The aim is a therapy produced by the tumor, against the tumor, in the tumor, so potent drugs stay local.
We created the first genetic switches made out of DNA that only turn on in cancer cells. You inject them and they go everywhere, but they only flip on inside a cancer cell, like a light switch. We only get into about 1% of the cancer cells, so the cell produces a message, a smoke signal, that brings the immune system to attack the rest, like a domino chain reaction. The hard part is keeping all of it inside the tumor so you avoid off-target effects.
Source: Tomorrow’s Medicine, with Cyriac Roeding (eCornell Keynote)