Mechanisms of Resistance to Radio Inducible Gene Therapy

描述(申请人提供)：这个项目的目标是探索Ad.Egr-TNF基因治疗增强肿瘤对放射治疗的反应的机制。我们已经报道，电离辐射(IR)靶向的基因治疗通过在辐射诱导启动子(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效果。小鼠和人类肿瘤模型显示，在单次剂量或分次照射后，Ad.Egr-TNF被激活，并达到肿瘤内治疗浓度的肿瘤坏死因子-α蛋白。在这些肿瘤模型中，与单独治疗相比，Ad.Egr-TNF和IR的联合治疗显著增加了肿瘤的消退和治愈，而对正常组织的毒性几乎没有增加。Ad.Egr-TNF目前正在三个第二阶段临床试验中进行放射治疗研究，此前两个第一阶段试验证明是安全的。在阶段试验中，20%的放射抵抗患者(黑色素瘤、肉瘤、直肠癌)或非常大的肿瘤(高达13,500厘米~3)患者完全缓解，到目前为止没有复发的证据，这一事实表明了治疗效果。本文概述的实验将利用遗传学和药理学模型来探索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式的疗效提供实验依据。为了实现这些目标，我们提出了以下具体目标。 具体目的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。 具体目的2.探讨肿瘤细胞分泌血管内皮生长因子(VEGF)是否通过增强肿瘤内皮细胞的抵抗力来介导对Ad.Egr-TNF+IR的抵抗。 具体目的3.探讨Ad.Egr-TNF+IR在肿瘤细胞抵抗中的作用。

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.