BiSim Tool: a binding simulation tool to aid and simplify ligand-binding assay design and development.

Ligand-binding assays (LBAs) rely on the reversible, noncovalent binding between the analyte of interest and the assay reagents, and understanding their dynamic equilibrium is key to building robust LBA methods. Although the dynamic interplay of free and bound fractions can be calculated using mathematical models, these are not routinely applied. This approach is costly in terms of both assay development time and reagents, and can result in an under-exploration of the possible parameter combinations. Therefore, we have created a user-friendly simulation tool to facilitate LBA development (the BiSim Tool). We describe the models driving the mathematical simulations and the main features of our software solution by means of case studies, illustrating the tool's value in drug development. To support drug development for all patients worldwide, the BiSim Tool is now available as an open-source code project and as a free web-based tool at https://proteinbindingsimulation.shinyapps.io/BiSim-ProteinBindingSimulation [1].