Navigating Current Standards and Compliance for Cell and Gene Therapy (CGT) Storage Containers

Pharmacopeial Standards

The USP has written multiple chapters detailing requirements for plastic packaging systems used in pharmaceuticals. Because CGT standards have yet to be written, these pharmaceutical standards serve as a benchmark for CGT storage container selection:

• Chapter 661 provides guidance on plastic packaging systems and their materials of construction to ensure safety and efficacy. This introduction highlights factors that may influence material suitability, including polymer composition, additives, and testing protocols for safety and efficacy.
• Chapter 661.1 Plastic Materials of Construction focuses on analytical techniques like infrared (IR) spectroscopy and differential scanning calorimetry to identify polymers, and stresses that all materials should comply with U.S. Food and Drug Administration (FDA) standards for indirect food additives.
• Chapter 661.2 Plastic Packaging Systems for Pharmaceutical Use emphasizes the need for chemical and toxicological safety assessments for packaging systems to ensure patient safety, outlining specific testing methods and compliance standards for extractables, leachables, and material suitability.
• Chapter 671 Performance Testing addresses physical performance, including mechanical strength and barrier properties.
• USP 1663 and USP 1664 provide essential guidelines for extractables testing and leachables assessment, establishing safety standards for pharmaceutical packaging and delivery systems. These guidelines emphasize the need for thorough evaluation of potential interactions between drug formulations and packaging materials.

Combined, these chapters emphasize the importance of non-reactivity, material integrity, and compatibility with biologic products to prevent contamination and ensure product stability. However, they may leave some container questions unanswered, specifically to CGT applications.

Legal and Regulatory Requirements

Regulatory agencies, including the FDA, have specific statutory mandates for storage containers that may not be specific to CGT, yet are informative:

The Container Closure System Guidance issued by the FDA's Center for Drug Evaluation and Research (CDER) and Center for Biologics Evaluation and Research (CBER), ensures that containers must meet safety and efficacy standards before drug administration.

Statutory Requirements:

• Section 501(a)(3) of the Federal Food, Drug, and Cosmetic Act deems a drug adulterated if its container introduces harmful substances.
• Section 502 addresses misbranding issues due to packaging omissions.

Container Closure Integrity Testing

Container Closure Integrity (CCI) testing evaluates the ability of a packaging system to maintain a sterile barrier and prevent contamination throughout the product's lifecycle. This process is essential for ensuring the safety, efficacy, and quality of drugs and biologics. CCI testing methods can include physical approaches, such as vacuum decay, pressure decay, and helium leak testing, as well as microbial ingress studies. These tests are typically conducted during development, manufacturing, and stability studies to verify the packaging system's performance under various conditions, including extreme temperatures and mechanical stresses. By identifying potential vulnerabilities, CCI testing plays a crucial role in mitigating risks and ensuring compliance with regulatory requirements.

Storage and shipping temperatures have been shown to majorly impact container performance, and maintaining CCI during extreme temperature fluctuations within a manufacturing process (sometimes as wide as 233°C) with added physical challenges is not an easy feat. Glass vials with elastomeric closures and screw cap cryovials, for example, have been found to be suboptimal at cryogenic temperatures due to differential dimensional changes at low temperatures. (4)

Non-Reactive Nature of Containers

For CGT storage containers, the non-reactive nature is non-negotiable. Containers must:

• Avoid leachable-induced reactions: Prevent leachable constituents from adversely affecting the product. Materials with low levels of leachables, such as Cyclic Olefin Copolymer (COC), have been found to help developers meet this criterion.
• Preserve cell viability and functionality: Ensure minimal impact on cell phenotype, recovery, and viability, considering:
  • Structural properties
  • Material composition
  • Processing conditions, including time and temperature

Particulate Risk Reduction

The presence of particulates in final drug delivery is a known problem in the pharmaceutical industry. EP 2.9.20 & EP 5.17.2 (Visible Particulates) or USP <1>, <790>, <1790> are current guidelines written to help drug manufacturers understand, navigate, control, and remedy the different sources of particulates within their manufacturing process. However, with CGTs, the product itself is essentially a particulate - how do you filter out or avoid the unwanted particles? Additionally, small or single unit lot sizes make statistical evaluation of particulate levels, as recommended in the referenced USP chapters, challenging.

Figure 1 (Left). PDA Journal of Pharmaceutical Science and Technology's life-cycle approach to visible particulate contamination control that addresses the prevention, inspection, identification, and remediation of visible particulate contamination. (2)

Figure 2 (Right). Example of particulate detection within a CGT vial in front of a black backing board under bright lights.

Inspection Standards

Visual inspections are critical to maintaining quality control. The FDA's Guidance for Inspection of Injectable Products for Visible Particulates has helped standardize inspection parameters like:

• Cleaning: External cleaning of containers using isopropyl alcohol and wipes to remove particulates.
• Inspection Setup: Conduct inspections with a black-and-white board under lighting intensity of 2000-3750 lux.
• Technique: Swirl and invert solutions to suspend particulates, inspecting for approximately 10 seconds under both backgrounds at a 45° angle to the light source.

Figure 3. Example of a visual inspection setup for injectable products with a black-and-white board under bright lights.

Visual Inspection Expectations

The FDA's Guidance for Inspection of Injectable Products for Visible Particulates lists the following criteria to ensure thorough quality assessments:

• 100% Defect Inspection: All containers should be inspected for particulate matter (≥50µm), structural integrity, color consistency, and volume accuracy.
• Defect Classification: Define and separate unit-level and lot-level defects.
• Standardized Process Controls; establish requirements for:
  • Light intensity and background contrast
  • Inspection rate and movement
  • Magnification levels

These rigorous standards ensure that containers meet the stringent requirements of CGT storage.

Figure 4. BioLife Solutions' new CellSeal® CryoCase™ rigid storage container is transparent, making it easier to spot unwanted contaminants and particulates. The above figure compares a standard TAPPI inspection chart viewed through a cryobag and the CellSeal CryoCase.

Conclusion

The storage of cell and gene therapy products demands uncompromising standards to protect the viability and safety of these groundbreaking therapies. By evaluating container options against USP and/or EU Pharmacopoeia guidelines, legal regulations, and rigorous inspection protocols, stakeholders can ensure the reliability and performance of their storage containers, paving the way for successful therapeutic outcomes. Until we can eliminate the source(s) of particulates, implementing an inspection standard and life cycle control plan for storage containers will help reduce risk to the patient. Particulate control is and will continue to be an area of focus for BioLife Solutions.

Need help assessing or navigating any of the guidelines listed above? Consult our team of scientists with experience in these endeavors.

References

1. Durand, Nisha, et al. "Particulates in CGT Guidance Survey Results - An ISCT Process Development and Manufacturing Committee Perspective on Cell and Gene Therapy Industry Knowledge Awareness." Cytotherapy, International Society for Cell & Gene Therapy, 2024, pp. 1-8.

2. Figure 1: PDA JPST May 2020, 74(3) 359-366; DOI: https://doi.org/10.5731/pdajpst.2019.010462

3. Intertek. "USP 1663 & USP 1664 Extractables & Leachables." Intertek Pharmaceutical Services, https://www.intertek.com/pharmaceutical/analysis/usp-1663-usp-1664-extractables-leachables/ (accessed January 3, 2025).

4. Kirkland, Douglas J., et al. "Visual Inspection and Particulate Control in Cell Therapy Products." PDA Journal of Pharmaceutical Science and Technology, vol. 72, no. 4, 2018, pp. 367-379. https://journal.pda.org/content/72/4/367.

5. United States Food and Drug Administration. Pharmacopeia Standards for Storage Container Selection. U.S. Department of Health and Human Services, 2025, www.fda.gov/media/162175/download.

6. United States Food and Drug Administration. Container Closure Systems for Packaging Human Drugs and Biologics: Guidance for Industry. U.S. Department of Health and Human Services, 1999, www.fda.gov/media/162175/download.