High-Performance CHO-Stabilized Cell Lines for Biopharmaceutical Development

Biological therapeutics and diagnostics (theranostics) are rapidly growing products in the pharmaceutical market. They include various monoclonal antibodies (mAbs), vaccines, hormones, and other proteins, all of which have wide range of applications. Biotherapeutic proteins represent a mainstay of treatment for a multitude of conditions, for example, autoimmune disorders, hematologic disorders, hormonal dysregulation, cancers, infectious diseases and genetic disorders. The technologies behind their production have changed substantially since biotherapeutic proteins were first approved in the 1980s. Most biotherapeutic proteins developed to date have been produced using the mammalian Chinese hamster ovary (CHO) cell lines.

The CHO Expression Platform for Pharmaceutical Recombinant Protein Expression

Chinese hamster ovary (CHO) cells represent the most frequently applied host cell system for industrial manufacturing of recombinant protein therapeutics. CHO cells are capable of producing high quality biologics exhibiting human-like post-translational modifications in gram quantities. Mammalian expression-based systems involve various cell lines of different origins, from hamster (CHO, BHK), human (HEK293, HT-1080, PER.C6, CAP, HKB-11, Huh-7) and mouse (NS0, Sp2/0). However, 70% of biologics, and almost all mAbs, are produced in Chinese hamster ovary (CHO) cells, as the most commonly used and preferred hosts for biopharmaceutical protein production.

Factors Influencing Protein Drug Development

Cell Line Stability

One of the most crucial factors in the development of protein drugs is cell line stability. Cell lines are the factories that produce the therapeutic proteins, and their stability is essential to maintain consistent and high-quality drug manufacturing. If the cell line becomes unstable, it can result in changes in protein expression, leading to inconsistencies in drug potency, efficacy, and safety. Therefore, scientists must choose robust and genetically stable cell lines that can consistently produce the desired protein throughout the drug development and manufacturing process.

Productivity

Productivity is another critical factor in the successful development of protein drugs. High productivity ensures that sufficient quantities of the therapeutic protein can be produced to meet the demands of patients worldwide. Factors that can influence productivity include the choice of cell line, culture conditions, media optimization, and genetic engineering techniques. Maximizing productivity not only ensures an adequate drug supply but also helps to reduce manufacturing costs, making the drug more accessible to patients.

Scalability

Scalability is another important consideration in protein drug development. As the demand for a drug increases, it is crucial to have a manufacturing process that can be scaled up without compromising the quality of the final product. Factors such as the choice of bioreactors, purification methods, and process optimization play a vital role in ensuring scalability.

Advantages of CHO Cell Lines

CHO cells represent the most frequently used mammalian production host for therapeutic proteins due to several key advantages over other cell types such as:

High productivity (0.1–1 g/L in batch and 1–10 g/L in fed-batch cultures).
Exhibiting consistently good growth phenotypes.
Suitable for large-scale industrial culturing.
Easily be adapted to various chemically defined media.
Less susceptible to infections by human viruses.
Be able to perform human compatible glycosylation.
Due to the long period of time that this cell line has been used, there is a degree of familiarity with the CHO platform within development and manufacturing organizations, regulatory agencies, and suppliers (e.g. cell culture media suppliers), which could potentially decrease overall timelines.

CHO Cell Line Optimization

A main strategy for host cell engineering was based on overexpressing genes beneficial for cell proliferation, longevity, stress and apoptosis resistence, protein production and secretion. Numerous studies have demonstrated that transient or stable overexpression of key genes involved in cellular metabolism, protein biosynthesis and glycosylation increased growth rates, productivity, and resulted in better product quality, respectively. Cell viability and culture performance have also been shown to be improved by the overexpression of various transcription factors, anti-apoptotic (e.g. BCL2, XIAP, AVEN, MCL1) and pro-proliferative genes. In addition, advances in proteomics and genetic engineering techniques have also contributed to the rational engineering of host cells.

These changing priorities have contributed to new directions in innovation regarding the CHO expression platform. The focus of industrial cell line development has shifted towards the issues of host cell line stability for ensuring stable long-term production, the use of targeted integration techniques for expression optimization, especially for complex engineered recombinant therapeutics, and the development of selection and screening systems for faster and more effective clone selection.

High-Performance CHO-Stabilized Cell Lines for Biopharmaceutical Development Fig. 1 Current focus areas of innovative research in industrial cell line development. (Tihanyi, et al., 2020)

Production of CHO cell lines for biotherapeutic proteins are expanding, with several products currently approved for clinical use and others in clinical development in different therapeutic areas. In the future, as additional research investments and technological advances that have already led to improvements in the use of the CHO cell line for protein manufacturing continue, the CHO cell line will be further optimized, more sophisticated product collection strategies will be developed, and the CHO cell line may become one of the platforms of choice for protein biotherapeutic production.

References

Tihanyi, B.; et al. Recent advances in CHO cell line development for recombinant protein production. Drug Discov Today Technol. 2020 Dec; 38: 25-34.
Dumont, J.; et al. Human cell lines for biopharmaceutical manufacturing: history, status, and future perspectives. Crit Rev Biotechnol. 2016 Dec;36(6):1110-1122.

* For research use only. Not intended for any clinical use.

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High-Performance CHO-Stabilized Cell Lines for Biopharmaceutical Development

The CHO Expression Platform for Pharmaceutical Recombinant Protein Expression

Factors Influencing Protein Drug Development

Advantages of CHO Cell Lines

CHO Cell Line Optimization

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