Expression of Programmed Death-1 Ligand in Renal Cell Carcinoma and Its Relationship with Pathologic Findings and Disease-Free Survival

Background: Renal cell carcinoma (RCC) is an invasive malignancy of kidney origin. The programmed death-1 ligand (PD-L1) with its receptor (PD-1) on T-cells can inactivate antitumor response and possibly lead to poor outcomes in patients with RCC. Methods: Our study assessed the expression of PD-L1 by immunohistochemical staining on 86 radical or partial nephrectomy samples with RCC diagnoses with diverse types, tumor grades, and stages. Tumor specimens were collected from the pathology archive of 2014 - 2017 in Sina Hospital, Tehran, Iran. Results: Out of 86 studied RCC samples, 68 cases (79.1%) were clear cell types. PD-L1 expression was observed more in non-clear cell carcinoma samples than in clear cell carcinoma (P = 0.008). PD-L1 expression had significant relationships with nuclear grade and tumor necrosis (P = 0.025 and 0.010, respectively). However, PD-L1 expression was not correlated with tumor size, lymphovascular invasion, and sarcomatoid differentiation. The disease-free survival rate in patients with PD-L1 expression was significantly less than in patients with PD-L1 negative staining (P = 0.032). Conclusions: According to our findings, PD-L1 could be regarded as an important biomarker with worse prognosis and aggressive clinicopathologic findings in patients with RCC.