This blog contains information originally published as part of the business of Biotech podcast

Pillar, M. (Host). (2021, August 16). Cold Chain Integrity & Sustainability With Celyad Oncology's Thomas Lequertier [Audio podcast episode]. The Business of Biotech. BioProcess Online.

Cryopreservation, a process wherein cells and other biological products are preserved through controlled cooling, can be a difficult proposition for biomolecules due to risk of osmotic shock, membrane damage, and other dangers that can threaten the efficacy of highly sensitive cell therapies.

Because cell therapies must be stored and shipped at very low temperatures – typically lower than -130 degrees C – maintaining a therapeutic’s integrity through cryopreservation has far-reaching implications for both its efficacy and long-term commercial success. This extends to CAR-T therapies, which represent highly specialized, bespoke cancer treatments which utilize either a donor’s T cells or a patient’s own cells in their production. But CAR-T therapies are part of a nascent corner of the cell therapy space, and the technologies involved in their development and transport still need significant improvement in order to support burgeoning demand for these more targeted treatments.

Thomas Lequertier, head of the Cell Therapy Manufacturing Unit at Celyad Oncology, a clinical-stage biotech focused on CAR-T therapeutics, has spent years thinking about the solutions to these problems. Lequertier, who oversees all GMP and GDP production at Celyad, including validation, technical transfer, production, quality control, maintenance, and supply chain management, sat down with the Business of Biotech podcast to discuss how the company has approached cold chain technology for its CAR-T therapies.

The Logistics of Cryopreservation

At Celyad, researchers are working to perfect both major types of CAR-T therapies – allogeneic and autologous – for a number of indications, and each has its own challenges when it comes to cryopreservation. For both, cells are collected and shipped to a manufacturing center, where they are engineered, cryopreserved, and stored in a cryogenic tank. Once the final product has been tested and released, it is shipped back to the clinical site for infusion in a specially fitted cryogenic storage container, ensuring it is maintained at the appropriate temperature from start to finish.

Transporting each therapy safely requires careful planning and coordinated execution, but for autologous therapies, which are single-batch treatments derived from a patient’s own cells, the stakes are even higher. “For allogeneic therapies, you have plenty of time to schedule everything, because you’re collecting from healthy donors rather than the patient,” Lequertier says. “For autologous therapies, we take the cells from the patient, so you need to start the manufacturing as soon as possible. From a logistical perspective, allogeneic therapies are much simpler.”

Understanding cryopreservation from that logistical perspective is integral to any sort of scale-up activity in CAR-T therapeutics. Avoiding degradation and cell death during the cryogenic cold chain process is key to improving yields and optimizing scale-up, and companies like Celyad are on the cutting edge of the cryogenic process improvements that will enable more widespread access to these therapies. Additives such as cryoprotectants, substances which protect living tissue from damage caused by freezing, can work in some instances, though there is still much research to be done in order to find the best solutions for preserving certain types of cells. “Cryoprotectants can sometimes be toxic to the cells, and can sometimes impact their viability. This is really a critical process that needs to be mastered in order to protect the efficacy of your product.”

Predictability, Stability, and the Importance of In-House Expertise

Another important facet of establishing a cold chain process is in validating its predictability. Defining the critical parameters of the process, from the time and temperature to the concentration of cryoprotectant, as early as possible allows researchers to iterate without heavily impacting a product’s viability. “For allogeneic therapies in particular, the challenge is in producing as much as possible,” Lequertier told BioProcess Online. “Identifying equipment that can manage hundreds or even thousands of doses and cryopreserve them is a big challenge for the future.”

CAR-T cells are very stable when stored at low temperatures. The trickier step in the process comes with shipping the product to a clinical site, as this is when it must come in contact with cryoprotectants that can compromise its efficacy: “I would say the viability of the cells that come in contact with the cryoprotectant is a couple of hours, so the difficulty is really focused there.”

As with any transformational additions to a process, incorporating cryopreservation into cell therapy production comes with a significant up-front investment. Beyond cryogenic equipment is expertise in cryopreservation, as well as investment in safety measures, training, and other costs associated with implementing these technologies in a production paradigm. “You can have a lot of money in the cryogenic tanks, in manufacturing and management, in all those assets, and the support of the equipment suppliers, but what you really need is expertise in the cryopreservation process,” Lequertier says. “Because it’s included in the manufacturing process of your CAR-T, it needs to be properly controlled, validated, and monitored.”

Comparing a cell pre- and post-cryopreservation for changes is a difficult ask, according to Lequertier, but from what Celyad has been able to observe, its cold chain process has not impacted the viability of the CAR-T therapies it produces. Simplification and scale-up for the process remains the biggest challenge for cryopreservation in the cell therapy space, Lequertier says, but the need to optimize these technologies will only grow alongside the therapies themselves. “All of the players – manufacturers, suppliers, the clinical side – should continue to invest in this area.”

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