Project 4: Novel epigenetic treatment of IDH mutant gliomas

项目4：IDH突变胶质瘤的新型表观遗传治疗 总结/摘要 异柠檬酸脱氢酶（IDH）1和2的突变在几种癌症类型中发现，包括大多数癌症。 低级别胶质瘤和继发性胶质母细胞瘤（GBM）。尽管它们的生存时间相对较长 相对于野生型IDH患者，IDH突变型神经胶质瘤患者几乎总是死于其自身免疫缺陷。 疾病突变IDH导致癌代谢产物D-2-羟基戊二酸（2 HG）的异常产生。如何 2 HG对胶质瘤形成的作用还不清楚，但据推测2 HG干扰了胶质瘤的形成。 许多α-酮戊二酸依赖性酶，包括参与DNA去甲基化的酶。一些 大量证据表明，去甲基化因子TET 2的失活可导致DNA高甲基化 在许多IDH突变体肿瘤中观察到。用突变IDH的选择性抑制剂治疗已显示出希望 在急性髓性白血病（AML），但在神经胶质瘤的临床前研究的结果已经混合。我们 初步数据表明，转录因子OLIG 2可能负责下调TET 2 mRNA，与2 HG组合，潜在地使TET 2活性在IDH 1突变体中几乎不存在。 神经胶质瘤因此，单独抑制突变体IDH将不足以恢复TET 2功能。是我们 IDH突变型胶质瘤依赖于TET 2表达的抑制， 功能，以及抑制突变IDH的酶功能与抑制IDH的酶功能的组合方法沿着。 OLIG 2的抑制将对IDH突变型神经胶质瘤的治疗具有有益效果。在目标1中，我们 验证OLIG 2在IDH突变型胶质瘤中的重要性，使用基于CRISPR的基因编辑在体外和体内， vivo.这些实验还将确定是否IDH突变神经胶质瘤具有不同的背景突变， 例如，在一个实施例中，P53突变或1 p/19 q缺失，将对OLIG 2产生不同的依赖性。在目标2中，我们将 确定单独破坏OLIG 2和与抑制突变体IDH 1功能组合是否-- 使用研究化合物AG-881（一种新的脑渗透泛IDH突变抑制剂）-破坏 TET 2功能并抑制肿瘤生长。由于OLIG 2的直接小分子抑制剂尚未被发现， 我们的临床策略将集中在使用FDA批准的组蛋白去乙酰化酶（HDAC） 抑制剂帕比司他下调OLIG 2。在临床前研究中，我们将测试帕比司他的效果 和其他HDAC抑制剂与和不与AG-881对OLIG 2表达和TET 2功能的影响，以及对 IDH突变体肿瘤在体外和体内的生长。在目标3中，我们将继续进行2阶段临床研究。在 第一阶段，我们将进行药代动力学/药效学临床试验，以验证 帕比司他对IDH突变型肿瘤患者的OLIG 2表达的影响。在第二阶段，我们会进行 比较AG-881加帕比司他与AG-881单药对以下疾病的影响的II期随机临床试验： 肿瘤缓解率和无进展生存期（PFS）。到项目结束时，我们将拥有 验证了我们的治疗策略是否是IDH突变型胶质瘤患者的可行选择。

Project 4: Novel epigenetic treatment of IDH mutant gliomas SUMMARY/ABSTRACT Mutations in isocitrate dehydrogenase (IDH) 1 and 2 are found in several cancer types, including the majority of low-grade gliomas and secondary glioblastomas (GBM). Although their survival is relatively prolonged relative to patients with wild-type IDH, patients with IDH mutant gliomas still almost invariably succumb to their disease. Mutant IDH causes the aberrant production of the oncometabolite D-2-hydroxyglutarate (2HG). How 2HG contributes to glioma formation is not well-understood, but it is postulated that 2HG interferes with a number of α-ketoglutarate dependent enzymes, including those involved in DNA demethylation. A number of lines of evidence indicate that inactivation of the demethylator TET2 could result in the DNA hypermethylation observed in many IDH mutant tumors. Treatment with selective inhibitors of mutant IDH have shown promise in acute myelogenous leukemia (AML), but results of pre-clinical studies in glioma have been mixed. Our preliminary data indicate that the transcription factor OLIG2 may be responsible for downregulating TET2 mRNA which, in combination with 2HG, potentially renders TET2 activity virtually non-existent in IDH1-mutant gliomas. As such, inhibition of mutant IDH alone would be insufficient to recoup TET2 function. It is our fundamental hypothesis that IDH mutant gliomas are dependent on repression of TET2 expression and function, and that a combined approach of inhibition of the enzymatic function of mutant IDH along with the suppression of OLIG2 will have a beneficial effect on the treatment of IDH mutant gliomas. In Aim 1, we will validate the importance of OLIG2 in IDH mutant gliomas, using CRISPR-based gene editing in vitro and in vivo. These experiments will also determine whether IDH mutant gliomas with different background mutations, e.g., P53 mutation or 1p/19q deletion, will have different dependency on OLIG2. In Aim 2, we will then determine whether disruption of OLIG2 alone and in combination with inhibition of mutant IDH1 function -- using the investigational compound AG-881 (a novel brain-penetrant pan-IDH mutant inhibitor) -- disrupts TET2 function and inhibits tumor growth. Since direct small molecule inhibitors of OLIG2 have not been developed, our clinical strategy will focus on the use of the FDA-approved histone deacetylase (HDAC) inhibitor, panobinostat to downregulate OLIG2. In pre-clinical studies, we will test the effects of panobinostat and other HDAC inhibitors with and without AG-881 on OLIG2 expression and TET2 function, as well as on growth of IDH mutant tumors in vitro and in vivo. In Aim 3, we will then proceed with a 2-stage clinical study. In the first stage, we will perform a pharmacokinetic/pharmacodynamic clinical trial to verify the effects of panobinostat on OLIG2 expression in patients with IDH mutant tumors. In the second stage, we will conduct a Phase II randomized clinical trial comparing the effects of AG-881 plus panobinostat versus AG-881 alone on tumor response rate and progression-free survival (PFS). By the end of the project period, we will have verified whether our therapeutic strategy is a viable option for patients with IDH mutant glioma.