Potentiation of Topo Inhibitors by HDAC Inhibitors

描述（由申请人提供）：组蛋白脱乙酰酶抑制剂（HDACi）是一类有前途的新型抗癌药物。它们在临床上的效用目前正在深入研究中。HDACi引起组蛋白的乙酰化，从而削弱DNA和组蛋白之间的紧密结合。这使DNA松弛，并可能使其更容易接近与DNA相互作用的分子，如拓扑异构酶II（topo II）抑制剂。Topo II抑制剂广泛用于几种癌症类型的临床实践;然而，它们受到耐药性和狭窄治疗范围的限制。我们的体外数据表明，HDACi在特定的时间表与拓扑异构酶II抑制剂的组合是协同的。此外，这种协同作用主要见于“正常”或topo II α和II β水平升高的细胞中，并与组蛋白超乙酰化和topo II α表达的反常降低有关，但与II β无关。我们发现，在临床前试验中，几种HDACi与topo II抑制剂协同作用。抗癫痫药物丙戊酸（VPA），已知是HDACi，在几种癌细胞系中显示出有效的协同作用。使用这种药物的一个优点是其充分理解和全面记录的毒性和安全性。在临床前研究中，这种协同作用是独立的细胞来源，但依赖于预处理拓扑异构酶II的表达。在具体目标1中，我们建议进行一项I期试验，以特定顺序组合HDACi、VPA和拓扑异构酶II抑制剂表阿霉素，以评估该组合的毒性和耐受性。在特定目标2和3中，我们将收集并分析本试验的药理学和分子学终点，以确定A）VPA和表阿霉素水平与毒性和结局之间是否存在相关性，B）VPA浓度与组蛋白高乙酰化之间是否存在剂量反应关系，C）外周血单核细胞和肿瘤细胞中VPA诱导的组蛋白过度乙酰化的差异，以及D）VPA诱导的组蛋白过度乙酰化与VPA诱导的组蛋白过度乙酰化之间的关联。治疗表达水平和VPA诱导的具有应答的肿瘤样品中拓扑异构酶II α和II β的变化。这一建议可能有助于建立HDACi和拓扑异构酶抑制剂的序列特异性组合的新范式，并定义一种方法来研究预测和替代反应标志物。这些发现可能有助于将VPA确立为临床上有用的HDACi，并指导未来涉及其他HDACi的临床试验的合理设计。最后，拓扑异构酶II抑制剂的效用可以提高，如果他们的疗效可以增加而不恶化的毒性，因为我们的临床前数据似乎表明。

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.