Novel Approaches to Modeling and Treating IDH1 Mutant Glioma

IDH1 突变神经胶质瘤建模和治疗的新方法

基本信息

批准号：
10247533
负责人：
Samuel Kent McBrayer
金额：
$ 13.94万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2022-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10247533
关键词：
ATRX gene Address Adult Anabolism Anaplastic astrocytoma Area Aspartate Astrocytoma Brain Brain Neoplasms Branched-Chain Amino Acids CRISPR/Cas technology Cells Chemicals Clinical Clinical Data Clinical Research DHODH gene Data Development Dihydroorotate dehydrogenase Dioxygenases Disease Disease model Engineering Enzymes Future Genes Genetic Genetic Engineering Genetically Engineered Mouse Glioblastoma Glioma Gliomagenesis Histones Hot Spot Human Hypersensitivity Impairment In Vitro Incidence Isocitrate Dehydrogenase Knowledge Link Lysine Malignant neoplasm of brain Mediating Metabolic Modeling Molecular Mus Mutate Mutation Neuroglia Neurons Nitrogen Nucleotides Oncogenes Pathogenesis Pathway interactions Patients Penetrance Pharmacology Procollagen-Proline Dioxygenase Production Pyrimidine Pyrimidine Nucleotides Radiation therapy Recurrence Specificity Testing Therapeutic Tissues Translating Tumor Biology Xenograft Model Xenograft procedure alpha ketoglutarate base branched-chain-amino-acid transaminase cell transformation cytotoxicity test effective therapy efficacy testing enzyme biosynthesis glioma cell line in vivo in vivo Model inhibitor/antagonist insight leukemia mouse model mutant mutant mouse model novel novel strategies novel therapeutic intervention novel therapeutics nucleotide metabolism pre-clinical preclinical study predictive marker research clinical testing response response biomarker therapeutically effective treatment strategy tumor

项目摘要

PROJECT SUMMARY Hot-spot mutations in the isocitrate dehydrogenase 1 (IDH1) gene are highly recurrent in lower grade gliomas (LGGs) and secondary glioblastomas (GBMs) and encode the mutant IDH1-R132H enzyme. This enzyme displays neomorphic activity, converting 2-oxoglutarate (2OG) to the oncometabolite (R)-2-hydroxyglutarate ((R)-2HG). (R)-2HG accumulates to millimolar levels in IDH1 mutant gliomas and promotes gliomagenesis by competitively modulating 2OG-dependent enzymes that regulate glial cell transformation. Although these discoveries have profoundly reshaped our understanding of the molecular pathogenesis of these diseases, these insights have not yet translated to the development of new, effective therapeutic strategies for glioma patients. Direct inhibitors of the mutant IDH enzyme have shown poor activity in early preclinical and clinical studies of IDH mutant glioma relative to the robust efficacy they display against IDH mutant leukemias. These findings highlight the clinical need for alternative therapeutic strategies to treat IDH1 mutant gliomas. I hypothesize that novel treatment strategies can be developed by exploiting synthetic lethality with the IDH1- R132H oncogene. I performed a chemical synthetic lethality screen using isogenic IDH1 mutant and wild-type glioma cell lines and found that multiple pyrimidine synthesis inhibitors preferentially killed IDH1 mutant cells. My preliminary data shows that (R)-2HG-mediated inhibition of the 2OG-dependent branched chain amino acid transaminases BCAT1 and BCAT2 impairs nitrogen incorporation into the pyrimidine biosynthesis pathway. Therefore, in Aim 1 I will test whether reduced BCAT activity represents the molecular mechanism underlying mutant IDH1-induced pyrimidine synthesis inhibitor hypersensitivity. I will go on to assess whether the IDH1- R132H mutation is a predictive biomarker for response to pyrimidine synthesis inhibitors by testing the cytotoxicity of these agents against a panel of IDH1 mutant and wild-type glioma neurosphere lines. Finally, I will test a novel brain-penetrant inhibitor of the pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase (DHODH) alone and in combination with radiotherapy in xenograft models of IDH1 mutant glioma. Another major impediment to the development of new, effective therapeutic strategies for IDH1 mutant glioma is a paucity of genetically-engineered mouse (GEM) models of this disease that can be used to evaluate such strategies. In Aim 2 I propose to establish the first Crispr/Cas9-based GEM models of glioma driven by mutant IDH1. I have successfully produced mutant Idh1-driven Grade III anaplastic astrocytomas in mice and I will optimize my approach to increase astrocytoma penetrance in this GEM model. I will also modify my strategy to generate isogenic GEM models of IDH1 mutant and wild-type GBM that can be used for future in vivo studies of synthetic lethality with the Idh1-R132H oncogene. If successful, these projects will establish rationale for clinical testing of pyrimidine synthesis inhibitors for IDH1 mutant glioma therapy and generate GEM models of this disease to support future testing of newly devised treatment strategies.

项目摘要在低级神经胶质瘤中，异戊酸脱氢酶1（IDH1）基因中的热点突变是高度复发的（LGGS）和二级胶质母细胞瘤（GBMS），并编码突变体IDH1-R132H酶。这种酶显示新形态活性，将2-氧化甲酸酯（2oG）转换为oncometabolite（R）-2-羟基戊二酸酯酸盐（R）（（R）-2HG）。（R）-2HG在IDH1突变胶质瘤中积累至毫米水平，并通过竞争性调节调节神经胶质细胞转化的2OG依赖性酶。虽然这些发现深刻地重塑了我们对这些疾病分子发病机理的理解，这些见解尚未转化为开发新的有效治疗策略的神经胶质瘤患者。突变体IDH酶的直接抑制剂在早期临床前和临床上的活性较差 IDH突变胶质瘤相对于它们针对IDH突变白血病所表现出的强大效率的研究。这些发现突出了治疗IDH1突变胶质瘤的替代治疗策略的临床需求。我假设可以通过用IDH1-利用合成致死性来制定新的治疗策略 R132H癌基因。我使用异源IDH1突变体和野生型进行了化学合成的致死性筛查神经胶质瘤细胞系，发现多种嘧啶合成抑制剂优先杀死IDH1突变细胞。我的初步数据表明，（R）-2HG介导的2OG依赖性分支链氨基酸的抑制转氨酶BCAT1和BCAT2损害氮掺入到嘧啶生物合成途径中。因此，在AIM 1中，我将测试降低的BCAT活性是否代表了底层的分子机制突变IDH1诱导的嘧啶合成抑制剂超敏反应。我将继续评估IDH1-是否 R132H突变是通过测试对嘧啶合成抑制剂反应的预测生物标志物这些药物针对IDH1突变体和野生型神经胶质瘤线的细胞毒性。最后，我将测试一种新型的嘧啶生物合成酶二羟基二苯二甲酸酯脱氢酶的脑培养剂抑制剂（Dhodh）单独并与IDH1突变胶质瘤异种移植模型中的放射疗法结合使用。其他对IDH1突变胶质瘤的新有效治疗策略发展的主要障碍是可用于评估这种疾病的遗传工程小鼠（GEM）模型的稀少度策略。在AIM 2中，我建议建立由突变体驱动的第一个基于CRISPR/CAS9的GEM模型 IDH1。我成功地产生了小鼠中的突变IDH1驱动的III级融合星形胶质细胞瘤，我将优化我在该宝石模型中增加星形胶质细胞渗透率的方法。我还将修改我的策略生成IDH1突变体和野生型GBM的等源性宝石模型，可用于未来的体内研究与IDH1-R132H癌基因合成致死性。如果成功，这些项目将为 IDH1突变胶质瘤治疗的嘧啶合成抑制剂的临床测试，并生成GEM模型这种疾病以支持新设计的治疗策略的未来测试。