Optimizing clarification processes in biopharmaceutical manufacturing through quality by design: Strategies, implications, and future prospects.

Biopharmaceutical manufacturing processes in which the product of interest is extracellularly expressed typically employ a clarification step following cell culture or fermentation. During clarification, crude cell culture fluid or fermentation broth is processed to remove insoluble solids, cells, debris, and other particulates, with the extracellular product of interest retained in the filtrate. Soluble impurities, such as host cell proteins (HCPs), may also be partially removed. Historically, the clarification process has been considered a limited contributor to Critical Quality Attributes (CQA). As part of upstream harvest, many biopharmaceutical companies have not fully developed quality control strategies from process development to manufacturing, complicating the application of Quality by Design (QbD) principles to this step. However, advancements in upstream and downstream processing (DSP) technologies, alongside increasing cell counts and titers, necessitate reevaluating clarification as a critical process contributing to drug product quality. Conducting controlled studies to define the process and establish parameters using QbD principles can improve control over process impurities and facilitate a logical quality control strategy, integrating quality into the process. This article describes a systematic approach to QbD for a harvest clarification process where the product of interest is extracellular and impurities are removed in the filtrate post-clarification. It highlights methods for optimizing the clarification unit operation using QbD principles, ensuring better process efficiency, and product quality.