Identification of performance drivers for an antibody producing CHO-S cell line culture in the Allegro™ XRS 20 single-use bioreactor utilizing historical data
© Sanderson et al. 2015
Published: 14 December 2015
During the development of processes for high production CHO fed batch cultures, there is usually insufficient time for thorough process optimization. Once defined, these processes often have ranges rather than specific values for many parameters, resulting in minor variations in the runs. These small process variations, combined with resultant differences in performance, can be used to further optimize the process. Over the course of one year, eleven 20 L fed batch cultures of an antibody producing CHO-S cell line were generated in the Allegro XRS 20 bioreactor. In addition to normal minor process variation, small process changes occurred due to method optimization efforts or culture timing requirements. An analysis of the combined historical data was undertaken to better understand the specific culture performance drivers, leading to further improvement in culture outputs, specifically final antibody concentration and maximum viable cell density (VCD).
Materials and methods
Allegro XRS 20 fed batch process conditions.
Industrial suspension CHO producing mAb biosimilar
0.3 - 0.5 × 106 viable cells/mL in 5 L CDFortiCHO (Life Technologies)
Expand at 2 - 4 viable cells/mL to 14 L
CD EfficientFeed C (EFC, Life Technologies), initial feed at 8.0 ± 2.0 M viable cells.mL
Additional bolus feeds every 24 hours for a total of 5 feeds (1.2 L/feed)
Glucose kept above >2 f/L (bolus target >5f/L)
Added as needed
DO set point:
O2 control at 40%
pH set point:
7.2 ± 0.05
5 L: 25 RPM, 5°X, 5°Y; 14 - 20: 30 or 35 RPM, 15°X, 5°Y
The Allegro XRS 20 single use bioreactor generated highly reproducible cell culture performance for this CHO mAb production process, allowing for a holistic analysis of relatively small changes in process conditions and the resultant differences in performance. In three separate paired runs, the first being identical and the second two differing by 30 vs. 35 rpm agitation, the parallel culture results are extremely similar, highlighting the overall reproducibility of the system. This bioreactor reproducibility makes it possible to review historical data to identify performance drivers that were missed in limited optimization testing done at smaller scale prior to the 20 L runs. The VCD at the time of the first feed addition proved very important for overall mAb yield. Although a relationship was not surprising, the optimal range was tighter than previously believed. Nutrient feed timing can be easily modified as there is very good understanding of the growth curves for this CHO-S cell line in the Allegro XRS 20 bioreactor. This opportunistic analysis of historical data has some limitations compared to experiments designed specifically to look at process controls. Despite these limitations the value is clear, it can provide additional process understanding without additional experimentation. Thus, this approach could further understanding of performance drivers for any production run, and can be expanded to other cell line / media combinations in any culture system having sufficient reproducibility to distinguish relatively small changes in process conditions and the resultant small but significant differences in performance.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.