Prognostic value of stromal CD39+CD8+ T cells in predicting platinum sensitivity and survival outcomes in epithelial ovarian cancer

This study aimed to investigate the expression levels of CD8⁺ and CD39⁺CD8⁺ T cells in both intratumoral (CK⁺) and stromal (CK^-) regions, in conjunction with clinical parameters, to assess their potential impact on chemotherapy response and prognosis in epithelial ovarian cancer (EOC) patients. Formalin-fixed, paraffin-embedded (FFPE) surgical specimens from 129 patients with EOC were used to construct tissue microarrays (TMAs) for assessing the expression of CD8⁺ and CD39⁺CD8⁺ tumor-infiltrating lymphocytes (TILs). Cytokeratin (CK) immunolabeling was employed to distinguish epithelial tumor regions (CK⁺) from stromal regions (CK^-) in EOC tissues. Independent prognostic factors were identified using univariate and multivariate Cox regression analyses, and these variables were incorporated into nomogram models to predict overall survival (OS). Patients in the platinum-sensitive group exhibited significantly higher expression levels of stromal CD8⁺ cells and CD39⁺CD8⁺ T cells, which were strongly correlated with platinum sensitivity compared with the platinum-resistant group (p < 0.0001 and p = 0.0004, respectively). Multivariate Cox regression analysis in the training cohort indicated that elevated stromal levels of CD39⁺ T cells and CD39⁺CD8⁺ T cells were independently associated with improved OS (HR = 2.587, p = 0.033; HR = 3.090, p = 0.008, respectively). Nomograms were developed to visually predict OS by integrating these biomarkers with relevant clinical indicators identified in the Cox regression analyses. Calibration curves demonstrated excellent concordance between predicted and observed survival outcomes. Elevated stromal levels of CD39⁺CD8⁺ T cells represent a promising prognostic biomarker for predicting platinum sensitivity and favorable prognosis in patients with advanced EOC. These findings may provide valuable insights into the tumor microenvironment and its role in modulating therapeutic responses.