Evolutionary trajectories of tumors following resistance to immune checkpoint blockade

项目总结 免疫检查点阻断(ICB)已经彻底改变了癌症的治疗，但大多数患者 接受ICB会产生抵抗力，最终需要接受多种疗法治疗。映射 预期的进化模式使得许多癌症疗法的治疗能够合理排序， 特别是有针对性的治疗。然而，我们目前对ICB是如何治疗的了解有限 塑造了肿瘤的进化轨迹。大多数癌症疗法直接杀死肿瘤细胞，并在治疗后留下 小残留细胞-本质上耐药的肿瘤细胞；从进化的角度来看，这导致了 耐药细胞接管肿瘤的治疗后的克隆性扫描。相比之下，ICB的行动方式是 动员患者自身的免疫细胞，特别是T细胞来对抗肿瘤，肿瘤经常会发展 通过建立一个不利于T细胞生存的“冷”肿瘤微环境来抵抗ICB。在案件中 在ICB耐药是由整个肿瘤微环境介导的情况下，尚不清楚耐药是否会 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 如果他们自己对ICB敏感，如果他们与邻居一起居住，可能会受到保护，因为这些邻居可以创造足够的 “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，一种进化的 在许多ICB中发现了克隆持续的模式-许多肿瘤群体在治疗中存活下来- 耐药肿瘤。在这项建议中，我们将寻求绘制出ICB后肿瘤的进化轨迹。 无论是小鼠鳞状细胞癌的模型还是膀胱癌患者的模型。我们将特别致力于 测试克隆持续性是ICB后的主导进化模式的假设，特别是在肿瘤中 呈现出一种“冷”的微环境。我们已经建立了一个新的小鼠模型系统，在这个系统中，我们可以 跟踪同一肿瘤中的多个肿瘤种群--例如，“免疫热”和“免疫冷”种群-- 通过荧光标签。我们将用这个模型来询问是否存在一种“免疫感冒”肿瘤 驱动“冷”微环境的群体可以保护原本敏感的“免疫热”肿瘤细胞免受 ICB介导的清除。“寒冷”的肿瘤群体的这种保护将建立一种机械联系 在“寒冷”的微环境和克隆持久的进化模式之间。我们将互为补充 这些研究对接受ICB治疗的肿瘤进行了基因组分析，调查了两只小鼠 A-PD-1/a-TGFb联合治疗鳞状皮肤癌与患者膀胱肿瘤 用a-PD-L1治疗。通过构建ICB前后肿瘤克隆结构的详细图像 这两组，我们将绘制ICB治疗肿瘤的进化轨迹，并确定 克隆性持续模式与ICB耐药相关，尤其与“冷”瘤有关 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.