Targeting the aberrant kinome-epigenome in AML

描述（由申请人提供）：参与造血分化的基因的表观遗传沉默和编码参与造血细胞增殖的酪氨酸激酶受体（TKRs）的基因突变是髓性白血病发生的关键因素。尽管针对AML中kinome （TKR抑制剂）和表观基因组（DNMT抑制剂）异常特征的新化合物已经在临床试验中进行了测试，但作为单一药物对它们的反应是短暂的，这表明单一机制可能不足以克服AML。我们推断，与单靶点方法相比，并发分子靶向可能产生更好的抗白血病活性。为了开发这种方法，需要了解白血病发生的机制。最近，我们发现miR-29b通过靶向和抑制TKRs （KIT和FLT3）和DNMTs的表达，在AML中调控表观基因组（DNA甲基化）和kinome中起着核心作用。此外，我们发现高水平的miR-29b可预测老年AML患者对低甲基化药物地西他滨的敏感性。在临床前研究中，我们发现内源性miR-29b可以通过TKI（索拉非尼）、Sp1/NFkB干扰化合物（硼替佐米）和组蛋白去乙酰化酶抑制剂在药理学上增加。因此，我们在这里假设，先发制人地增加内源性低水平的miR-29b细胞将增强地西他滨的抗白血病活性，并导致老年AML患者更持久的临床反应。我们建议通过以下具体目标来实现这一策略：具体目标#1：在老年（60岁至60岁）AML患者中进行硼替佐米和索拉非尼联合使用地西他滨的1期临床试验，以确定：(a)硼替佐米/索拉非尼联合使用的生物有效和耐受剂量（BETD）；(b) II期推荐剂量和(c)与miR-29b靶向活性相关的药效学（PD）终点。具体目标#2：在新诊断的老年（60岁以下）AML患者中进行硼替佐米和索拉非尼联合地西他滨的2期临床试验，以便：(a)评估该组合的临床疗效；(b)通过将生物学终点（如miR-29b）与临床反应相关联来验证联合用药活性的生物学机制。特定目的#3：研究HDAC抑制剂（即AR42）是否也会破坏HDAC/Sp1-NF:B复合物，当在临床前环境中与硼替佐米和索拉非尼联合使用时，是否会增强miR-29b的表达，进而进一步提高对地西他滨的反应率。我们将进行临床前体内研究，以便：(a)通过进行PK/PD建模来确定导致miR-29b最高表达的AR42的最佳剂量；(b)评估AR42/硼替佐米/索拉非尼联合使用地西他滨与硼替佐米/索拉非尼或AR42单独使用地西他滨的生存率；(c)推荐AR42/硼替佐米/索拉非尼加地西他滨的I期人体试验的最佳剂量/方案。

DESCRIPTION (provided by applicant): Epigenetic silencing of genes involved in hematopoietic differentiation and mutations in genes encoding tyrosine kinase receptors (TKRs) involved in hematopoietic cell proliferation are critical players in myeloid leukemogenesis. Although novel compounds targeting the aberrant features of kinome (TKR inhibitors) and epigenome (DNMT inhibitors) in AML have been tested in clinical trials, the response to them as single agents has been short-lived, suggesting that a single mechanism may not be sufficient to overcome AML. We reasoned that concurrent molecular targeting may result in better antileukemic activity compared with single target approaches. In order to develop such approach, the mechanism of leukemogenesis needs to be understood. Recently, we have shown that miR-29b is central to regulation of both epigenome (DNA methylation) and kinome in AML by targeting and repressing the expression of TKRs (KIT and FLT3) and DNMTs. Furthermore, we showed that high levels of miR-29b are predictive of sensitivity to the hypomethylating agent decitabine in older AML patients. In preclinical studies, we showed that endogenous miR-29b can be pharmacologically increased with TKI (sorafenib), Sp1/NFkB interfering compounds (bortezomib) and histone deacetylase inhibitors. Therefore, we hypothesize here that a pre-emptive pharmacologic increase of otherwise low endogenous levels of miR-29b cells will enhance the antileukemia activity of decitabine and lead to a more durable clinical response in older AML patients. We propose to pursue this strategy through the following specific aims: Specific Aim #1: To conduct a Phase 1 clinical trial with bortezomib and sorafenib in combination followed by decitabine in elderly (>60) AML patients in order to determine: (a) the biologically effective and tolerable dose (BETD) of bortezomib/sorafenib combination; (b) a phase II recommended dose and (c) pharmacodynamic (PD) endpoints related to the targeting activity of miR-29b. Specific Aim #2: To conduct a Phase 2 clinical trial with bortezomib and sorafenib followed by decitabine in newly diagnosed elderly (>60) AML patients in order to: (a) assess clinical efficacy of the combination;(b) to validate the biologic mechanisms of activity of the combination by correlating biologic endpoints (e.g,miR-29b,) with clinical response. Specific Aim #3: To investigate whether HDAC inhibitors (i.e., AR42), which also disrupts the HDAC/Sp1-NF:B complex, enhance miR-29b expression when combined with bortezomib and sorafenib in the preclinical setting and in turn improve even further the response rate to decitabine. We will conduct preclinical in vivo studies in order to: (a) determine the optimal dose of AR42 that leads to the highest expression of miR-29b by performing PK/PD modeling; (b) asses survival of the combination AR42/bortezomib/sorafenib followed by decitabine as compared with bortezomib/sorafenib or AR42 alone followed by decitabine; (c) recommendation of an optimal dose/schedule of the AR42/bortezomib/sorafenib followed by decitabine for testing in the phase I setting in humans. PUBLIC HEALTH RELEVANCE: Over the past 20 years there has been little improvement in AML treatments, especially for elderly (>60) patients with only a few of them survival for more than 2 years. Lack of significant improvement in the current results calls attention to the need for development of novel therapeutic strategies. The overall goal of this proposal is to test in the clinic a novel approach to target leukemia mechanisms with drugs (bortezomib and sorafenib) that have been already approved for use in mankind, but combined in a new manner that will allow increase of a molecules (miR-29b) that can control these leukemia mechanisms and may improve the clinical response and outcome of AML patients treated with decitabine, an agent that by itself already has shown encouraging results.