Comparability and biosimilarity: considerations for the healthcare provider

BACKGROUND: Healthcare providers use recombinant biologics such as monoclonal antibodies to treat a variety of serious illnesses. Manufacturing of approved biotechnology products is complex, and the quality of the resulting biologic is dependent on careful control of process inputs and operating conditions. Biosimilars, which are similar but not identical to innovator biologics, are entering regulatory evaluation, approval, and marketing in regions with biosimilar approval pathways. SCOPE AND FINDINGS: This article describes the evaluation and potential impact of manufacturing process changes and biosimilar product development, and explores the similarities and distinctions between the two. Regulatory agencies generally require a comparability exercise following a manufacturing process change. This comparability is focused primarily on analytical characterization of the approved product before and after the manufacturing process change, with non-clinical and clinical confirmation required when determined necessary. When developing a biosimilar, the manufacturer does not have access to key information including the innovator manufacturer's cell line, cell culture conditions, purification procedures, and fill and finish processes. Further, the biosimilar manufacturer does not have access to information about the innovator manufacturer's product development history, including knowledge about the quality attributes of lots used in non-clinical and clinical development. We define the biosimilar manufacturer's lack of information as the knowledge gap. As a result, a biosimilarity exercise to compare a biosimilar to an approved innovator biologic requires a rigorous evaluation to ensure the safety and efficacy of the biosimilar. CONCLUSION: Given the knowledge gap under which biosimilars are developed, data to establish biosimilarity should go beyond a simple comparability exercise.     

Are biosimilars patentable?

Introduction: This paper explores whether, and under what circumstances, a biosimilar approved in the United States under the Biologics Price Competition and Innovation Act (hereafter ‘BPCIA’) can be patented. The possibility that a biosimilar product could have meaningful patent protection arises from specific requirements for biosimilarity under the BPCIA, which account for the fact that manufacturing processes of biologics are inherently imprecise. The requirements for biosimilar approval may provide sufficient leeway to a biosimilar applicant to patent structural or formulation differences that provide non-clinical but business-relevant advantages over the reference molecule, such as improved shelf-life or ease of manufacture, without compromising clinical biosimilarity.

Areas covered: Examination of the BPCIA and related Acts, Food and Drug Administration (FDA) guidance papers, case law, patent database searching, and relevant scholarly articles.

Expert opinion: Legislative and regulatory requirements for the approval of a biosimilar under the BPCIA are focused on clinical results and allow a degree of leeway for differences to exist between a biosimilar’s structure and non-clinical components and those of the biosimilar’s reference molecule. This leeway can be exploited to provide the biosimilar with potentially patentable business-relevant advantages over its reference product while maintaining clinical biosimilarity to the reference product.     

Analytical Similarity Assessment in Biosimilar Studies

For assessment of biosimilarity, the US Food and Drug Administration (FDA) recommends a stepwise approach for obtaining the totality-of-the-evidence for demonstrating biosimilarity between a proposed biosimilar product and an innovative (reference) biological product. The stepwise approach starts with analytical studies for functional and structural characterization at various stages of manufacturing process of the proposed biosimilar product. Analytical similarity assessment involves identification of critical quality attributes (CQAs) that are relevant to clinical outcomes. FDA proposes first classifying the identified CQAs into three tiers according to their criticality or risking ranking relevant to clinical outcomes and then performing equivalence test (for CQAs in Tier 1), quality range approach (for CQAs in Tier 2), and raw data or graphical presentation (for CQAs in Tier 3) for obtaining totality-of-the-evidence for demonstrating biosimilarity between the proposed biosimilar product with the reference product. In practice, some debatable issues are evitably raised due to this complicated process of analytical similarity assessment. In this article, these debatable are described and discussed.     

Sample size requirement in analytical studies for similarity assessment

ABSTRACT

For the assessment of biosimilar products, the FDA recommends a stepwise approach for obtaining the totality-of-the-evidence for assessing biosimilarity between a proposed biosimilar product and its corresponding innovative biologic product. The stepwise approach starts with analytical studies for assessing similarity in critical quality attributes (CQAs), which are relevant to clinical outcomes at various stages of the manufacturing process. For CQAs that are the most relevant to clinical outcomes, the FDA requires an equivalence test be performed for similarity assessment based on an equivalence acceptance criterion (EAC) that is obtained using a single test value of some selected reference lots. In practice, we often have extremely imbalanced numbers of reference and test lots available for the establishment of EAC. In this case, to assist the sponsors, the FDA proposed an idea for determining the number of reference lots and the number of test lots required in order not to have imbalanced sample sizes when establishing EAC for the equivalence test based on extensive simulation studies. Along this line, this article not only provides statistical justification of Dong, Tsong, and Weng’s proposal, but also proposes an alternative method for sample size requirement for the Tier 1 equivalence test.     

Role of Modeling and Simulation in the Development of Novel and Biosimilar Therapeutic Proteins

Modeling and simulation (M&S) is an important enabler of knowledge integration in novel biological product development programs. Given the volume of data generated from clinical trials and the complexity of pharmacokinetic (PK) and pharmacodynamic (PD) properties for reference products, extending the use of M&S to biosimilar development is logical. Assessing PK and PD similarity is normally a critical part of demonstrating biosimilarity to a reference product. Thoughtful considerations are necessary in study design to minimize the PK and PD variability, thereby increasing the sensitivity for detecting potential differences between products. In addition, the sensitivity of PD biomarkers depends partly on their relevance to the mechanism(s) of action and the dynamic range of PD response(s), including the impact of certain structural differences on PD in the relevant population. As such, opportunities exist for leveraging the available M&S knowledgebase to maximize the efficiency in the design and interpretation of PK and PD similarity studies. This article describes M&S applications which have contributed to and can continue to enhance biosimilar development programs.     

Improving the power to establish clinical similarity in a Phase 3 efficacy trial by incorporating prior evidence of analytical and pharmacokinetic similarity

ABSTRACT

To improve patients’ access to safe and effective biological medicines, abbreviated licensure pathways for biosimilar and interchangeable biological products have been established in the US, Europe, and other countries around the world. The US Food and Drug Administration and European Medicines Agency have published various guidance documents on the development and approval of biosimilars, which recommend a “totality-of-the-evidence” approach with a stepwise process to demonstrate biosimilarity. The approach relies on comprehensive comparability studies ranging from analytical and nonclinical studies to clinical pharmacokinetic/pharmacodynamic (PK/PD) and efficacy studies. A clinical efficacy study may be necessary to address residual uncertainty about the biosimilarity of the proposed product to the reference product and support a demonstration that there are no clinically meaningful differences. In this article, we propose a statistical strategy that takes into account the similarity evidence from analytical assessments and PK studies in the design and analysis of the clinical efficacy study in order to address residual uncertainty and enhance statistical power and precision. We assume that if the proposed biosimilar product and the reference product are shown to be highly similar with respect to the analytical and PK parameters, then they should also be similar with respect to the efficacy parameters. We show that the proposed methods provide correct control of the type I error and improve the power and precision of the efficacy study upon the standard analysis that disregards the prior evidence. We confirm and illustrate the theoretical results through simulation studies based on the biosimilars development experience of many different products.     

Adjustment for unbalanced sample size for analytical biosimilar equivalence assessment

ABSTRACT

Large sample size imbalance is not uncommon in the biosimilar development. At the beginning of a product development, sample sizes of a biosimilar and a reference product may be limited. Thus, a sample size calculation may not be feasible. During the development stage, more batches of reference products may be added at a later stage to have a more reliable estimate of the reference variability. On the other hand, we also need a sufficient number of biosimilar batches in order to have a better understanding of the product. Those challenges lead to a potential sample size imbalance. In this paper, we show that large sample size imbalance may increase the power of the equivalence test in an unfavorable way, giving higher power for less similar products when the sample size of biosimilar is much smaller than that of the reference product. Thus, it is necessary to make some sample size imbalance adjustments to motivate sufficient sample size for biosimilar as well. This paper discusses two adjustment methods for the equivalence test in analytical biosimilarity studies. Please keep in mind that sufficient sample sizes for both biosimilar and reference products (if feasible) are desired during the planning stage.     

On safety margin for drug interchangeability

ABSTRACT

As more and more generic (or biosimilar) drug products become available in the market place, it is a concern whether the approved generic (or biosimilar) drug products are safe and efficacious and hence can be used interchangeably. According to current regulation, most regulatory agencies such as the United States Food and Drug Administration (FDA) indicate an approved generic (or biosimilar) drug product can serve as a substitute for the innovative drug product. Bioequivalence (biosimilarity) assessment for regulatory approval among generic copies (or biosimilars) of the innovative drug product are not required. In practice, approved generic (or biosimilar) drugs are commonly used interchangeably without any mechanism of safety monitoring. In this article, current bioequivalence (or biosimilarity) limit is adjusted according to the observed geometric mean ratio and corresponding variability for development of safety margins for monitoring of drug interchangeability by minimizing the relative change in response with and without the switching.     

Biosimilar epoetins: an analysis based on recently implemented European medicines evaluation agency guidelines on comparability of biopharmaceutical proteins

Patents of innovator biopharmaceutical products, such as epoetin, are expiring, and biosimilar versions of these products may soon enter European and American markets. Copies of these products, termed biosimilars or follow-on biologics, are not truly equivalent and cannot gain market approval through the procedure typically applied to generic drugs. We evaluated literature reports of both analytic and clinical studies conducted with biosimilar epoetin products currently marketed outside the United States and Europe in light of recently implemented European Medicines Evaluation Agency guidelines. The analytic studies reported that products differed widely in composition, did not always meet self-declared specifications, and exhibited batch-to-batch variation. Although several clinical studies demonstrated correction of anemia with biosimilar epoetins by using an open-label or placebo-controlled study design, only 4 of 22 studies were competitor controlled. Most of the studies were small (median 41 patients, range 18-1079 patients) and of short duration (median 12 wks, range 6 wks-1 yr). Clinical experience with epoetin shows that the dosage required to achieve similar hemoglobin levels varies among patients, making it impossible to demonstrate bioequivalence without a comparator. The analytic reports did not demonstrate comparability of biosimilar epoetin products with innovator epoetin alfa, and the clinical studies were not rigorous enough to show equivalent safety and efficacy of a biopharmaceutical product. The variation between products illustrates the challenge in replicating and consistently producing biopharmaceutical proteins. Immunogenic reactions with epoetin indicate that large, long-term studies are needed to adequately monitor safety.     

Statistical Considerations in Demonstrating CMC Analytical Similarity for a Biosimilar Product

Demonstration of analytical similarity between a reference product and a biosimilar product is required as part of the biosimilarity approval process. A statistical two one-sided test (TOST) based on the difference of means proposed in the literature and recommended by the FDA for Tier 1 quality attributes is demonstrated to have a Type I error rate greater than the specified level, which cannot be corrected by increasing sample size. In this article, an alternative TOST based on the effect size is demonstrated to maintain the desired Type I error rate, and in some situations, provide greater power than the TOST based on the mean difference. Results are demonstrated both analytically and with computer simulations. An example with calculations is provided in the article. Supplementary materials for this article are avalilable online.     

Comparability and biosimilarity: considerations for the healthcare provider

Abstract

Background:

Healthcare providers use recombinant biologics such as monoclonal antibodies to treat a variety of serious illnesses. Manufacturing of approved biotechnology products is complex, and the quality of the resulting biologic is dependent on careful control of process inputs and operating conditions. Biosimilars, which are similar but not identical to innovator biologics, are entering regulatory evaluation, approval, and marketing in regions with biosimilar approval pathways.     

Systematic Verification of Bioanalytical Similarity Between a Biosimilar and a Reference Biotherapeutic: Committee Recommendations for the Development and Validation of a Single Ligand-Binding Assay to Support Pharmacokinetic Assessments

For biosimilar drug development, it is critical to demonstrate similar physiochemical characteristics, efficacy, and safety of the biosimilar product compared to the reference product. Therefore, pharmacokinetic (PK) and immunogenicity (antidrug antibody, ADA) assays that allow for the demonstration of biosimilarity are critical. Under the auspices of the American Association of Pharmaceutical Scientists (AAPS) Ligand-Binding Assay Bioanalytical Focus Group (LBABFG), a Biosimilars Action Program Committee (APC) was formed in 2011. The goals of this Biosimilars APC were to provide a forum for in-depth discussions on issues surrounding the development and validation of PK and immunogenicity assays in support of biosimilar drug development and to make recommendations thereof. The Biosimilars APC’s recommendations for the development and validation of ligand-binding assays (LBAs) to support the PK assessments for biosimilar drug development are presented here. Analytical recommendations for the development and validation of LBAs to support immunogenicity assessments will be the subject of a separate white paper.

Electronic supplementary material

The online version of this article (doi:10.1208/s12248-014-9669-5) contains supplementary material, which is available to authorized users.KEY WORDS: bioanalytical method validation, biological product, biosimilar, ligand-binding assay, pharmacokinetic     

A Functional Metric Approach to Assess Biosimilarity With Application to Rheumatoid Arthritis Trials

Abstract

In recent years there has been a lot of interest to test for similarity between biological drug products, commonly known as biologics. Biologics are large and complex molecule drugs that are produced by living cells and hence these are sensitive to the environmental changes. In addition, biologics usually induce antibodies which raise the safety and efficacy issues. The manufacturing process is also much more complicated and often costlier than the small-molecule generic drugs. Because of these complexities and inherent variability of the biologics, the testing paradigm of the traditional generic drugs cannot be directly used to test for biosimilarity. Taking into account some of these concerns we propose a functional distance based methodology that takes into consideration the entire time course of the study and is based on a class of flexible semiparametric models. The empirical results show that the proposed approach is more sensitive than the classical equivalence tests approach which are usually based on arbitrarily chosen time point. Bootstrap based methodologies are also presented for statistical inference.     

Comparative subcutaneous repeated toxicity study of enoxaparin products in rats

Enoxaparin is a low-molecular-weight heparin widely used for the prevention and treatment of thromboembolism. With the development of several enoxaparin biosimilars, real medical concerns about their safety and efficacy have been raised. This repeated dose toxicity study consists of preclinical toxicological evaluation of a biosimilar biological version of enoxaparin, the drug product “Enoxa”, compared to the enoxaparin reference drug product, “Lovenox”. Eighty white Wistar rats were treated with “Enoxa” versus the reference product, using subcutaneous therapeutic and toxic doses, varying from 3.5 to 100 mg/kg/day. Dose levels were adjusted and ultimately fixed at 3.5 and 20 mg/kg/day as therapeutic and toxic doses, respectively. A sodium chloride solution (0.9%) was used as the control, and the comparative study was conducted over periods of 14 and 28 days. Comparable effects were observed with few adverse effects at the administration dose of 20 mg/kg/day, for both enoxaparin biosimilar and reference products. Interestingly, mortality started only at high doses of 40 mg/kg/day and reached 25% at 100 mg/kg/day for both products. These results, as part of the recommended biosimilarity monitoring, demonstrated comparable toxicity profiles of “Enoxa” and “Lovenox” products in rats. Continuing investigation of biosimilarity on humans to confirm safety and efficacy is suggested.     

Current Japanese Regulatory Systems for Generics and Biosimilars

Currently, biosimilar products are being actively developed around the world. One reason for this is the expiry of patents of original biopharmaceutical products with an extremely large market share because the biosimilar companies need to avoid infringing patents. A representative example of this is biosimilar versions of monoclonal antibodies. In Japan, the Ministry of Health, Labour and Welfare is promoting the use of biosimilar products because the market share of such products is currently extremely low compared with that of generic products. The Pharmaceuticals and Medical Devices Agency is responsible for reviewing generic and biosimilar products in Japan. However, no comparison of review systems for generics and biosimilars in Japan has been published. A more detailed understanding of review systems is important for using generic and biosimilar products. This article presents the current Japanese review systems for generic and biosimilar products and also the future challenges to facilitate the better regulation of both types of product.     

Clinical trials for authorized biosimilars in the European Union: a systematic review

AimIn 2006, Omnitrope (by Sandoz) was the first approved biosimilar in Europe. To date, 21 biosimilars for seven different biologics are on the market. The present study compared the clinical trials undertaken to obtain market authorization.MethodsWe summarized the findings of a comprehensive review of all clinical trials up to market authorization of approved biosimilars, using the European public assessment reports (EPARs) published by the European Medicines Agency (EMA). The features compared were, among others, the number of patients enrolled, the number of trials, the types of trial design, choice of endpoints and equivalence margins for pharmacokinetic (PK)/pharmacodynamic (PD) and phase III trials.ResultsThe variability between the clinical development strategies is high. Some differences are explainable by the characteristics of the product; if, for example, the PD marker can be assumed to predict the clinical outcome, no efficacy trials might be necessary. However, even for products with the same reference product, the sample size, endpoints and statistical models are not always the same.ConclusionsThere seems to be flexibility for sponsors regarding the decision as to how best to prove biosimilarity.     

Biosimilarity assessment of biosimilar therapeutic monoclonal antibodies

The concept of biosimilar was established in the early 2000s in EU. Currently, the regulatory framework for biosimilar has also been established in the US, Japan, and other countries. As of 2018, biosimilars for infliximab, adalimumab, rituximab, trastuzumab, and bevacizumab have been approved. During the development of a biosimilar, product quality should be evaluated and compared with those of the reference product extensively. Among the quality attributes of therapeutic antibodies, FcRn binding and related structures are well known to affect the pharmacokinetic profile of the product. Other quality attributes such as antigen binding, glycan structure, and isoelectric point are considered to have a potential impact on the pharmacokinetic profile of the product. Based on the high similarity of the quality attributes of the biosimilar to those of its reference product, comparative non-clinical and clinical studies are conducted. Comparable pharmacokinetic profile of the biosimilar and the reference product is important for biosimilar evaluation. In this review, the basic concept of biosimilar development as well as pharmacokinetic data obtained via non-clinical and clinical studies of biosimilar therapeutic antibody is introduced, and future perspective is discussed.     

Recommendations and requirements for the design of bioanalytical testing used in comparability studies for biosimilar drug development

With the imminent expiry of patents on a number of biological products on the market, the development of biosimilars (or 'follow-on biologics') creates an increasing opportunity in the biotechnology industry. Although general guidelines on the quality and safety of biological products also apply to biosimilars, there is a need to address specific requirements for developing biosimilar drugs. Since it is critical to show comparability of the biosimilar products to their reference (or innovator) products, developing the appropriate bioanalytical methods to support such preclinical and clinical comparability studies is of great importance. The present work recommends the requirements for the development and validation for both pharmacokinetic and immunogenicity assays to support the biosimilar drug development.