Objective

Methods are needed to study selective binding and localization of candidate drugs and their target interactions in relevant clinical specimen during drug discovery and development. We describe a target engagement-mediated amplification (TEMA) technology, where target interactions by oligonucleotide-linked small molecules is visualized and measured with circularized oligonucleotide probe (padlock probe) via rolling-circle amplification (RCA). We established TEMA using kinase inhibitor precursor compounds and applied the assay for investigating target interaction at low nanomolar drug concentrations in a commercial array of 9000 recombinant human proteins and in pathology tissue section. The TEMA method proved useful to reveal the localization of drug binding in fixated cells and tissues. We also identified specific drug-target interaction and selectivity profiles among large collection of arrayed proteins. We conclude that TEMA is promising as a means to validate target binding by drugs during lead optimization, and for candidate selection during drug discovery.