Targeting an unrecognized checkpoint on T cell function in tumors

工程 摘要/摘要 浸润性免疫细胞的多样化积累是几乎所有癌症的显著特征1。通过指导 杀癌T细胞的效应功能，免疫系统具有特异性靶向和介导的能力 清除大的已建立的肿瘤2-5。然而，T细胞效应器的功能通常受限于 肿瘤，使疾病恶化。关于肿瘤如何限制T细胞功能的最新见解已经转化为 新的癌症治疗类别，如免疫检查点阻断(α、CTLA-4和PD-1)和过继 转移大量自体肿瘤特异性T细胞6，7。而基于免疫的疗法 在短时间内改变了肿瘤学的实践，这样的治疗只在很小的 癌症患者采用多种非多余手段逃避免疫系统。AS 我们对肿瘤导致T细胞功能障碍的生物驱动因素的了解仍然有限，癌症的界限 免疫疗法仍然没有明确的定义。 在许多肿瘤中发现大量的细胞死亡，这与预后不良有关。细胞死亡 导致细胞内钾(K+)的释放，从而增加细胞外的钾([K+]e) 肿瘤微环境。我们首先认识到，高[K+]e抑制T细胞抗肿瘤功能 细胞因子的产生，限制抗肿瘤免疫(EIL R等人，《自然》2016&《科学》2019)。从机制上讲，K+ 介导的T细胞信号抑制需要PP2A的磷酸酶活性。从基因上讲 T细胞K+转运的重新编程在体外和体内都转化为更好的功能。而这些 发现了一种未被识别的离子检查点，这是由癌细胞死亡的副产品引起的，其他人 建议通过细胞死亡和组织损伤来增加免疫活性，从而释放相关的损伤 髓系细胞的分子模式(DAMP)和炎性小体激活。然而，炎症体信号 也被高[K+]e抑制。因此，我们的中心假设是细胞内K+是 可用于增强T细胞抗肿瘤功能的免疫生物学。 肝内胆管细胞癌(ICC)是导致原发性肝癌的第二大常见原因，并且是致命的 在几乎所有病例中，除非由于对细胞毒性和靶向治疗的耐药性而进行手术切除19，20。 以高度的基因组瘤内异质性和坏死性为特征，以及最近的 对以T细胞为基础的免疫疗法的反应，提供了一个理想的环境来追求 在此提出的研究。如果成功，本意见书中提出的研究将：1)定义 细胞死亡副产物在人肝内的免疫抑制作用 胆管细胞癌；2)测试基于增强T细胞离子转运的新癌症治疗方法3)澄清 由细胞内K+浓度控制的细胞生物学以前未被认识的方面。

PROJECT SUMMARY/ABSTRACT A diverse accumulation of infiltrating immune cells is a prominent feature of nearly all cancers1. By directing the effector functions of cancer-killing T cells, the immune system has the ability to specifically target and mediate clearance of large established tumors2–5. However, T cell effector function is typically constrained within tumors, allowing disease progression. Recent insights into how tumors limit T cell function have translated into new classes of cancer treatments such as immune checkpoint blockade (αCTLA-4 and PD-1) and the adoptive transfer of large numbers of autologous tumor specific T cells6,7. While immune based therapies have transformed the practice of oncology over a short period of time, such treatments only work in a small percentage of patients, as cancers deploy multiple and non-redundant means to evade the immune system. As our knowledge of the biologic drivers of tumor induced T cell dysfunction remains limited, the bounds of cancer immunotherapy remain undefined. A high abundance of cell death is found in many tumors and is associated with poor prognosis. Cell death results in the release of intracellular potassium (K+), thereby increasing the extracellular potassium ([K+]e) the tumor microenvironment. We first recognized that this that high [K+]e suppresses T cell antitumor function and cytokine production, limiting antitumor immunity (Eil R et al, Nature 2016 & Science 2019). Mechanistically, K+ mediated suppression of T cell signaling required the phosphatase activity of PP2A. Genetically reprogramming of T cell K+ transport translated into improved functionality in vitro and in vivo. While these findings point to an unrecognized ionic checkpoint resulting from cancer cell death byproducts, others have proposed cell death and tissue damage to increase immune activity due to the release of damage associated molecular patterns (DAMPs) and inflammasome activation in myeloid cells. However, inflammasome signaling is also suppressed by high [K+]e. Thus,our central hypothesis is thatintracellular K+ is a central regulator of immunobiology that can be leveraged to augment T cell antitumor function. Intrahepatic Cholangiocarcinoma (ICC) is the second most common cause of primary liver cancer and is fatal in nearly all cases unless surgically resected owing to resistance to cytotoxic and targeted therapies19,20. ICC is characterized by a high degree of genomic intratumoral heterogeneity and necrosis as well as a recently appreciated responsiveness to T cell-based immunotherapy, providing an ideal context in which to pursue the research proposed herein. If successful, the research proposed in this submission will, 1) define the degree of immune suppression enforced by cell death byproducts in the context of human intrahepatic cholangiocarcinoma; 2) test novel cancer treatments based on augmenting T cell ion transport 3) clarify previously unrecognized aspects of cellular biology controlled by intracellular K+ concentration.