Hardly anybody wants new drugs that act like a sledgehammer, bashing diseased and healthy cells like old-school cancer chemotherapy. Many drugs today are supposed to be smart enough to work like laser-guided missiles that hit the diseased cells and mostly spare the healthy ones.
But if your goal is to create one of these amazing “targeted” therapies, you’ve got to start by having a great biological target to aim at in the first place. These are the protein receptors on the cell surface, the enzymes that perform dirty work inside cells, the signaling pathways that cells use to send messages, or the RNA sequences that give rise to bad proteins. Much as the biologists can study these targets, nobody really knows for sure what will happen—good and bad—until a drug to inhibit the target’s activity gets tested in human beings.