(233ay) The Utilization of Amino Acid Consumption Rate Assessment As a Tool for CHO Clonal Stability Evaluation.  

<span">CHO cells are commonly utilized for the production of therapeutics.To ensure product reproducibility and quality, assessment of clonal stability is important for both regulatory and economic reasons. We are continuously striving to improve methods for assessing CHO cell bank stability. One new tool we are currently evaluating is specific amino acid (AA) consumption rate and how it relates to CHO clonal stability. By calculating AA consumption data generated at various PDL ages we are able to observe trends between the AA consumption rates per cell per day of multiple clones throughout the process. Clones which exhibit increased AA consumption as they age can potentially result in total depletion of one or more amino acids within the culture. As a result false conclusions may be drawn that a clone is unstable when in reality the feed strategy may need to be further assessed in order to maintain a high level of productivity.

<span"> For this experiment we ran selected clones in an AMBR250 using a platform process. Time point samples were analyzed for AA content using a Hitachi L-8900 amino acid analyzer and titers were analyzed using RP-HPLC. These data were used to calculate specific productivity (Q_P) and specific amino acid consumption (Q_AA). The data presented shows that of three high producing clones, C10 exhibits increased AA consumption and decreased titer as the PDL increases. C81 AA consumption and titer production remain constant, while C88 AA consumption levels decrease but titer remains constant across PDL ages. Based on this information, C81 and C88 are better candidates for establishment of stable master and working cell bank. It also points to the potential to prevent the loss of Q_Pin C10 by exploring additional feeds for late PDL cells.