Epigenetic Targeted Therapy for Chronic Lymphocytic Leu*

描述（由申请人提供）：在许多恶性肿瘤中，关键肿瘤抑制基因的表观遗传转录沉默的重要性已得到充分证实。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理解，从而产生了DNA甲基化以动态方式与核组蛋白修饰相互作用以抑制或增强转录的概念。我们的染色质重塑团队积极参与了这项提案，他们在慢性淋巴细胞白血病（CLL）中的临床前工作已经证明了这些基因沉默机制与临床相关。具体而言，我们已经证明了CLL患者样品中异常甲基化量的显著变化，与正常B细胞相比，特定基因甲基化增加1%至6%。此外，我们已经证明，选定的基因，如真皮表达-1（DERMO-1），TWIST，和代谢型谷氨酸受体7（GRM 7）的差异甲基化的原发性肿瘤细胞来源于CLL患者。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细胞促进DNA甲基转移酶1（DNMT 1）在DNA上的捕获和游离DNMT 1蛋白的消耗，随后在体外CLL细胞中基因再表达和半胱天冬酶依赖性细胞凋亡。基于这一点和我们以前的工作与组蛋白脱乙酰酶抑制剂，包括丙戊酸，我们试图测试的总体假设，即应用表观遗传治疗靶向染色质在CLL将缓解异常转录抑制肿瘤抑制基因，恢复正常模式的细胞增殖，分化和凋亡，并最终导致临床受益的CLL患者。该提案的具体目的是：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学剂量（MEPD）探索研究，然后进行地西他滨联合丙戊酸的MEPD探索研究，2）作为目标1临床试验的一部分，在进行详细药理学和药效学研究的同时进行MEPD指导的研究。本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疗效。此外，该提案的完成将提供CLL中DNMT 1抑制的动力学和相关基因再表达的知识，以允许在未来追求表观遗传靶向治疗的替代组合。

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.