Productivity improvement and charge variant modulation for intensified cell culture processes by adding a carboxypeptidase B (CpB) treatment step

Abstract The goal of cell culture process intensification is to improve productivity while maintaining acceptable quality attributes. In this report, four processes, namely a conventional manufacturing Process A, and processes intensified by enriched N‐1 seed (Process B), by perfusion N‐1 seed (Process C), and by perfusion production (Process D) were developed for the production of a monoclonal antibody. The three intensified processes substantially improved productivity, however, the product either failed to meet the specification for charge variant species (main peak) for Process D or the production process required early harvest to meet the specification for charge variant species, Day 10 or Day 6 for Processes B and C, respectively. The lower main peak for the intensified processes was due to higher basic species resulting from higher C‐terminal lysine. To resolve this product quality issue, we developed an enzyme treatment method by introducing carboxypeptidase B (CpB) to clip the C‐terminal lysine, leading to significantly increased main peak and an acceptable and more homogenous product quality for all the intensified processes. Additionally, Processes B and C with CpB treatment extended bioreactor durations to Day 14 increasing titer by 38% and 108%, respectively. This simple yet effective enzyme treatment strategy could be applicable to other processes that have similar product quality issues.