Modern drug discovery is largely based on the identification and validation of a biochemical target, and then screening and optimizing molecules that engage that target. Over time, this has given rise to an extensive set of small molecule drugs approved for human use with activity at specific biological targets.
We wanted to answer the question of how many different targets are addressed by existing agents, and how the rate of addition of newly addressed-target has varied over time. To do this, we reviewed every small molecule drug approved since 1970 and sorted them by target. We removed all entities with either an unclear, broad (e.g. anti-mitotics) or non-human (i.e. antibiotics) mechanisms of action. We then enumerated targets from the time first addressed. The results are shown below.
The first striking element is that progression has been eerily stable: 5-6 previously unexploited targets are covered by newly approved small molecules every year. The second is that we now have available on our shelves a remarkably extensive armamentarium of generic small molecule drugs. However, whether the conditions are met to leverage this for further therapeutic innovation by mixing and matching target classes remains in question as is discussed here.
Acknowledgment: This analysis was conducted by Mariska Raglow-DeFranco in collaboration with Marc Herant