Potentiation of Topo Inhibitors by HDAC Inhibitors

描述（由申请人提供）：组蛋白去乙酰化酶抑制剂（HDACi）是一类很有前途的新型抗癌药物。目前正在深入研究它们在临床中的应用。HDACi引起组蛋白乙酰化，从而削弱DNA和组蛋白之间的紧密结合。这会使DNA松弛，使其更容易接触到与DNA相互作用的分子，如拓扑异构酶II （topo II）抑制剂。Topo II抑制剂广泛应用于几种癌症类型的临床实践；然而，它们受到耐药性和治疗范围狭窄的限制。我们的体外数据表明，在特定的时间表将HDACi与topo II抑制剂联合使用是协同的。此外，这种协同作用主要出现在拓扑α α和il β水平“正常”或升高的细胞中，并与组蛋白超乙酰化和拓扑α α表达的矛盾下降有关，而不是i β。在临床前试验中，我们发现几种HDACi与topo II抑制剂协同作用。抗癫痫药物丙戊酸（VPA）是一种已知的HDACi，在几种癌细胞系中显示出强大的协同作用。使用这种药物的一个优点是其充分了解和全面记录的毒性和安全性。在临床前研究中，这种协同作用与细胞来源无关，但依赖于预处理topo II的表达。在Specific Aim 1中，我们建议进行一项I期试验，将HDACi、VPA和topo II抑制剂表柔比星按特定顺序联合使用，评估该组合的毒性和耐受性。在Specific Aims 2和3中，我们将收集和分析该试验的药理学和分子终点，以确定是否存在A) VPA和表阿霉素药物水平与毒性和结局之间的关联，B) VPA浓度与组蛋白超乙酰化之间的剂量反应关系。C) vpa诱导的外周血单核细胞和肿瘤细胞组蛋白超乙酰化的差异；D)治疗前表达水平与vpa诱导的肿瘤样品中topo il - α和i - β的变化之间的关联。该建议可能有助于为HDACi和topo抑制剂的序列特异性组合建立一个新的范例，并定义一种研究预测和替代反应标记的方法。这些发现可能有助于确立VPA作为临床有用的HDACi，并指导未来涉及其他HDACi的临床试验的合理设计。最后，正如我们的临床前数据所表明的那样，如果topo II抑制剂的疗效可以增加而毒性不会恶化，那么它们的效用可以得到增强。

DESCRIPTION (provided by applicant): The histone deacetylases inhibitors (HDACi) are a promising new class of anti-cancer drugs. Their utility in the clinic is currently under intensive research. HDACi cause acetylation of histones and thereby weaken the tight bond between DNA and histones. This relaxes the DNA and may render it more accessible to molecules that interact with DNA, such as topoisomerase II (topo II) inhibitors. Topo II inhibitors are widely used in clinical practice in several cancer types; however they are limited by resistance and by their narrow therapeutic margins. Our in vitro data indicate that combining HDACi in a specific schedule with topo II inhibitors is synergistic. Furthermore, this synergy is seen predominantly in cells with "normal" or increased levels of topo lIalpha and Ilbeta and is associated with histone hyperacetylation and a paradoxical decrease in expression of topo IIalpha, but not IIbeta. We found that several HDACi synergized with topo II inhibitors in preclinical assays. The anti-seizure drug valproic acid (VPA), which is known to be an HDACi showed potent synergy in several cancer cell lines. An advantage of using this drug is its well-understood and comprehensively documented toxicity and safety profile. In preclinical studies, this synergy was independent of cell origin but dependant on pretreatment topo II expression. In Specific Aim 1, we propose to conduct a Phase I trial combining the HDACi, VPA and the topo II inhibitor epirubicin in a specific sequence evaluating toxicity and tolerability of this combination. In Specific Aims 2 and 3, we will collect and analyze pharmacological and molecular endpoints of this trial to determine whether there is A) an association between VPA and epirubicin drug levels with toxicity and outcome, B) a dose response relationship between VPA concentrations and histone hyperacetylation, C) a difference in VPA-induced histone hyperacetylation in peripheral blood mononuclear cells and tumors cells and D) an association between pre-treatment expression levels and VPA-induced changes of topo Ilalpha and IIbeta in tumor samples with response. This proposal may help to establish a new paradigm for sequence-specific combinations of HDACi and topo inhibitors and to define a methodology to study predictive and surrogate markers of response. These findings may help to establish VPA as a clinically useful HDACi and to direct the rational design of future clinical trials involving other HDACi. Finally, the utility of the topo II inhibitors could be enhanced if their efficacy could be increased without worsening toxicity, as our preclinical data appears to indicate.