Mechanisms of Resistance to Radio Inducible Gene Therapy

项目描述（申请人提供）：本项目的目的是探索Ad.Egr-TNF基因治疗增强肿瘤对放射治疗反应的机制。 我们已经报道了电离辐射（IR）靶向的基因治疗通过在辐射诱导型启动子（Egr-1）的控制下激活编码肿瘤坏死因子-α（TNF-α）的cDNA的表达来增强放射治疗的抗肿瘤作用。 鼠和人肿瘤模型证明在单剂量或分次辐射后Ad.Egr-TNF的活化，并达到肿瘤内TNF-α蛋白的治疗浓度。 与单独治疗相比，Ad.Egr-TNF和IR联合治疗显著增加了这些肿瘤模型中的肿瘤消退和治愈，而正常组织毒性很少或没有增加。 Ad.Egr-TNF目前正在三项II期临床试验中与放射治疗一起进行研究，随后在两项I期试验中证明了安全性。 阶段性试验中的治疗功效由以下事实表明：> 20%的具有放射抗性（黑色素瘤、肉瘤、直肠癌）或非常大的肿瘤（高达13，500 cm 3）的患者实现了完全缓解，并且迄今为止没有复发的证据。 本实验拟采用遗传学和药理学模型，探讨AD、Egr-TNF和IR的抗肿瘤机制，为合理提高这一新的联合治疗方案的疗效提供实验依据。 为了实现这些目标，我们提出以下具体目标。 具体目标1。探讨肿瘤微血管内皮细胞是否介导了对Ad.Egr-TNF和IR的抵抗。 具体目标2。 探讨肿瘤分泌的血管内皮生长因子（VEGF）是否通过增强肿瘤内皮细胞的抵抗性介导了对Ad.Egr-TNF +IR的抵抗。 具体目标3。探讨肿瘤细胞对Ad.Egr-TNF+ IR耐药的作用。

DESCRIPTION (provided by applicant): The goal of this project is to explore the mechanisms by which Ad.Egr-TNF gene therapy enhances the response of tumors to radiotherapy. We have reported that gene therapy targeted by ionizing radiation (IR) enhances the anti-tumor effects of radiotherapy by activating the expression of a cDNA encoding tumor necrosis factor-alpha (TNF-alpha) under the control of a radiation-inducible promoter (Egr-1). Murine and human tumor models demonstrate activation of Ad.Egr-TNF following single dose or fractionated radiation and achieves therapeutic concentrations of intratumoral TNF-alpha protein. Combined treatment with Ad.Egr-TNF and IR significantly increased tumor regression and cures in these tumor models compared with either treatment alone with little or no increase in normal tissue toxicity. Ad.Egr-TNF is currently being investigated with radiation therapy in three Phase 2 clinical trials following demonstration of safety in two Phase 1 trials. Treatment efficacy in the phase trials was suggested by the fact that > 20% patients with radioresistant (melanoma, sarcoma, rectal cancer) or very large tumors (up to 13,500 cm3) achieved complete responses and are without evidence of recurrence to date. Experiments outlined here will employ genetic and pharmacological models to explore the anti-tumor mechanisms of AD.Egr-TNF and IR to provide the experimental basis to rationally improve the efficacy of this new combined modality treatment. To achieve these goals we propose the following specific aims. Specific Aim 1. Explore whether the tumor microvascular endothelium mediates resistance to Ad.Egr-TNF and IR. Specific Aim 2. Explore whether the tumor secretion of vascular endothelial growth factor (VEGF) mediates resistance to Ad.Egr-TNF +IR by enhancing resistance of the tumor endothelium. Specific Aim 3. Explore the role of tumor cell resistance to Ad.Egr-TNF+IR.