Steven J. Meier

Implementing high-temperature short-time media treatment in commercial-scale cell culture manufacturing processes

The production of therapeutic proteins by mammalian cell culture is complex and sets high requirements for process, facility, and equipment design, as well as rigorous regulatory and quality standards. One particular point of concern and significant risk to supply chain is the susceptibility to contamination such as bacteria, fungi, mycoplasma, and viruses. Several technologies have been developed to create barriers for these agents to enter the process, e.g. filtration, UV inactivation, and temperature inactivation. However, if not implemented during development of the manufacturing process, these types of process changes can have significant impact on process performance if not managed appropriately. This article describes the implementation of the high-temperature short-time (HTST) treatment of cell culture media as an additional safety barrier against adventitious agents during the transfer of a large-scale commercial cell culture manufacturing process. The necessary steps and experiments, as well as subsequent results during qualification runs and routine manufacturing, are shown.

Effect of cell culture medium additives on color and acidic charge variants of a monoclonal antibody

This manuscript summarizes the effect of certain cell culture medium additives on antibody drug substance coloration and acidic charge variants. It has been shown previously that B‐vitamins and iron in the cell culture medium could significantly impact color intensity. In this manuscript, we detail the effect of several other cell culture components that have been shown to impact coloration. It is shown that if cystine is used instead of cysteine in the cell culture medium, coloration was reduced. Hydrocortisone has been shown to reduce coloration and boost specific productivity. The effect of a peptone/hydrolysate on coloration was investigated in cell culture experiments, which showed its use can lead to reduced coloration. Mechanisms by which these compounds influence coloration will be briefly discussed. Since it has been previously shown that antibody oxidation could potentially lead to coloration, the current effort was focused on screening for specific antioxidant additives to the culture medium to reduce coloration. An in‐vitro incubation model was used to screen antioxidant compounds, several of which were found to significantly reduce antibody color, while some led to significantly increased color. Hypotaurine and carboxymethylcysteine, which had the most significant color reducing effect in the incubation study, were further tested in small‐scale bioreactor cell culture experiments. These studies demonstrated that these compounds lead to reduced coloration in cell culture without affecting cell growth and titer. Hypotaurine, hydrocortisone, peptone, and cystine were also shown to reduce the acidic charge variant levels, which was previously shown to correlate with color.

Platform Validation of Dissolved Oxygen Ranges for Cell Culture Processes

Process understanding gained through use of a platform process for multiple, similar, products can be leveraged to further streamline the development, characterization and validation of new processes based on the platform. Genentech has developed and commercialized several therapeutic monoclonal antibody (mAb) products using Chinese Hamster Ovary (CHO) cell cultures in a standardized fed-batch culture. A strategy for implementing platform validation of dissolved oxygen ranges has been developed for new processes when they are sufficiently similar to the platform process. A platform validation data set was developed from characterization studies of several antibody processes demonstrating that a consistent set of dissolved oxygen ranges do not significantly impact cell culture metrics or mAb quality attributes. These ranges are applicable to new products when the cell culture processes are sufficiently similar to the platform process, and the mAb quality attributes are included in the platform validation data set.