The Opportunities and Use of Imaging to Measure Target Engagement.

Lack of efficacy and poor safety outcomes are deemed to be the greatest causes of clinical failure of novel therapeutics. The use of biomarkers that give accurate information on target engagement, providing confidence that pharmacological activity in the target organ is being achieved, is key in optimizing clinical success. Without a measurement of target engagement, it can be very difficult to discern the basis for any lack of efficacy of a drug molecule within the pharmaceutical industry. Target engagement can be measured in both an in vitro and in vivo setting, and in recent years imaging measurements have been used frequently in drug discovery and development to assess target engagement and receptor occupancy in both human and animal models. From this perspective, we assess and look at the advancements in both in vivo and ex vivo imaging to demonstrate the enormous potential that imaging has as an application to provide a greater understanding of target engagement with a correlative therapeutic impact.