Application Of Definitive Screening Design (DSD) To The icIEF Assay Development Of Antibodies And Therapeutic Proteins

Post-translational modifications (PTMs) of therapeutic proteins and antibodies have a great impact on their biological function and stability. Charge heterogeneity arising due to PTMs is an important quality attribute in therapeutic  proteins and antibodies. Therefore, understanding charge heterogeneity and its impact on the stability of biologics is of paramount importance. Imaged‐capillary Iso-Electric Focusing (icIEF using iCE280) is a pI-based high‐resolution technique that can
be used to monitor charge heterogeneity of antibodies and proteins caused by PTMs. Here we describe a Design of Experiment (DoE) approach using a Definitive Screening Design (DSD) model to optimize the icIEF development of a glycosylated protein transferrin and an IgG1 monoclonal antibody. Initial scouting experiments were performed to identify critical factors. By applying a DSD model, we were able to efficiently optimize the icIEF assay development for transferrin and IgG1 with five factors in a small number of experiments. Overall, the use of DSD to icIEF method development has minimized the high cost associated to multiple icIEF runs when using One-factor‐at‐a‐time (OFAT) approach, reduced development time, and most importantly, improved robustness of the assay.