Dissecting the Role of Radiation in Regulation of MHC-I and Neoantigen Presentation

摘要： 免疫疗法最近已成为治疗癌症的一种很有前途的新方法。耐久抗肿瘤药 免疫检查点抑制物(ICIS)如抗PD1和抗CTLA4已获得应答。 然而，大多数癌症患者对ICIS的反应很差，包括软组织肉瘤患者。一个重要的 改善软组织肉瘤患者治疗的研究目标是了解 与对ICIS的抵抗有关。抗原提呈途径的下调与 在各种癌症中对ICIS具有耐药性。另一方面，放射治疗已经被证明是增加的 抗原呈递。虽然已经假设放射治疗可以增强ICIS的治疗效果 辐射诱导MHC-I分子上调的调控途径(S) 人们对此仍然知之甚少。为了研究放射治疗在调节肿瘤抗原提呈中的作用，我 将使用转基因小鼠模型的本土软组织肉瘤来解剖 负责调节辐射后MHC-I表达的机制。 这个项目的长期目标是阐明放射治疗有助于克服 免疫治疗耐药。这项建议的主要目标是调查潜在的途径。 放射治疗通过此途径调节MHC-I抗原递呈途径。这一点的中心假设是 研究表明，放射治疗上调了软组织肉瘤中MHC-I的表达，从而增加了新抗原 呈现给免疫系统，并使肿瘤细胞对细胞毒性T细胞杀伤和ICI治疗敏感。我 我将在以下两个具体目标中检验这一假设： 目的1：研究MHC-I在软组织肉瘤中的表达调控网络。 目的2：检测辐射是否增加肿瘤细胞和抗原提呈细胞上的新抗原提呈 活着。

Abstract: Immunotherapy has recently emerged as a promising new approach to cancer treatment. Durable anti-tumor responses have been achieved with immune checkpoint inhibitors (ICIs) such as anti-PD1 and anti-CTLA4. However, most cancer patients respond poorly to ICIs, including soft tissue sarcoma patients. An important research objective in improving therapy for soft tissue sarcoma patients is to understand pathways that are associated with resistance to ICIs. Downregulation of the antigen presentation pathway has been associated with resistance to ICIs in various cancers. Radiation therapy, on the other hand, has been shown to increase antigen presentation. Although it has been postulated that radiotherapy enhances therapeutic effects of ICIs through upregulation of MHC-I molecules, the regulatory pathway(s) for radiation-induced MHC-I upregulation remains poorly understood. To investigate the role of radiotherapy in modulating tumor antigen presentation, I will use genetically engineered mouse models of autochthonous soft tissue sarcomas to dissect the mechanisms responsible for modulating MHC-I expression after radiation. The long-term goal of this project is to elucidate the mechanisms by which radiotherapy can help to overcome immunotherapy resistance. The primary objective of this proposal is to investigate the underlying pathway through which radiotherapy modulates the MHC-I antigen presentation pathway. The central hypothesis of this study is that radiotherapy upregulates MHC-I expression in soft tissue sarcomas, which increases neoantigen presentation to the immune system and sensitizes tumor cells to cytotoxic T cell killings and ICI treatments. I will test this hypothesis in the following two specific aims: Aim 1: Investigate regulatory networks responsible for MHC-I expression in soft tissue sarcomas. Aim 2: Test whether radiation increases neoantigen presentation on tumor cells and antigen-presenting cells in vivo.