Programmed Cell Death Ligand-1 (PDL-1) Correlates with Tumor Infiltration by Immune Cells and Represents a Promising Target for Immunotherapy in Endometrial Cancer

Abstract

Background/Aim: Endometrial carcinoma (EC) is one of the most common gynecological cancers in the Western Hemisphere. Nevertheless, there are not enough appropriate treatment options, especially for advanced stages. The immune checkpoint blockade represents a promising alternative to established cancer therapies by suppressing the immune-inhibitory activity of the immune checkpoint factors programmed cell death-1 (PD-1) and programmed cell death ligand-1 (PD-L1). In the present study, we characterized the clinical relevance of the biomarker PD-L1 expression in terms of its prognostic capabilities in EC. Patients and Methods: Tumor tissue samples from 87 EC patients were retrospectively analyzed by immunohistochemistry (PD-L1, p16, estrogen receptor, progesterone receptor, HER2/neu, Ki67, CD3, CD20, CD68). Results: A total of 17.3% of EC patients were PD-L1 positive. PD-L1 status did not represent a suitable prognostic marker in EC, but correlated with T3/T4stage, positive lymph node status, p16 expression, and absence of estrogen and progesterone receptor. PD-L1 positive tissues showed increased infiltration with lymphocytes, monocytes, and macrophages, although not statistically significant in every case. Conclusion: In EC, PDL1 expression has no prognostic significance, but correlates with other oncogenic factors and indicates increased infiltration of the tumor with immune cells. Thus, PD-1/PDL1 immunecheckpoint blockade seems to be very promising, at least in a subset of EC patients.