Old to new ligand-binding assay method modifications.

This article aims to address approaches to ensuring method changes for regulated ligand-binding assays of biologics drugs from old to newer formats and technology are properly understood, characterized and validated to meet current industry expectations and regulatory requirements. Sections in the chapter will include descriptions of different formats of ligand-binding assays, reasons that may drive updating of methods and procedures for qualifying method changes for immunoassays that are designed to support PK and immunogenicity analyses for clinical and nonclinical applications. Case studies from the authors' experience, as well as literature references will be provided as examples of challenges, as well as providing guidance of when and how to provide smooth transitions of older methods to newer, more robust or sensitive methods as reagents or technology are available.