Drug-loaded, iron-stabilized micelles increase anti-tumor efficacy compared to free drug in subcutaneous xenograft models. Body weights do not change more than 20% from starting weight in efficacy studies. Relative tumor volume in HCT116 colorectal model treated with IT-141 compared to irinotecan (A), HT-29 colorectal adenocarcinoma model treated with IT-141 (B), and HCT116 colorectal model treated with IT-147 (C). Arrows indicate dosing days. (D, E, F) Percent body weight change during HCT116 efficacy study using IT-141 (D), HT-29 efficacy study using IT-141 (E), and HCT116 efficacy study using IT-147 (F).