Technological Innovations Enhancing Downstream Productivity and Their Critical Process Parameters for Real-Time Control

Effective downstream processing of biologic drug substances is crucial for ensuring the production of high-quality, safe, and effective drug products. In-line monitoring and control of critical process parameters (CPPs) enables the development of robust, consistent, and reliable downstream unit operations that are scalable, efficient, and highly productive and that yield products that meet the highest quality standards. While process analytical technologies (PATs) are more widely used for upstream applications, they provide many benefits for downstream processing and are accessible in commercially available skids for key unit operations.

Several Downstream Unit Operations, Numerous Critical Process Parameters

Recombinant proteins and monoclonal antibodies (mAbs) have revolutionized treatment regimes in many therapeutic areas. In addition, cell and gene therapies for personalized medicine will further contribute to improve the quality of life for people all around the world. What all these biopharmaceutical treatments have in common is that their production requires the use of living cells (typically mammalian, but also bacterial and yeast). After bioproduction, these biopharmaceutical products must be purified and concentrated before administered to patients. The production phase through cell culture or fermentation is called upstream processing (USP); the purification and concentration phase is called downstream processing (DSP).

The latter phase involves several unit operations, including buffer preparation/dilution, chromatography, ultrafiltration/diafiltration, viral inactivation, and other optional operations, such as centrifugation and protein refolding. In compliance with the U.S. Food and Drug Administration’s (FDA) Process Analytical Technologies (PAT) initiative,1 each unit operation must be developed so that critical process parameters (CPPs) impacting critical quality attributes (CQAs) are appropriately controlled over a broad process design space to ensure process robustness, reproducibility, and scalability, as well as product quality, safety, and efficacy.2 In other words, the CPPs are “switches” that can be controlled in real time to make sure that the CQAs stay within the predefined values, ensuring the product is safe and provides its intended therapeutic effect.

The most common CQAs for DSP relate to purity (protein purity and host-cell protein (HCP), DNA, and RNA contaminant levels), protein structure and stability (primary, secondary, and tertiary structures; posttranslational modifications (PTMs); and aggregate and product-related variant levels), sterility (microbial and endotoxin contaminant levels), and viral clearance.

The CPPs relating to these various CQAs include pH, conductivity (ionic strength), impurity analysis, temperature, flow rate/pressure, redox environment, dissolved oxygen (DO, for oxygen-sensitive proteins), and turbidity. Each of these CPPs correlates to two or more CQAs. The specific CPPs and their impacts on different CQAs will depend on the biologic drug substance, the production culture type, and the downstream process steps employed.

The more critical parameters that are controlled in real time, the higher the chance that the desired CQAs will be obtained. Real-time monitoring requires in-line and/or on-line monitoring technologies. Several such technologies are already available, such as the aforementioned pH, conductivity, protein fraction/concentration, and flow rate / pressure. For some CPPs, however, off-line analysis is still required, owing to the lack of suitable in-line solutions. Although both in-line/on-line and off-line technologies can be used for PAT, the more desirable “PAT tools” are the former, as they provide real-time measurements.  

Advantages of In-line Monitoring for Downstream Unit Operations

In-line CPP monitoring with PAT tools supports quality-by-design (QbD) approaches to process development — which aim to prevent system downtime and/or batch failures.

PATs are more commonly studied in upstream processing than for real-time monitoring of downstream purification operations due to the complexity and variability of the latter processes. At the same time, especially recently, progress has been made in overcoming some of the challenges regarding the use of PAT tools for real-time monitoring of downstream operations.

The recent COVID-19 pandemic offers an instructive example. The bottleneck for the production of the COVID-19 vaccines involved DSP rather than USP operations. The available DSP capacity could not keep pace with the demand to purify and concentrate huge amounts of antigens. This triggered greater attention on the part of all DSP technology groups of the need to enhance the productivity of their processes with in-line monitoring and control. It may be worthwhile to look in depth into each DSP operation unit to understand which CPPs best suits the tight control of CQAs. Below are some examples of approaches to improve DSP productivity.

On-Demand Buffer Solutions and Related CPPs

Increasing the sustainability, efficiency, and cost-effectiveness of biopharmaceutical manufacturing remain primary goals for biologic drug manufacturers. In addition to improving process performance through in-line monitoring, identifying opportunities for process intensification is an active area for many companies and a focus for industry trade groups, such as the BioPhorum.

Each DSP operation unit requires different buffers to support its function: the biopharmaceuticals are always processed in liquid suspension state. As a result, huge volumes of buffers have to be available at the point of use. Buffer preparation thus dictates plant capacity and production schedules. Buffer preparation is traditionally labor intensive and involves the use of large quantities of reagents and large mixer tanks, which occupy a significant portion of the manufacturing footprint.

A recent approach leverages in-line dilution of buffer concentrates along with single-use fluid handling and mixing solutions. Concentrated mixtures of various buffer solutions are prepared in advance in fixed vessels and then diluted as needed for each process. With this approach, it is possible to reduce the floor space required for buffer storage by 75% and the cost per liter for buffer preparation by up to 12% and to make buffer management more time-efficient.

One of the keys to successful in-line buffer preparation is control of pH and conductivity. Reliable and precise real-time process monitoring is essential to maintain optimal conditions and ensure efficient, high-quality biopharmaceutical production, especially when buffers are prepared “just-in-time.”

The Cytiva Allegro™ Connect Buffer Management System is an example of an effective in-line buffer preparation skid.3 In this system, pH and conductivity are monitored with Hamilton SU OneFerm Arc 120 and Conducell 4USF Arc 120 in-line sensors, respectively.

Low-Pressure Liquid Chromatography In-line Monitoring

Chromatography is the purification step where, for example, mAbs are captured and separated from other components using protein affinity or charge differences. For proteins, low-pressure liquid chromatography (LPLC) systems are typically used, operating at pressures less than 6 bar. It is used to desorb captured product from chromatography columns once impurities have been allowed to flow through the column. It is typically used for fine separation of high-value molecules (>$2/g), such as mAbs (as previously mentioned), separation of molecules of similar size, purification of fragile molecules and cells, and a range of other applications. Notably, it is an adaptable process that can be used for many types of molecules, including proteins, oligonucleotides, sugars, lipids, cells, viral vectors, enzymes, and nucleic acids.

To achieve the highest product recovery and purity, all CPPs, such as pH, conductivity, flow rate, protein titer, and temperature, must be carefully controlled. For processes to benefit from real-time monitoring, the sensors for monitoring these critical parameters must be very precise and reliable.

An example of a skid for LPLC, the Verdot FlexiProTM benchtop system is adaptable to a wide range of chromatography processes.4 The system also offers the capability to leverage in-line dilution or gradient preparation of aqueous buffers. Hamilton OneFerm and Conducell 4USF sensors are used to monitor buffer pH and conductivity and to control the flow rate and dilution conditions. Protein titer, flow rate, and temperature are also monitored.

PAT Solution for Tangential-Flow Filtration

Tangential-flow filtration (TFF) is used for ultrafiltration/diafiltration steps to remove impurities, exchange one buffer solution for another, and/or increase the concentration of the final product. In addition, by choosing the appropriate filter type, TFF can be used for particulate filtration, microfiltration, nanofiltration, and many other applications. Furthermore, because TFF enables continuous and gradual concentration with the product stream moving parallel rather than perpendicular to the filter, as is the case with traditional dead-end impact filters, the desired concentration can be achieved approximately 2.5 times faster.

The keys to implementing successful TFF processes that purify and concentrate the biopharmaceutical product within the expected timeframe while preserving product stability are realizing efficient functioning of the membranes and maintaining proper buffer conditions. Flow rates in production-scale TFF skids for monoclonal antibody purification, for example, can reach to 600 L/hour.

Monitoring of the CPPs needed to achieve these goals must be accurate and have a quick response time. These parameters include pH to maintain the desired buffer conditions, conductivity for monitoring the efficiency of buffer exchange and salt removal, transmembrane pressure to prevent membrane fouling and damage, and feed and permeate flow rates to ensure proper fluid dynamics.

Protein concentration and temperature are additional CPPs that can be valuable to monitor in real time. Protein concentration impacts product recovery, concentration, and quality. In-line UV sensors or spectrophotometers installed directly in the TFF skid’s permeate or retentate lines provide protein concentration values, as UV absorbance is proportional to protein concentration. It is important to note, however, that calibration curves established using a series of protein standards with known concentrations and compliant with each specific application must be used to accurately determine the protein concentration.

As is the case with temperature measurement during chromatography, in-line monitoring can provide information on whether the TFF process is proceeding within the optimal temperature range, and it is particularly important for temperature-sensitive molecules. However, it is not typically used for control purposes, because controlling the process temperature often involves approaches that do not rely on in-line sensor readings.

Examples of effective TFF skids incorporating PAT tools include the Donaldson (SolarisTM) Kronos and Tytan systems. Hamilton intelligent pH and conductivity arc sensors have been digitally integrated into the Solaris Process Control System to provide benefits over analog sensor outputs.5 For instance, the communication protocol is more robust and is not sensitive to electrical noise; the software directly tracks sensor health and diagnostic information in real time, helping to avoid lost batches due to probe fouling; and calibration is simplified and accelerated.

Moving to In-line

For downstream processing, each unit operation has its own set of CPPS and CQAs. In any scenario, the correct monitoring and control of CPPs via suitable process sensors is crucial for achieving the desired product quality and ensuring the success of biopharmaceutical manufacturing. Ultimately, for each biomolecule and bioprocess, a unique set of CPPs must be monitored with a unique combination of in-line — and currently off-line — analytical techniques/technologies.

Studies by the BioPhorum industry trade group confirm the real benefits to be gained from the use of in-line monitoring with respect to yield, quality, time savings, and reduced product/batch failures.6

At Hamilton, we pioneer sensor technology to enable biopharma users to solve their development and production challenges and improve their efficiency. Our goal is to provide accurate measurements that enable real-time control of the relevant CPPs. In our view, this must be done seamlessly, meaning that the process sensors should be easily implemented (e.g., digital integration) and not time-consuming to maintain (e.g., quick and easy to calibrate). When this is achieved, the advantages of real-time monitoring can be applied from R&D scale-up to pilot and production scale.

In the short term, it is likely that some improved in-line measurement solutions will be introduced for some process parameters, while others will remain challenging and continue to require off-line analysis (Table 1). Ideally, in the longer term, new technologies will be identified to make in-line monitoring of even these challenging parameters possible. Hamilton intends to remain at the forefront of those discoveries.

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Partnerships Continue to Drive Innovation

As an innovator company, Hamilton values partnerships with other innovators in the pharmaceutical industry — equipment vendors and drug developers and manufacturers. This includes every company with ideas about how to innovate and improve the efficiency of bioprocessing, both upstream and downstream. Our goal is to be the leading one-stop-shop provider of all relevant CPP monitoring solutions for both upstream and downstream processes.

References

  1. Guidance for Industry. PAT – A Framework for Innovative Pharmaceutical Development, Manufacturing, and Quality Assurance.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research (CDER), Center for Veterinary Medicine (CVM), and Office of Regulatory Affairs (ORA). Sep. 2004.
  2. Biopharma Downstream Critical Process Parameters.” Hamilton. 2023.
  3. Production of In-Specification Buffer on Demand for Batch Processes.” Cytiva. Application Note. Allegro™ Connect Buffer Management System. USD 3411. 2020
  4. “FlexiPro Single-Use LPLC System for Process Scale-up and Manufacturing.” Verdot – ips2. Bulletin DP-MKT-299-07 FlexiPro. January 2022.
  5. Why Use Tangential Flow Filtration (TFF)?” Solaris™ Biotech (a Donaldson Brand). Accessed 4 Nov. 2023.
  6. In-line monitoring/real-time release testing in biopharmaceutical processes—prioritization and cost-benefit analysis.” BioPhorum Operations Group Ltd. 12 May 2020.

Originally published on PharmasAlmanac.com on January 4, 2024.

Restarting a Manufacturing Campus and Revitalizing a Community

In 2017, Federal Equipment Company learned that a modern pharmaceutical manufacturing campus located in Huntsville, Alabama, was on the real estate market after its owner, Par Pharmaceuticals, an Endo International company, shut down operations. While our team has purchased entire facilities in the past, liquidated the equipment, and sold the facilities to other entities, we had never taken on a project of this magnitude.

Balancing Risk

The massive Huntsville campus is situated on over 110 acres of land, with three buildings each exceeding 300,000 ft2. The campus is still relatively new, having been built in 2001, and has since been upgraded with modern equipment. It is a state-of-the-art cross-dock facility, with plenty of room for expansion, and it is ideal for manufacturing, production, assembly, and distribution. However, regardless of the attractive attributes of the campus, which also included a skilled workforce; close proximity to the airport, expressway, and downtown Huntsville; and a thriving metropolitan area, the fact remains that it is highly difficult for a pharmaceutical company to purchase a manufacturing site without a product line included in the deal, which we were not going to be able to provide to potential buyers after Par Pharmaceuticals shut down operations. The high degree of risk and uncertainty was balanced by the incredible opportunity that such a world-class facility, people, and community had to offer, and we made the daring decision to accept the challenge of crafting a strategy to buy and sell this massive pharmaceutical manufacturing complex.

We had conducted a lot of business with Qualitest Pharmaceuticals, the previous owner of the Huntsville facility, before they were acquired by Par Pharmaceuticals, and we had great relationships with many of the site stakeholders but did not have the same level of connection at the executive level. We had also been slowly purchasing equipment for resale as Par was shutting down process lines, and over the years we were able to get a firsthand glimpse into all of the wonderful attributes that the site had to offer. What began as an endeavor based on liquidating equipment suddenly became the opportunity of a lifetime.

The campus boasts three buildings, each designed for large-scale pharmaceutical manufacturing. The first building of the facility was used to produce tablets and capsules, with over one billion units produced each year, and high-speed, serialized packaging lines had just been installed. The second building was utilized for the production of liquids, creams, and ointments, with serialized packaging lines and two state-of-the-art laboratories. The third building had been used as a distribution center and contained a host of corporate offices.

While the opportunity to purchase and sell this campus was tantalizing, it came with many risks. Although taking on a project of this magnitude seemed outlandish, with the support of Federal Equipment Company Chairman, Michael Kadis, the company began to seriously consider the potential. Initially, we garnered the interest of a few interested clients who would potentially buy the site if we were to acquire it, but the discussions didn’t materialize. Undeterred, we continued to press on and evaluate our options. What partially fueled our passion to acquire this site went far beyond the simple acquisition and sale of property — it was about the people. With the shutdown of the site, over 1,400 talented people were now out of work, many of whom we had dealings and relationships with over the years. We understood how much it would mean to them, Par, and the city of Huntsville, if we could successfully pull this off, as any interested contract development and manufacturing organization (CDMO) could leverage the local talent pool to get operations off the ground and begin to scale. 

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Collaboration and Partnership

Due to the size and scope of the project and the stalled negotiations, we realized we would need to collaborate with some first-rate partners with specific expertise in key areas to be able to bring this project successfully to fruition. We put together a strong team of partners, including Capital Recovery Group, an international private equity firm with expertise in complex industrial facilities with idle or marginally productive assets; Heritage Global Partners, one of the world’s largest industrial auction companies; and PPL Group, who specialize in creative and agile liquidity solutions for companies with distress or special situations through the purchase and sale of commercial and industrial assets, real estate, and entire facilities, with ownership ranging from sole proprietors to Fortune 500 companies. With a strong, concerted effort, we purchased the Huntsville site in its entirety in December 2018.

A Three-Pronged Approach

We realized that we would likely need to take a phased approach, focusing on the three individual buildings rather than the sale of the entire site. At the time, the OSD building, which was used for the production of tablets and capsules, was over capacity and not an option for CDMOs in the United States. Ultimately, we decided that the most prudent course of action was to sell the equipment in the first phase and focus on the actual building later. We held an auction and were able to sell the equipment to a variety of CDMOs—following this, we were able to clear the building and begin plans for remodeling and redevelopment of the space to accommodate interested buyers or tenants. We are in the process of demolishing the interior and white-boxing it for interested entities to be able to easily customize and imagine their operations in the space. This gorgeous, self-contained building boasts its own systems, DEA cages, offices, two laboratories and optimal shipping capabilities. This 323,486-ft2 building remains vacant today and is available for lease or sale.

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The Birth of TriRx Pharmaceutical Services

The second building was designed as a liquids, creams, and ointments production facility, but like the tablet and capsules building, it lacked the capacity to interest most U.S. CDMOs. However, rather than liquidating all of the equipment, we reached out to Tim Tyson, a world-renowned pharmaceutical industry leader with whom we had a long history.  In his career, Tim has negotiated complex multibillion-dollar mergers and acquisitions, led major turnarounds that have fueled growth and value, and been instrumental in bringing more than 50 lifesaving and life-improving medicines to market. He had just left his previous company, and our previous interactions afforded us a great deal of mutual respect and trust, so when we told him about the site, he was intrigued, albeit with understandable caution. 

As Tim noted, “The first key point to a successful CDMO is to have world-class facilities, with world-class capability, with world-class people that understand on-time delivery and regulatory compliance.” Tim believed that Huntsville met the criteria, with its world-class facilities, long history of performance, and recognition of being a world-class supplier. However, Tim recognized the risk in acquiring a manufacturing operation without the immediate revenue to cover the operating expenses, which takes an average of 18–24 months.  However, as he further noted, “the second key point to a successful CDMO is trust.” Owing to his history working closely with myself and Federal Equipment Company, Tim was convinced that it was a worthwhile risk that could pay dividends in the near-term due to the excellent facilities and the existing relationships.

Given this opportunity, Tim founded TriRx Pharmaceutical Services, a global CDMO that operates out of the facility, where he operates as CEO and Chairman. TriRx was able to reemploy over 250 former employees from the Par site, including the former director of engineering, Tom Woods, and the former director of technology, Kevin Rupe, who were both instrumental in the transition. TriRx just celebrated its one-year anniversary, and the city of Huntsville is very happy to have them as a part of their community.

The Present and Future of Federal Equipment Company

The third building on the Huntsville campus, which was previously utilized as a distribution center, with a state-of-the-art warehouse and corporate offices, was leased to a Fortune 500 defense contractor. Huntsville is a hot market for defense, automotive, and technology, and getting a long-term tenant in the building aligned perfectly with the overall vibe of such an industrious town.

The Huntsville campus is four to five times larger than any other project we’ve taken on previously. To see a site like this come back and thrive has, unfortunately, become a rarity in the industry.

Federal continues to evolve, and we are continuing to take on larger-scale projects because most of the time, there is no single solution. We have to be flexible, as not every auction is going to go well, and we need to be able to offer solutions that help companies divest from their buildings and/or process lines. 

This is our path forward. We receive countless calls from API manufacturers, sterile manufacturers, and many CDMOs that are looking for sites in the United States. We are looking for other U.S. sites that will satisfy our clients’ manufacturing facility needs, and the U.S. government has programs available to help businesses who want to manufacture domestically. Given the drastic changes that have rocked the world in 2020, particularly the shift in how business is done coupled with a renewed interest in a domestic manufacturing model, we are poised for growth. As with the TriRx opportunity, we are confident that in the near term, we will find a suitable buyer or tenant for this one-of-a-kind building. 

Originally published on PharmasAlmanac.com on September 30, 2020