It will be fascinating to see how the interlocking regulatory/corporate structures handle this one. A group of scientists at the University of Alberta in Edmonton have tested an existing drug, dichloroacetate (DCA) on human cells cultured outside the body. It killed lung, breast and brain cancer cells but not healthy cells. It also shrunk tumors in rats.
DCA has been used to treat rare metabolic diseases and has been around so long, used with relative safety, that it is out of patent. That's a two-edged sword. It means any generic company could manufacture it and it would be relatively cheap. But since no company can repatent it and make the big bucks, none might be willing to sponsor clinical trials that would demonstrate efficacy more soundly.
Doctors can prescribe drugs for "off-label" uses, or uses that weren't part of the original approval process but were discovered later. But the FDA, not exactly a big fan of the First Amendment, has been known to discourage or even prohibit advertising of off-label uses. A non-pharmaceutical example is the half-aspiring that has been shown to be good for heart health. When the studies first came out and the news was featured, aspirin use went way up. But because the FDA censored ads by aspirin companies that would have been nothing more than citing solid, peer-reviewed scientific studies, aspirin use then tailed off. It would be difficult to calculate how many unnecessary deaths have resulted.
I'm hoping for an aggressive generic company to run with this and advertise heavily, challenging the FDA if the FDA is in a censorious mood. There are attorneys around who could help them.