Finding new drug targets in the 21st century.

The past 30 years have witnessed a steady decline in the number of new drug targets. This review concentrates on the initial process of target identification and argues that current problems have resulted from a decrease in clinical research, an overemphasis on the discovery of new targets through an understanding of the molecular causes of disease and the adoption of cell and animal models that are poor predictors of human disease. To resolve this situation, we argue for increased clinical research and show that an intervention at the physiological level, using drugs to target at the extracellular signalling pathways, will facilitate identification of novel drug targets in the 21st century.