I actually tried something like this. I introduced the same tumor that a rat was bearing, with the introduction of a human major histocompatibility protein complex. The MHC is often something that the immune system recognizes for xenograph rejection. At any rate, the theory was that if we reintroduced the same tumor cells with an easy marker for rejection, the immune system might translate the rejection to the other tumor cells. It didn't work in that experiment, however that doesn't mean it can't. I am convinced that the approach described is probably a good way to develop strategies. Except for some unique tumors that are the result of some very specific molecular changes, you have to consider the environment, because these are heterogeneous competing organisms that adapt to, and change, their environment. As an aside, I used to work in stroke research. My mentor once wondered if we could introduce a brain tumor into the focus of the stroke. Brain tumors release a lot of growth factors, and spur new blood vessel growth. The tough part would be getting the tumor to stop when you wanted it too. You could give it a suicide gene, but there's always the chance it could get away from you. Probably a very tough sell for any sort of trial: "You had a stroke. Ok, now we are going to give you a brain tumor."Interesting idea: introduce a different form of cancer into a patient to weaken the deadlier cancer...
Wow, that sounds incredibly interesting. How would you be able to introduce a suicide gene and how could you attempt to control the lifespan of the cell through that?
There's a number of ways that you can control the expression of an introduced gene via chemical induction. That is, you can put a gene into cells that has an expression promoter that can turn on when you add a specific compound. I haven't done it myself, but it's fairly common. There are even strains of mice that have genes that can be turned on and off chemically. One strategy would be to turn on a gene that induced apoptosis in this manner. Thus, the cells self-destruct when exposed to a certain compound. Introducing a gene into cultured cells is very easy, and there are a number of ways to do it. Basically, you force the cells to take up a ring of DNA that has the gene you want to introduce a small number of these cells will incorporate the DNA into their genome, or you construct a virus that introduces the gene. If you want to keep only those cells expressing your gene, you introduce the gene with another one that confers resistance to a compound that kills the cells. You add the compound, and the only cells that survive are those that incorporated your DNA.