Published on 01/12/2025

Stability & Hold-Time in ATMP: What’s Defensible

Advanced Therapy Medicinal Products (ATMPs) represent a significant advancement in therapeutics, providing treatments for conditions that were previously challenging or impossible to manage. The validation of these products, particularly in the context of stability and hold-time, is crucial. In this guide, we’ll explore the methodologies and regulatory expectations surrounding stability studies, hold-time evaluations, and their relationship to the principles of process validation (PPQ) and commercial process validation (CPV) within the framework of the FDA, EMA, and MHRA guidelines.

1. Overview of Stability Studies in ATMP Development

Stability studies are integral to the development of ATMPs, as they ensure that products maintain their quality, safety, and efficacy throughout their shelf life. This section outlines the critical components of stability studies and the applicable regulatory frameworks.

1.1 Definition and Importance of Stability Studies

Stability studies assess how the quality of a drug substance or drug product varies with time under the influence of environmental factors such as temperature, humidity, and light. For ATMPs, stability is particularly important because these products often involve complex cellular and molecular components that require strict control to ensure they remain viable and effective.

1.2 Regulatory Guidelines and Requirements

Various guidelines provide the framework for stability studies in ATMPs, notably:

• FDA Guidance for Industry: Q5A(R2) – This document outlines the requirements for the stability of biotechnological and biological products.
• European Medicines Agency (EMA) Guidance on ATMPs – This guidance elaborates on stability testing specific to ATMPs.
• MHRA Guidance on Clinical Trials and Advanced Therapies – It emphasizes the importance of stability in the context of clinical trials.

These documents collectively recommend that sponsors generate comprehensive stability data to support product claims and regulatory submissions.

2. Understanding Hold-Time Studies for ATMPs

Hold-time studies evaluate the time a drug substance or drug product can be stored under specified conditions before further processing or administration. This section delves into the planning, execution, and analysis of hold-time studies.

2.1 Designing a Hold-Time Study

When designing hold-time studies, several factors must be considered, including the nature of the ATMP, the storage conditions, and the intended use of the product. Hold-time studies must be designed to simulate real-world conditions as closely as possible to ensure relevance.

Key components of hold-time study design include:

• Selection of Test Conditions – Choose environmental conditions that reflect storage and transport scenarios.
• Time Points – Determine appropriate intervals for testing (e.g., 0, 24, 48 hours).
• Sample Size – Ensure a statistically significant number of samples for reliable data.

2.2 Data Collection and Analysis

Data collection in hold-time studies often involves measuring critical quality attributes (CQAs) that relate to the product’s potency, identity, and purity. Contemplating CQAs, especially those associated with cellular products, is crucial for demonstrating that the product remains within acceptable limits. Analytical methods must be validated and stability-indicating, ensuring they can accurately reflect any changes in the product during hold times.

2.3 Regulatory Considerations

Regulatory agencies expect sponsors to provide robust data demonstrating that the hold-time conditions do not adversely affect product quality. This includes thorough documentation and justification for the chosen methods and conditions based on guidelines such as ICH Q1A, Q5A(R2), and specific EMA and MHRA expectations.

3. Viral Clearance Validation in ATMPs

Ensuring viral safety is critical for ATMPs, especially given their biological origin and sensitive nature. Viral clearance validation involves techniques that demonstrate the product’s ability to reduce or eliminate viral contamination. This section discusses methodologies and validation approaches.

3.1 Key Principles of Viral Clearance Validation

Viral clearance validation typically involves several key principles:

• Assessment of Viral Risks – Identify potential viral contaminants based on sourcing and production processes.
• Application of Validated Clearance Techniques – Implement techniques such as filtration, inactivation, and affinity purification.
• Use of Control Studies – Employ spiking studies to mimic viral contamination and validate clearance mechanisms.

3.2 Regulatory Framework for Viral Clearance

The expectations for viral clearance validation are delineated in various regulatory guidelines, including FDA guidelines on viral safety and EMA’s guidance on viral clearance for biological products. It is essential to adhere to these guidelines to ensure consistency and regulatory acceptance.

3.3 Conducting Spiking Studies

Spiking studies are practical experiments where a known quantity of virus is added to the ATMP sample. This step involves several crucial elements:

• Establish the virus strain for spiking, which should reflect the types of viruses that may pose a risk to the product.
• Determine appropriate analytical methods for quantifying viral load pre- and post-treatment.
• Evaluate various scales of filtration or inactivation processes to select appropriately effective measures.

4. The Role of Closed and Single-Use Systems in ATMP Validation

Closed systems and single-use systems present significant advantages in the manufacture of ATMPs. These systems help in reducing contamination risk and improving efficiency. This section outlines their role in ensuring compliance with regulatory expectations.

4.1 Advantages of Closed Systems

Closed systems are designed to minimize the risk of contamination during the manufacturing process. By maintaining aseptic conditions throughout processing, these systems support regulatory compliance with Aseptic Controls Annex 1 requirements.

4.2 Implementation of Single-Use Systems

Single-use systems facilitate the reduction of cross-contamination between batches and eliminate the need for extensive cleaning validation, which is particularly beneficial in viral clearance applications. Key considerations include:

• Integration with Process Validation – Ensure that single-use components align with process validation principles during PPQ evaluations.
• Supplier Qualification – Evaluate suppliers to confirm that components meet specific regulatory standards and material requirements.

4.3 Regulatory Validation for Inline Systems

Regulators expect comprehensive validation for closed and single-use systems, demanding clear documentation demonstrating that these systems can consistently produce safe and effective ATMPs. Adherence to the requirements set forth in the FDA and EMA guidance documents will bolster confidence in these systems.

5. CQA and Chain of Identity Custody in ATMPs

Control over CQAs is paramount in ensuring product integrity and compliance. This section explores how to establish a chain of identity custody and ensures that all CQAs are met throughout the lifecycle of ATMP production.

5.1 Identifying and Defining CQAs

Critical Quality Attributes (CQAs) for ATMPs must be carefully defined. These attributes typically include potency, identity, purity, and safety. To effectively monitor CQAs, continuous assessment through analytical testing must be integrated throughout the production process.

5.2 Establishing the Chain of Identity Custody

The Chain of Identity (COI) is crucial for ensuring that ATMPs are not compromised during development, processing, or distribution. Implementing a thorough COI strategy includes:

• Traceability – Maintain records of all materials and processes used in ATMP production.
• Documentation of Testing – All testing data must be accurately documented and easily accessible for verification.
• Compliance with Regulatory Guidance – Ensure adherence to regulatory expectations related to the management of CQAs.

5.3 Regulatory Expectations for CQA Management

Regulatory entities expect detailed submission of CQAs and COI measures in product development filings. This includes documentation of compliance with relevant guidelines established by the FDA, EMA, and MHRA.

6. Conclusion: Ensuring Robust Validation for ATMPs

Effective validation of Advanced Therapy Medicinal Products relies on a solid understanding of stability and hold-time protocols, viral clearance validation, and stringent compliance with regulatory guidelines. Integrating principles such as CQAs, the Chain of Identity, and the implementation of closed/single-use systems contributes to ensuring ATMPs are safe, effective, and ready for patient use.

As the landscape of ATMP development evolves, remaining abreast of regulatory changes and emerging practices is essential for professionals involved in pharma, clinical operations, regulatory affairs, and medical affairs. Applying these best practices facilitates successful submissions and ensures the continued safety and efficacy of critical therapies.