CD27 and renal cell carcinoma: In recent years, several CAR T cell therapies targeting CD70+ tumor cells have been designed with various antigen-recognition domains (CD27 receptor, single chain variable fragment (scFv), or nanobodies) and intracellular co-stimulatory domains (CD27, CD28 or 4-1BB) [46–54], and some even entered clinical trials mostly targeting hematological malignancies or renal cell carcinoma [6].