In-vivo efficacy and selective tumor accumulation of KU174 in rat prostate tumor models. Six hours following a single i.p. dose, the tumor to plasma ratio of KU174 was determined to be ~3.6:1 suggesting selective tumor accumulation (Figure 7A, **p value < 0.01). Median percent increase in tumor volume relative to the initial tumor size from a pilot study in a rat PC3-MM2 tumor xenograft dosed with KU174 (15, 25, and 75 mg/kg) Tumor growth inhibition was evident between vehicle (n = 4) and the 75 mg/kg group (** p = 0.08, n = 4) (Figure 7B). Microscopic examination of kidneys from both vehicle (captisol) and 75 mg/kg KU174 treated animals showed prominent vacuolization compared to untreated (Figure 7C) indicating captisol resulted in some degree of toxicity.