Optimizing decitabine regimen + formulation for nonDNA damaging DNMT1 depletion

优化地西他滨方案配方以消除非 DNA 损伤性 DNMT1

• 批准号: 8268939
• 负责人: Yogen Saunthararajah
• 金额: $ 31.93万
• 依托单位: CLEVELAND CLINIC LERNER COM-CWRU
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8268939
• 关键词: Aberrant DNA Methylation; Adjuvant; Biological Availability; Cancer Histology; Cell Survival; Cells; Chronic; Clinical; Clinical effectiveness; Cytarabine; Cytidine Deaminase; Cytidine Deaminase Inhibitor; DNA; DNA Damage; Decitabine; Dose; Drug Formulations; Drug Kinetics; Dysmyelopoietic Syndromes; Elderly; Ensure; Enzymes; FDA approved; Future; Genes; Health; Hematopoietic stem cells; Individual; Maintenance; Malignant Neoplasms; Mediating; Modeling; Molecular Target; National Heart, Lung, and Blood Institute; National Institute of Diabetes and Digestive and Kidney Diseases; Normal tissue morphology; Oral; Patient Selection; Patients; Pharmaceutical Preparations; Pharmacodynamics; Pharmacogenomics; Prevention; Procedures; Quantum Dots; Recruitment Activity; Regimen; Relapse; Request for Proposals; Resistance; Sickle Cell Anemia; Stem cells; Tetrahydrouridine; Therapeutic Index; Toxic effect; Transferase; Translating; United States National Institutes of Health; Variant; base; cancer cell; cancer prevention; chemotherapy; clinical effect; clinical practice; cytosine analog; gene repression; improved; killings; leukemia; leukemic stem cell; neoplastic; nucleoside analog; phase 1 study; prevent; resistance mechanism; response; self-renewal; treatment duration; tumor

DESCRIPTION (provided by applicant): Most chemotherapy for leukemia is limited by its toxicity to both leukemia cells and normal tissue. Ideally, therapy would target bio-molecules which are essential for leukemia stem-cell (LSC) but not normal hematopoietic stem-cell (HSC) survival. We demonstrate that the DNA methyl-transferase enzyme DNMT1 constitutes such an ideal molecular target; in HSC, DNMT1 is necessary for the self-renewal gene repression that must precede lineage-specific differentiation. In contrast, in LSC, DNMT1 is aberrantly recruited to repress pro-differentiation genes, prevent terminal differentiation and maintain dysregulated proliferation. Therefore, intermittent depletion of DNMT1 with non-DNA damaging doses of the cytosine analogue decitabine terminally differentiates LSC but increases self-renewal of HSC. This constitutes a very favorable therapeutic index. In the first aim of this proposal, we translate these observations into clinical practice. Decitabine was originally developed as a DNA-damaging agent. Doses were escalated to maximum tolerated levels in traditional phase I studies. Current regimens of decitabine still employ relatively high doses and drug administration is cycled to allow the patient to recover from toxicity. However, we show that effective DNMT1 depletion can be produced with levels of decitabine that do not damage DNA. Therefore, we propose lowering the dose of decitabine to minimize/avoid DNA damage and toxicity while maintaining DNMT1 depletion. The lack of toxicity will allow weekly, multi-year therapy to sustain the differential effect on LSC and HSC and introduces the possibility of adjuvant, maintenance or cancer prevention applications. We have demonstrated the remarkable clinical effectiveness and tolerability of using decitabine in this way in the treatment of severe sickle cell disease, where decitabine is administered 1-3X/week for multi-year treatment durations 2,3 4. In Specific Aim 1 of this proposal, we seek proof of concept of this regimen in treating malignancy. We believe the effort described in Aim 1 will be a significant advance in the treatment of malignancy. However, obstacles to realizing the full clinical potential of DNMT1 depletion by decitabine remain: (i) pharmacogenomic variation in cytidine deaminase (CDA), the enzyme which breaks-down decitabine, produces significant inter-individual variation in pharmacokinetics (PK) and pharmacodynamics (PD), compromising the ability to predict clinical effects in response to a specific dose; (ii) because of CDA- mediated drug destruction, decitabine has limited oral bioavailability, a significant impediment to the proposed treatment paradigm of multi-year, chronic therapy; (iii) we show that the major tumor stratagem for resistance to decitabine is CDA-mediated destruction of the drug. Such resistance may be especially likely in the intended chronic low-dose application of decitabine. In Specific Aim 2, we propose to surmount all three obstacles by combining decitabine with the CDA inhibitor tetrahydrouridine (THU) in a single oral formulation. PUBLIC HEALTH RELEVANCE: We demonstrate that the DNA methyl-transferase enzyme DNMT1 constitutes an ideal molecular target for leukemia therapy; in hematopoietic stem cells, DNMT1 is necessary for the self-renewal gene repression that must precede lineage-specific differentiation. In contrast, in leukemia cells, including models of leukemia stem cells, DNMT1 is aberrantly recruited to repress pro-differentiation genes, prevent terminal differentiation and maintain dysregulated proliferation. This proposal requests support to translate these observations into effective anti-malignancy therapy by optimizing regimen and formulation of the nucleoside analogue decitabine to deplete DNMT1 without causing DNA damage, even in malignant cells that are usually resistant to decitabine or cytosine arabinoside alone.

描述（由申请人提供）：大多数白血病化疗受到对白血病细胞和正常组织的毒性的限制。理想情况下，治疗将针对白血病 - 干细胞（LSC）所必需的生物分子，但不是正常的造血干细胞（HSC）生存。我们证明DNA甲基转移酶DNMT1构成了这种理想的分子靶标。在HSC中，DNMT1对于必须先于谱系特异性分化之前的自我更新基因抑制是必需的。相比之下，在LSC中，DNMT1被异常招募以抑制促差基因，防止末端分化并保持失调的增殖失调。因此，DNMT1与非DNA损坏剂量的胞质模拟替替替替替替端菜的间歇性耗尽可在终末区分LSC，但增加了HSC的自我更新。这构成一个非常有利的治疗指数。在该提案的第一个目的中，我们将这些观察结果转化为临床实践。去替他最初是作为DNA损害剂开发的。在传统的I期研究中，剂量被升级为最大耐受水平。德替他目前的方案仍采用相对较高的剂量，药物给药以使患者从毒性中恢复。但是，我们表明，可以用不损害DNA的去替他滨水平产生有效的DNMT1耗竭。因此，我们提出降低去替他的剂量，以最大程度地减少/避免DNA损伤和毒性，同时保持DNMT1消耗。缺乏毒性将允许每周进行多年治疗，以维持对LSC和HSC的差异影响，并引入辅助，维持或预防癌症应用的可能性。我们已经证明了以这种方式使用德甲滨在严重的镰状细胞疾病的情况下，在多年治疗持续时间为1-3倍/周使用Decitabine的出色临床有效性和耐受性。在此提案的特定目的1中，我们寻求这种治疗疾病的概念证明。我们认为，AIM 1中描述的努力将是治疗恶性肿瘤的重大进步。然而，仍然存在障碍，即确定DNMT1耗竭的全部临床潜力仍然存在：（i）cytidine deaminase（CDA）的药物基因组变异，该酶是破坏降低的去替替邦的酶，可在药物（PK）和药物对临床动力（PD）的响应（PD）中产生显着的跨性别变化（PD），对临床的响应（PD），对临床的影响（PD），对PDS，PDS，PDS，PDS，PDS，PDS，PDS，PDS，PDS，PD的​​响应范围，构成临床的影响。剂量（ii）由于CDA介导的药物破坏，切替他的口服生物利用度有限，这是对多年慢性治疗的拟议治疗范式的重大障碍； （iii）我们表明，耐药性的主要肿瘤策略是CDA介导的药物破坏。这种耐药性可能在预期的慢性低剂量施用法解替滨时尤其有可能。在特定的目标2中，我们建议通过单个口服配方将切替滨与CDA抑制剂四氢苯胺（THU）结合起来来克服这三个障碍。公共卫生相关性：我们证明DNA甲基转移酶DNMT1构成白血病治疗的理想分子靶标。在造血干细胞中，DNMT1对于必须先于谱系特异性分化之前的自我更新基因抑制是必需的。相反，在包括白血病干细胞模型的白血病细胞中，DNMT1被异常募集以抑制促分化基因，防止末端分化并保持失调的增殖失调。该提案要求支持这些观察结果通过优化方案和制定核苷类似物剪切替替替替菜的疗法，以耗尽DNMT1而不会造成DNA损伤，即使在通常抗Decitabine或单独抗性的阿拉伯糖苷中，也会造成DNA损伤。