Epigenetic Targeted Therapy for Chronic Lymphocytic Leu*

慢性淋巴细胞 Leu 的表观遗传靶向治疗*

• 批准号: 6923616
• 负责人: JOHN C. BYRD
• 金额: $ 30.65万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-16 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6923616
• 关键词: acetylation; amidohydrolases; antineoplastics; apoptosis; cell growth regulation; cell proliferation; chronic lymphocytic leukemia; clinical research; clinical trial phase I; combination cancer therapy; combination chemotherapy; drug resistance; enzyme inhibitors; fludarabine; gene induction /repression; genetic regulation; human subject; human therapy evaluation; methylation; methyltransferase; neoplasm /cancer chemotherapy; neoplasm /cancer genetics; neoplasm /cancer pharmacology; patient oriented research; pharmacokinetics; tumor suppressor genes

DESCRIPTION (provided by applicant): The importance of epigenetic transcriptional silencing of key tumor suppressor genes in many malignancies has been well established. The molecular mechanisms leading to this transcriptional silencing has recently begun to be understood over the last few years, leading to the concept that DNA methylation interacts in a dynamic way with nuclear histone modifications to either repress or enhance transcription. Pre-clinical work in chronic lymphocytic leukemia (CLL) by our chromatin remodeling team actively involved in this proposal has demonstrated these mechanisms of gene silencing is clinically relevant. Specifically, we have demonstrated marked variation in the amount of aberrant methylation in CLL patient samples ranging from 1% to 6% increase in specific gene methylation as compared to normal B cells. In addition, we have demonstrated that selected genes such as Dermis expressed-1 (DERMO-1), TWIST, and the metabotrobic glutamate receptor 7 (GRM7) are differentially methylated in primary tumor cells derived from patients with CLL. In addition, DERMO-1 and TWIST are associated with specific VH gene subtypes and prior treatment status. Furthermore, treatment of CLL cells with the hypomethylating agent decitabine promotes trapping of DNA methyltransferase 1 (DNMT1) on DNA and depletion of free DNMT1 protein with subsequent gene re-expression and caspase dependent apoptosis in CLL cells in vitro. Based upon this and our previous work with histone deacetylase inhibitors including valproic acid, we seek to test the overall hypothesis that application of epigenetic therapy targeting chromatin in CLL will relieve aberrant transcriptional repression of tumor suppressor genes, restore normal patterns of cell proliferation, differentiation and apoptosis and ultimately result in clinical benefit to patients with CLL. The specific aims of this proposal are: 1) to perform a minimal effective pharmacologic dose (MEPD) finding study of decitabine and then decitabine combined with valproic acid in fludarabine-refractory CLL patients, and 2) to perform the MEPD-directed studies concurrent with detailed pharmacologic and pharmacodynamic studies as part of the aim 1 clinical trial. This study will provide sufficient preliminary data to later pursue, as part of a separate application, a randomized phase II study to determine the clinical and gene re-expression efficacy of these two therapeutic approaches in fludarabine-refractory CLL. In addition, completion of this proposal will afford knowledge of the kinetics of DNMT1 inhibition in CLL and associated gene re-expression to allow pursuit of alternative combinations of epigenetically targeted therapies in the future.

描述（由申请人提供）：关键肿瘤抑制基因的表观遗传转录沉默在许多恶性肿瘤中的重要性已经得到充分证实。在过去的几年里，导致这种转录沉默的分子机制最近开始被人们所理解，从而产生了这样的概念：DNA 甲基化以动态方式与核组蛋白修饰相互作用，从而抑制或增强转录。我们的染色质重塑团队积极参与该提案，对慢性淋巴细胞白血病 (CLL) 进行的临床前工作证明了这些基因沉默机制具有临床相关性。具体来说，我们已经证明，与正常 B 细胞相比，CLL 患者样本中的异常甲基化量存在显着差异，具体基因甲基化增加了 1% 至 6%。此外，我们还证明，选定的基因，如真皮表达-1 (DERMO-1)、TWIST 和代谢性谷氨酸受体 7 (GRM7) 在源自 CLL 患者的原发性肿瘤细胞中存在差异甲基化。此外，DERMO-1 和 TWIST 与特定的 VH 基因亚型和既往治疗状态相关。此外，用低甲基化剂地西他滨处理 CLL 细胞可促进 DNA 甲基转移酶 1 (DNMT1) 在 DNA 上的捕获和游离 DNMT1 蛋白的消耗，随后在体外 CLL 细胞中进行基因重新表达和 caspase 依赖性细胞凋亡。基于这一点以及我们之前对包括丙戊酸在内的组蛋白脱乙酰酶抑制剂的研究，我们试图检验一个总体假设，即在 CLL 中应用针对染色质的表观遗传疗法将缓解肿瘤抑制基因的异常转录抑制，恢复细胞增殖、分化和凋亡的正常模式，并最终为 CLL 患者带来临床益处。该提案的具体目标是：1) 在氟达拉滨难治性 CLL 患者中进行地西他滨的最小有效药理剂量 (MEPD) 发现研究，然后将地西他滨与丙戊酸联合使用，2) 作为目标 1 临床试验的一部分，与详细的药理和药效学研究同时进行 MEPD 指导的研究。这项研究将提供足够的初步数据，以便以后作为单独申请的一部分进行随机 II 期研究，以确定这两种治疗方法在氟达拉滨难治性 CLL 中的临床和基因再表达功效。此外，该提案的完成将提供有关 CLL 中 DNMT1 抑制动力学和相关基因重新表达的知识，以便将来寻求表观遗传靶向治疗的替代组合。