In animals, RTA 408 significantly reduces tumor nitrotyrosine burden, inhibits the activity of MDSCs, and augments T-cell anticancer activity at relevant doses. Thus, through inhibition of MDSC activity and suppression of tumor ROS/RNS, RTA 408 may work in combination with T-cell-activating therapeutics such as ipilimumab to enhance the natural immune anticancer response. RTA 408 also has direct anticancer effects via inhibition of NF-kappa B. Chronic activation of NF-kappa B is associated with tumor progression, metastasis, and resistance to therapy.