卵巢癌（OC）患者常常因复杂的肿瘤微环境（TME）而显示出较差的免疫治疗反应。迫切需要探索新的免疫治疗标志物。通过对高级别浆液性卵巢癌（HGSOC），中度严重边缘瘤和配对的正常卵巢进行单细胞RNA测序（scRNA-seq）分析，我们发现了一种与OC预后不良相关的新型疲惫T细胞亚群。使用组织学染色、多细胞免疫荧光和流式细胞术验证了scRNA-seq的一些结果。此外，建立了一个携带肿瘤的小鼠模型，以研究TNFRSF1B治疗对体内肿瘤生长的影响。与中度严重边缘瘤和配对的正常卵巢相比，HGSOC显示出高度免疫抑制性的TME。随后，我们发现一种新型的疲惫亚群CD8+ TNFRSF1B+ T细胞，与低生存率相关。体外实验证明，TNFRSF1B在激活的CD8+ T细胞上特异性上调，并抑制干扰素-γ分泌。TNFRSF1B在CD8+ T细胞上的表达与OC临床恶性有密切关系，并通过140名OC患者的验证成为糟糕预后的标志物。此外，TNFRSF1B的阻断通过深度重建OC小鼠模型中的免疫微环境，抑制肿瘤生长。我们通过scRNA-seq分析的转录组结果揭示了OC TME整个肿瘤生态系统的高分辨率快照。我们的研究发现主要应用于预测OC患者预后的CD8+ TNFRSF1B+疲惫亚群以及TNFRSF1B的潜在治疗价值。这些发现证明了TNFRSF1B作为潜在免疫治疗靶点的临床价值，并扩展了我们对OC免疫治疗失败因素的了解。© 2023 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.

Ovarian cancer (OC) patients routinely show poor immunotherapeutic response due to the complex tumour microenvironment (TME). It is urgent to explore new immunotherapeutic markers.Through the single-cell RNA sequencing (scRNA-seq) analyses on high-grade serous OC (HGSOC), moderate severity borderline tumour and matched normal ovary, we identified a novel exhausted T cells subpopulation that related to poor prognosis in OC. Histological staining, multiple immunofluorescences, and flow cytometry were applied to validate some results from scRNA-seq. Furthermore, a tumour-bearing mice model was constructed to investigate the effects of TNFRSF1B treatment on tumour growth in vivo.Highly immunosuppressive TME in HGSOC is displayed compared to moderate severity borderline tumour and matched normal ovary. Subsequently, a novel exhausted subpopulation of CD8+ TNFRSF1B+ T cells is identified, which is associated with poor survival. In vitro experiments demonstrate that TNFRSF1B is specifically upregulated on activated CD8+ T cells and suppressed interferon-γ secretion. The expression of TNFRSF1B on CD8+ T cells is closely related to OC clinical malignancy and is a marker of poor prognosis through 140 OC patients' verification. In addition, the blockade of TNFRSF1B inhibits tumour growth via profoundly remodeling the immune microenvironment in the OC mouse model.Our transcriptomic results analyzed by scRNA-seq delineate a high-resolution snapshot of the entire tumour ecosystem of OC TME. The major applications of our findings were an exhausted subpopulation of CD8+ TNFRSF1B+ T cells for predicting OC patient prognosis and the potential therapeutic value of TNFRSF1B. These findings demonstrated the clinical value of TNFRSF1B as a potential immunotherapy target and extended our understanding of factors contributing to immunotherapy failure in OC.© 2023 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.