Full Fat QbD
For companies that want to perform a full QbD for biologics production, then according to Dr. Menezes they have to do an end-to-end analysis, which involves analyzing the raw material of their media batches and their cell banks, as well as the upstream and downstream bioprocess conditions, and doing this during development and at specific points in time during routine manufacturing (the product lifecycle). This can help predict the impact of defined sources of variability on their product quality and help improve consistency through increased process knowledge.
“QbD is helping us to realize that you have to take a systems’ view and that the current QbD formulation is suboptimal, if as expected the different systems’ components interact with each other,” Dr. Menezes says. “The current QbD formulation is not equivalent to the design-for-six-sigma approach that can really ensure an overall optimal solution in terms of product consistency over its lifecycle.”
This concept that putting together optimized stages may result in an unknown impact on CQA was demonstrated by Fai Poon, Ph.D., director of cell culture at Hisun Pharmaceuticals. “We develop biosimilars and in 2011 we wanted to optimize the titer of our first biosimilar so we worked with different feeds and found we could improve our titer by six fold,” Dr. Poon explains. “But by optimizing the culture media supplement we decreased the sialic acid content of our media by 20%, and this meant the antibody yield decreased because it lead to low yield purification so it had a major impact on the CQA of our biosimilar product.”
To overcome this problem, Dr. Poon and his team looked carefully at the media components with the aim of improving the sialic acid content by 20% while still retaining their titer increase. They analyze the components of four feeds all based on the commercial feeds: HyClone™ Cell Boost 5™ Supplement; Irvine Scientific BalanCD™ CHO Feed 3; Life Technologies CD EfficientFeed™ C AGT™ Nutrient Supplement and SAFC® EX-CELL® CD Hydrolysate Fusion. They then performed a Principle Component Analysis (PCA) using SIMCA MVDA software, and this identified six significant components that are critical to the sialic acid content. They then added the six components to their media and performed small-scale spin tube experiments with their antibody clones to determine which components would increase titer and sialic acid content. Two components increased sialic acid content by greater than 20%, and these were then used in scale-up work at 2 L, 30 L, and 1,500 L to show that the sialic acid and titer increases were reproducible at large scale. Dr. Poon concludes: “Titer improvement can sometimes lead to changes in CQA. This is where MVDA is useful to pinpoint which media components are important and is a potentially important media development tool.”