Fluctuations in dissolved oxygen concentration during a CHO cell culture process affects monoclonal antibody productivity and the sulfhydryl‐drug conjugation process

Abstract

During a CHO cell culture production process, important parameters are generally well controlled by a feedback mechanism (PID loop) in order to ensure consistency in both productivity and product quality. These parameters typically include pH, dissolved oxygen (DO), and temperature. While most of these parameters are very well controlled within their specific deadband, stable DO control can be challenging. Oscillations in DO concentration are not uncommon and these fluctuations can be exacerbated with an efficient mass transfer aeration strategy. In this study, where an IgG producing cell line was used, we observed increased lactate accumulation accompanied by decreased titer production in lots with fluctuations in DO concentration (DO ) when compared with lots with stable DO control (DO ). We demonstrate that DO had a greater impact on performance with respect to titer production and lactate accumulation than DO setpoint. Furthermore, we report that estimated specific oxygen uptake rates (qOURs) were lower in DO lots when compared with DO lots. We also report that purified mAb sourced from DO lots yielded lower drug-to-antibody ratio (DAR) after the sulfhydryl-targeted maleimide conjugation process when equivalent reducing agent was used. All mAb lots were within the analytical specifications for release, though a slight increase in measureable trisulfides were observed in DO mAb lots. DO control aimed to minimize fluctuations around DO setpoint was essential for us to produce consistent DAR without adjusting the conjugation process. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018.

Development of a miniature bioreactor model to study the impact of pH and DOT fluctuations on CHO cell culture performance as a tool to understanding heterogeneity effects at large‐scale

“…A previous study has found that fluctuating DOT in a hybridoma cell line caused higher lactate yield 37 . These results also match other studies where a cell line producing a conjugated IgG2 was shown to have decreased product titre, increased lactate accumulation as well as lower drug‐to‐antibody (DAR) ratio after being exposed to DOT fluctuations 50 . Other recent papers have shown that reducing the DOT, in order to mimic the DOT levels cells are expected to be exposed to at large‐scale, caused an increase in peak lactate and reduced the lactate consumption rates 51 .…”

“…37 These results also match other studies where a cell line producing a conjugated IgG2 was shown to have decreased product titre, increased lactate accumulation as well as lower drug-to-antibody (DAR) ratio after being exposed to DOT fluctuations. 50 Other recent papers have shown that reducing the DOT, in order to mimic the DOT levels cells are expected to be exposed to at large-scale, caused an increase in peak lactate and reduced the lactate consumption rates. 51 They also showed that lower DOT cultures matched the profiles of 5000 L cultures and this negative impact was attributed to DOT heterogeneity, or more specifically hypoxic conditions.…”

Enhancing and stabilizing monoclonal antibody production by Chinese hamster ovary (CHO) cells with optimized perfusion culture strategies

“…Consequently, a consistent and steady culture condition with metabolized by-product rapidly removal results in a stable and uniform product of high quality under perfusion culture process (Schwarz et al, 2020;Yin et al, 2021). In general, culture environmental parameters including temperature, osmolality, levels of dissolved oxygen (DO), CO 2 partial pressure (pCO 2 ), and perfusion rate could affect the performance of recombinant protein production in CHO cells (Sou et al, 2017;Wang Q. et al, 2018b;Hippach et al, 2018;Madabhushi et al, 2021). Some studies found that the specific productivity of recombinant CHO cell lines and the product quality can be improved by lowering the culture temperature (Tait et al, 2013;Wang K. et al, 2018a).…”

Improved control strategies for the environment within cell culture bioreactors

“…Consistent active pharmaceutical production is a major concern to the biopharmaceutical industry, which requires precise control of all manufacturing process aspects. Factors influencing the quality of CHO based therapeutic proteins are discussed by Ha et al (2021). They categorise the factors into three groupings (culture environment, chemical additives and host cell proteins) and review the literature relating to each.…”