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: 8082793
• 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/8082793
• 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(申请人提供)：大多数白血病的化疗受到其对白血病细胞和正常组织的毒性的限制。理想情况下，治疗的目标应该是白血病干细胞(LSC)生存所必需的生物分子，而不是正常的造血干细胞(HSC)。我们证明DNA甲基转移酶DNMT1构成了这样一个理想的分子靶点；在HSC中，DNMT1是必须在谱系特异性分化之前进行自我更新基因抑制所必需的。相反，在LSC中，DNMT1被异常招募来抑制促分化基因，防止终末分化和维持失调的增殖。因此，间歇性耗尽DNMT1和非DNA损伤剂量的胞嘧啶类似物地西他滨可终末分化LSC，但增加HSC的自我更新。这构成了一个非常有利的治疗指标。在这项建议的第一个目标中，我们将这些观察结果转化为临床实践。地西他滨最初是作为一种DNA损伤剂开发的。在传统的I期研究中，剂量被提高到最大耐受水平。目前的地西他滨方案仍然使用相对较高的剂量，并且药物给药是循环的，以使患者从毒性中恢复。然而，我们表明，在不损害DNA的地西他滨水平下，可以产生有效的DNMT1耗竭。因此，我们建议降低地西他滨的剂量，以最大限度地减少/避免DNA损伤和毒性，同时保持DNMT1的耗竭。这种毒性的缺乏将使每周、多年的治疗能够维持对LSC和HSC的不同效果，并引入辅助、维持或癌症预防应用的可能性。我们已经证明了以这种方式使用地西他滨治疗重症镰状细胞病具有显著的临床疗效和耐受性，其中地西他滨每周1-3次，持续多年，疗程2，3，4。在本建议的具体目标1中，我们寻求该方案在治疗恶性肿瘤方面的概念证据。我们相信，目标1中描述的努力将是恶性肿瘤治疗方面的重大进步。然而，实现地西他滨耗尽DNMT1的全部临床潜力的障碍仍然存在：(I)胞苷脱氨酶(CDA)的药物基因组变异，这种酶分解地西他滨，在药代动力学(PK)和药效学(PD)方面产生显著的个体间差异，降低了预测特定剂量反应的临床效果的能力；(Ii)由于CDA介导的药物破坏，地西他滨的口服生物利用度有限，这是建议的多年慢性治疗范例的显著障碍；(Iii)我们表明耐药的主要肿瘤策略是CDA介导的药物破坏。这种耐药性可能特别可能发生在预期的慢性低剂量地西他滨应用中。在具体目标2中，我们建议通过将地西他滨与CDA抑制剂四氢尿苷(清华)合并为单一口服制剂来克服所有这三个障碍。公共卫生相关性：我们证明DNA甲基转移酶DNMT1是白血病治疗的理想分子靶点；在造血干细胞中，DNMT1是自我更新基因抑制所必需的，而自我更新基因抑制必须先于谱系特异性分化。相比之下，在白血病细胞中，包括白血病干细胞模型，DNMT1被异常招募来抑制促分化基因，防止终末分化和维持失调的增殖。这项提案要求支持将这些观察结果转化为有效的抗恶性肿瘤治疗，方法是优化方案和开发核苷类似物地西他滨，以在不造成DNA损伤的情况下耗尽DNMT1，即使在通常仅对地西他滨或阿糖胞苷具有耐药性的恶性肿瘤细胞中也是如此。