Continuous manufacturing offers benefits such as reduced manufacturing scale, equipment costs, and facility footprint, making it an attractive option for challenging-to-produce proteins. However, imagine applying optimized continuous process strategies for the production of monoclonal antibodies, WuXi Biologics has achieved this with their WuXiUP™ integrated continuous bioprocess platform, attaining a productivity of 6 g/L/day for a monoclonal antibody therapeutic at pilot scale. Additionally, they’ve developed the WuXiUI™ platform, which utilizes intermittent perfusion in an ultra-intensified fed-batch mode. Both platforms provide significant productivity increases, and making the choice between which to use depends on factors like the competitive landscape, facility capabilities, product demand, process development and optimization stage and timeframe.

In this Ask the Expert session, we spoke with Dr. Jun Tian, WuXi Biologics’ Vice President, Process and Analytical Development about the WuXiUP and WuXiUI platforms.

Our questions and answers are below.

Can you tell us about your WuXiUP integrated continuous bioprocess, which has achieved a productivity of 6 g/L/day at pilot scale for a monoclonal antibody therapeutic?

Yes, we have successfully integrated continuous processing from upstream perfusion cell culture through each of the downstream unit operations, including the capture step, the purification or polishing steps, and all the way to the final UF/DF pool of the drug substance.

I was intrigued that this continuous process was applied to an antibody, as I understood continuous processing was typically used for labile, unstable, or difficult-to-express recombinant proteins with low titers. Can you explain why this approach works for an antibody as well?

Historically perfusion cell culture served as a great way to mitigate issues with difficult to produce proteins, but due to recent technological advancements and extensive R&D in this area from companies like WuXi Biologics, we’re observing a shift in how continuous bioprocessing can be used from an economic perspective for high titer products, such as monoclonal antibodies, to drive down manufacturing costs on a batch-to-batch basis.

Can you highlight some of the cost savings behind using continuous manufacturing for antibody therapeutics?

Yes, one of the major motivations to develop the WuXiUP continuous process platform was for cost savings.  Since the process productivity can be ultra-high, the manufacturing scale can be greatly reduced to get the same quantity of material you generated using a much larger bioreactor. For example, we can produce 60+ kg of protein from a 1000 L disposable bioreactor in a single batch, which may otherwise require a 10,000 L – 20,000 L production scale with a traditional fed-batch process. Also, using smaller apparatus and equipment, from production bioreactors to filtration devices, results in considerable savings on overall fixed and variable costs. In addition, continuous capture can also significantly reduce the usage of Protein A resin per batch, resulting in lower resin cost at the clinical manufacturing stage.

Is it just the facility, materials and equipment savings?

Well, the high productivity of the process means that more proteins can be produced annually from the same facility or a facility with a reduced footprint and lower manufacturing costs. This significantly reduces the cost per gram of protein produced.

One of the historical concerns with continuous perfusion cell culture is the extended duration of production and occupancy of manufacturing suites. However, I noticed in your recent press release that the total process time, including initial scale-up, was only 25 days. This brings the timing close to that of fed-batch processing, correct?

Yes, as many of your listeners may know, antibody therapeutics typically achieve high titers and productivity in mammalian cell cultures. By implementing perfusion cell culture, you can produce a substantial quantity of product in a relatively short timeframe, sometimes even less than 25 days, to as few as 16-18 days. With WuXiUP, we generally see a 5-10 fold increase in productivity compared to traditional fed-batch processes.

That is great performance, so why aren’t more companies instituting continuous cell culture for their antibody therapeutics?

That’s a great question with a complex history going back nearly two decades or more. Regulatory agencies were not familiar with these types of processes, and there was a lack of expertise to establish them. Finding CDMOs with significant experience in this area was difficult, and there certainly were not any “plug-and-play” platforms for continuous manufacturing of antibodies. In addition, facility readiness is another limiting factor especially for companies with a fed-batch facility.

Have the regulatory concerns now been mitigated?

For the most part yes. The point I made about developing a well-vetted continuous manufacturing platform for antibodies is something WuXi Biologics has worked diligently to establish since our inception. In fact, the WuXiUP platform has been used to establish more than 130 different processes since we first offered the platform to our clients as a manufacturing option.

Do you think that one day soon continuous manufacturing platforms like WuXiUP, will be in routine use throughout the industry?

It’s hard to say definitively, but I’d like to believe the answer is yes. I think that the mainstream use of continuous cell culture platforms like WuXiUP or bioprocess platforms like WuXiUI, which uses intermittent perfusion in an intensified fed-batch mode for antibodies, will become more common in late clinical stage process development in the near future as companies look to reduce costs for eventual commercial manufacturing. This is especially true for biosimilar or biobetter products, or even animal health products where costs of goods becomes a critical factor for the business success.

Can you explain what intensified fed-batch is compared to fed-batch cell culture?

Intensified fed-batch uses perfusion cell retention devices to increase the viable cell mass within a bioreactor at the N-1 stage, which then can generate a 5-10 fold higher initial cell density for the N production bioreactor, compared to the traditional fed-batch process.  This simply means there are more cells in the bioreactor able to express the protein compared to traditional fed-batch and thus you can get higher overall titers.

You mentioned a new platform WuXiUI – How does the WuXiUI platform work?

With our proprietary WuXiUI platform, we have not only utilized the perfusion device to increase the cell mass at the N-1 stage but also incorporated a concentration step using the same device. This approach drives the initial cell density as high as 80 million cells/mL which is much higher than fed-batch and it is even significantly higher than that of traditional intensified fed-batch.

With that many cells in the bioreactor environment won’t there eventually be issues with maintaining a healthy cell culture environment and product quality?

To mitigate media component depletion or toxicity issues, we conduct 2-3 media exchanges through intermittent perfusion during production. This strategy helps expand the lifespan of the cells, ensuring that they are expressing high quantities and high quality products throughout the entire production period. Furthermore, we have designed and optimized our in-house MagniCHO^TM media series, that are tailored specially for intensified processes such as WuXiUI. These specialized basal and feed media formulations can mitigate some of the aforementioned challenges and empower WuXiUI performance even further.

What are we talking about with regard to titer or cell productivity compared to standard fed-batch?

We have routinely been able to achieve a 3-6-fold productivity increase and attain titers of 10-35 grams per liter using our WuXiUI platform. Such performance substantially reduces the cost of goods for commercial processes by 60-80% compared to the conventional fed-batch process at the same scale, and this performance can be obtained utilizing disposable bioreactor systems across a range of scales from 2,000 to 12,000 liters.

I’d like to revisit the topic of toxicity concerns within the bioreactor environment. Is it really as straightforward as doing media exchanges to mitigate this potential toxicity issue stemming from such a high cell mass density?

Actually no, we did a fair amount of cell culture and media development work to optimize the cell growth environment because standard “off-the-shelf” commercially available media was not sufficient to mitigate all issues and also achieve optimal productivity.  Ultimately, we developed our own in-house media formulation for our global clients.  Thus, the success we achieved with the WuXiUI process is in part also due to the media we developed.

Is this media only suitable for the WuXiUI process?

No, we have developed the MagniCHO media library not only for WuXiUI but also for other fed-batch and intensified fed-batch processes and the WuXiUP platform. We have also evaluated the media with many different CHO cell lines expressing a variety of product modalities, and observed great performance against the commercially available media. Our media platform also provides fast and intelligent media formulation development tools to support the precise design of formulations according to the needs of any specific drug candidate produced from various host cells. So overall, we expect to see wide applications of our MagniCHO and other in-house media series.

How was the media able to make such an impact on the process?

In a recent webinar titled, Strategic Process Innovations Drive to Reduce CoGs for Biologics Commercial Manufacturing in Disposable Bioreactors, I review all of the process improvements and more details on our proprietary media that allowed us to achieve a significant reduction in Cost of Goods (CoGs). The webinar includes more information on our ultra-intensified fed-batch system and it explains the WuXiUP and WuXiUI platforms in greater detail.

Given that both WuXiUP and WuXiUI provide significant productivity increases – how do you decide which process should utilize WuXiUP or WuXiUI?

Indeed, the response to that question is multifaceted and contingent upon several factors. These include your competitive landscape, the current state of your process in early development stages or clinical trials, the projected total demand of material required, any preferred bioreactor scale for manufacturing, the chosen facility, and the time you can spend in development optimizing the process.

Certainly I understand that cost of goods is an important factor for the competitive landscape in the case of biosimilar or biobetters, can you elaborate on the facility aspects?

Well, many biomanufacturing facilities were never designed, equipped or set-up for perfusion or continuous downstream operations without having to undergo significant facility modifications. To make these changes will increase costs and may introduce risk to the manufacturing timelines. At WuXi Biologics, we have designed many of our global manufacturing sites with continuous processes in mind. If a client chooses us for commercial manufacturing, we can implement either WuXiUP or WuXIUI processes and perform seamless technical transfer from development to another WuXi Biologics GMP environment around the globe. This ensures we can meet the regional manufacturing needs using the same process at each site.

I’d like to go back to something you mentioned about early-stage production or manufacturing of Phase I lots.  It seems that WuXiUP and WuXiUI are currently targeted towards transitioning traditional fed-batch processes in late-stage development to help companies meet their productivity and cost objectives.  But what about using either one of these platforms for the initial process used for Phase I lots?

Certainly, they could. For certain products such as labile or challenging-to-express recombinant proteins, these processes might be the sole option available. However, both WuXiUP and WuXiUI, despite our comprehensive understanding of these platforms, require additional development efforts for optimization. Therefore, fed-batch still holds significant value for its capacity to swiftly move forward without extensive development work, particularly if there’s a well-established “plug-n-play” CMC development platform for antibodies, as we possess. This enables smooth progression through toxicology studies and into the proof-of-concept phases of clinical trials, utilizing existing bioreactor sizes and cost structures. Fed-batch remains the most efficient route to Phase I clinical trials presently, though this could potentially shift in the future. Moreover, we can expedite the development of intensified or continuous processes to a timeline comparable to that of the fed-batch platform.

For more information, please see the webinar – Strategic Process Innovations Drive to Reduce CoGs for Biologics Commercial Manufacturing in Single-use Bioreactors

About the Expert

Dr. Jun Tian is WuXi Biologics’ Vice President, Process and Analytical Development. His group focuses on late phase and commercial process development and optimization, process characterization, PPQ campaign support and BLA enabling activities.

Prior to this role, Jun has accumulated extensive experience in the biopharmaceutical industry from his time with Takeda (previously Shire), Bristol-Myers Squibb, and Life Technologies, leading a variety of early to late-stage process development activities as well as pilot plant operations.

Dr. Tian holds a Ph.D. degree in Chemical and Biological Engineering from the State University of New York at Buffalo.