SPDL1 and renal cell carcinoma: Building on a previous meta-analysis (n = 1,040) of sPD-L1 in different solid tumors, including RCC, which showed a negative association between sPD-L1 and survival outcomes, Mahoney et al. [82] analyzed serum levels of sPD-L1 in two cohorts of RCC (Checkmate 009, n = 91) and melanoma (Checkmate 038-Part 1, n = 78) patients treated with nivolumab.