Repurposing molecular imaging to map drug targets in vivo

Abstract Background Understanding where drug targets are expressed in the human body is essential for precision medicine, yet this information is difficult to obtain in living patients. Molecular imaging offers a non-invasive way to visualize target expression, but its application remains fragmented. We aim to develop a systematic framework to link approved drugs, their molecular targets, and existing imaging agents, with a focus on repurposing imaging strategies for clinical use. Methods We integrate drug, target, and disease data from public databases and combine these with imaging probe annotations and transcriptomic data from more than 240,000 patient samples across multiple diseases. Co-expression analysis is used to identify candidate surrogate imaging targets for proteins that lack direct imaging agents. Statistical associations are assessed using correlation analysis with multiple testing correction. Results Here we show that existing imaging agents can be linked to 704 therapeutic targets across 1345 diseases. Nearly half of these targets are directly imageable, while the remainder can be connected to surrogate imaging targets through co-expression. In total, more than 4000 imaging agents are identified, enabling the systematic prioritization of candidate imaging strategies across diseases. Conclusions This study provides a framework for repurposing molecular imaging agents to visualize drug targets in vivo. The approach expands the potential of imaging to guide patient selection and treatment monitoring, and highlights opportunities to translate existing but underused imaging agents into clinically actionable biomarkers.