The mitochondria in many cancer cell behave abberantly. For example, in many cases, they can start promoting glycolysis, in process known as the Warburg effect. They're also involved in other processes such as apoptosis and cell migration. I'd hypothesize that these drugs target pathways or processes that are dysregulated in the mitochondria of those cancers.

i think it's because most cells have multiple forms of metabolism available to them, but cancer cells are limited to just this one