CD33 and renal cell carcinoma: Sunitinib, a receptor tyrosine kinase inhibitor decreased both HLA-DR− CD33+ CD15+ and HLA-DR− CD33+ CD15− MDSCs in the blood of renal cell carcinoma patients which was associated with the reversal of Th1 response by enhanced production of T-cell IFN-γ and reduction in CD3+ CD4+ CD25high Foxp3+ T-regs [149].