SPDL1 and nonpapillary renal cell carcinoma: Surprisingly, not much attention has been given to the evaluation of soluble PD-1 (sPD-1) and PD-L1 (sPD-L1) in plasma as potential biomarkers in patients with CCRCC, a heterogeneous neoplasm in serious need of identification of molecular markers that clinicians could use to facilitate an earlier diagnosis, to monitor the disease and to predict prognosis and clinical response to different therapies.