Clear cell renal cell carcinoma patients responding to nivolumab experienced a decrease in sPD-1 (from a median of 13.25 to 1.23 ng/mL) after two cycles of treatment [87]; however, in that study, changes in sPD-1 after nivolumab treatment were not investigated in non-responders. Here, HOXD13 is linked to clear cell renal carcinoma.