It does sound like a very promising avenue, but I imagine that this route could still be a problem for people already pre-disposed to autoimmune diseases. Still, most of those aren't as bad as the alternative here. Any drug based on this doesn't have to not have side effects, it just has to be better than normal chemotherapy.
You raise another good point here, that the allowable side effect profiles for cancer drugs are much less stringent than for drugs indicated for less life-threatening diseases.
