Single Cell Dissection of the Tumour Microenvironment Reveals Dynamic Interplay Shaping the Tumour Immunity Continuum in Ovarian Cancer

Diverse tumour immune phenotypes with distinct T cell infiltration patterns result in different responses to cancer immunotherapies. However, the key determinants and biology underpinning these phenotypes remain elusive. Here, we provide a high-resolution dissection of the tumour microenvironment representative of different tumour immune phenotypes. By performing single-cell RNA sequencing (scRNAseq) of the tumour, immune, and stromal compartments from 15 ovarian cancer patients, we characterized the diverse cellular and functional phenotypes, as well as dynamic interplay within and between these components. Infiltrated and excluded tumours markedly differed from desert tumours in several tumour cell intrinsic features, including high interferon response, antigen presentation and oxidative phosphorylation. Moreover, these tumours were characterized by tumour associated macrophage (TAM)-like myeloid subsets, while desert tumours were enriched in myeloid derived suppressive cell (MDSC)-like myeloid subsets. Infiltrated and excluded tumours differed in their T cell composition and fibroblast subsets. While dysfunctional CD8+ GZMB T cells and IL1-activated fibroblasts (IL1 CAFs) were associated with infiltrated tumours, pre-dysfunctional CD8+ GZMK T cells and TGFB-activated fibroblasts (TGFB CAFs) were enriched in excluded tumours. These findings validated in bulk transcriptomic profiles of 1071 ovarian tumours and using in situ hybridization. Furthermore, our study revealed chemokine receptor-ligand interactions within and across compartments as potential mechanisms mediating immune cell infiltration, exemplified by the tumour cell-T cell crosstalk via a CXC16-CXCR6 axis, stromal-immune cell crosstalk via CXCL12/14-CXCR4 signalling, and TAM-like macrophage-T cell crosstalk through CXCR3-CXCL9/10/11 signalling. Our in-depth characterization of the tumour environment and intercellular interactions provides novel insights into potential molecular mechanisms that shape the distinct biology of tumour immune phenotypes. Our findings may inform novel therapeutic strategies for potentially shifting tumours along the immunity continuum to improve clinical benefit from cancer immunotherapies.EGA study EGAS00001004935

具有不同T细胞浸润模式的多样化肿瘤免疫表型（tumour immune phenotypes），会导致癌症免疫治疗（cancer immunotherapies）产生各异的应答反应。然而，支撑这些表型的关键决定因素与生物学机制仍未明确。本研究针对代表不同肿瘤免疫表型的肿瘤微环境（tumour microenvironment）开展了高分辨率解析。通过对15名卵巢癌（ovarian cancer）患者的肿瘤、免疫及基质区室（stromal compartments）开展单细胞RNA测序（single-cell RNA sequencing, scRNAseq），我们解析了多样化的细胞与功能表型，以及这些组分内部及组分间的动态互作。浸润型与排斥型肿瘤在多项肿瘤细胞内在特征上与荒漠型肿瘤存在显著差异，包括高干扰素应答、抗原呈递及氧化磷酸化过程。此外，浸润型与排斥型肿瘤以肿瘤相关巨噬细胞（tumour associated macrophage, TAM）样髓系亚群为特征，而荒漠型肿瘤则富集髓系来源抑制细胞（myeloid derived suppressive cell, MDSC）样髓系亚群。浸润型与排斥型肿瘤在T细胞组成及成纤维细胞亚群方面也存在差异。功能失调性CD8+ GZMB T细胞与IL1激活的成纤维细胞（IL1-activated fibroblasts, IL1 CAFs）与浸润型肿瘤相关，而预功能失调性CD8+ GZMK T细胞与TGFB激活的成纤维细胞（TGFB-activated fibroblasts, TGFB CAFs）则富集于排斥型肿瘤中。上述研究结果在1071例卵巢肿瘤的批量转录组谱（bulk transcriptomic profiles）及原位杂交（in situ hybridization）实验中得到了验证。此外，本研究揭示了区室内部及跨区室的趋化因子受体-配体互作（chemokine receptor-ligand interactions），可作为介导免疫细胞浸润的潜在机制，具体例证包括：肿瘤细胞与T细胞通过CXC16-CXCR6轴的串扰、基质细胞与免疫细胞通过CXCL12/14-CXCR4信号通路的互作，以及TAM样巨噬细胞与T细胞通过CXCR3-CXCL9/10/11信号通路的串扰。本研究对肿瘤微环境及细胞间互作的深度解析，为阐明塑造肿瘤免疫表型独特生物学特征的潜在分子机制提供了全新视角。本研究结果可为开发新型治疗策略提供参考，即通过调整肿瘤在免疫连续谱中的状态，以提升癌症免疫治疗的临床获益。EGA研究 EGAS00001004935