Project 4: Novel epigenetic treatment of IDH mutant gliomas

项目4：IDH突变型胶质瘤的新表观遗传学治疗 摘要/摘要 异柠檬酸脱氢酶(IDH)1和2的突变在几种癌症类型中被发现，包括大多数 低级别胶质瘤和继发性胶质母细胞瘤(GBM)。尽管它们的寿命相对较长 相对于野生型IDH患者，IDH突变型胶质瘤患者仍然几乎总是死于 疾病。突变的idh导致肿瘤代谢物D-2-羟基戊二酸(2HG)的异常产生。多么 2HG在胶质瘤形成中的作用尚不清楚，但推测2HG干扰 α-酮戊二酸依赖酶的数量，包括参与DNA去甲基化的那些。一批 一系列证据表明，去甲基化子TET2的失活可能会导致DNA超甲基化 在许多IDH突变肿瘤中观察到。突变型IDH选择性抑制剂的治疗显示出希望 在急性髓细胞白血病(AML)中，但神经胶质瘤的临床前研究结果喜忧参半。我们的 初步数据表明，转录因子OLIG2可能是下调TET2的原因 与2HG结合，可能使TET2活性在IDH1突变体中几乎不存在 神经胶质瘤。因此，仅抑制突变的IDH不足以恢复TET2的功能。这是我们的 IDH突变型胶质瘤依赖于抑制TET2表达和 功能，以及一种联合抑制突变的idh的酶功能与 抑制OLIG2将对IDH突变型胶质瘤的治疗产生有益的影响。在目标1中，我们将 使用基于CRISPR的体外和体外基因编辑，验证OLIG2在IDH突变型胶质瘤中的重要性 活着。这些实验还将确定IDH突变的胶质瘤是否具有不同的背景突变， 例如，p53突变或1p/19q缺失，对OLIG2有不同的依赖性。在《目标2》中，我们将 确定单独干扰OLIG2和联合抑制突变的IDH1功能-- 使用研究化合物AG-881(一种新型的脑穿透性泛IDH突变体抑制剂)--破坏 TET2具有抑制肿瘤生长的作用。由于OLIG2的直接小分子抑制剂尚未被 开发后，我们的临床策略将集中在FDA批准的组蛋白脱乙酰酶(HDAC)的使用上 抑制剂，Panobinostat下调OLIG2。在临床前研究中，我们将测试潘诺比妥的效果 以及其他HDAC抑制剂与AG-881对OLIG2表达和TET2功能的影响 IDH突变型肿瘤的体内外生长。在目标3中，我们将继续进行两个阶段的临床研究。在……里面 第一阶段，我们将进行药代动力学/药效学临床试验，以验证 泛影葡胺对IDH突变肿瘤患者OLIG2表达的影响。在第二阶段，我们将进行 AG-881联合帕诺比妥与单用AG-881的疗效比较 肿瘤缓解率和无进展生存期(PFS)。到项目期结束时，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.