Drug repositioning beyond the low-hanging fruits

Approved drug molecules have undergone safety and efficacy examination, succeeding in a series of screens with typically high attrition rates. Today, these privileged entities are well characterized: the amount of data that has been collected for drugs — from mechanisms of action to all sorts of molecular signatures — is far beyond that of the rest of compounds available to researchers. As biomedicine is going omics, and with the advent of systems biology, drug molecules constitute a standard toolbox to probe and challenge disease models, which are increasing in complexity and start to account for patient variability. Here, we discuss why drug repositioning is not only an economically attractive idea, but also one of the most realistic settings for systems pharmacology.