A Cell-Based Reporter Gene Assay for TNF-α Neutralization: Analytical Qualification and Application to Adalimumab and Its Biosimilars

Purpose: To qualify a mechanism‑of‑action (MoA)–reflective reporter gene assay (RGA) for measuring the biological activity of adalimumab (Humira) and its biosimilars, supporting assessment of product quality, comparability, and functional consistency across the product lifecycle. Methods: The assay evaluates TNF‑α neutralization by monitoring inhibition of NF‑κB signaling in a reporter system. Qualification focused on key performance attributes, including system suitability, working range, reproducibility, and intermediate precision, to confirm fitness for routine use. Results: The RGA yielded MoA‑relevant readouts of NF‑κB pathway inhibition in the presence of adalimumab, demonstrating strong system suitability, a broad working range, high reproducibility, and consistent intermediate precision across repeated measures. These characteristics support reliable measurement of functional activity among adalimumab products and biosimilars. Conclusions: The qualified, MoA‑reflective RGA provides a robust tool for lifecycle management of adalimumab products, enabling quality assessment, comparability exercises, and monitoring of functional consistency across indications in which adalimumab is broadly used (e.g., rheumatoid arthritis, Crohn’s disease, psoriasis).