Integrated economic and experimental framework for screening of primary recovery technologies for high cell density CHO cultures

Employing QbD strategies to assess the impact of cell viability and density on the primary recovery of monoclonal antibodies

Quality by Design (QbD) is one of the most important tools for the implementation of Process Analytical Technology (PAT) in biopharmaceutical production. For optimal characterization of a monoclonal antibody (mAb) upstream process a stepwise approach was implemented. The upstream was divided into three process stages, namely inoculum expansion, production, and primary recovery, which were investigated individually. This approach enables analysis of process parameters and associated intermediate quality attributes as well as systematic knowledge transfer to subsequent process steps. Following previous research, this study focuses on the primary recovery of the mAb and thereby marks the final step toward a holistic characterization of the upstream process. Based on gained knowledge during the production process evaluation, the cell viability and density were determined as critical parameters for the primary recovery. Directed cell viability adjustment was achieved using cytotoxic camptothecin in a novel protocol. Additionally, the cell separation method was added to the Design of Experiments (DoE) as a qualitative factor and varied between filtration and centrifugation. To assess the quality attributes after cell separation, the bioactivity of the mAb was analyzed using a cell-based assay and the purity of the supernatant was evaluated by measurement of process related impurities (host cell protein proportion, residual DNA). Multivariate data analysis of the compiled data confirmed the hypothesis that the upstream process has no significant influence on the bioactivity of the mAb. Therefore, process control must be tuned towards high mAb titers and purity after the primary recovery, enabling optimal downstream processing of the product. To minimize amounts of host cell proteins and residual DNA the cell viability should be maintained above 85% and the cell density should be controlled around 15 × 10⁶ cells/ml during the cell removal. Thereby, this study shows the importance of QbD for the characterization of the primary recovery of mAbs and highlights the useful implementation of the stepwise approach over subsequent process stages.

Antibody capture process based on magnetic beads from very high cell density suspension

Cell clarification represents a major challenge for the intensification through very high cell density in the production of biopharmaceuticals such as monoclonal antibodies (mAbs). The present report proposes a solution to this challenge in a streamlined process where cell clarification and mAb capture are performed in a single step using magnetic beads coupled with protein A. Capture of mAb from non-clarified CHO cell suspension showed promising results; however, it has not been demonstrated that it can handle the challenge of very high cell density as observed in intensified fed-batch cultures. The performances of magnetic bead-based mAb capture on non-clarified cell suspension from intensified fed-batch culture were studied. Capture from a culture at density larger than 100 × 10⁶ cells/ml provided an adsorption efficiency of 99% and an overall yield of 93% with a logarithmic host cell protein (HCP) clearance of ≈2-3 and a resulting HCP concentration ≤≈5 ppm. These results show that direct capture from very high cell density cell suspension is possible without prior processing. This technology, which brings significant benefits in terms of operational cost reduction and performance improvements such as low HCP, can be a powerful tool alleviating the challenge of process intensification.

Automation of Dead End Filtration: An Enabler for Continuous Processing of Biotherapeutics

Dead end filtration is a critical unit operation that is used for primary and secondary clarification during manufacturing of both microbial and mammalian cell based biotherapeutics. Dead end filtration is conventionally done in batch mode and requires filter pre-sizing using extensive scouting studies, along with filter over-sizing before deployment to handle potential variability. However, continuous manufacturing processes require consistent use of dead-end filtration over weeks or months, with potential unpredictable variations in feed stream attributes, which is a challenge currently facing the industry. In this work, a dead-end filtration skid is designed for continuous depth filtration, incorporating multiple small-sized filters along with turbidity, and pressure sensors with immediate switching to a fresh filter whenever turbidity or pressure breakthrough above a pre-determined cut-off is detected in real time. The skid has been successfully tested for manufacturing of granulocyte colony stimulating factor from Escherichia coli, human serum albumin from Pichia pastoris, and a monoclonal antibody therapeutic from CHO cells. The proposed skid can be directly applied for any dead-end filtration application with minimal prior scouting studies or sizing calculations for scale-up. It is a useful solution for continuous processing trains where the nature of the feed, such as its turbidity or host cell proteins content, may change over long continuous campaigns, rendering previous sizing calculations inaccurate. The skid also allows significant cost savings by eliminating the sizing safety factor of 1.5-2x which is generally added before filter deployment at manufacturing scale.

Computer-Aided Strategies for Determining the Amino Acid Composition of Medium for Chinese Hamster Ovary Cell-Based Biomanufacturing Platforms

Chinese hamster ovary (CHO) cells are used for the production of the majority of biopharmaceutical drugs, and thus have remained the standard industry host for the past three decades. The amino acid composition of the medium plays a key role in commercial scale biologics manufacturing, as amino acids constitute the building blocks of both endogenous and heterologous proteins, are involved in metabolic and non-metabolic pathways, and can act as main sources of nitrogen and carbon under certain conditions. As biomanufactured proteins become increasingly complex, the adoption of model-based approaches become ever more popular in complementing the challenging task of medium development. The extensively studied amino acid metabolism is exceptionally suitable for such model-driven analyses, and although still limited in practice, the development of these strategies is gaining attention, particularly in this domain. This paper provides a review of recent efforts. We first provide an overview of the widely adopted practice, and move on to describe the model-driven approaches employed for the improvement and optimization of the external amino acid supply in light of cellular amino acid demand. We conclude by proposing the likely prevalent direction the field is heading towards, providing a critical evaluation of the current state and the future challenges and considerations.

Economic Analysis of Batch and Continuous Biopharmaceutical Antibody Production: A Review

PURPOSE

There is a growing interest in continuous biopharmaceutical processing due to the advantages of small footprint, increased productivity, consistent product quality, high process flexibility and robustness, facility cost-effectiveness, and reduced capital and operating cost. To support the decision making of biopharmaceutical manufacturing, comparisons between conventional batch and continuous processing are provided.

METHODS

Various process unit operations in different operating modes are summarized. Software implementation, as well as computational methods used, are analyzed pointing to the advantages and disadvantages that have been highlighted in the literature. Economic analysis methods and their applications in different parts of the processes are also discussed with examples from publications in the last decade.

RESULTS

The results of the comparison between batch and continuous process operation alternatives are discussed. Possible improvements in process design and analysis are recommended. The methods used here do not reflect Lilly's cost structures or economic evaluation methods.

CONCLUSION

This paper provides a review of the work that has been published in the literature on computational process design and economic analysis methods on continuous biopharmaceutical antibody production and its comparison with a conventional batch process.

Progression of continuous downstream processing of monoclonal antibodies: Current trends and challenges

Rapid advances in intensifying upstream processes for biologics production have left downstream processing as a bottleneck in the manufacturing scheme. Biomanufacturers are pursuing continuous downstream process development to increase efficiency and flexibility, reduce footprint and cost of goods, and improve product consistency and quality. Even after successful laboratory trials, the implementation of a continuous process at manufacturing scale is not easy to achieve. This paper reviews specific challenges in converting each downstream unit operation to a continuous mode. Key elements of developing practical strategies for overcoming these challenges are detailed. These include equipment valve complexity, favorable column aspect ratio, protein-A resin selection, quantitative assessment of chromatogram peak size and shape, holistic process characterization approach, and a customized process economic evaluation. Overall, this study provides a comprehensive review of current trends and the path forward for implementing continuous downstream processing at the manufacturing scale.