Prognostic Value of Serum Soluble PD-L1 in Metastatic Renal Cell Carcinoma Patients Treated With Nivolumab

Background/Aim: Increasing availability of effective treatment options for metastatic renal cell carcinoma (mRCC) has highlighted the importance of identifying predictors of treatment response. Although PDL1 expression in renal cancer has been reported as a predictor of treatment response and prognosis, its assessment by immunohistochemistry is invasive and difficult to perform repeatedly. Soluble PD-L1 (sPD-L1) has recently been proposed as a predictive biomarker for several tumour types. Therefore, we evaluated sPD-L1 levels in patients with mRCC treated with nivolumab and investigated its association with treatment response. Patients and Methods: We performed a prospective single-arm study in patients with mRCC treated with nivolumab as second line or later therapy. We measured serum sPD-L1 before and during treatment, classified patients based on baseline values (sPDL1 & GE;0.23 ng/ml vs. <0.23 ng/ml) and compared outcomes between the two groups. Results: A total of 43 patients with mRCC were included in this study, with 17 (39.5%) classified as low sPD-L1 and 26 (60.5%) as high sPD-L1. The International Metastatic RCC Database Consortium risk score was significantly poorer in the high sPD-L1 group. The objective response rate was significantly higher (41.2% vs. 7.7%) and overall survival significantly longer (p=0.0323) in the low group compared to the high group. There were no significant differences in progressionfree survival between the two groups. Conclusion: Our study findings indicate that sPD-L1 might be a predictor of treatment response to nivolumab in patients with mRCC.