Elesclomol, also known as STA-4783, is a HSP-90 Inhibitor, and is a small-molecule bis(thio-hydrazide amide) with oxidative stress induction, pro-apoptotic, and potential antineoplastic activities. Elesclomol induces oxidative stress, creating high levels of reactive oxygen species (ROS), such as hydrogen peroxide, in both cancer cells and normal cells. Because tumor cells have elevated levels of ROS compared to normal cells, the increase in oxidative stress beyond baseline levels elevates ROS beyond sustainable levels, exhausting tumor cell antioxidant capacity, which may result in the induction of the mitochondrial apoptosis pathway.