[maxander]

Presumably, making it more targeted means they can use more, potentially to the point that the effect on the tumor would correspond to a lethal systemic dose using a course of normal doxorubicin. The patient wouldn’t feel any better while undergoing the therapy in that case, but worse tumors could be successfully treated. The effect/toxicity ratio is the key factor in a lot of these kinds of drugs.

[mejiaoneto]

That is absolutely right. By honing the drug to the tumor, and minimizing the effects on the rest of the body, you are essentially able to unlock power on the tumor that would have put the patient's life at risk before. Taken it even a step further, if you have a system that selectively gets the drug to the tumor, then you can give combinations of cancer drugs that would be otherwise lethal, also preventing the possibility of mutations that would make the tumor unaffected by a single drug. The possibilities are immense.