Designer EcN for treatment of solid tumors

目前治疗实体瘤的方式包括手术切除、化疗和放疗， 这些方法通常不足以导致治愈，并且通常与许多副作用相关。 基于免疫治疗的干预措施，包括阻断免疫反应的免疫刺激性单克隆抗体， 检查点，正在彻底改变癌症的治疗，因为它们提供了一种让患者自己参与治疗的手段。 免疫系统识别和对抗癌症。然而，这些疗法的全身施用通常是不必要的。 与可能非常严重的显著不良反应相关，特别是当使用多种药物时 结合起来。将免疫刺激分子直接靶向肿瘤的有效递送的新方法 和肿瘤沉积物。有趣的是，多种细菌物种选择性地定殖和增殖 到肿瘤中的高滴度，其中一些如沙门氏菌和梭菌物种促进肿瘤消退， 清除，至少部分通过诱导宿主炎症反应。这些细菌的减毒版本是 在小鼠模型中观察到有效根除肿瘤，但在人体试验中显示成功有限， 因为它们从体循环中被迅速清除， 在肿瘤中的位置。有趣的是，Nissle 1917 E.大肠杆菌（EcN），一种常用于 治疗炎症性肠病，也是实体瘤的宿主和定植。然而，尽管达到滴度 高达1010菌落形成单位的细菌/克肿瘤，EcN不诱导应答。在此，我们建议 测试能够递送阻断免疫调节剂活性免疫刺激性纳米抗体的EcN变体 检查点蛋白直接进入实体瘤的微环境。然后我们将调查这些 使用黑色素瘤小鼠模型，我们还将在全基因组范围内 转座子插入筛选以鉴定参与固体内归巢和增殖的EcN决定簇 肿瘤的我们期望在完成这项为期2年的探索性资助后，我们将进行概念验证 我们正在开发的基于免疫的可编程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.