Increased Immunohistochemical Expression of Stimulator of Interferon Genes (STING) in Renal Cancer with Venous Tumor Thrombus Is Associated with Worse Prognosis.

Background/Objectives: We focused on the expression of a novel immune marker, cytoplasmic stimulator of interferon genes (STING), in the cohort of primary renal cell cancer (RCC) with venous tumor thrombus (VTT), in conjunction with the assessment of tumor-infiltrating leucocytes (TILs). Methods: The study group comprised 82 patients with clear cell RCC and VTT, operated on in the years 2012-2019 in two university urological centers. Tissue microarrays were constructed, and respective antibodies were used for staining purposes. The biomarkers were analyzed in primary RCC and VTT. Results: The frequency of STING expression in both analyzed compartments was similar (p = 0.18). Its presence correlated with no clinicopathological features but for necrosis in VTT only (p = 0.0023). PD-L1 expression in the primary tumor was associated with STING in tumor cells in the same compartment (p = 0.02). On the contrary, VISTA expression was correlated with the presence of STING in VTT. TIL presence was associated with positive PD-L1 (p = 0.008) and STING (p < 0.05) expression in the primary tumor. Strong STING expression in VTT was associated with inferior overall survival (OS) (p = 0.0061). TIL presence emerged as a robust prognostic factor for OS in both primary tumor (p = 0.021) and VTT (p = 0.034). Conclusions: We presented for the first time the prognostic values of STING in a contemporary cohort of RCC patients with VTT. STING expression in VTT showed prognostic potential, while TIL assessment proved to be a particularly valuable prognostic tool that can be readily implemented in routine pathological evaluation.