Manufacturers of biological products often make changes to manufacturing processes during development and post-approval. These changes are driven by multiple factors, including improving the manufacturing process, increasing scale, enhancing product stability, incorporating new product and process knowledge, changing manufacturing sites, and complying with regulatory requirements. However, process changes can contribute to risks, scientific hurdles, and further regulatory filings. Consequently, manufacturers face the challenge of confirming product comparability between pre- and post-manufacturing changes and ensuring that process changes do not have an impact on immunogenicity or compromise the quality, safety, and efficacy of the product. Therefore, developing a robust, risk-based comparability assessment and following established regulatory guidelines, such as those provided by the U.S. Food and Drug Administration (FDA), are essential for successful implementation of process changes and achieving regulatory compliance.
The Need for Late-Stage Process Changes in Biologic Drug Development
Biologic drug substances, such as recombinant proteins and monoclonal antibodies (mAbs), are highly complex biomolecules manufactured using living systems. As drug candidates progress through the development cycle, increased product and process knowledge often lead to changes in manufacturing operations to enhance yield or product quality or to incorporate novel understandings of the nature of the new biologic drug. These changes may also be driven by evolving regulatory requirements or unforeseen problems that arise during development. Changes can include, but are not limited to:1,2
Process efficiency improvements: Modifying steps to increase output or reduce waste.
Analytical method modifications: Updating technologies or methods to better control, understand and interpret processes.
Raw material adjustments: Switching to higher purity or quality materials or different suppliers due to supply chain disruptions.
Equipment upgrades: Implementing new production equipment to improve efficiency, quality, or timelines.
Scale-up adjustments: Adapting processes to meet higher demand.
Facility relocation: Moving production to different facilities.
Formulation revisions: Adjusting the final product formulation to better meet patient safety and comfort.
Packaging and drug delivery device innovations: Introducing new drug delivery device or primary packaging materials or solutions.
In recent years, the increased use of expedited development programs has led to a rising need for process changes, particularly at later stages of development and even post-commercialization.3 Under traditional timelines, most changes can be implemented during early process development. However, accelerated programs face significant pressure to expedite timelines, often resulting in process improvements being deferred to much later in the development cycle.
Expedited development programs, such as those facilitated by regulatory agencies through various pathways, such as the Breakthrough Therapy designation from the FDA or the Priority Medicines (PRIME) scheme established by the European Medicines Agency (EMA), aim to bring lifesaving drugs to market faster while ensuring patient safety and regulatory compliance. While these programs provide significant benefits, they also pose challenges for process development and manufacturing, as rapid advancements in the clinical phases leave less time for comprehensive optimization early on.
It is essential to carefully plan and execute process changes, including associated risks assessments, to ensure they do not adversely affect the quality, safety, or efficacy of the biologic drug product. Although regulatory guidelines, such as ICH Q5E, provide a framework for demonstrating comparability of biotechnological products subject to manufacturing changes, scientists and engineers must ensure through thorough and proper risk assessment that any modifications made will not impact the product’s clinical performance. By adopting a strategic approach to process changes and leveraging advanced analytical, biophysical, and biochemical technologies, robust comparability protocols should guide biotechnology manufacturers to navigate the dense matrix of complexities of late-stage process modifications while maintaining product integrity and compliance with regulatory standards.
Ensuring Quality and Safety Through Comparability Assessments and Associated Risk
Although minor process modifications are unlikely to lead to a change in product quality, significant amendments to existing processes can cause alterations in the protein structure and intrinsic dynamics, leading to attenuation of the biological activity of the drug. Major process changes can impact the quality, safety, and efficacy of the product, and the potential impact on product critical attributes has been well documented.4
For instance, one study investigated the effects of different process changes on the structure and function of two IgG1 mAb candidates.5 The researchers found that changing the cell line and modifying the upstream and downstream processes affected posttranslational modifications. Furthermore, scale-up, transfer to a commercial production site, and switching from a lyophilized to a liquid final product form did not impact the structural or functional integrity of the mAbs.
While some product modifications may be readily noticeable, others may not become apparent without extensive analysis and testing. Comprehensive comparison of products before and after a process change is crucial.1 It is essential to demonstrate "suitability for use" in early development and "comparability" during later stages, post-approval, and marketing to minimize any risk to patients.3
The requirements for comparability assessments are outlined in several regulations, including:
ICH Q5E: Comparability of Biotechnological/ Biological Products Subject to Changes in Their Manufacturing Process6
FDA Guidance for Industry: Comparability Protocols for Human drugs and Biologics: Chemistry, Manufacturing, and Controls Information7
FDA Guidance for Industry: Comparability Protocols for Postapproval Changes to the Chemistry, Manufacturing, and Controls Information in an NDA, ANDA, or BLA8
The United States Pharmacopeia (USP) chapter <1033>: Biological Assay Validation9
CHMP: Guideline on Comparability of Biotechnology-Derived Medicinal Products After a Change in the Manufacturing Process: Non-clinical and Clinical Issues10
For biologic drugs, manufacturers must demonstrate that any process changes do not impact safety, efficacy, potency, or overall quality, including immunogenicity. The products obtained before and after a process change do not need to be identical, but they must be highly similar. Prior product knowledge should be leveraged as early as possible to support process changes and should include product-specific and cross-product facts, clinical data, internal findings, analytical and biophysical results, and published literature. Based on existing product knowledge, it should be predictable that certain differences in quality attributes may have minimal impact on safety or efficacy of the product, and therefore these quality attributes may not require further testing.
Establishing a Robust Comparability Protocol
To demonstrate comparability, manufacturers must establish a comparability protocol (CP) containing risk assessment. This protocol outlines the methods and processes that will be used to assess the impact of proposed process changes on the primary and higher-order structure, strength, quality, purity, and potency of the drug. The CP should enable manufacturers to communicate the comparability of pre- and post-change batches clearly and concisely to regulators, using robust scientific principles and a thorough understanding of the product.1
The studies included in a comparability assessment depend on the development phase and may involve:
Analytical and biophysical characterization: Detailed analysis to compare the physicochemical properties, primary and higher-order structure, intrinsic dynamic and thermostability of the drug product before and after the change.
Storage and accelerated stability studies: Evaluations of the product's stability over time under various conditions to predict shelf-life and identify any potential degradation pathways.
Forced degradation studies: Deliberately stressing the product to understand its degradation mechanisms and identify stress-related stability issues, either through thermostability or kinetic mechanisms.
Statistical analyses: Using statistical methods to compare data sets and identify those factors and parameters that discreetly or individually impact CQAs with perceptible trends.
A comprehensive analytical package must be defined before initiating any testing. This package should include the methods and acceptance criteria for each test. Stability studies should also be carefully planned and outlined. The number of lots chosen for the comparability exercise is dependent on development phase, and a justification for lot selection should be provided in the CP package. The selection of methods is crucial to ensure a thorough and accurate comparison of the product before and after the process change.11
If the assessment results are inconclusive, further "bridging" studies may be necessary. In the worst-case scenario, this could involve additional clinical studies to ensure the continued safety and efficacy of the product. Careful planning and execution of the CP are essential to ensure that process changes do not adversely affect the drug product or patient safety. This includes early communication with regulators and a clear, science-based approach to demonstrating comparability.
Implementing a Risk-Based, Phase-Appropriate Approach for Comparability Assessments
The primary goal of comparability assessments is to ensure that process changes do not adversely impact the safety, efficacy, or quality of drug products. These assessments generate evidence to support the similar nature of a biological product in the aforementioned parameters before and after process changes. Adopting a risk-based approach for implementation of comparability assessment is therefore crucial.12 Ideally, this should be complemented by a phase-based approach, accommodating the different levels of risk inherent in early- versus late-stage development.3 Such a combined strategy balances the level of risk with the degree of molecular understanding, development time, and cost, guiding the testing strategy effectively.
During preclinical and early clinical phases, platform characterization and screening of limited-scale forced degradation conditions (such as thermal stress studies) may be sufficient.1 As candidates advance to phase II and early phase III studies, more extensive characterization is recommended, including potentially confirmation of the forced degradation conditions, covering a full scale of potential degradation pathways (e.g., oxidative stress, thermal stress, sheer stress, photostability). For phase III to commercial and post-approval stages, extended characterization, including structural, biophysical and biological (potency) comparability, real-time stability, and forced degradation studies, should be employed.
An effective risk-based approach leverages existing product and process knowledge, advanced analytical and biophysical technologies, and protocols based on established regulatory procedures. Early and open communication with regulatory entities is critical to align expectations and reduce uncertainty.3 Utilizing a portfolio of state-of-the-art analytical and biophysical technologies, such as high-pressure liquid chromatography (HPLC), spectroscopy techniques, and computational modelling, can significantly contribute to in-depth understanding of the drug at the molecular level and therefore can help demonstrate comparability and mitigate risks from a process change. Early-phase development technologies, such as multi-attribute methods, process modeling, and accelerated stability studies, can speed up access to process and product knowledge, thereby reducing the risk associated with process changes when combined with standard comparability approaches.
Incorporating a risk-based approach involves:
Risk assessment: Identifying and evaluating potential risks associated with process changes and realistic estimates of plausible impact.
Analytical and biophysical technology utilization: Employing advanced analytical and biophysical methods to detect and characterize any differences.
Regulatory alignment: Ensuring early and transparent communication with regulatory authorities to align on comparability strategies.
Phase-appropriate testing: Adapting the depth and scope of testing to the development phase, balancing thoroughness with efficiency.
By systematically addressing these elements, manufacturers can effectively manage process changes, ensuring continued product quality and compliance with regulatory standards throughout the development and commercialization life cycle.
Developing an Effective and Robust Comparability Assessment Strategy
During accelerated development, managing comparability assessments for multiple process changes across the entire development life cycle can be challenging, particularly for complex biologic candidates. Evaluating the impacts of every process change on various product attributes, including primary, secondary, and higher-order structure, charge variants, posttranslational modifications (PTMs), glycan variants, thermostability, and biological activity, can be time-consuming but is essential for successful comparability assessment during accelerated development.3 Only through systematic and detailed studies, including all aforementioned parameters, can one achieve the goal of demonstrating the virtual identity of the drug before and after process changes.
To ensure an effective comparability assessment (CA) strategy, planning for extended characterization and forced degradation studies should be initiated well in advance of major manufacturing changes.1 Only batches that are representative of the pre- and post-change processes, meeting release specifications, should be selected, and testing should be performed within a short period of time to avoid further differences due to storage changes or data fluctuations.
All CAs should begin with the collection of historical process data and the creation of a comprehensive product profile, including a list of CQAs and clear descriptions of the process changes.11 Potentially affected quality attributes can then be identified by a cross-functional team comprising analytical, process development, manufacturing, quality, and regulatory representatives from the product comparability-assessment team. Once a list of attributes has been defined, the team should determine at what step in the process the comparability assessment should be made for each attribute. While testing is most often performed on the drug substance, in some cases, evaluation may need to be performed on the drug product.
Appropriate analytical and biophysical methods are then selected, and acceptance criteria are set depending on the development phase. Specific product lots are chosen for comparison, with at least two validation batches commonly used for late-stage clinical materials.
Planning and pursuing these activities in advance and establishing a partnership with regulators are both essential to success.3 Access to quick regulatory review of proposed CAs ensures alignment on approaches to demonstrating risk-based comparability and increases the likelihood of acceptance of results.
Leveraging Forced Degradation Studies in Comparability Assessments
Stability studies, including intended storage condition, accelerated or stressed, although not mandatory for CAs, are often highly recommended because most process changes have some risk of impacting the structure, thermostability, kinetic stability, and/or purity of biologic drugs.11 Forced degradation studies have become a crucial component of CAs, as they help determine and understand the impact of process changes on the quality, safety, and efficacy of biologic drug products. Moreover, forced degradation studies help in understanding factual and alternative degradation pathways, which enables proactive planning to mitigate risks. Additionally, these studies have the potential to reveal unexpected results. However, a significant challenge with the widespread use of forced degradation studies is the lack of clear guidance on their design and implementation.13
It is strongly recommended that screening of forced degradation conditions — such as thermal, oxidation, pH, agitation, and light exposure — be performed as early in the development cycle as possible. This approach provides a better understanding of the drug substance and drug product, its degradation pathways, molecular interactions, and the optimal study conditions and requirements for sufficient analytical testing.1 Such information can help mitigate risks before projects progress to late-stage development.
Forced degradation study designs should be phase-appropriate, increasing in complexity as candidates advance to later clinical stages. This includes the use of more molecule-specific analytical and biophysical techniques, side-by-side evaluations, and multiple batches to ensure robustness and reliability.
Key aspects of forced degradation studies include:
Early screening: Conducting early degradation studies to identify potential degradation pathways and optimize testing conditions.
Phase-appropriate complexity: Adjusting the complexity of studies based on the development phase, ensuring more detailed analysis as the product moves through clinical stages.
Advanced analytical and biophysical techniques: Utilizing state-of-the-art technologies to thoroughly characterize the drug substance and drug product under various stress conditions.
Side-by-side evaluations: Comparing pre- and post-change batches under identical degradation conditions to ensure comparability.
Multiple batches: Testing multiple batches to account for variability and ensure consistent results.
By incorporating these strategies, forced degradation studies can effectively support comparability assessments, ensuring that process changes do not adversely affect the quality, safety, or efficacy of biologic drug products.
Conclusion
To benefit from biopharmaceutical medicines, patients must be assured that they are receiving high-quality, safe, and effective drug products. The development of manufacturing processes for biologic drugs is a lengthy and complex venture, involving many changes, even during late-stage clinical trials and after commercialization. While these changes are generally made to improve the process and/or product, manufacturers must clearly demonstrate that the critical attributes of the product are not negatively impacted in terms of quality, safety, and efficacy.
Successful demonstration of comparability requires upfront planning of risk- and phase-based comparability assessments. These assessments should leverage comprehensive process and product knowledge, state-of-the-art analytical technologies, and appropriately designed stability and degradation studies. Transparent relationships with regulatory authorities are also crucial, ensuring alignment on comparability strategies and increasing the likelihood of regulatory acceptance.
By integrating these elements, manufacturers can produce strong comparability results that support the confident approval and ongoing reliability of novel biologic drugs. This approach ultimately ensures that patients have access to safe, effective, and high-quality biopharmaceutical medicines.
References
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9. <1033> Biological Assay Validation. USP-NF/PF. 2024.
10. Guideline on Comparability of Biotechnology-Derived Medicinal Products after a Change in the Manufacturing Process: Non-clinical and Clinical Uses. European Medicines Agency. 19 Jul. 2007
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