Improvements in cell culture media and supplementation have enabled significant advancements in bioproduction titers. But optimization to meet the specific needs of individual production cell lines is key to achieving desired production and protein quality, especially for biosimilars. Not only is it desirable to achieve cost-effective levels of production, but quality characteristics also are essential — and for biosimilars must closely resemble those of the originator molecules.
Fully chemically defined (CD) media formulations are desirable for their presumed consistency and risk reduction, such formulations may or may not meet production or quality requirements. Depending on nutritional and culture requirements of a cell line and process, both CD supplements and protein hydrolysates have been shown to provide necessary supplementation for desired production and protein quality. In a webinar on 2 September 2015, Dr. James Brooks (R&D manager at BD) illustrated how his company has used those to address production and protein quality. Below is a summary of his presentation. Find more detail and the full slide presentation online.
Dr. Brooks’s Presentation
Although chemically defined media formulations are still ultimately desired, interest has been rekindled in peptone supplements, particularly in biosimilar development. CD media don’t always deliver desired titers or protein quality. Both peptones and CD supplements are viable options, but it is important to understand what each brings to the cell culture process.
With a wide range of components, peptones are primarily nutritional buffers. They also serve as buffers from toxic agents; have been shown to affect cell cycle and suppress apoptosis; and enhance cell density, viability, and/or titer.
CD supplements also enhance density, viability, and titer, but typically serve only as culture stimulators. With fully defined components, these supplements are more limited in composition than peptones.
Dr. Brooks offered two brief case studies involving peptones and CD supplements. The first involved a customer developing a biosimilar monoclonal antibody and needing to match protein quality; the second involved a customer wanting to increase production.
Quality in the first case was defined by charge variants of the originator molecule. BD developed both multiple CD and peptone-containing media for the first customer, then analyzed those for growth and production initially. Lead formulations were used for charge-variant profile analysis. Along with growth and productivity targets, the overall desire was to match the originator profile.
In this case, both CD and peptone- containing media were shown to provide correct profiles. But for the cell line and process of interest, the peptone-containing media met the growth and production targets.
The second customer wanted to increase production at least 100% in a short time frame. BD’s approach was to run a parallel media screen of its proprietary CD and peptone media libraries with the client’s cell line. The production goal was achieved quickly with the peptone-supplemented medium; the CD media showed some improvement but required optimization to meet and exceed the production target. This process took 10–12 weeks.
Questions and Answers
Q: How do we find out what is driving our cell culture process and identify which supplements will improve it?
A: Multiple components affect your process, not only media and supplements, but also cell line and process parameters. Each cell line has unique requirements (nutritional and otherwise). I recommend comprehensive spent-media analysis. With those results, you can move forward. There is a lot of information available on peptones. BD has extensively analyzed its peptones.
Q: What about lot-to-lot variability?
A: It is important to recognize that peptones are not fully chemically defined. But BD takes many steps to control peptone production.
Q: When is it best to supplement chemically defined processes with hydrolysates?
A: Time is a major consideration. If a rapid solution is needed, hydrolysates often can provide that. Otherwise, it’s important to know what’s driving your cells and then to make sure to match the appropriate supplement. We’re seeing more in the industry that CD supplements aren’t giving the best titers and may compromise protein quality. Then it’s time to consider looking at hydrolysate options, especially animal- free hydrolysates.
Q: How about feeding time effects?
A: Variation in feeding regimen can enhance and change protein production titers. It can also have effects on protein quality. That’s another aspect of a cell culture process that needs to be understood.
Watch the full presentation on-demand.