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Manufacturers must address scale-out challenges of autologous cell therapy for commercial manufacturing.
Although only a few cell-therapy treatments have regulatory approval, recent years have seen a sharp increase in the number of treatments in development, many are now moving rapidly from late clinical stage to commercialization. Most approved autologous (i.e., patient-specific) cell therapies are being produced for small numbers of patients in laboratory facilities. To support the accelerating commercialization of autologous cell-therapy products and to provide wider access to these innovative treatments globally, cell-therapy manufacturers are increasingly scaling out production.
There are various operational challenges that production facilities face. The following sections discuss how these challenges are being addressed in a rapidly evolving environment.
Sterile processing. The manufacture of cell therapy products must address the requirements for sterile processing. Cell therapy products are administered to patients via a leukapheresis process, and products are not sterile filtered or terminally sterilized prior to filling. Process operations and room classification, therefore, must take into consideration the requirement for sterile processing, with process operations driving the room classification.
Product testing. Numerous in-process and final-product release methods must be applied to cell therapy products to verify that the process can produce the products within the desired critical quality attributes. Many cell therapy products are fragile preparations that must be shipped and applied to a patient rapidly.
This time pressure means that standard product release testing procedures are not feasible. In particular, sterility testing often cannot be completed before patient treatment. This unique challenge in cell-therapy manufacturing requires tighter environmental and handling controls to greatly reduce the risk of sterility failure.
Batch variation. Additionally, each dose of a cell therapy product is a single batch and is derived from a different source. Although the cell type will be the same for a given therapeutic approach, the cells from different patients will still behave differently when cultured. Source material will contain a variety of cell types with varying growth and differential capacity. Therefore, the duration of cell expansion and the overall cell product manufacturing timeframe for each batch may vary.
Scale out. The scale-up of autologous cell therapy manufacturing does not result in the use of larger equipment, but rather, the increased handling of small, laboratory scale equipment. Therefore, to increase the manufacturing capacity of the cell therapy facility, the facility and operations require “scale out,” which requires the introduction of additional stations and/or suites to support cell therapy manufacturing for an increased number of patients.
Cell therapy processing involves multiple operation and process steps that can be performed in different room classifications, based on the open versus closed process steps being performed. The primary operations may include:
Support operations include quality control/quality assurance (QC/QA) laboratories, warehousing, and utilities generation/supply.
An additional challenge facing cell therapy facility operators is the fact that key process equipment used for cell therapy operations, such as cell washer, cell counter, cell separation, cell selection, and controlled rate freezing, is not standard equipment typically used in the production of therapeutics and vaccines.
This equipment is new to the good manufacturing practice (GMP) manufacturing environment and will require a robust validation and generation of procedures for operation and control. Additionally, this equipment is new to the regulatory agencies and may result in a more detailed review to confirm the use in cell processing. Primarily, cell therapy equipment is benchtop design with an internal process control system for operation, and connections and transfers between the process equipment and steps are manual.
Additionally, the design and layout of early-phase clinical autologous manufacturing facilities is different from late-phase clinical and commercial manufacturing facilities. The production of clinical cell therapy product is typically done in a single lab limited to one or two biosafety cabinets that allow for simultaneous production of two patient products at a time (one in each biosafety cabinet). All open manipulations are performed in the biosafety cabinet, and the products may be expanded in a common incubator, providing that each patient product is located on a separate shelf.
The production of autologous product in a launch or commercial manufacturing facility setting has expanded to large ballroom/single room design process suites with more than six stations for cell expansion. All process operations are functionally closed, with limited to no use of biosafety cabinets. Expansion may occur in either incubators, with each patient product located on a separate shelf, or in rocker bioreactors, with each dedicated to a single patient. All connections made to the rocker bioreactors are through sterile tube-welding aseptic connections, enabling the ISO 8/Grade C room classification. Separate process suites are provided for isolation, cell expansion/harvest, for antibody and viral vector preparation, and for filling. If the process if fully closed, filling may be performed in the expansion/harvest suite.
There is a need for a greater focus on the ballroom design to mitigate the risk of mix-up and contamination. A full evaluation of the flow of apheresis, in-process and final product, samples, solutions, raw materials/consumables, and waste should be performed.
In general, there is limited to no flow of process equipment, nor the provision of an equipment wash area because single-use process systems are primarily used that are received pre-sterilized. Regulatory preference is for the flows in and flows out operations of the process suites to be unidirectional. Therefore, airlocks for material in and out and personnel in and out should be provided. Dynamic pass-throughs may be provided for the transfer of in-process product, final product, and samples.
The need to define a biosafety boundary is driven by the use of viral vectors and, as appropriate, the processing of human cells. The classification of the viral vector, the process operations performed, and the rooms where the handling of the viral vector occurs must be considered to determine if the processing requirements must be good large scale practice (GLSP) or biosafety level (BSL) 1, 2, or 3.
Handling of BSL 2 or higher viruses requires provision for waste decontamination. BSL2 allows for the transfer of contained waste to external facilities either on-site or off-site for waste decontamination. BSL3 requires waste treatment prior to exiting the biosafety boundary.
Typically, viral vectors are purchased from contract manufacturing organizations and, therefore, only require limited processing prior to addition. In general, viral vector processing in the cell therapy facility is limited to thawing, transfer to syringe/addition device, and addition to the cells during expansion.
Due to the high demand for viral vectors, cell therapy facilities are considering that they be manufactured in-house, which raises the need to provide separate suites with the appropriate biosafety classification and design controls. Dynamic pass-throughs may be provided to enable transfer of the prepared viral vectors into the cell processing suite.
Media and buffers required for cell therapy manufacturing may be purchased preformulated or prepared within the facility. A common solution preparation area may support multiple cell therapy processing suites. Single-use systems are commonly used for the preparation of media and buffer solutions. The bags of media and buffers are transferred into the process suites for addition to the product during processing.
Kitting areas are provided for the preparation of materials and consumables as they transition from the warehouse to each process suite. A common practice is to prepare a single kit for each station in the process suites. In relation to kitting, best practices in these facilities involve provision for:
Provision of a common kitting area minimizes the sanitization procedures that would need to be performed in the airlock for transition of the supplies into the process suite, because only a final, overall sanitization of the external kit container needs to be performed in the airlock.
As an example, a client’s US-based autologous manufacturing facility provides space to produce both late-stage clinical and commercial cell therapy products. The facility is a multiproduct cell therapy facility with initial focus on chimeric antigen receptor T-cell (CAR-T) manufacturing.
All open batch manipulations occur within BSCs located in ISO 7/Grade B rooms, and all processes utilize sterile, single-use equipment. All other processing occurs in ISO 8/Grade C cleanrooms. The primary manufacturing process operations consist of isolation and freezing, thaw, initiation and transduction, expansion, harvest, and freezing. Support operations include materials receipt, solution preparation, kitting, apheresis receipt, product shipping, and QC testing.
The facility has five, independent cell process suites; all are accessed from a common CNC corridor. Each suite has unidirectional, in-and-out airlocks for materials and personnel. Process support suites within three of the cell therapy suites support the preparation of antibody and viral vectors.
Viral vector preparation is limited to thaw and open transfer to appropriate devices for transduction/addition to cell expansion. Dynamic pass-throughs are provided for the transfer of the antibody and viral vector into the cell therapy suite.
Multiple stations for different operations within the cell therapy suite include six for initiation, 10 for expansion, and three for harvest. At the completion of harvest, if the cell count is appropriate, patient product is filled into bags via closed addition and transferred for freezing.
The design of each process suite took into consideration the need for required segregation at each station to prevent risk of mix-ups, utilization of closed processing to prevent product contamination and cross-contamination, use of closed processing to support classification of the process suite as ISO 8/Grade C, in-process testing, staging of materials within each station, and unidirectional flows in and out of the suites.
QC laboratory space is located on the second floor of the facility. All waste is placed in closed containers and is transferred out of each suite via separate waste airlocks to the waste holding area. Waste is transferred offsite for treatment. Separate rooms are provided for in-process product freezing and final product freezing, all in liquid nitrogen freezers.
Because autologous cell therapy manufacturing facilities are new and differ from the more traditional monoclonal antibody (mAb) therapeutics and vaccine manufacturing facilities, cell therapy facility operators need to give consideration to a presentation to the regulatory agency during the early phase of the design process.
Typically, presentations to FDA for a Type C meeting involves submitting a written report that fully describes the products, operations, and facility and defines key questions that the manufacturer requires regulatory feedback on as part of their review and facility drawings. The Type C meeting can provide strong confidence that the design is acceptable or identify what risks or changes should be considered. Key aspects that have been defined by FDA in Type C meetings for both clinical and commercial manufacturing cell therapy facilities include:
Within FDA, manufacturing of cellular therapies is reviewed in the Division of Cell and Gene Therapies in the Office of Cellular, Tissue, and Gene Therapies, and there are two separate product review branches, one for cell therapies and one for gene therapies.
Within the structure of the European Medicines Agency (EMA), the Committee for Advanced Therapies (CAT) plays a central role in the scientific assessment of advanced therapy medicines. It provides the expertise that is needed to evaluate advanced therapy medicines.
Additionally, the international regulatory requirements that apply to the manufacture of cell therapy products include guidance from FDA (1–4), EMA (5), and the National Institutes of Health (6).
The operational and regulatory challenges facing cell therapy operators are numerous and complex. These include the need for sterile processing and for cell therapy products to be shipped and applied rapidly. Adding a layer of complexity is the fact that testing often cannot be completed before patient treatment, which requires tighter environmental and handling controls. Also, as equipment is new to the GMP manufacturing environment, it requires validation and regulatory review, while from a design perspective there is a need for a greater focus on the ballroom design to mitigate the risk of mix-up and contamination.
From a regulatory perspective, cell therapy manufacturers should present to the relevant regulatory agency during the early phase of the design process. This proactive engagement will ensure that the manufacturer will receive a detailed review from regulators and that all key issues are addressed. In turn, this review provides strong assurances that the design is acceptable or can identify risks or what changes should be considered.
1. CFR Title 21, Current Good Manufacturing Practices, Parts 600 and 610 (April 2020).
2. FDA, Guidance for Industry. cGMP for Phase 1 Investigational Drugs (July 2008).
3. FDA, “Current Good Tissue Practice for Human Cell, Tissue, and Cellular and Tissue-Based Product Establishments; Inspection and Enforcement,” Final Rule, Federal Register, 69 FR 68611-68688.
4. FDA, Guidance for Industry. Sterile Drug Products Produced by Aseptic Processing–Current Good Manufacturing Practice (September 2004).
5. EC, Eudralex Volume 4: Good Manufacturing Practice Guidelines, “Guidelines on Good Manufacturing Practice Specific to Advanced Therapy Medicinal Products,” (Brussels, 2017).
6. CDC, Biosafety in Microbiological and Biomedical Facilities, 5th Edition (December 2009).
Francesca McBride is director of Regulatory Compliance at Jacobs, Francesca.McBride@Jacobs.com.
Vol. 33, No. 7
When referring to this article, please cite it as F. McBride, "Overcoming Operational and Regulatory Challenges in Autologous Cell-Therapy Facilities," BioPharm International 33 (7) 2020.