The concept of quality by design (QbD), although not new, has presented implementation opportunities and challenges to both the bioprocessing industry and regulators (1,2,3,4). Tools such as design of experiments (DoE), cause and effect analysis, and multivariate analysis provide for systematic risk assessment and help identify critical quality attributes (CQAs) and critical process parameters (5,6,7). QbD is intended to ensure that manufacturing processes make products that meet predefined quality parameters. Key elements in defining such parameters (quality profile)…