Role of progenitor exhausted CD8 T cells and the progenitor niche in anti-PD1 efficacy

项目摘要 抗PD-1治疗使耗尽的CD8 T细胞重新恢复活力，这可以导致尽早完全根除肿瘤。 3周。然而，尽管在> 78%的患者中有强大的T细胞复苏，但只有不到40%的患者治愈。的目标 这一建议是为了理解为什么α PD-1治疗对耗尽的CD8 T细胞的强大复苏， 转化为临床疗效。 耗尽的CD8 T细胞（TEX）是响应PD-1阻断的主要细胞类型。我们和其他人已经证明 α PD-1治疗（α PD-1）可以使衰竭的CD8 T细胞重新恢复活力，如增殖增强所定义的， 细胞因子产生。TEX是异质的，祖细胞和终末分化的TEX具有不同的 在抗肿瘤免疫反应中的作用。祖细胞TEX（ProgEX）补充终末分化TEX（TermEX）， 其又提供抗肿瘤活性。因此，类似于干细胞，ProgEX代表CD8 T细胞的储存库， 对肿瘤的反应。重要的是，它是ProgEX，而不是TermEX，响应α PD-1， 几乎完全有助于CD8 T细胞再生的早期爆发。TEX的复兴导致 加速了ProgEX向TermEX的分化，导致TermEX的数量更大， 肿瘤控制但与此同时，α PD-1诱导的加速分化增加， 强调ProgEX体内平衡。这提出了一种可能性，即ProgEX生态位是提供细胞的关键， 这是防止ProgEX耗尽所必需的信号，并且可能证明对于PD-1阻断的功效至关重要。 我们的中心假设是，α PD-1后ProgEX的耗竭损害了临床疗效， 相关的生态位是重要的，在维持池的ProgEX。在目标1中，我们将检验以下假设： α PD-1导致ProgEX的分化增强，ProgEX的缺失与临床 进展我们将使用组合四聚体和单细胞RNA + TCR测序来了解 α PD-1改变黑色素瘤特异性ProgEX池，以及ProgEX池的大小如何反过来影响临床 α PD-1的功效。在目标2中，我们检验了三级淋巴结构作为肿瘤的假设- 与ProgEX相关的小生境，α PD-1后ProgEX小生境的数量或大小增加与 ProgEX的保存和临床疗效。我们将使用多参数免疫荧光和空间 转录组学来定义ProgEX生态位的细胞组成，转录电路被 ProgEX在生态位中的重要性，以及ProgEX生态位在保护ProgEX库中的重要性。

Project Summary Anti-PD-1 therapy reinvigorates exhausted CD8 T cells, which can lead to complete tumor eradication as early as 3 weeks. Yet, despite robust T cell reinvigoration in >78% of patients, less than 40% are cured. The goal of this proposal is to understand why robust reinvigoration of exhausted CD8 T cells by αPD-1 therapy does not necessarily translate to clinical efficacy. Exhausted CD8 T cells (TEX) are a major cell type responding to PD-1 blockade. We and others have shown that αPD-1 therapy (αPD-1) reinvigorates exhausted CD8 T cells, as defined by enhanced proliferation and cytokine production. TEX are heterogeneous with progenitor and terminally differentiated TEX that have different roles in anti-tumor immune responses. Progenitor TEX (ProgEX) replenish terminally differentiated TEX (TermEX), which in turn provide anti-tumor activity. Thus, similar to stem cells, ProgEX represent a reservoir for CD8 T cell responses against the tumor. Importantly, it is the ProgEX, rather than TermEX, that respond to αPD-1 and almost exclusively contribute to the early burst of CD8 T cell reinvigoration. Reinvigoration of TEX results in accelerated differentiation of ProgEX to TermEX, resulting in a numerically greater pool of TermEX and improved tumor control. However, at the same time, the accelerated differentiation induced by αPD-1 places increased stress on ProgEX homeostasis. This raises the possibility that a ProgEX niche is key for providing the cells and signals necessary to prevent the depletion of ProgEX, and may prove crucial for the efficacy of PD-1 blockade. Our central hypothesis is that depletion of ProgEX after αPD-1 impairs clinical efficacy and that a tumor- associated niche is important in maintaining the pool of ProgEX. In Aim 1, we will test the hypothesis that αPD-1 results in enhanced differentiation of ProgEX and that that depletion of ProgEX is associated with clinical progression. We will use combinatorial tetramers and single cell RNA+TCR sequencing to understand how αPD-1 alters the pool of melanoma-specific ProgEX, and how the size of ProgEX pool in turn, impacts the clinical efficacy of αPD-1. In Aim 2, we test the hypothesis that tertiary lymphoid structures serve as a tumor- associated niche for ProgEX, and that increased number or size of ProgEX niches after αPD-1 is associated with the preservation of ProgEX and clinical efficacy. We will use multiparameter immunofluorescence and spatial transcriptomics to define the cellular composition of the ProgEX niche, the transcriptional circuits utilized by ProgEX in the niche, and the importance of the ProgEX niche in preserving the pool of ProgEX.