The Infiltration of ICOS+ Cells in Nasopharyngeal Carcinoma is Beneficial for Improved Prognosis.

Nasopharyngeal carcinoma (NPC) is a highly malignant tumor, associated with poor patient prognoses, and high rates of morbidity and mortality. Currently, immune checkpoint therapy has brought new treatment strategy for NPC. The inducible T cell co-stimulator (ICOS) belongs to the B7-CD28 immunoglobulin superfamily, which is currently the subject of intense study due to great successes gained in treatment of different malignancies by disrupting their family members. However, the role of ICOS played in NPC remains poorly understood. Immunohistochemistry (IHC) was stained with the ICOS specific antibody and ICOS expression is decreased in patients with either lymphatic or distant metastasis and inversely associated with TNM stage of NPC patients. Importantly, high ICOS expression is significantly correlated with overall survival (OS) of NPC patients (N = 185, p < 0.001), and ICOS expression is also proved to be an independent prognostic factor by multivariate analysis. Surgical excised fresh NPC specimens (N = 185) were homogenized to analyze the specific cytokine expression by ELISA assay. ICOS expression level is associated with increased cytotoxic T lymphocyte number and high interferon IFNγ expression, the characteristics of Th1 cells. In addition, the correlation between the percentage of ICOS+ T cells in tumor tissue and survival was detected. Conclusively, expression of ICOS is associated with improved survival in NPC and percentage of ICOS+ cells acting as Th1 cells in primary tumor tissue may be a clinical biomarker for good prognosis of NPC patients.