Designer EcN for treatment of solid tumors

目前实体瘤的治疗方式包括手术切除、化疗和放射治疗， 方法往往不足以导致治愈，而且通常与许多副作用有关。 基于免疫治疗的干预措施，包括阻断免疫的免疫刺激单抗 检查站，正在给癌症的治疗带来革命性的变化，因为它们提供了一种让患者自己参与的手段 免疫系统识别和抗击癌症。然而，这些疗法的系统给药通常是 与显著的不良反应有关，可能非常严重，特别是当使用多种药物时 结合在一起。靶向高效免疫刺激分子直接输送至肿瘤的新方法 而且还需要肿瘤沉积。有趣的是，多种细菌物种选择性地定植和繁殖 到肿瘤中的高滴度，其中一些如沙门氏菌和梭状芽孢杆菌促进肿瘤消退，甚至 清除，至少部分是通过诱导宿主炎症反应。这些细菌的减毒版本是 观察到可以有效地根除小鼠模型中的肿瘤，但在人体试验中可能显示出有限的成功 因为它们被迅速从体循环中清除，这样细菌就永远不会到达和建立 住在肿瘤里。有趣的是，Nissle 1917大肠杆菌(ECN)，一种通常用于 炎症性肠病的治疗，也是实体肿瘤的家园和聚居地。然而，尽管达到了滴度 ECN最高可达1010个菌落形成单位/克肿瘤，无反应。在此，我们建议 ECN的测试变种能够提供免疫刺激纳米抗体，从而阻断免疫活性 检查点蛋白直接进入实体肿瘤的微环境。然后我们将调查这些人的能力 利用黑色素瘤小鼠模型研究促进肿瘤消退的菌株。我们还将进行全基因组 利用转座子插入筛选确定ECN在固体中定位和增殖的决定因素 肿瘤。我们期望在完成这项为期两年的试探性拨款后，我们将拥有概念验证 我们正在开发的基于程序化免疫的细菌疗法有可能成为一种新的 癌症治疗平台。

Current modalities for the treatment of solid tumors include surgical resection, chemotherapy, and radiation, approaches that often are not sufficient to lead to cure and are generally associated with numerous side effects. Immunotherapy based interventions, including immunostimulatory monoclonal antibodies that block immune checkpoints, are revolutionizing the treatment of cancers as they provide a means to engage the patient’s own immune system to recognize and fight cancer. However, the systemic administration of these therapies is often associated with marked adverse reactions that can be very serious, particularly when multiple agents are used in combination. Novel means to target the efficient delivery of immunostimulatory molecules directly to tumors and neoplasmic deposits are needed. Interestingly, multiple bacterial species selectively colonize and proliferate to high titers in tumors where some like Salmonella and Clostridial species promote tumor regression and even clearance, at least in part by inducing host inflammatory responses. Attenuated versions of these bacteria are observed to effectively eradicate tumors in mouse models, but have shown limited success in human trials, likely because they are rapidly cleared from the systemic circulation such that the bacteria never reach and establish residence in the tumors. Interestingly, Nissle 1917 E. coli (EcN), a probiotic strain commonly used in the treatment of inflammatory bowel disease, also homes to and colonizes solid tumors. Yet, despite reaching titers as high as 1010 colony forming units of bacteria/gram of tumor, EcN induces no response. Here we propose to test variants of EcN capable of delivering immunostimulatory nanobodies that block that activity of immune checkpoint proteins directly into the microenvironment of solid tumors. We will then investigate the ability of these strains to promote tumor regression using a mouse model of melanoma. We will also conduct genome-wide transposon insertion screens to identify EcN determinants involved in the homing to and proliferation within solid tumors. It is our expectation that at the completion of this exploratory 2-year grant we will have proof-of-concept that the programmable immune-based bacteriotherapy we are developing has the potential to become a novel cancer therapeutics platform.