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As Chief Technical Lead and a Head of R&D at Samsung Biologics America, Soojin Han examines the challenges, tactics, and best partnering practices in cell line development (CLD). She emphasises the need to ensure a balance between shortening commercial CLD timelines, increasing efficiencies and maintaining product quality.
Advances in treatments for oncological, autoimmune, and infectious diseases have driven the need for increasingly sophisticated commercial-scale biologics development and manufacturing capabilities.This includes biopharma’s growing demand for cell line development (CLD) services and the foundation needed to launch vaccine, recombinant protein, and bi-specific and monoclonal antibody (mAb) drug programmes. Improvements in CLD processes have the potential to increase speed to market as they can accelerate Investigational New Drug (IND) applications with the FDA and streamline approvals.The market for CLD services is expected to grow from 2020 to 2028 to reach a value of $1.7 billion1.This predicted growth is fuelled by technological advancements in cell line engineering, screening techniques and process methodologies. However, facilitating CLD improvements and navigating the complexities surrounding development of stable cell lines, and managing contamination risk is not simple. Many developers seek expert partners to traverse this critical first step in biopharmaceutical development.
With more patients relying on drugs that are biological in nature, the need for shortened CLD timelines is a pressing challenge in biopharma development and manufacturing. Despite advances in the capabilities of biopharma’s contract development and manufacturing organisation (CDMO) partners, there are areas requiring improvement to achieve accelerated CLD processes. Even for well-established, automated platforms, it can take up to three months to complete CLD on the road to (IND) filing. This is largely because of the manual and time-consuming processes that CLD relies on. Eg, detecting gene integration using a selection marker will often require extensive screening of thousands of clones. By developing new production cell lines to accommodate fast-track approaches and optimising the protein expression platform, it is possible to overcome these challenges and deliver important drugs to patients faster. However, achieving shortened timelines isn’t possible without technical innovation and operational excellence to meet the demand for development efficiency.
Overcoming the challenge
Solving the challenge surrounding CLD to speed-up IND filing and drug delivery to patients in shortened timeframes relies on:
Technical and capacity innovation is important to meet the challenges of developing complex therapeutic molecules. Implementing innovations in the CLD process should be carried out aiming to increase specific productivity (particularly for those that are difficult-to-express) by improving cell growth and viability for commercialisation. Both technical and capacity capabilities should be continuously improved to accelerate developability.
- Speed and quality
Although innovations in technologies and capacities could improve CLD productivity, a balance must be found between speed and product quality. The requirements of high titer, favourable product quality, and the maintenance of regulatory compliance should not be put aside in favour of speed. It is important to remember: if the quality of the cell lines is compromised, there will be no IND approval. Manufacturers must consider how technologies and optimisation of processes could be implemented to facilitate shortened timelines and high product quality. The introduction of new screening technologies, optimising cell culture conditions, and the development of new cell lines could all be used to help maximise CLD output and fast-track timelines.
- A robust CLD strategy
Achieving a robust CLD programme built around the implemented innovations and with the aim to balance process speed and product quality can allow manufacturers to start future programmes more effectively. A key aim of the strategy should also be to improve communications. A thorough understanding of programme needs, as well as the characteristics of the molecule, need to be developed throughout CLD. This requires a culture that fosters communication between all stakeholders to identify and overcome challenges. Therapeutic product programmes are also likely to be successful and meet project timelines when critical data is accessible and sharable. Communication that is in real-time, organised and well-defined will allow issue-resolving protocols to be quickly developed and minimise potential delays.
A solid CLD foundation
As balancing speed and quality is of utmost importance in a CLD programme, it is essential that the cell line chosen for a project can achieve both. There are many potential expression systems that have been successfully used in commercial-scale biologics production, including mammalian and insect cells, bacteria, yeast, and transgenic plants. Cultivating bacteria and yeast cell lines is often easier as compared with mammalian, insect, and other species cells. They can typically be grown in a medium containing basic elements and only in specific cases will additional supplements such as amino acids or vitamins be required. Their relatively faster growth and simpler requirements can potentially accelerate drug product production timelines.However, mammalian cells can provide characteristics to the molecule that cannot be mimicked by lower levels of organisms. Proper post-translational modifications (PTMs) are essential when producing biological products for use in humans. Ensuring proper PTMs of biologics to be used in humans is challenging when lower levels of organisms have been used for expression.
Glycosylation is an important PTM for some mammalian-based molecules. Eg, glycans attached to mAbs play an important role in pharmacokinetics, efficacy, and safety2.However, glycosylation cannot be achieved by prokaryotic cells. Although yeast expression systems can perform glycosylation, it may be done in a way that is inappropriate for biologics used in humans. By using mammalian cell lines in CLD, these modifications are more likely to be carried out correctly.Similarly, correct folding and assembly of humanised mAbs, bi-specific antibodies, and recombinant proteins are more likely to be achieved by most mammalian cells than certain other cell types2. Formation of disulfide bonds in antibodies is essential for their structure and function and requires a cross-linking reaction under oxidising conditions. However, common bacterial expression systems like Escherichia coli translate proteins in the reducing environment of the cytoplasmic compartment, resulting in mostly non-functional aggregates. The use of an expression system that offers accelerated speed of production but cannot perform correct protein folding, assembly and PTMs, won’t produce a viable product. It is essential to use a reliable and well-characterised cell line so time won’t be wasted fixing issues arising from poor expression and assembly later. The foundation of CLD requires a reliable cell line for production of a molecule synthesised as intended. This production can be optimised to produce the biologic at both high speed and quality.
CHO platform technologies
Chinese Hamster Ovary (CHO) cell lines are a popular cell systems used in the development and manufacture of therapeutic proteins, including mAbs. As a mammalian cell line, they are well equipped to deliver biologics to be used in humans, as well as having several advantages:
- Scalability: CHO cells not only grow well as adherent cultures but also suspension cultures, which can be beneficial and space-saving for large-scale manufacturing. They also have high tolerance to condition variation (such as pH, temperature, pressure), making them ideal for processes that will require scaling.
- High productivity:A high yield and good quality of recombinant protein can be achieved with optimisation.
- Proper PTM capability:It has been proven that many CHO cell lines can produce biosimilar products for humans with excellent biocompatibility and pharmaceutical functional activity, performing the required PTMs as they would naturally.
- Simplified selection system:Selection of high-producing clones is achievable using dihydrofolate reductase (DHFR) or glutamine synthase (GS) deficiency attenuated markers in the CHO platform.
- Well-characterised:The CHO platform is widely understood and has been extensively characterised. As a result, there are many useful tools available for cell engineering for CHO cells to increase productivity and product quality. These techniques have been recognised by the FDA and used for many years. With nearly 50 biotherapeutics already approved in the US and EU, its recognition as a suitable platform could ease gaining approval.
Accelerating CLD using CHO
In order to accelerate the programme and delivery of drugs to patients, the CLD process needs to be optimised first. With differing and competing priorities at each phase of CLD to consider, it can be easy to lose sight of the larger IND/Biologic License Application (BLA) development goals. Therefore, all aspects of the product lifecycle should be considered to identify areas for optimisation early with these goals in mind to avoid retracing steps and false starts.
- Utilise proprietary cell lines
Many CDMOs are developing their own proprietary CHO lines by cell line engineering to achieve robust cell growth while improving high recombinant protein yield, specific productivity, and product quality. One example of a proprietary cell line developed to support faster and more efficient CLD processes is Samsung Biologics’ S-CHOice. This cell line offers an excellent cell growth rate and cell growth profile, resulting in high productivity (7+ g/L titer). It has been designed to be beneficial for increasing the productivity of low-yield, complicated molecules.
- Optimise upstream and downstream processes
Having strong upstream process foundations is essential for CLD to start on a strong footing. Before implementing new techniques, upstream and downstream processes should be optimised to meet high production demand. Process optimisation should focus on achieving a high specific cell growth rate to ensure high viable cell density, resulting in increased production of the qualified protein. Customising cell culture media with optimised formulation could further contribute to stabilising cell lines and increasing productivity for commercial-scale manufacturing.
- Implement innovative technologies
By using high throughput tools and advanced analytical technologies, CLD programmes can be further accelerated. For example, implementation of high throughput technologies, including affinity capture technologies, can accelerate cell isolation, screening, and selection via the automation system. Sorting using advanced techniques and learning new automation technologies could further speed-up production.Establishing appropriate technologies and suppliers can streamline early-stage development, enabling a smooth transition to manufacturing and commercial scale-up.
- Outsource effectively
The best-performing development programmes come from outsourcing CLD to strong partners. Working with a single, end-to-end CDMO partner limits gaps between development and manufacturing stages. Advantages include: Access to an innovative, efficient CLD platform that is optimised to deliver better process and quality outcomes. Allows organisations to focus on core competencies and direct internal resources. Cost-efficient CLD platforms offered by partners can help reduce the cost of the drug in part by producing higher yields.
A robust CLD strategy ensures processes are assessed for a balance of speed and high product quality. This relies on a reliable cell line to ensure a quality product from the onset. With further process optimisation, cell line engineering, implementation of innovative technologies and increasing manufacturing capability, manufacturers can ensure faster, more efficient paths to IND filing. Adopting this strategy sets leading CLD service providers apart, as they possess the expertise to fuel programme development and accelerate commercial timelines.
Volume 23, Issue 2 – Spring 2022
About the author:
Soojin Han has over 10 years CLD experience. In 2021, Han joined Samsung Biologics’ San Francisco R&D Center as Director of the CLD Group. She also led the CLD and upstream groups in MedImmune, AstraZeneca and Kite. She earned her PhD in Biochemistry and Molecular Biology from Hanyang University
2. Frenzel A, Hust M, Schirrmann T. Expression of recombinant antibodies. Front Immunol. 2013;4:217. Published 2013 July 29