By Janmeet Anant, Regulatory Advocate, MilliporeSigma
Unlike well-defined chemical medicinal products and their generic counterparts, biologics and their biosimilar counterparts employ sophisticated bioprocessing technologies that utilize living systems for their manufacture. Because these complex heterogeneous protein molecules are produced in living systems, their exact characteristics are subject to inherent batch-to-batch variability. Given the variability of biologics characteristics including its manufacturing complexity, biosimilars must undergo a much more rigorous regulatory pathway for approval compared to generic drugs.
Regulatory approval requires comprehensive knowledge of both the manufacturing process and the molecule like for any biologic. Moreover, extensive characterization and comparability data are required by regulatory agencies to demonstrate biosimilarity to the reference biologic product.1, 2
Biosimilars Regulatory Frameworks
As the first major regulatory authority to implement a framework for biosimilars development3, the European Medicines Agency (EMA) has been leading efforts to advance this important therapeutic class. Today, the EMA has the most detailed and stringent guidelines for biosimilars development, which includes a focus on quality, consistency, manufacturing process, safety and efficacy. The EMA also provides product-specific guidelines that outline data requirements and studies necessary to demonstrate comparability for granulocytecolony stimulating factor, low-molecular-weight heparins, human insulin/insulin analogues, interferon beta, monoclonal antibodies, erythropoietins, folliclestimulating hormone, and somatropin. These guidelines are widely considered the gold standard, with countries such as Australia, Canada, Japan, Korea, and South Africa using them as a basis for their own regulations.
The US Food and Drug Administration (FDA) developed a regulatory pathway for approval of biosimilars, when the Biologics Price Competition and Innovation Act of 2009 was signed into law in 2010, and released draft guidelines in 2012.4 The FDA uses a step-wise totality-of-the-evidence approach as the basis for approval, which is an overall assessment that a biological product is – or is not – biosimilar to its FDA-licensed reference product (Figure 1). In biosimilar development, a foundation of knowledge already exists based on the reference product; therefore, analytical data serve as the foundational component for regulatory approval and serve as a surrogate for a larger clinical dataset.
The FDA does not take a one-size-fits-all approach to biosimilars assessment. Instead, FDA scientists meet with biosimilar sponsors during the development phase to evaluate each applicant’s integration of various types of information and provide counsel on the scope of the development plan.
Shared Basic Principles
The biosimilar regulatory frameworks from Europe, US, Asia Pacific, and the World Health Organization (WHO) all share the same basic principles:
According to the EMA guidelines, biosimilars development and documentation should cover the molecular characteristics and quality attributes of the target product profile as compared to the reference biologic, as well as performance and consistency of the manufacturing process of the biosimilar.1 The quality target product profile should be established at an early stage to form the basis of biosimilar development. Furthermore, it is important to identify the critical quality attributes that may impact the safety and efficacy of the product.
An extensive comparability exercise is required to demonstrate that the biosimilar has a highly similar quality product profile to the reference biologic.1 Selected methods should be able to detect slight differences in all aspects pertinent to the evaluation of quality, including composition, primary and higher order structure, amino acid composition, post-translational modifications, biological activity, immunological properties, purity and impurities.
In 2015, the FDA published guidance on quality and scientific considerations in demonstrating biosimilarity to a reference protein product.5,6 Biosimilarity is demonstrated by “analytical studies that demonstrate that the biological product is highly similar to the reference product notwithstanding minor differences in clinically inactive components.”5
To evaluate whether the proposed biosimilar product and its reference product are highly similar, extensive and robust comparative structural analysis, as well as physicochemical and functional studies should be performed. The studies should include the following:
The FDA intends to consider the totality of the evidence provided by a sponsor to support a demonstration of biosimilarity. The step-wise totality-of-the-evidence approach includes: analytical testing to demonstrate physical, chemical and functional similarity to the reference biologic; non-clinical studies to demonstrate function, activity and toxicity; and clinical studies to demonstrate whether a proposed biosimilar stays in the body for the same amount of time, and can be expected to have a highly similar efficacy and safety profile as the reference product.
Regulators view the manufacturing process as a key factor in the assessment of biosimilarity, as different processes could alter the biosimilar product in a way that affects its safety and efficacy.
The biosimilars manufacturing process can be separated into three areas:
There are multiple steps in the biosimilars manufacturing process, and it is important to understand which of the process parameters are critical to the final product attributes. Drug manufacturers understand that the genetics of the cell line determine product attributes; therefore, utilization of the same host cell or protein expression system as the reference product is essential. It is also important to base clone selection not only on productivity but also on product similarity to the reference product. Finally, cell culture conditions, media and feeds need to be optimized to produce a biosimilar aligned with the critical quality attributes of the reference product.
It should be noted, however, that the quality attributes are not expected to be identical for the biosimilar and reference biologic. Minor structural differences may be acceptable if verified as non-clinical attributes. In contrast, variability in post-translational modifications or differences between the impurity profiles may have an impact on the critical quality attributes and subsequent safety and efficacy of the biologic drug. Therefore, a combination of rigorous analytical and functional studies is typically conducted. Stability study results are also recognized to be sensitive to slight changes in the biologic drug product, which may not be detectable by the most sophisticated analytical techniques.
Regulators highlight a special consideration for biologics regarding immunogenicity. However, an increased adverse immune response from biosimilars versus reference products is difficult to evaluate, especially for monoclonal antibodies (mAbs). Current nonclinical immunotoxicity studies are inadequate to address all safety issues in relation to the possible immunotoxicity of mAbs, and clinical studies rarely include validated end-points dedicated to the prediction of immunotoxicity. Because of this complexity, industry experts recommend pre-IND meetings with the FDA to review the biosimilar strategy and development program. The European Medicines Agency also emphasizes the importance of presubmission meetings, approximately six months prior to the anticipated date of submission of the similar biological medicine application.
The manufacturing standards required by regulatory agencies for reference products are also required for biosimilars, including the implementation of Good Manufacturing Practices (GMP), modern quality control and assurance procedures, in-process controls, and process validation. All available knowledge of the reference product should be assembled with regard to the type of host cell, formulation, and container closure system. For the biosimilar, a complete description and data package delineating manufacturing process, obtaining and expressing target genes, optimization and fermentation of cells, clarification and purification of products, formulation and testing, and aseptic filling and packaging needs to be submitted to regulatory agencies.
Regulatory approval of a biosimilar requires comprehensive knowledge of both the process and the molecule. Process development with the end goal in mind will help to achieve a robust manufacturing process. Efficiencies in manufacturing, cell line testing and characterization, and protein comparability analytics are among the highest priorities for successful biosimilar drug approvals. For that reason, it is best to collaborate with a partner and leverage many years of experience supporting drug manufacturers with complex biologics production, purification and analysis, and biosimilar comparability. MilliporeSigma is firmly positioned to help partners navigate the complexities of biologics and biosimilars manufacturing.
1. European Medicines Agency. Guideline on similar biological medicinal products containing biotechnology-derived proteins as active substance: quality issues. EMA/CHMP/BWP/247713/2012
2. US FDA Guidance for Industry. Quality Considerations in Demonstrating Biosimilarity of a Therapeutic Protein Product to a Reference Product. CDER and CBER. 2015
3. European Medicines Agency. Guideline on similar biological medicinal products. CHMP/437/04. 2005
4. Public Law No. 111-148. Sections 7001-7003 (Biologics Price Competition and Innovation Act of 2009) of the Patient Protection and Affordable Care Act
5. US FDA Guidance for Industry: Quality Considerations in Demonstrating Biosimilarity to a Reference Protein product. CDER and CBER. 2015
6. US FDA Guidance for Industry: Scientific Considerations in Demonstrating Biosimilarity to a Reference product. CDER and CBER. 2015