Prognostic significance of PD-1 and PD-L1 positive tumor-infiltrating immune cells in ovarian carcinoma

Abstract

Introduction: Ovarian carcinoma is associated with the highest mortality of all gynecologic malignancies. Even after optimal treatment, prognosis remains poor. There is no established biomarker to predict individual patient outcome.

Objective: To evaluate the prognostic significance of PD-1 and PD-L1 expression in tumor tissues from patients with ovarian cancer.

Methods: Tissue micro-arrays were prepared from routinely formalin-fixed, paraffin-embedded tumor tissues and examined immunohistochemically for the expression of programed cell death protein 1 (PD-1) and one of its ligands (PD-L1) on epithelial tumor cells, as well as on tumor- and stroma-infiltrating immune cells.

Results: The presence of PD-1 positive tumor-infiltrating immune cells was significantly associated with prolonged overall survival. PD-1 and PD-L1 positive tumor-infiltrating immune cells were associated with the presence of lymph node metastases and higher tumor grade. Interestingly, the amount of PD-1/PD-L1 positive tumor- and stroma-infiltrating immune cells independent of PD-1 or PD-L1 expression did not show any significant correlation with prognostic variables.

Conclusion: Our results highlight the prognostic value of PD-1 and PD-L1 positive tumor-infiltrating immune cells in ovarian carcinoma. Their association with favorable prognosis supports the hypothesis that the expression of PD-1 and PD-L1 on tumor-infiltrating immune cells represents a strong immune response.

Keywords: cystadenocarcinoma; cystadenocarcinoma, serous; ovarian cancer; ovarian neoplasms; pathology.