ICH Q5C Stability testing of biotechnological/biological products

ICH Q5C is the harmonized guideline for stability testing of biotechnological and biological products. As the counterpart to ICH Q1A (for small molecules), it addresses the unique challenges of biologics, where stability is tied not just to chemical purity but to maintaining molecular structure and biological activity throughout the shelf-life.

The guideline defines the stability data package needed for a regulatory submission, emphasizing that potency and higher-order structural integrity are central to ensuring safety and efficacy.

Applicability to Advanced Therapies

Q5C was developed for well-characterized protein and polypeptide biologics and it does not formally apply to ATMPs; its concepts may be selectively adapted, but sponsors should rely primarily on ATMP-specific FDA/EMA guidance.

• Relevant carryover concepts: Stability-indicating assays, container–closure evaluation, real-time and stress studies, in-use stability, and batch comparability.

• Key differences: Advanced therapies often require potency assays specific to the vector, transgene, or cell function; stability concerns may involve genome integrity, infectivity, or viability rather than protein structure; storage conditions may involve ultra-low temperatures (≤ –65 °C) or cryopreservation.

• Regulatory sources for ATMPs:

  • FDA Chemistry, Manufacturing, and Control (CMC) Information for Human Gene Therapy INDs

  • EMA Guideline on the quality, non-clinical and clinical aspects of gene therapy medicinal products

Q5C remains a useful reference, but it should be applied selectively and supplemented with product-class–specific guidance for ATMPs.

The ICH initiated a formal process to modernize this foundational guideline to reflect advances in analytical technology and biologics development.

Core Principle

A biologics stability program must demonstrate that the product maintains critical quality attributes—including structural integrity, purity, and potency—throughout storage.

Key Requirements for Biologics Stability

Stability-Indicating Profile (Tests)

• Relevant potency assay is required, with full validation expected by licensure

• Physicochemical tests – Appearance, clarity, pH, protein concentration.

• Purity/impurity tests – Sensitive methods to detect aggregation, fragmentation, and chemical modifications such as deamidation and oxidation.

• Structural characterization tests may be included to confirm stability but are typically supportive rather than routine release tests.

Storage Conditions

• Real-time studies at the proposed long-term storage condition (commonly refrigerated or frozen, but product-specific)

• Accelerated and stress studies stress testing supports method qualification but does not replace real-time stability data for shelf-life claims. Conditions are product-specific and may include elevated temperature, light (ICH Q1B), agitation, and freeze–thaw cycles.

Batches

• At least three representative batches from the intended manufacturing process and scale.

Other Considerations

• Container–closure system – Stability in final marketed package.

• Lyophilized products – Stability in both dried state and after reconstitution.

• In-use stability – If applicable, after opening, dilution, or reconstitution.