Identification of novel biological therapeutic agents comprises multiple steps from target selection, initial screening to identify lead candidates, affinity maturation and subsequent rounds of lead characterisation and optimisation to improve binding affinity and/or potency. Competition assays are particularly relevant in the latter stages, when identifying variants with higher target binding affinity. One advantage of identifying higher affinity antibodies is these are more likely to have improved clinical efficacy, requiring less frequent patient treatment doses. If the target protein is a cell receptor, common competition assay formats use a labelled form of the endogenous ligand which can then be competed away using the test biologic e.g. antibody. The labelled component is used at a partially saturating concentration, usually at the EC50. No-wash assay formats are advantageous to ensure that binding is at equilibrium when plates are read. In addition, homogeneous assay formats offer a simple and convenient workflow that is amenable to automation and free up FTE time compared to multi-step, multi-wash ELISA or flow cytometry protocols.