STAT3 and cancer: For example, the herb derivative curcumin, which is a regulator of STAT3 signaling, was found to exhibit several pharmacologic effects (e.g., anti-inflammatory, antioxidant, and anti-cancer activities), as well as reduce the number of MDSCs at tumor sites and in the blood of tumor-bearing mice.661,662 The siRNA-inhibition of STAT3 eliminated the immunosuppressive effects of MDSCs on CD8+ T-cell functions by reducing the expression of Arg-1.663 However, small molecule inhibitors targeting STAT3 displayed limited efficacy and broad side-effects.664