CD4 and nonpapillary renal cell carcinoma: The complete regression of clear cell renal cell carcinoma (ccRCC) obtained pre-clinically with newer anti-CAIX (humanized G36 clone) chimeric antigen receptor (CAR) T cells in doses equivalent to ≅108 CAR T cells/kg in a CD4/CD8 mixture renewed the potential of this target to treat ccRCC and other hypoxic tumors [18,19].