Q: Freeze-thaw is becoming an increasingly important topic as companies look for ways to improve current methods. What is driving companies to look for these improvements?
A: Currently 60% of drugs and vaccines include a freezing/thawing process and demand has been fueled by the pandemic response of vaccine developers and manufacturers and their global external manufacturing networks. Also by 2024, there are expected to be more than 400 new drugs and vaccines that require cold storage.
With biotech companies outsourcing 81% of their fill-finish requirements, this has created the need for shipping bulk drug substance, either by road or air - so robust storage, freezing, transport and thawing is critical. This means an industrialized end-to-end solution is required.
Knowing the impact of extractables and leachables is critical and maintaining the same biocontainer bag film through the bioprocessing workflow from upstream through downstream to bulk drug substance filling and freezing and even during formulation and filling, reduces that risk.
So, the ability to utilize pre-qualified biocontainer bags protected by robust shells throughout the entire process train including storage, freeze-thaw and shipping, is optimal. Robust shells that protect the biocontainer bags and reduce the risk of loss (which can be as high as 1-5% due to leakages and product loss worth millions of dollars annually) are at the heart of any solution.
Fast and controlled freezing and thawing is also optimal to maximize homogeneity of the drug substance, and transportation shippers need to ensure the sub-zero temperatures can be maintained for multiple days and meet ISTA or ASTM shipping standards.
All these factors are driving biotech manufacturers and their external manufacturing networks to look for better solutions.
Q: What are the current methods for freeze-thaw?
A: Historically, bottles have been used to store, freeze and ship drug substance; however the use of single-use biocontainer bags, protected by shells, is rapidly growing. This is largely due to the flexibility and closed system that can be maintained by using biocontainer bags with sterile connectors and disconnectors making it possible to fill, freeze, thaw and drain in CNC or even warehouse environments. This is not possible with bottles that must be filled using laminar flow, as a closed system cannot be maintained.
Regarding freeze-thaw, static or lab freezers and blast freezers are the oldest freezing technology used in industry. However, this has its downside.
There is now a move to plate-based freezing and thawing which offers fast and controlled freezing, as the plates are in direct contact with the bottles or the shell encasing the biocontainer bag.
Q: You mentioned blast freezing, could you talk a little about the disadvantages of blast freezing in bottles?
A: In blast freezing, the air is circulated slowly with warm air ascending, cold air descending – standard convection practices. The airflow is not well- controlled, which results in low surface heat transfer. The airflow or uncontrolled environment leads to unpredictable and deviating freezing kinetics, even within the same run. This means that up to 56% of protein viability can be lost and individual zones can have as much as a 5-6 degrees Celsius (41-43 degrees Fahrenheit) temperature differences.
Blast freezing also takes two to five times longer than controlled plate freezing which takes five to eight hours – a standard working shift. This slow freezing in blast freezers results in cryoconcentration and a lack of drug substance homogeneity. Proteins, vaccines and excipients form concentration gradients near the freeze front and get excluded from the ice-liquid interface. This can lead to pH shifts and phase separation among the components, resulting for example, in protein structural damage.
Controlled fast freezing on the other hand, results in smaller ice crystal formation and controlled scale-up offers the same thermal parameters.
If you then consider the amount of cold storage space required for frozen bottles, this is large and costly. In contrast, biocontainer bags protected in shells can be simply stacked, thereby increasing cold storage density and reducing the costs of storage.
Q: Scale-up is always an important topic in biomanufacturing and thus freezing technologies must be scalable. Can plate freezing be scaled up to meet increasing demands?
A: Yes - plate freezing in biocontainer bags can be easily scaled. Consistent temperature kinetics have been demonstrated during freezing small 1 liter biocontainer bags to larger 10 and 20 liter biocontainer bags. The average number of hours to last point of freeze is almost identical across all volumes and temperature curves for freezing and thawing are similar irrespective of the load. In contrast, the average number of hours to last point of freeze is increased as the volumes increase.
Q: As an industry we are always looking for ways to increase integration and automation of processes. Could you describe how modern freeze- thaw methods could be integrated into existing processes and what benefits could be gained from this type of integration?
A: A severe technology gap has been identified between downstream and fill/finish integrations. This area is the filling, freezing, transportation and thawing of bulk drug substance, and has always been fragmented. Where you can buy a filling machine from Supplier A and the biocontainer bag from Supplier B and then add a freezer from Supplier C, and shipper from Supplier D. There are a number of threats and disadvantages from this disjointed approach.
The severe lack of robustness, the limited number of platform qualifications, let alone the comprehensive validation packages that are available, and there is no genuine scalability, and no reassurance of supply. This has proven a challenge for customers so streamlining the process and enabling an integrated solution between downstream and fill/finish is preferred.
So how can this be achieved? It really starts with selecting a supplier that offers a one-stop solution for biocontainer bags together with protective shells, filling units, freeze-thaw units and a validated transportation solution. This solution integrates seamlessly with downstream and fill-finish processes and has the advantage of minimizing extractables and leachables through utilization of the same biocontainer film and maintaining a closed system throughout.
Q: If a company wants to look at employing plate freezing in their operations, how would you recommend that they get started?
A: I’d recommend starting small, and scaling up which can easily be done with plate-based freezing. At development and clinical stage, you could use a lab scale plate freezer to establish optimum freeze-thaw conditions with volumes as low as 500 milliters.
The same kinetics can then be transferred to large scale plate freezers without the need to re-validate the freeze-thaw process. Recipe driven automation means you can program and select specific freeze-thaw conditions as required.
Q: Thank you so much for your time today, I know that we have just scratched the surface of new freezing technologies and what is possible when these methods are employed. How would you recommend listeners learn more?
A: Visit the product page or contact your local representative.
This is a transcript of the podcast featuring a question-and-answer session with Claire Jarmey-Swan and originally published at Cell Culture Dish (and reproduced here with our thanks).
Discuss your drug product freezing needs with an expert
Claire Jarmey-Swan – Global Product Manager