的失衡，从而导致无反应性血红素/血红素内的生物合成增加，使活性氧气的细胞内铁和毒性氧气的毒性积累增加。我们已经设计并完成了一项临床试验的应计和随访，以研究EPAG在DBA（20-H-0021）中的安全性和活动。只有1/15例患者反应，但是大多数患者需要减少剂量或由于血小板病而导致的药物中断。现在，关于血红素耗竭如何改善DBA中的红血化产量的基本假设，目前有两个患者的反应令人鼓舞。现在，我们专注于一种可以减慢血红素合成而无需诱导血小板病的新药。在口服Gly1t甘氨酸转运抑制剂中，Bitopterin在产生血红素的第一步中依赖于甘氨酸的红细胞前体中的血红素合成。我们已经表明，该药物在体外和体内在鼠模型中的体外和体内都具有活跃性。该试验现在已经开始招募患者。我们正在进行相关实验室和成像研究，以评估EPAG的铁状态和机制以及对初次DBA试验患者的样品的铁状态和Bitopertin作用。我们还指出，在我们先前的试验中，最初对EPAG做出反应的DBA患者是马赛克，在早期的HSC中进行了体细胞恢复，导致野生型HSC HSC造血输出的一部分。尽管有这种镶嵌性，但患者在EPAG之前仍然严重贫血和输血依赖，这表明发生的突变体可以抑制红细胞岛中的野生型细胞。我们已经探讨了这一假设，分析了EPAG的镶嵌和影响的谱系特性，以及与华盛顿大学的Janis Abkowitz合作，记录了突变体DBA对WT细胞对WT细胞对实验性鼠类移植奇马群的抑制作用的明显抑制作用，该工具已及其录制了，该作品已于202年（均已出现）。我们正在进行单细胞RNASEQ和来自DBA患者（包括镶嵌患者）和镶嵌小鼠的发育中的红细胞细胞的基因分型，以研究涉及的可能机制和途径。这些研究与DBA基因疗法的发展具有很大的意义，如果残留突变细胞可以抑制野生型红细胞生成，这将是无效的