Optimizing demethylating therapy for IDH1 Mutant Malignant Gliomas

异柠檬酸脱氢酶1(IDH1)的驱动突变存在于70%-80%的II级和III级胶质瘤中， 大多数最终进展为多形性胶质母细胞瘤(GBM)。在这类分子上截然不同的 恶性胶质瘤，突变的IDH1酶产生2-羟基戊二酸(2-HG)，这是一种抑制肿瘤代谢物 α-酮戊二酸依赖的组蛋白和DNA去甲基酶导致的特征性甲基化 基因组DNA与细胞分化抑制。我们已经证明了临床前的疗效和 已批准的DNA去甲基化药物5-氮杂胞苷(5-aza)的作用机理及其揭示的组合 这进一步提高了存活率。在具有天然IDH1突变的模型中，5-aza给药可减少肿瘤 负重、延长存活时间和体内诱导分化。5-氮杂环己烷与标准护理的结合，使用 分化和促凋亡药物都显示出进一步的好处。这项修订拨款的重点是优化 为II级或高级别IDH1突变胶质瘤量身定做的治疗和验证机制。 在目标1中，我们建议演示5-氮杂氮诱导细胞生长抑制的机制，并进一步 优化5-氮杂氮与IDH1突变型胶质瘤的标准护理治疗。我们最近展示了 在我们的IDH1突变型PDX模型中，使用5-aza可以更好地减轻肿瘤负担和延长生存期 与替莫唑胺联合使用，而不考虑给药顺序。在目标2中，我们将确定影响 DNA去甲基化联合维甲酸诱导分化治疗IDH1突变型胶质瘤。 我们的初步数据显示，5-氮杂氮调节维甲酸信号转导，在IDH1突变型PDX胶质瘤模型中 这两种药物可以协同作用减缓肿瘤的生长。在目标3中，我们建议将5-aza与促凋亡剂相结合 药物PAC-1治疗IDH1突变型胶质瘤并探讨其作用机制。初步数据显示， Procaspase激活化合物-1(PAC-1)，一种新的脑穿透性原天冬氨酸酶3裂解小分子， 在IDH1突变的脑胶质瘤模型中增加细胞凋亡和存活的功能。我们的团结 其中每个目标的假设是逆转病理机制的组合 去甲基化将增强DNA损伤、细胞衰老和/或已知的抗癌机制 这种相互依赖的机制将结合在一起，安全地提高存活率。 在临床前研究中，每一种被提议的小分子疗法都显示出单一药物疗效的证据。 治疗神经胶质瘤。我们建议确定去甲基化、分化治疗和caspase的机制 3激活最好安全地结合在一起以获得治疗反应。我们的主要目标是产生临床前数据 这可能支持对IDH1突变胶质瘤患者进行新的试验。这些疗法有可能导致 DNA损伤将保留在高级别胶质瘤，而毒性较低的治疗方案被建议用于低级别胶质瘤。 胶质瘤，其中有可能对生存有很大影响的好处。

Driver mutations in Isocitrate Dehydrogenase 1 (IDH1) are present in 70-80% of grade II and III gliomas, with the majority eventually progressing to glioblastoma multiforme (GBM). In this molecularly distinct class of malignant gliomas, mutant IDH1 enzyme produces 2-hydroxyglutarate (2-HG), an oncometabolite that inhibits α-ketoglutarate dependent histone and DNA demethylases resulting in characteristic hypermethylation of genomic DNA and suppression of cellular differentiation. We have demonstrated the preclinical efficacy and mechanism of action of the approved DNA demethylating drug 5-Azacytidine (5-Aza) and revealed combinations that further enhance survival. In models with the native IDH1 mutation, 5-Aza administration reduces tumor burden, extends survival and induce differentiation in vivo. Combination of 5-Aza with standard of care, use of differentiation, and pro-apoptotic drugs all show further benefit. The focus of this revised grant is to optimize treatment and validate mechanism tailored to either grade II or high grade IDH1 mutant gliomas. In Aim 1 we propose to demonstrate the mechanism of 5-Aza induced cell growth reduction and further optimize 5-Aza with standard of care treatment for IDH1 mutant glioma. We have recently demonstrated reduction in tumor burden and extend survival in our IDH1 mutant PDX model works better when using 5-aza in combination with temozolomide regardless of the order of administration. In Aim 2 we will determine the impact of DNA demethylating agent in combination with differentiation therapy using retinoic acid in IDH1 mutant glioma. Our preliminary data shows that 5-Aza regulates retinoic acid signaling, and in IDH1 mutant PDX glioma model the two work synergistically to slow tumor growth. In aim 3 we propose to combine 5-Aza with the proapoptotic drug PAC-1 in IDH1 mutant glioma and explore the mechanism of response. Preliminary data indicate that Procaspase Activating Compound-1 (PAC-1), a novel brain penetrant procaspase 3 cleaving small molecule, functions to increase apoptosis and survival in an intracranial model of IDH1 mutant glioma. Our unifying hypothesis for each of these aims is that the combination of the mechanisms of reversing pathological demethylation will enhance known anticancer mechanisms of DNA damage, cellular senescence and/or apoptosis, and that interdependent mechanisms will combine to safely increase survival. Each of the small molecule therapies proposed show evidence of single agent efficacy in preclinical studies for glioma. We propose to determine how the mechanisms of demethylation, differentiation therapy and caspase 3 activation best combine safely for a therapeutic response. Our major goal is to produce the preclinical data that might support a new trial for patients with IDH1 mutant glioma. Those therapies with the possibility of causing DNA damage will be reserved for high grade gliomas, while less toxic therapies are proposed for low grade gliomas, where there is the possibility of a large impact on survival benefit.