Epigenetic Potentiation of Interferon using Decitabine

描述(由申请人提供)：DNA启动子区域内CpG岛的异常高甲基化改变了与影响肿瘤细胞生长和行为的各种细胞过程有关的基因的表达。最近的研究表明，启动子甲基化在沉默DNA修复酶、诱导药物敏感或耐药表型的表达方面起着重要作用。例如，癌细胞对干扰素-a的敏感性被认为是由关键基因的启动子甲基化调节的。核苷类似物5-氮杂-2‘-脱氧胞苷(地西他滨)在体外是一种有效的DNA甲基化的药理抑制剂。地西他滨诱导的DNA低甲基化、基因重新激活和对细胞功能的影响需要在体外进行几个细胞分裂周期的DNA整合。我们之前进行了地西他滨的I期试验，确定每天2 mg/m2，连续静脉注射168h。输注可显著降低MAGE-1启动子特异性甲基化和总基因组DNA甲基化，且毒性最小。进一步的临床前研究表明，肿瘤细胞暴露地西他滨后，干扰素信号通路重新激活。我们建议在之前临床前实验的基础上进行I期临床试验，以测试地他滨输注是否能在体内使癌细胞对干扰素-a敏感。在特定的Aim1中，我们计划进行一项I期临床试验，以评估在难治性转移癌患者中持续静脉滴注地西他滨和递增剂量的聚乙二醇化干扰素的毒性。临床方案的设计是为了确定聚乙二醇干扰素的剂量限制毒性和最大耐受量。在特定目标2中，我们将进行分子相关性研究，以评估患者血液、皮肤和肿瘤的治疗前后样本，以确定全球(基因组)DNA甲基化的变化，以及评估启动子特异性甲基化。其他实验将评估正常细胞和肿瘤细胞中的干扰素信号和DNA损伤反应通路。

DESCRIPTION (provided by applicant): Aberrant hypermethylation of CpG islands within promoter regions of DNA modifies expression of genes involved in diverse cellular processes that impact tumor cell growth and behavior. Recent studies have shown that promoter methylation is important in silencing DNA repair enzymes, and inducing expression of drug sensitivity or resistance phenotypes. For example, cancer cell sensitivity to interferon-a is believed to be regulated by promoter methylation of key genes. The nucleoside analogue 5-aza-2'- deoxycytidine (decitabine) is a potent pharmacological inhibitor of DNA methylation in vitro. Decitabine-induced DNA hypomethylation, gene reactivation, and effects on cell function require incorporation into DNA followed by several cellular division cycles in vitro. We previously performed a phase I trial of decitabine, which established that 2mg/m2/day, given as a 168h continuous i.v. infusion resulted in significantly decreased MAGE-1promoter-specific and total genomic DNA methylation with minimal toxicity. Further preclinical studies suggested that the interferon-signaling pathway is reactivated following decitabine exposure of cancer cells. We propose to build on our previous preclinical experiments to perform a phase I clinical trial to test whether a decitabine infusion can sensitize cancer cells to interferon-a in vivo. In Specific Aim1 we plan to perform a phase I clinical trial to assess the toxicities of a continuous intravenous infusion of decitabine with escalating doses of subcutaneous PEG-IFN in patients with refractory metastatic cancer. The clinical protocol is designed to identify the dose limiting toxicity and the maximum tolerated dose of PEG-IFN in this combination. In Specific Aim 2 we will perform molecular correlation studies to evaluate pretreatment and post treatment samples of blood, skin and tumor from patients to identify changes in global (genomic) DNA methylation, as well as evaluating promoter-specific methylation . Additional experiments will evaluate interferon signaling and DNA damage response pathways in normal and neoplastic cells.