Drug development is expensive and difficult. New approaches are needed to more effectively develop highly specific drugs against a wide range of proteins. In the context of our successful work to develop proximity ligation for protein diagnostics, we note that detection of proteins requires the use of pairs of antibodies to achieve the desired specificity. We now want to utilize our knowledge of proximity ligation, as well as our experience in using DNA-coupled drugs for detection purposes, to develop a new technique to select pairs of drug substances that bind together to target molecules. The aim is to greatly improve treatment effects and minimize side effects. Our work, conducted in collaboration with SciLifeLab and its drug development arm, will utilize commercial libraries of drug compounds, linked to unique DNA strands. We will use proximity ligation to find pairs of compounds that together bind drug targets. The expected increase in binding strength will allow utilization of lower amounts of drugs, and reduce the risk of interference from extraneous proteins. We will also adapt such coincidental binders for exploitation as drugs, and we will compare their pharmacological effects with more conventional drugs in model experiments.