Mechanism of Action and Target Identification: A Matter of Timing in Drug Discovery

Two opposing viewpoints are held regarding the need for understanding a drug's molecular target and mechanism of action. One extreme viewpoint is that it is unnecessary, because, after all, there are many beneficial drugs in use for which the target and mechanism of action remain unknown. A second extreme viewpoint is that target identification and mechanism of action should be elucidated very early in the drug discovery process due to the tangible benefits provided by this knowledge. I offer an intermediate perspective that considers the complexity of the disease of interest, the existence of a standard-of-care treatment, and the resources available to the investigator.