CTLA4 and nonpapillary renal cell carcinoma: The preoperative serum levels of B7‐H4, PD‐L1, and VEGF were significantly higher in ccRCC patients than in the healthy controls (Fig. 1 and Table 1), but those of PD‐1, B7‐H3, CTLA‐4, CD28, CD80, and CD86 were not (Fig. 1, Tables 1 and S1).