CMV-SPECIFIC ANTI-TUMOR IMMUNE RESPONSE IN ASTROCYTOMAS

恶性胶质瘤(MG)是一种常见的致命性肿瘤，其有效治疗受到对正常组织的附带损伤的限制。针对肿瘤特异性抗原的免疫治疗可以使肿瘤细胞更精确地被靶向，我们以树突状细胞(DC)为靶点的针对突变的肿瘤特异性表皮生长因子受体的疫苗已经在MG患者中产生了免疫学和放射学反应。MGs是巨细胞病毒(CMV)重新激活的避难所，而不是正常大脑周围的MGs，这一发现为颠覆高度免疫原性的CMV蛋白pp65提供了一个无与伦比的机会。尽管以DC为基础的疫苗靶向MG中的CMV抗原有许多优点，但许多因素明显限制了这些患者的ANT/肿瘤免疫反应。 创新的互补策略，消除CD25+调节性T细胞或阻断细胞毒3； 淋巴细胞抗原-4诱导的T细胞耐受可能会增强这种免疫反应，但不加选择地使用这些有效佐剂会带来诱发自身免疫性脑脊髓炎的风险。为了了解在MG中靶向CMV抗原的局限性和风险，我们开发了一种新的小鼠星形细胞瘤细胞系，该细胞系支持小鼠CMV感染，并在同基因小鼠中致瘤。我们的初步小鼠研究表明，这些脑肿瘤可以通过RNA负载的树突状细胞靶向。我们还发现，携带pp65mRNA的MG患者的DC可以诱导干扰素-γ，以抗原特异性的方式从CD4+和CDS+T细胞中产生，并刺激T细胞杀伤感染了人CMV的恶性星形细胞。有趣的是，我们还发现巨细胞病毒特异性T细胞优先聚集在MG患者的肿瘤部位。我们相信，我们的小鼠模型系统和所提出的补充人体研究将允许选择和翻译最有效的策略来靶向MGs患者的CMV相关抗原，而不会诱导自身免疫。在这个项目中，我们将使用小鼠模型，结合体外人类研究来评估CMV相关蛋白在恶性胶质瘤中的安全性，并更好地了解CMV相关蛋白在恶性胶质瘤中的靶向治疗机制。然后，这些结果将被用于合理设计和进行以CMV为靶向的临床试验。

Malignant gliomas (MGs) are univerally fatal, and effective therapy is limited by collateral damage to normal tissue. Immunotherapy directed against tumor-specific antigens may allow neoplastic cells to be targeted more precisely, and our dendritic cell (DC)-based vaccinations targeting of a mutated tumor-specific epidermal growth factor receptor have produced immunologic and radiographic responses in patients with MGs. The discovery that MGs, but not surrounding normal brain, serve as a refuge for Cytomegalovirus (CMV) reactivation provides an unparalleled opportunity to subvert, as a tumor-specific antigen, the highly immunogenic CMV protein, pp65. Despite the numerous advantages of targeting CMV antigens in MGs with DC-based vaccines, a number of factors clearly limit ant/tumor immune responses in these patients. Innovative complementary strategies that eliminate CD25+ regulatory T cells or block cytotoxic 3; lymphocyte antigen-4-induced T cell tolerance may enhance such immune responses, but the indiscriminate application of these potent adjuvants carries the risk of inducing autoimmune encephalomyelitis. In order to understand the limitations and risks of targeting CMV antigens in MGs, we have developed a novel murine astrocytoma cell line that supports infection with murine CMV and is tumorigenic in syngeneic mice. Our preliminary murine studies demonstrate that these tumors in the brain can be targeted with RNA-loaded DCs. We have also shown that DCs from patients with MGs that are loaded with pp65mRNA, induce interferon-gamma, production from CD4+ and CDS+ T-cells in an antigen-specific manner and incite T-cells to kill malignant astrocytes infected with human CMV. Interestingly, we have also found that CMV-specific T-cells preferentially accumulate at the tumor site in patients with MGs. We believe that our murine model system and the complementary human studies proposed will allow selection and translation of the most effective strategies for targeting CMV-associated antigens in patients with MGs, without the induction of autoimmunity. In this project, we will use the murine model, in combination with in vitro human studies to evaluate the safety of, and to gain a better understanding of the mechanisms involved in the therapeutic targeting of CMV-associated proteins in malignant gliomas. The results will then be used to rationally design and conduct a clinical CMV-targeted clinical trial.