Potency bioassays must evolve alongside product understanding to remain fit-for-purpose across the drug lifecycle. Early development programs frequently rely on binding-based ELISAs as surrogate potency assays; however, as molecules advance toward late-stage clinical development, regulatory expectations increasingly favor bioassays that are reflective of the product’s mechanism of action (MOA).
This presentation describes the strategic transition of an early-phase binding ELISA to a late-phase, regulatory-accepted cell-based reporter gene assay designed to directly reflect biological activity. The reporter gene assay provides a robust, quantitative readout aligned with the known signaling pathway and therapeutic MOA, while offering improved sensitivity, precision, and long-term assay sustainability relative to binding approaches.
To support biological relevance, orthogonal data were generated using primary cell-based functional studies. These data demonstrated concordance between reporter gene activity and native cellular responses, supporting that the reporter assay appropriately captures the intended MOA.
In parallel, a proactive critical reagent management strategy was implemented to ensure assay robustness and lifecycle continuity. Both the engineered assay cell line and key coating reagents were non-commercial materials, requiring early planning for assay development, validation, bridging, and long-term supply. Reagent characterization and comparability strategies were incorporated in the final assay development to mitigate risk as the program progressed into late-phase validation.
This case study highlights a phase-appropriate, risk-based approach to potency assay modernization, demonstrating how orthogonal biology and critical reagent planning can be integrated to support MOA-reflective, regulator-ready bioassays for late-stage development and submission.
