IL2 and renal cell carcinoma: Dannull et al. used a recombinant IL-2:diphtheria toxin conjugate (DAB389IL-2; also known as denileukin diftitox and ONTAK) to eliminate CD25-expressing Tregs in metastatic RCC patients, and reported that depletion of Tregs in RCC patients followed by vaccination with tumor RNA-transfected DCs led to improved stimulation of tumor-specific T cells compared with vaccination alone [75].