The OSM Series 4 project is at the lead optimisation stage, with minor structural modifications being made in the search for improved solubility, potency and metabolic clearance. As is typical in such a search, analogs are being made that possess low potency, and these represent expensive "failures" (ca. $2K per compound for one postdoc-week per analogue). Better predictions of compound potency would save valuable resources and accelerate the science, so a predictive model was high on the list of priorities for the OSM consortium.