Evolutionary Trajectories of Tumors Following Resistance to Immune Checkpoint Blockade

项目摘要 免疫检查点阻断（ICB）已经彻底改变了癌症治疗，但大多数患者 接受ICB的患者会产生耐药性，最终需要接受多种治疗。映射 预期的进化模式使得能够对许多癌症疗法的治疗进行合理的排序， 特别是靶向治疗。然而，我们目前对ICB治疗的了解有限， 塑造了肿瘤的进化轨迹大多数癌症治疗直接杀死肿瘤细胞，并留下一个 细胞固有的耐药肿瘤细胞的小残余;从进化的角度来看，这导致了 治疗后的克隆扫描，其中耐药细胞接管肿瘤。相比之下，ICB通过以下方式行事： 动员患者自身的免疫细胞，特别是T细胞，对抗肿瘤， 通过建立对T细胞不友好的“冷”肿瘤微环境来抵抗ICB。情况下 在ICB抗性由整个肿瘤微环境介导的情况下，尚不清楚抗性是否会被肿瘤微环境介导。 伴随着这样的克隆扫描;相反，它提出了一个问题，即肿瘤细胞是否会 对ICB敏感的人，如果他们与邻居住在一起， “冷”的微环境为了支持这一点，一项对黑色素瘤患者的研究表明， 在许多ICB中发现了克隆持续性模式，其中许多肿瘤群体在治疗中存活， 耐药肿瘤在这个建议中，我们将试图绘制出ICB后肿瘤的进化轨迹， 鳞状细胞癌小鼠模型和膀胱癌患者。我们将特别寻求 验证克隆持续性是ICB后主要的进化模式的假设，特别是在肿瘤中 其表现出“冷”微环境。我们建立了一个新的小鼠模型系统， 跟踪同一肿瘤中的多个肿瘤群体-例如，一个“免疫热”和一个“免疫冷”的群体- 通过荧光标记。我们将使用这个模型来询问是否存在“免疫冷”肿瘤， 驱动“冷”微环境的细胞群可以保护否则敏感的“免疫热”肿瘤细胞， ICB介导的清除。“冷”肿瘤群的这种保护作用将建立一种机制联系， 一个“寒冷”的微环境和克隆持久性的进化模式之间的联系。我们将补充 这些研究对用ICB治疗过的肿瘤进行了基因组分析，研究了小鼠和小鼠 用a-PD-1/a-TGFb组合疗法治疗的鳞状皮肤癌和患者膀胱肿瘤 用a-PD-L1治疗。通过构建ICB前后肿瘤克隆结构的详细图片， 在这两个队列中，我们将绘制ICB治疗肿瘤的演变轨迹，并确定ICB治疗的肿瘤是否是一种恶性肿瘤。 克隆持续性模式与ICB抗性相关，特别是与“冷”肿瘤相关 微环境

PROJECT SUMMARY Immune checkpoint blockade (ICB) has revolutionized cancer treatment, but the majority of patients who receive ICB develop resistance and ultimately need to be treated with multiple therapies. Mapping the expected patterns of evolution has enabled rational sequencing of treatments for many cancer therapies, particularly targeted therapies. However, we currently have a limited understanding of how treatment with ICB shapes the evolutionary trajectory of a tumor. Most cancer therapies kill tumor cells directly and leave behind a small remnant of cell-intrinsically drug-resistant tumor cells; from an evolutionary perspective, this results in a clonal sweep after treatment in which drug-resistant cells take over the tumor. In contrast, ICB acts by mobilizing a patient’s own immune cells, particularly T cells, against the tumor, and tumors frequently develop resistance to ICB by establishing a “cold” tumor microenvironment that is inhospitable to T cells. In cases where ICB resistance is mediated by the entire tumor microenvironment, it is not clear that resistance will be accompanied by such a clonal sweep; rather, it raises the question as to whether tumor cells which would be sensitive to ICB on their own might be protected if they reside alongside neighbors that can create a sufficiently “cold” microenvironment. In support of this, a study of melanoma patients has suggested that an evolutionary pattern of clonal persistence—in which many tumor populations survive therapy—is found in many ICB- resistant tumors. In this proposal, we will seek to map out the evolutionary trajectories of tumors after ICB in both a mouse model of squamous cell carcinoma and in bladder cancer patients. We will in particular seek to test the hypothesis that clonal persistence is dominant pattern of evolution following ICB, particularly in tumors which exhibit a “cold” microenvironment. We have established a novel mouse model system in which we can track multiple tumor populations in the same tumor—e.g., an “immune hot” and an “immune cold” population— via fluorescent tags. We will use this model to interrogate whether the presence of an “immune cold” tumor population that drives a “cold” microenvironment can protect otherwise-sensitive “immune hot” tumor cells from ICB-mediated clearance. Such protection by a “cold” tumor population would establish a mechanistic link between a “cold” microenvironment and an evolutionary pattern of clonal persistence. We will complement these studies with genomic analysis of tumors that have been treated with ICB, investigating both mouse squamous skin carcinomas treated with a-PD-1/a-TGFb combination therapy and patient bladder tumors treated with a-PD-L1. By constructing a detailed picture of pre- and post-ICB tumor clonal architecture across these two cohorts, we will map the evolutionary trajectories of ICB-treated tumors and determine whether a pattern of clonal persistence is associated with ICB resistance and specifically with a “cold” tumor microenvironment.