Exploring the limits of conventional small-scale CHO fed-batch for accelerated on demand monoclonal antibody production

Establishment of a high-throughput scale-down clone screening platform for intensified fed-batch culture of CHO cells

PURPOSE

To develop a scale-down clone screening platform for the intensified fed-batch (IFB) process to allow efficient identification of high expressing clones fitting the IFB culture strategy in bioreactor.

RESULTS

Three monoclonal antibodies (mAbs) were used in the development and validation of the IFB specific clone screening platform for CHO cells. The IFB platform significantly improved titer levels, achieving an average titer of 8 g/L and the highest titer of 9.6 g/L. With similar cell viability, lactate profile and titer levels, both the spin tube model and the AMBR250@ bioreactor system were effective in screening clones suitable for IFB process. The addition of aurintricarboxylic acid (ATA) and uridine in the process optimization led to a further increase in expression levels in both systems, achieving the highest titer of 12.2 g/L.

CONCLUSION

This IFB-process specific clone screening serves as an alternative platform for industry application that can increase the effectiveness and efficiency of screening high-expressing CHO cell lines for IFB production.

Bioprocess biomarker identification and diagnosis for industrial mAb production based on metabolic profiling and multivariate data analysis

Monoclonal antibody (mAb) production is a complex bioprocess influenced by various cellular and metabolic factors. Understanding these interactions is critical for optimizing manufacturing and improving yields. In this study, we proposed a diagnostic and identification strategy using quantitative proton nuclear magnetic resonance (1H qNMR) technology-based pharmaceutical process-omics to analyze bioprocess variability and unveil significant metabolites affecting cell growth and yield during industrial mAb manufacturing. First, batch level model (BLM) and orthogonal partial least squares-discriminant analysis (OPLS-DA) identified glucose and lactate as primary contributors to culture run variability. Maintaining an optimal glucose set point was crucial for high-yield runs. Second, a partial least squares (PLS) regression model was established, which revealed viable cell density (VCD), along with glutamine, maltose, tyrosine, citrate, methionine, and lactate, as critical variables impacting mAb yield. Finally, hierarchical clustering analysis (HCA) highlighted one-carbon metabolism metabolites, such as choline, pyroglutamate, and formate, as closely associated with VCD. These findings provide a foundation for future bioprocess optimization through cell line engineering and media formulation adjustments, ultimately enhancing mAb production efficiency.

Polyethylene glycol precipitation: fundamentals and recent advances

Downstream processing continues to face significant bottlenecks due to current purification technologies and improvements in upstream. Chromatography systems have been the primary method for purification due to their high yields and purities. However, the use of high-titer-producing strains has highlighted limitations in chromatographic steps, including mass transfer limitations, low capacity, and scalability issues. These challenges, combined with the growing interest in fully continuous manufacturing processes, have led to a widespread interest in alternative to affinity chromatography systems. Polyethylene glycol precipitation has been demonstrated to be a powerful, flexible, easily scalable, and titer-independent methodology for purifying therapeutic proteins such as monoclonal antibodies, achieving yields and purities comparable to chromatography systems. Furthermore, it also holds great potential for simplifying the current purification processes of new modalities and overcome current bottlenecks in downstream processing. Herein, we discuss the latest advances in polyethylene glycol precipitation as a purification technology and explore its future research directions and potential applications.

Application of Pseudoinfectious Viruses in Transient Gene Expression in Mammalian Cells: Combining Efficient Expression with Regulatory Compliance

Transient gene expression (TGE) is commonly employed for protein production, but its reliance on plasmid transfection makes it challenging to scale up. In this paper, an alternative TGE method is presented, utilizing pseudoinfectious alphavirus as an expression vector. Pseudoinfectious viruses (PIV) and a replicable helper construct were derived from the genome of the Venezuelan equine encephalitis virus. The PIV carries a mutant capsid protein that prevents packaging into infectious particles, while the replicable helper encodes a wild-type capsid protein but lacks other viral structural proteins. Although PIV and the helper cannot independently spread infection, their combination results in increased titers in cell cultures, enabling easier scale-up of producing cultures. The PIV-driven production of a model protein outperforms that of alphavirus replicon vectors or simple plasmid vectors. Another described feature of the expression system is the modification to immobilized metal affinity chromatography (IMAC), allowing purification of His-tagged recombinant proteins from a conditioned medium in the presence of substances that can strip metal from the IMAC columns. The PIV-based expression system allows for the production of milligram quantities of recombinant proteins in static cultures, without the need for complex equipment such as bioreactors, and complies with regulatory requirements due to its distinction from common recombinant viruses.

Enhancing monoclonal antibody production efficiency using CHO-MK cells and specific media in a conventional fed-batch culture

Chinese hamster ovary (CHO) cell lines, derived as subclones from the original CHO cell line, are widely used hosts for current biopharmaceutical productions. Recently, a highly proliferative host cell line, CHO-MK, was established from the Chinese hamster ovary tissue. In this study, we assessed the fundamental culture characteristics and capabilities of CHO-MK cells for monoclonal antibody (mAb) production using specified chemically defined media. To achieve this, we established fed-batch cultures of model CHO-MK cells in shake flasks and ambr15 and 2 L bioreactors under various conditions. The mAb-producing CHO-MK cell line A produced 12.6 g/L of antibody within 7 days in the fed-batch culture using a 2 L bioreactor, with a seeding density of 1 × 106 cells/mL. This performance corresponded to a space-time yield of 1.80 g/L/day, representing a productivity level that could be challengingly attained in fed-batch cultures using conventional CHO cells. In addition, when we subjected six different mAb-producing CHO-MK cell lines to fed-batch culture in the ambr15 bioreactor for 7 days, the antibody production ranged between 5.1 and 10.8 g/L, confirming that combining CHO-MK cells and specified media leads to enhanced versatility. These discoveries underscore that CHO-MK cells combined with specified media might represent a next-generation production platform, which could potentially respond to an increasing demand for antibody drugs, reducing production costs, and shortening antibody drug development times. This study is expected to serve as a benchmark for future production process development using CHO-MK cells.

Optimum blue light exposure: a means to increase cell-specific productivity in Chinese hamster ovary cells

Research for biopharmaceutical production processes with mammalian cells steadily aims to enhance the cell-specific productivity as a means for optimizing total productivities of bioreactors. Whereas current technologies such as pH, temperature, and osmolality shift require modifications of the cultivation medium, the use of optogenetic switches in recombinant producer cells might be a promising contact-free alternative. However, the proper application of optogenetically engineered cells requires a detailed understanding of basic cellular responses of cells that do not yet contain the optogenetic switches. The knowhow of ideal light exposure to enable the optimum use of related approaches is missing so far. Consequently, the current study set out to find optimum conditions for IgG1 producing Chinese hamster ovary (CHO) cells which were exposed to blue LED light. Growth characteristics, cell-specific productivity using enzyme-linked immunosorbent assay, as well as cell cycle distribution using flow cytometry were analyzed. Whereas too harsh light exposure causes detrimental growth effects that could be compensated with antioxidants, a surprising boost of cell-specific productivity by 57% occurred at optimum high light doses. The increase coincided with an increased number of cells in the G1 phase of the cell cycle after 72 h of illumination. The results present a promising new approach to boost biopharmaceutical productivity of mammalian cells simply by proper light exposure without any further optogenetic engineering. KEY POINTS: • Blue LED light hinders growth in CHO DP-12 cells • Antioxidants protect to a certain degree from blue light effects • Illumination with blue LED light raises cell-specific productivity.

Impact of fed-batch process intensification on the productivity and product quality of two CHO cell lines expressing unique novel molecular format proteins

While monospecific antibodies have long been the foundational offering of protein therapeutics, recent advancements in antibody engineering have allowed for the development of far more complex antibody structures. Novel molecular format (NMF) proteins, such as bispecific antibodies (BsAbs), are structures capable of multispecific binding, allowing for expanded therapeutic functionality. As demand for NMF proteins continues to rise, biomanufacturers face the challenge of increasing bioreactor process productivity while simultaneously maintaining consistent product quality. This challenge is exacerbated when producing structurally complex proteins with asymmetric modalities, as seen in NMFs. In this study, the impact of a high inoculation density (HID) fed-batch process on the productivity and product quality attributes of two CHO cell lines expressing unique NMFs, a monospecific antibody with an Fc-fusion protein and a bispecific antibody, compared to low inoculation density (LID) platform fed-batch processes was evaluated. It was observed that an intensified platform fed-batch process increased product concentrations by 33 and 109% for the two uniquely structured complex proteins in a shorter culture duration while maintaining similar product quality attributes to traditional fed-batch processes.

Treatment to cure: advancing AAV gene therapy manufacture

Advanced therapy medicinal products are a reality. With the opportunity to treat patients at the genetic level, the pharmaceutical industry has extended the treatment paradigm to innovative and potentially curative approaches. Gene therapy modifies or manipulates the expression of a gene, through gene repair, replacement, or modification, to alter living cells for therapeutic use, requiring delivery mechanisms through viral vectors. Market analysis not only demonstrates that the gene therapy sector has strong growth potential, but also indicates infancy with the number of currently approved products. Within gene therapy, adeno-associated viruses (AAVs) have high prominence, allowing for the targeted delivery of a transgene for therapeutic effect. To be able to realise the full potential of AAV-based gene therapy, focus has shifted to the ability to manufacture and deliver high titre, high quality, and efficacious product. However, manufacturing is not simple, with multiple complex challenges ranging from starting material generation, ensuring cellular production of high titres of viral vectors, to purification, where not all AAV particles contain the intended genetic payload. As an industry, we must learn from established manufacturing processes, such as for monoclonal antibodies (mAbs), to deliver rapidly scalable, robust, and cost-effective platform solutions that can be truly multiproduct, while working hand-in-hand with regulatory agencies. Additionally future innovation remains important and there are several opportunities for disruptive and further advanced manufacturing approaches. With a true end in mind approach, can we turn the tide from treatment to cure? Teaser: The gene therapy market shows considerable opportunity for growth, with the potential to change the treatment paradigm toward curative approaches. However, manufacture remains a challenge. Focussing on AAV, we look what is required for these products to be delivered to patients.

Progress in fed-batch culture for recombinant protein production in CHO cells

Nearly 80% of the approved human therapeutic antibodies are produced by Chinese Hamster Ovary (CHO) cells. To achieve better cell growth and high-yield recombinant protein, fed-batch culture is typically used for recombinant protein production in CHO cells. According to the demand of nutrients consumption, feed medium containing multiple components in cell culture can affect the characteristics of cell growth and improve the yield and quality of recombinant protein. Fed-batch optimization should have a connection with comprehensive factors such as culture environmental parameters, feed composition, and feeding strategy. At present, process intensification (PI) is explored to maintain production flexible and meet forthcoming demands of biotherapeutics process. Here, CHO cell culture, feed composition in fed-batch culture, fed-batch culture environmental parameters, feeding strategies, metabolic byproducts in fed-batch culture, chemostat cultivation, and the intensified fed-batch are reviewed. KEY POINTS: • Fed-batch culture in CHO cells is reviewed. • Fed-batch has become a common technology for recombinant protein production. • Fed batch culture promotes recombinant protein production in CHO cells.