Local Radiation as an Adjuvant for Immunotherapy

描述（由申请人提供）：CD 8 + T细胞介导的免疫可以消除大的肿瘤负荷。然而，大多数疫苗接种策略难以实现癌症患者和具有已建立的血管化肿瘤的小鼠的显著临床应答。肿瘤部位免疫细胞的运输和活化不足被认为至少部分是免疫治疗（IT）破坏实体瘤失败的原因。电离放射治疗（RT）是一种重要的局部癌症治疗方法。作为杀细胞剂，RT还可以改变肿瘤微环境并产生炎症。在转移性乳腺癌的4 T1小鼠模型中，我们已经表明RT与CTLA-4阻断剂组合激发了抑制转移并诱导原发性肿瘤消退的CD 8 + T细胞介导的应答。累积的数据支持的假设，RT可以作为一种免疫佐剂，以提高IT的有效性。然而，电离辐射，以促进抗肿瘤免疫的能力仍然是有争议的，涉及的机制仍然在很大程度上不明确。拟议的研究将确定RT促进抗肿瘤免疫的机制，通过分析这一过程的关键步骤。首先，将使用4 T1肿瘤模型及其表达报告抗原的衍生物来确定RT促进交叉引发的能力。将分析树突状细胞对肿瘤抗原的呈递以及肿瘤特异性T细胞的活化、传播和持续性。其次，将确定RT对肿瘤内效应T细胞运输和功能的影响。CXCR 6/CXCL 16相互作用在CD 8 + T细胞募集至经照射的肿瘤中的作用将采用CXCR 6基因座小鼠中的EGFP敲入和RNA干扰以沉默CXCL 16来建立。此外，活体显微镜将用于研究CXCR 6 + T细胞在已建立的4 T1肿瘤微环境中的动态行为及其对局部辐射的反应。第三，将测试RT与另一种免疫刺激性抗体（抗4-1BB/CD 137）组合诱导抗肿瘤应答的能力，并与CTLA-4阻断进行比较。研究结果将在自发性致癌的转基因小鼠模型中得到证实。RT可作为免疫佐剂来增强IT的有效性这一创新概念将开辟一个新的研究领域。总体而言，这些研究将为在未来的临床试验中测试这种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.