Comparison of compound administration methods in biochemical assays: effects on apparent compound potency using either assay-ready compound plates or pin tool-delivered compounds.

Compound sample preparation and delivery are the most critical steps in high-throughput screening (HTS) campaigns. Historically, several methods of compound delivery to assays have been used for HTS, including intermediate plates with prediluted compounds, assay-ready plates (ARPs) using either preplated dried compound films or nanoliter DMSO spots of compounds, as well as pin tool-delivered compounds. We and others have observed differences in apparent compound potency depending on the compound delivery method. To quantitatively measure compound potency differences due to the chosen delivery methods, we conducted a controlled study using a validated biochemical luciferase assay and compared potencies when compounds were delivered in either ARPs (using acoustic dispensed nanoliter spots) or by pin tool. Here we compare hit rates, confirmation rates, false-positive rates, and false-negative rates between the two delivery methods using the luciferase assay. We compared polystyrene (PS) and cyclic olefin copolymer (COC) plates using both delivery methods and examined whether ARPs stored at 4 °C were superior to those stored frozen at -20 °C. The data show that the choice of compound delivery method to the assay has an effect on the apparent IC(50)'s and that pin tool delivery results in more confirmed hits than preplated compounds, resulting in a lower false-negative rate. However, this effect is minimized through the use of COC plates and by obtaining plates in a "just-in-time" mode. Overall, this report provides guidance on using assay-ready compound plates and has affected the way HTS campaigns are using acoustically dispensed plates in our department.