Shawn Barrett

Profiling of glycosylation gene expression in CHO fed-batch cultures in response to glycosylation-enhancing medium components

Characterization of the glycosylation profile of a recombinant protein product is an important part of defining product quality in the bioproduction industry. Development of a protein with desired characteristics would require the capacity to modify and target specific glycosylation patterns as well as an understanding of the implications of changes to these glycosylation profiles. Previous cell culture studies have demonstrated the ability to modulate glycan profiles without negative impact to culture growth and product titer through the addition of glycosylation-enhancing medium components. With new methods, including increased measurement sensitivity and new capabilities in RNA-Seq technology, it is possible to develop a glycosylation gene expression profile for CHO cells. Specific glycosylation genes can then be tracked to ensure that the addition of these compounds will not negatively impact gene expression. Analyses comparing growth and titer, glycan distribution, and transcriptome differences can present us with potential insight into what changes are taking place on a genetic level in the cell in response to changes in medium and culture conditions.

Increasing antibody yield and modulating final product quality using the FreedomTM CHO-STM production platform

Background Cell line development (CLD) is a critical step in the generation of biotherapeutics, but it is still hindered by several pain points, including the lengthy and laborintensive workflow needed to isolate desirable clones, lack of reproducibility, as well as potential protein quality issues. Over the last decade, antibody titers in mammalian cell culture systems in excess of 3 g/L have been achieved through the use of novel media and feeds. However, it is still a challenge to consistently and rapidly create a stable cell line and a cell culture process capable of supporting both high antibody yield and acceptable post-translational modifications while managing the effort required for execution of the workflow. The goal of the study was to develop a robust and reproducible stable cell line workflow to generate scalable high-producing clones in less than 6 months, with industry-standard titers and desirable product quality using minimal effort. Using CHO-STM as the host cell line, we first evaluated if a single medium could be used for the entire CLD workflow, therefore avoiding the issues and complications of changing media during this process. We investigated if a formulation previously shown to increase titer as a production medium could in fact be used for all CLD steps, from transfection to stable pool isolation all the way through to clone productivity, without compromising titers or performance. The same rich production medium was used in limiting dilution cloning and compared to a lean cloning medium prototype. Furthermore, robustness of the workflow was verified by testing multiple molecules. We also explored reducing effort by streamlining all the steps of the workflow. Finally, we assessed top clone scalability and expressed product quality. We tested whether clones chosen only by titers responded well to scale-up and process development in a model bioreactor setting. In addition, product glycosylation from these clones was compared to the same molecule produced in CHO DG44 cells, a well-characterized production platform.