Implementing Quality by Design (QbD) in Biomanufacturing

Historically, the biopharmaceutical industry relied heavily on empirical "quality by testing" (QbT) approaches, where the quality of the final product was verified at the end of the manufacturing process. However, the modern paradigm has shifted towards Quality by Design (QbD). QbD is a systematic approach to development that begins with predefined objectives and emphasizes product and process understanding and process control, based on sound science and quality risk management.

Defining CQAs and CPPs

Implementing QbD starts with defining the Target Product Profile (TPP) and identifying Critical Quality Attributes (CQAs)—the physical, chemical, biological, or microbiological properties that must be within an appropriate limit to ensure desired product quality. Once CQAs are established, the next step is determining the Critical Process Parameters (CPPs) that impact them.

The Design Space in Downstream Processing

In downstream processing, this means rigorously characterizing how variables like resin lot variability, load density, buffer conductivity, and pH affect the clearance of host cell proteins, DNA, and aggregates. By mapping out this Design Space—the multidimensional combination of input variables and process parameters that provide assurance of quality—manufacturers gain incredible flexibility. Operating within the Design Space is not considered a change, meaning continuous improvement and process adjustments can occur without requiring lengthy regulatory re-approvals.