Faster. Leaner. Brighter: Transforming cAMP Assays for Improved Speed, Efficiency, and Sensitivity

GPCRs are central to many therapeutic areas, including metabolic, cardiovascular, inflammatory, and neurological diseases. The recent rise of GPCR-targeting incretin therapies for obesity and diabetes – such as GLP-1-based biologics, including the highly successful semaglutide and tirzepatide – has highlighted the need for robust GPCR potency assays. Most of these biologics rely on cAMP-based functional assays for potency and stability lot-release testing, as cAMP, a proximal second messenger of GPCR activation, provides a direct and biologically relevant measure of activity. Conventional cAMP assays performed in adherent cell formats are non-homogenous, often introduce operational complexity, including serum interference, media exchanges with wash steps, extended incubation times, and multi-day workflows. These factors can limit assay robustness, transferability, and GMP readiness. We describe a systematic development of a cAMP bioassay in a streamlined no-wash homogenous, suspension format designed to reduce variability, eliminate serum interference, and compress assay duration to less than three hours without compromising performance. The assay was evaluated using both continuous culture and thaw-and-use cell formats for multiple GPCRs targets to demonstrate versatility and phase-appropriate flexibility. Assay qualification was conducted using a structured, ICH-aligned framework with resulting data demonstrating the suspension assay as fit for purpose for GMP potency testing and lot release of biologic products. This case study provides a practical, end-to-end approach illustrating a systematic approach to functional bioassay development, optimization, and qualification for regulated environments. Contributing Authors: Gaurav Agrawal Eurofins DiscoverX, Fremont, CA, United States