Feasibility of implementing cell-based pathway reporter assays in early high-throughput screening assay cascades for antibody drug discovery.

Implementing functional cell-based screens in early antibody discovery has become increasingly important to select antibodies with the desired profile. However, this is limited by assay tolerance to crude antibody preparations and assay sensitivity. The current study aims to address this challenge and identify routes forward. Two common types of high-throughput screening (HTS) antibody sample, derived from either phage display or hybridoma techniques, have been screened across a wide range of CellSensor beta-lactamase reporter assays in a variety of cell backgrounds to more extensively characterize assay tolerance. Pathway-, sample-, and cell background-specific effects were observed. Reporter assays for agonism were less affected by crude antibody preparations, with 8 of 21 sample tolerant, and the potential to implement an additional 8 assays by choosing the best-tolerated sample type. Antagonist mode assays exhibited more complexity, with potentiating as well as inhibitory effects. However, 5 of 24 antagonist assays were fully tolerant, with the potential to implement an additional 11 assays. Different subsets of assays were affected in agonist versus antagonist mode, and hybridoma sample sets were better tolerated overall. The study clearly demonstrates the potential to use cell-based reporter assays in biologics HTS, particularly if the method of antibody production is considered in the context of the required assay mode (agonist/antagonist).