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Adapting Development Guidelines for Advanced Therapies

by Rebecca Stauffer, PDA | Apr 29, 2014
Traditional pharmaceutical manufacturing is very familiar to all of us. It is easy to picture the conventional setup whereby a company maintains a facility involving large batch manufacturing in an assembly line fashion, manages extensive supply chains and creates product with lengthy shelf lives.

Traditional pharmaceutical manufacturing is very familiar to all of us. It is easy to picture the conventional setup whereby a company maintains a facility involving large batch manufacturing in an assembly line fashion, manages extensive supply chains and creates product with lengthy shelf lives.

The picture for advanced therapy products is much different, emphasized Wilfried Dalemans, PhD, Chief Technical Officer, Tigenix, during his presentation at the 2014 PDA Annual Meeting (1).
“It’s not like pills or small biological molecules where the processes are well established,” he said. “When you are in the cell therapy world, your manufacturing [environment] looks more like a cell culture lab than a high tech manufacturing facility. So, it makes the approach quite different from the classical approach.”

Tigenix is a small Belgium-based biotech company founded in 2000. A few years ago, the company developed ChondroCelect, a cell-based medicinal product comprised of autologous cartilage cells. The product is used to repair knee cartilage defects in adults. This was the first cell therapy product to receive approval from the EMA. Production begins with a biopsy of the patient to extract cells. These cells are then manufactured in a controlled environment before being administered to the patient.

Adapting Development Guidelines for Advanced Therapies

The company also has another product—Cx601, a stem cell therapy—that is in Phase III development. This therapy would treat patients’ fistulas from Crohn’s disease. Two other stem cell treatments would treat autoimmune disorders.

Dalemans focused his talk on the company’s ChondroCelect product.

“First of all, cells have a very complex composition,” he said. “Very important also, its living material so all kinds of biochemical processes can take place in your product. And of course, everyone who works with cells knows they’re very fragile.”

This means traditional purification or sterilization methods cannot be used.

“On top of this, these products have a very short shelf life,” Dalemans emphasized.

Cell Variabilities Present Further Challenges

During development, process validation of autologous material proved to be a challenge due to the fact that each product was essentially different. Autologous cells are extracted and then reinserted into the same donor as opposed to allogeneic cells which are extracted from individuals other than the recipient. These autologous cells are unique to each individual patient, and thus possibly have different baselines for each patient. In response, his company chose to conduct a splitted biopsy sample approach together with parallel runs of individual biopsies for defining critical parameters.

“This gave us quite a comprehensive data package, despite the individual variability of the cells,” he said.

For the selection of critical quality attributes (CQAs), he explained that his team relied on their knowledge of cell biology, since most have worked closely with cells for a long time and they “know what the key quality parameters of your cells are.”

His group enlisted many different biological tests relevant for chondrocytes and each of them pointed in the same direction, indicative of thorough quality processes. He also pointed out that for complex products like cells, it’s important to not focus solely on one critical attribute but instead combine several of them.

“In addition, since many of the tests are biological assays, assay development and validation is also a challenging step,” he added.

Dalemans then described extensive product characterization as one of “the holy grails of cell therapy.” Ultimately, the company wanted the product to be used to regenerate healthy cartilage—creating high quality cartilage in patients. To achieve this potency target, his company looked at in vivo models, culture assays at the cellular level and marker analysis at the molecular level.

Short Shelf Lives, Sterility Testing are Poor Match

“Another important point is sterility testing,” he said.

This proved to be a challenge due to the 48-hour shelf life of the product, especially when it came to meeting the sterility requirements of the European Pharmacopoeia. After speaking with regulatory authorities, his team chose to develop the product in an aseptic process while conducting multiple testing (“intermediate sterility testings”) during manufacturing and anticipating final release testing by conducting a sterility test very close to the end of product formulation just before it is administered to the patient.

His team still conducts the compendial sterility test, but data becomes available only 14 days after product release and administration the patient.

In speaking to the PDA Letter following his presentation, Dalemans expanded on the challenges with sterility testing: “We have been thinking about using rapid sterility testing but you still need to perform a culture step for a certain amount of time, ranging between four to seven days. It thus still takes you beyond the end of the shelf life, so, yes, you have your results more rapidly but it’s not yet that rapid that you could say ‘I can release my product on the real data of the sterility test.’ It is improving but it is not solving the problem at this stage.”

His company, however, is looking further into newer tests under development.

“We have for instance been looking to a technology that looks directly into the cell suspension to see if bacteria are present, but results showed that this can only be done with quite clear solutions. When you have a cell suspension that’s loaded with cells and other molecules, there’s too much interference.”

The intermediate sterility tests Tigenix uses are, at the moment, the most suited method for ensuring the safety of the product because “having multiple sterility checkpoints together with a sterility test two or three days before the product is shipped, could eventually have major contamination issues already detected, and so feel comfortable that the sterility of the product is ensured.”

Dalemans also added that “at the end of the day, your sterility test is only a test. Having the sterility done is in your methods and your process, so the focus on the process verification and media fill is really where you try to guarantee at best your sterility.”

Cell Manufacturing Considerations

In his presentation, Dalemans also delved into the variety of logistical challenges presented by short shelf life with temperature sensitivity.

“With this short shelf life there is also highly managed logistics,” he said. These cells require specific temperatures. In addition, care has to be taken to avoid being irradiated if the cells are transported through an airport. This requires closely coordinating with the logistics provider.

“Also, an important point is manufacturing standardization,” Dalemans said. His team takes a lead role in training the surgeons removing the cells from patients as “they play a key role in extracting the starting material,” which needs to comprise high-quality cells.

Before concluding his talk, Dalemans explored some of the unique GMP aspects of producing cell therapies.

“Each batch is one product which means you’re working on a small scale,” he said. The development process is even more unique as you can have operators conducting many operations in parallel. But regulators want to see a quality-driven process even though each batch is different.

“So, it’s very important that you take into account that there is good separation of the individual biopsies,” Dalemans said. In addition, each batch will feature cells with different rates of growth, so, “when you’re planning, you need to take this into account.”

Due to the parallel production of different cell lines specific to individual patients, prevention of cross contamination is very critical and it’s important to have good line clearance.

In the Q&A following his talk, Dalemans went into greater detail regarding the Phase III development process, describing how extensive analysis of patient data plus product characterization allowed him to differentiate his product from other available therapies in discussions with regulators.

An audience member asked how the company ensures that cells extracted from a healthy patient do not lead to mutagenicity. Dalemans’ explained that the conditions his company’s cells are grown in use such a short time frame that potential mutagens are unable to grow during that time. His team also conducts expansion tests and other studies to address potential mutagenicity.

Additionally, Tigenix follows up with patients receiving ChondroCelect for five years to ensure the long-term health of patients.

Doctors Need Training Too!

Following the session, the PDA Letter asked Dalemans if he could describe differences between the U.S. and EU markets for advanced therapies. He said he does not see much variation, however, he noted that until recently there was less clarity on the regulation of these types of products in Europe compared to the United States. In the latter, these products fell under the BLA system and the U.S. FDA also issued a guidance for these products early on.

He also believed that the U.S. marketplace is perfectly conducive to the development of advanced cell and gene therapies, and pointed to the number of successful companies currently developing such products in the United States. In fact, he added, his company has no plans to market ChondroCelect in the United States because a similar product is already under development by a U.S. company.

Dalemans also provided additional insight into Tigenix’s role in training the surgeons who initially extract the cells from the patient. While medical doctors in certain specialties such as oncology regularly perform biopsies, the doctors extracting cells for the ChondroCelect product are orthopedic surgeons, who do not routinely conduct biopsies.

“When you put it into the orthopedic world, there is not much, let’s say, routine applications where you would take biopsies,” Dalemans explained. Depending on the product, his company works with surgeons in a variety of specialties.

“We have a program with stem cells running for Crohn’s disease, there we work with surgeons who do gastrointestinal surgery, so we really work with specific classes of surgeons who are used to working with the region where the cells have to go. In a lot of these applications, they are not used to taking biopsies,” he said.

The company did not immediately plan to train the doctors, but soon found out the hard way. Prior to careful training, the orthopedic surgeons compromised the quality of the starting material by biopsying cells while cleaning patient’s lesions.

“Well, you should realize this material that comes out of the lesion is inflamed and so on, and this is not the best material,” Dalemans explained. Orthopedic surgeons are not as familiar with extracting high quality cell material since they “don’t think that way.”

“You need to educate them. Say, ‘listen, if you want us to produce this in a decent amount of time with good cells, please provide us with a decent amount of starting cells, otherwise it will take five months before we can grow enough cells.’ So that’s the education.

“Education even in the administration of cells is very important as well,” he said, citing cases where surgeons have taken frozen cell therapy products and put them in microwave ovens to warm up; room temperature is the only way to prepare the products for administration.

Adapt the Rules for Future Medicines

While it can be challenging to follow CMC guidelines for manufacturing cell therapies, Dalemans recommended that companies involved in this area look at it as taking the CMC rules used for traditional products and then “translating” these rules to suit development of cell therapies.

Personalized medicines and other ATMPs present the future of drug development so this will mean working closely with regulatory authorities and close collaboration within industry to tackle these challenges.


  1. Dalemans, W. “Cell and Gene Therapy.” Presented at the 2014 PDA Annual Meeting, San Antonio, TX, April 2014.

About the Expert

Wilfried Dalemans is Chief Technical Officer at TiGenix, Belgium. He is responsible for the global technical operations of the company, encompassing coordination of product development and lifecycle in R&D and Industrialization, and overseeing the clinical and commercial manufacturing operations of the company.