CA9 and nonpapillary renal cell carcinoma: Recently, anti-CAIX G36 scFv CAR T cells containing 4-1BB as a co-stimulatory domain were tested in a CD4/CD8 ratio of 2:1, leading to complete remission in an orthotopic ccRCC model in NSG mice, which remained tumor-free 72 days after CAR-T cells infusion.