Local Radiation as an Adjuvant for Immunotherapy

描述(申请人提供)：CD8+T细胞介导的免疫可以消除大的肿瘤负担。然而，大多数疫苗接种策略很难实现癌症患者和已建立血管肿瘤的小鼠的显著临床反应。免疫细胞在肿瘤部位的运输和激活不足被认为至少在一定程度上是免疫疗法(IT)未能摧毁实体肿瘤的原因。电离放射治疗(RT)是一种重要的局部肿瘤治疗方法。作为细胞杀伤剂，RT也可改变肿瘤微环境，产生炎症反应。在4T1小鼠转移性乳腺癌模型中，我们发现RT联合CTLA-4阻断可引起CD8+T细胞介导的反应，抑制转移并诱导原发肿瘤的消退。积累的数据支持RT可以作为免疫佐剂来增强IT的有效性的假设。然而，电离辐射促进抗肿瘤免疫的能力仍然存在争议，涉及的机制在很大程度上仍不清楚。拟议的研究将通过分析这一过程的关键步骤来确定RT促进抗肿瘤免疫的机制。首先，RT促进交叉启动的能力将使用4T1肿瘤模型及其表达报告抗原的衍生品来确定。本课程将分析树突状细胞提呈肿瘤抗原以及肿瘤特异性T细胞的活化、扩散和持久性。其次，将确定RT对效应器T细胞在肿瘤内的运输和功能的影响。CXCR6/CXCL16相互作用在CD8+T细胞对照射肿瘤的募集中的作用将通过在CXCR6基因座小鼠中的EGFP敲打和RNA干扰沉默CXCL16来确定。此外，活体显微镜将用于研究CXCR6+T细胞在已建立的4T1肿瘤微环境中的动态行为及其对局部辐射的反应。第三，RT与另一种免疫刺激抗体(抗4-1BB/CD137)联合诱导抗肿瘤反应的能力将被测试，并与CTLA-4阻断进行比较。这些发现将在自发致癌的转基因小鼠模型中得到证实。RT可以作为免疫佐剂来增强IT的有效性这一创新概念将打开一个新的研究领域。总体而言，这些研究将为在未来的临床试验中测试这一新的治疗策略提供必要的临床前数据。

DESCRIPTION (provided by applicant): CD8+ T-cell mediated immunity can eliminate large tumor burdens. However, significant clinical responses of cancer patients and mice with established vascularized tumors are difficult to achieve with most vaccination strategies. Insufficient trafficking and activation of immune cells at tumor sites are thought to be, at least in part, responsible for the failure of immunotherapy (IT) to destroy solid tumors. Ionizing radiation therapy (RT) is an important local cancer treatment. Used as cytocidal agent, RT can also alter the tumor microenvironment and generate inflammation. In the 4T1 mouse model of metastatic breast cancer we have shown that RT in combination with CTLA-4 blockade elicits a CD8+ T cell-mediated response inhibiting metastases and inducing regression of primary tumors. Accumulated data support the hypothesis that RT can be used as an immunological adjuvant to enhance the effectiveness of IT. However, the ability of ionizing radiation to promote anti-tumor immunity is still controversial, and mechanisms involved remain largely undefined. Proposed studies will determine the mechanisms whereby RT promotes anti-tumor immunity by analyzing the critical steps of this process. First, the ability of RT to promote cross-priming will be determined using the 4T1 tumor model and its derivative expressing a reporter antigen. Presentation of tumor antigens by dendritic cells and activation, dissemination and persistence of tumor-specific T cells will be analyzed. Second, the effect of RT on effector T cell trafficking and function within tumors will be determined. The role of CXCR6/CXCL16 interactions in CD8+ T cell recruitment to irradiated tumors will be established employing EGFP-knockin in the CXCR6 locus mice, and RNA interference to silence CXCL16. In addition, intravital microscopy will be used to study the dynamic behavior of CXCR6+ T cells in the microenvironment of established 4T1 tumors and their response to local radiation. Third, the ability of RT to induce anti-tumor responses in combination with another immune stimulatory antibody (anti-4-1BB/CD137) will be tested and compared to CTLA-4 blockade. Findings will then be confirmed in a transgenic mouse model of spontaneous carcinogenesis. The innovative concept that RT can be used as an immunological adjuvant to enhance the effectiveness of IT will open a new field of investigation. Overall, these studies will provide the pre-clinical data necessary for testing this novel therapeutic strategy in future clinical trials.