Evofosfamide (TH-302) is potent and selective that has an IC50 of 19 nM. It exhibits 270-fold increased cytotoxicity under hypoxia compared to their potency under aerobic conditions and is stable to cytochrome P450 metabolism. Under hypoxia, TH-302 is selectively potent and liver microsomes tolerate it well. With a high hypoxic selectivity [Hypoxia cytotoxicity ratio (HCR) = 270], replacing the chlorine with bromine in the phosphorus mustard in 3b results in a 10-fold increase in potency. Under N2, TH-302 exhibits strong cytotoxicity against human lung cancer H460 cells and human colon cancer HT29 cells. With an IC90 of 0.1 μM and 0.2 μM, respectively, TH-302 inhibits HT29 cells and H460 cells.