CONTINUOUS MANUFACTURING

REVOLUTIONISING UPSTREAM BIOMANUFACTURING:

Supporting the implementation of continuous perfusion cell culture

Establishing continuous manufacturing (CM) workflows is becoming increasingly popular for intensifying manufacturing processes within the pharmaceutical industry. This is particularly true for small molecule drug manufacturing, following the successful regulatory approval of several CM processes. However, for biopharmaceutical manufacturers, implementation of CM is more complex.

Because biotherapeutics are produced using living cells, manufacturing requires highly specific process conditions. This is essential to maximise productivity and, most importantly, ensure the molecules produced fulfil the critical quality attributes (CQAs) which validate their safety and efficacy. A solution to meeting these required process parameters while intensifying production is a type of bioprocessing known as perfusion cell culture.

By using a cell retention device and a cell culture media exchange system, this method enables manufacturers to maintain a high cell density under constant conditions for an extended period. This can improve productivity and allow for a smaller footprint. There are a number of different perfusion processes; the most suitable for integration into upstream CM workflows is continuous perfusion.

ADVANTAGES OF CONTINUOUS PERFUSION

As media exchange replenishes nutrients and removes waste products, a cell bleed prevents excess cell density. This allows continuous perfusion

WHERE IS CONTINUOUS PERFUSION NOW?

Although there is significant interest focused on implementation of continuous perfusion processes, challenges remain.

One of the primary obstacles currently facing manufacturers is the lack of comprehensive regulatory guidance. Although many regulatory groups are actively supporting the transition to CM and are continuing to issue advice to support its implementation, there is not yet a full set of “default” standards to which manufacturers can refer. This uncertainty makes many manufacturers hesitant to fully commit to implementing a continuous process.

Outside of regulatory challenges, there are also limitations with existing bioprocessing equipment, as many installed fed-batch workflows are not capable of facilitating continuous perfusion. There has been significant innovation to help support manufacturers, however, that requires installing new equipment in some cases.

to maintain a steady-state bioreactor environment. This state enables high cell densities and viabilities to be preserved for long periods of time—often for around 30–90 days—and product of consistent quality to be produced.

By enabling manufacturers to intensify production, continuous perfusion can provide significant productivity benefits. Additionally, by removing the product of interest throughout the manufacturing process, improvements in overall product quality can also be achieved. These advantages can reduce overall cost of goods compared to traditional batch or fed-batch processes over the lifetime of the process.

INNOVATIONS TO SUPPORT CONTINUOUS PERFUSION Process development solutions

One of the primary challenges for manufacturers looking to establish continuous perfusion processes is the limited ability of current small-scale development tools. Specifically, existing small-scale bioreactors and high-throughput solutions are often unable to support

the mass transfer needs of highdensity cell cultures as well as continuous media exchange.

To overcome this challenge, R&D teams across the industry have developed approaches to simulate perfusion processes. Although many of these remain labour intensive and have limitations around the conditions that can be achieved, they are playing a vital role in developing the knowledge needed for progression towards continuous perfusion processes. There are also novel equipment solutions becoming available, including microbioreactors that are specifically designed for intensified and continuous process development, which could have a transformative effect.

Single-use technology

Compared to batch and fed-batch processes, initial continuous perfusion process development is often more time consuming. However, once the process has been established, this can be offset by productivity advantages. These advantages include allowing for smaller scale-up production operating volume targets, enabling manufacturers to reach clinical production volumes more easily.

These benefits can be amplified using single-use bioreactors. By using lower volume single-use equipment, manufacturers can reduce their capital expenditure costs compared to stainlesssteel alternatives. Additionally, the process itself can become easier to replicate. Consequently, parallel small-scale set-ups can be established in multiple locations rather than needing a large central facility, lowering costs and possibly lead times, in the long term.

Bioreactor design

Due to the high cell densities that perfusion achieves, existing equipment can struggle to meet the necessary mass transfer and agitation requirements of the cells.

To help support perfusion processes, equipment manufacturers now offer bioreactors with specific features that can overcome these challenges. This includes appropriately sized mass flow controllers to regulate gas flow at higher rates and better designed spargers to optimise oxygenation. Agitation design is also a critical factor as agitators need to provide increased movement without causing cavitation, sheer stress issues, or excessively influencing sparge behaviour.

Process analytics

Advances in process analytical technology (PAT) are also enhancing perfusion workflows due to their crucial role in helping to achieve, and then maintain, an optimal steady-state environment. In particular, spectroscopy and capacitance-based solutions are continuing to see increased use.

One recent PAT development that has simplified the monitoring of perfusion processes is increased use of autosamplers. These can play a major role as, due to the relatively slow changes in steady-state cell culture conditions, they are able to make pseudo, real-time process adjustments. Feedback from at-line instruments can enable manufacturers to automate identification of any deviations using the same at-line instrumentation they already use to qualify their processes.

Media formulation

In addition to the process equipment, another crucial element of perfusion workflows is the cell culture medium used. This is important as the medium provides the essential compounds and nutrients required for maintaining high cell density and achieving maximum productivity throughout the process. Crucially, the requirements for a cell culture medium used for perfusion are distinctly different to those used in batch and fed-batch processes.

For example, a perfusion medium must be formulated with a higher osmolality to offset the drop associated with typical perfusion workflows. It must also balance running richly on highly consumed components and lean on components that risk build-up in cells in a way that minimally inhibits cell growth rate.

To simplify process development, it is also optimal for the same medium to be used throughout the workflow—from initial seed-train steps through to steady-state perfusion. To meet these requirements, media manufacturers have developed commercially available media products specifically designed for use in perfusion processes.

FUTURE OF CONTINUOUS PERFUSION CELL CULTURE

Although there remain several key challenges preventing widespread uptake of CM within the biopharmaceutical industry, significant progress has been made over recent years. By combining the latest technological innovations with increasing process development knowledge and regulatory guidance, implementation of continuous perfusion is becoming increasingly achievable for manufacturers.

Through continued development in these areas, the biopharmaceutical industry has the opportunity to embrace the CM revolution alongside small molecule manufacturers and achieve fully intensified biologic manufacturing.

Author: CHRISTOPHER

BRAU, R&D process development manager, Thermo Fisher Scientific

There is not yet a full set of “default” standards to which manufacturers can refer. This uncertainty makes many manufacturers hesistant to fully commit to implementing a continuous process.

GROWING WITH DEMAND:

End-to-End High Potent Solutions with PCI

Author: David O’Connell, director of scientific affairs at PCI Pharma Services Tredegar site

Drug products containing high potency active pharmaceutical ingredients (HPAPIs) continue to be a major driving force in the global pharmaceutical market. Consequently, Contracted Development and Manufacturing Organisations (CDMOs) that are able to provide end-to-end solutions for the development and manufacture of highly potent solid oral dosage forms remain a vital part of the pharmaceutical outsourcing industry.

Recent data suggest that between 2021 and 2026, the small molecule drug discovery market will register a compound annual growth rate (CAGR) of 8.05 percent, indicating a growing need for these dosage forms. Oncology remains at the forefront of this demand, accounting for approximately 38 percent of all new small molecule drug candidates1, with around three-quarters containing HPAPIs.2

For an active pharmaceutical ingredient (API) to be considered highly potent, it requires an operational exposure limit (OEL) of less than 10 μg/m3. Whereas it can be safely assumed that many, if not all, small molecule oncology therapies may fall within this category, in reality many HPAPIs in development register a potency far greater than this. The greater the potency, the more targeted the medicine becomes, which is understandable given the innate complexity of oncologyrelated diseases, for example.

PCI has developed and manufacture potent products since the 1980s, and in 2013 the Contained Manufacturing Facility (CMF) in Tredegar, South Wales was launched to increase our capabilities in this field. The CMF was originally built to fulfil a relatively unmet need for highly potent solid oral dosage forms, and was designed in accordance with the latest safety, scalability and regulatory guidelines. After gaining almost a decade of operational experience with the first CMF, PCI has now expanded the Tredegar facility with a second CMF, essentially doubling our capacity for high potent development and manufacture. Combined with a new state-of-the-art high potent packaging facility, the Tredegar site is well-placed to deliver precision small molecule therapies to the market at commercial scale.

Using oncology as an example, such medicines are often classified as extremely potent,

which means they would fall within operational exposure band (OEB) 4 or 5. A molecule with an OEB 5 classification would register an OEL of less than 1 μg/m3. The design of the CMF, which prioritised engineered containment systems, allows for the safe handling of HPAPIs down to an OEL of 0.01 μg/m3. This ensures not just the safety of our operators when handling these molecules, but also the protection of our clients’ products. In order to on-board such potent drug substances with confidence, PCI routinely partners with recognised industry expert groups such as Affygility and Safebridge for the assignment of OELs to new molecules. By performing robust assessments of new molecules, PCI ensures the safe handling of the product throughout its lifecycle.

Like many CDMOs, PCI is a multi-product facility. In order to prevent crosscontamination when using our equipment for development and manufacturing activities, a robust approach to cleaning verification and validation is essential. Establishing permitted daily exposure (PDE) cleaning limits – known in the US as acceptable daily exposure (ADE) – early in the product lifecycle ensures no significant API carryover to the next product on the equipment train. An accurate risk assessment would include an understanding of the PDE/ ADE, equipment contact areas, batch sizes, API concentration and maximum carry over (MACO) data. Our experience with the original CMF places PCI in a strong position to ensure a strong NPI process, which

In the current market, there is a strong desire to work with fewer outsourcing partners throughout a product’s lifecycle. The top 5 CDMOs occupy just 15% of the market share, with the remaining 85% experiencing a high level of fragmentation3. With this fragmentation comes a large number of CDMOs who are not able to offer end-to-end services, from clinical development to commercial launch. PCI’s ability to support clients by scaling-up from development to commercial volumes is of central importance when positioning us as a true commercial CDMO. By utilising geometrically similar equipment and mathematical scaling models, this provides a greater success rate during this phase of process development.

As increasing numbers of these precision medicines move from development to commercialisation, PCI’s ability to offer clients long-term partnership is hugely beneficial in terms of product knowledge and supply chain security. Our success with the original CMF and the recent site expansions positions PCI as a CDMO capable of growing with our clients and their products.

As the market continues to evolve with increasing numbers of highly potent molecules in development, it is important to understand the requirements for the safe processing of such molecules, the differing regulatory requirements across the world, and – above all – the safety of employees and the environment. For pharmaceutical developers looking to outsource the development and manufacture of products containing HPAPIs, the challenge is finding a CDMO with the right technical capabilities, knowledge and experience to successfully manage the project. At PCI, we believe that applying in excess of 30 years’ experience of managing highly potent molecules, combined with our purpose-built CMF and high potent packaging suite, is the key to success making PCI the logical partner of choice. We pride ourselves on being able to offer a true end-to-end supply chain solution, allowing clients to move seamlessly from late-stage clinical manufacture to commercial launch and ongoing market supply.

https://pci.com/pharmaceutical-manufacturing/?utm_ source=EPM-Magazine&utm_ medium=Article&utm_campaign=EPM-Growing-HP-07-22

REFERENCES

1. Small Molecules, Sizable Market Opportunities [Internet].

The Medicine Maker. 2022 [cited 28 June 2022].

Available from: https://themedicinemaker.com/manufacture smallmolecules-sizable-market-opportunities 2. Why Small Molecules Are Still a Big Deal [Internet].

The Medicine Maker. 2022 [cited 28 June 2022].

Available from: https://themedicinemaker.com/manufacture/why-smallmolecules-are-still-a-big-deal 3. Less is more: Significant CDMO consolidation expected as pharma looks to work with fewer suppliers [Internet]

Outsourcing Pharma [cited 28 June 2022]

Available from: www.outsourcing-pharma.com/Article/2018/10/22/Top-5-

CDMOs-hold-15-of-the-market-as-industryconsolidation-is-expected-tocontinue