Experiments by Daniele Fanale et al. showed that the low expression of PD-1, PD-L1, BTN3A1, pan-BTN3As, BTN2A1, and BTLA can be used as markers for the diagnosis of advanced high-grade serous OV [33], and Xiazi Nie et al. also proved that immune checkpoints, CTLA4, IDO1, and LAG3 are all associated with poor prognosis in OV [34], in addition, CXCL10 and CD27 infiltration is associated with anti-tumor immunity and treatment response in OV subtypes [35, 36]. Here, IDO1 is linked to neoplasm.