Comparability exercise of critical quality attributes of clinical-grade human mesenchymal stromal cells from the Wharton's jelly: single-use stirred tank bioreactors versus planar culture systems.

BACKGROUND AIMS: The increasing demand of clinical-grade mesenchymal stromal cells (MSCs) for use in advanced therapy medicinal products (ATMPs) require a re-evaluation of manufacturing strategies, ensuring scalability from two-dimensional (2D) surfaces to volumetric (3D) productivities. Herein we describe the design and validation of a Good Manufacturing Practice-compliant 3D culture methodology using microcarriers and 3-L single-use stirred tank bioreactors (STRs) for the expansion of Wharton's jelly (WJ)-derived MSCs in accordance to current regulatory and quality requirements. METHODS: MSC,WJ were successfully expanded in 3D and final product characterization was in conformity with Critical Quality Attributes and product specifications previously established for 2D expansion conditions. RESULTS: After 6 days of culture, cell yields in the final product from the 3D cultures (mean 9.48 × 108 ± 1.07 × 107 cells) were slightly lower but comparable with those obtained from 2D surfaces (mean 9.73 × 108 ± 2.36 × 108 cells) after 8 days. In all analyzed batches, viability was >90%. Immunophenotype of MSC,WJ was highly positive for CD90 and CD73 markers and lacked of expression of CD31, CD45 and HLA-DR. Compared with 2D expansions, CD105 was detected at lower levels in 3D cultures due to the harvesting procedure from microcarriers involving trypsin at high concentration, and this had no impact on multipotency. Cells presented normal karyotype and strong immunomodulatory potential in vitro. Sterility, Mycoplasma, endotoxin and adventitious virus were negative in both batches produced. CONCLUSIONS: In summary, we demonstrated the establishment of a feasible and reproducible 3D bioprocess using single-use STR for clinical-grade MSC,WJ production and provide evidence supporting comparability of 3D versus 2D production strategies. This comparability exercise evaluates the direct implementation of using single-use STR for the scale-up production of MSC,WJ and, by extension, other cell types intended for allogeneic therapies.

Clinical evidence supporting the marketing authorization of biosimilars in Europe.

PURPOSE: To review the marketing authorization of biosimilars and provide a critical analysis of the pivotal trials supporting their approval by the European Medicines Agency (EMA). METHODS: EMA website to identify the biosimilars approved up to July 2019 and the European Public Assessment Report for information on pivotal trial design, duration, intervention and control, primary outcome, data on immunogenicity, and comparability margins. RESULTS: The EMA has approved 55 biosimilars (62% in 2017-2019) of 16 biologic products, used in several clinical indications. Some biosimilars were licensed as multiple products, with different commercial names, by the same or different companies. The comparability exercise and subsequent approval of 49/55 (89%) biosimilars were based on one or more pivotal phase III trials testing their clinical efficacy. In all, biosimilars were approved on the basis of 55 trials, mostly phase III (42/55, 76%) assessing clinical efficacy; these were mainly equivalence trials (31/55, 56%). The pivotal phase III trials assessed surrogate measures of clinical effect, and 71% reported immunogenicity data. CONCLUSION: Analysis of the approval of biosimilars in Europe depicts a complex and heterogeneous scenario. The requirement for showing similarity in terms of clinical efficacy and safety provides a robust demonstration of comparable clinical outcomes but lays a burden on biosimilar manufacturers and may delay the introduction of the drugs. The development, licensing, and monitoring of biosimilars would benefit from new strategies to accelerate access to these drugs while reducing uncertainties about their use in practice.

Pragmatic rules for comparability of biological medicinal products.

Comparability is a key concept in the evaluation of both manufacturing changes and biosimilars. It constitutes a pragmatic and flexible approach which recognises that biologicals are inherently variable and that minor variations in quality attributes are often clinically irrelevant. In this discussion paper, we argue that comparability exercises rely on a number of pragmatic criteria. These criteria have been remarkably robust for 20 years of comparability exercises; however, the increased scrutiny of biosimilar applications provides an impetus for both codification and improvement of criteria for establishing comparability. Such a more rigorous, methodologically sound, approach towards comparability seems both feasible and beneficial.

Biosimilars: Concepts and controversies.

Biosimilars are copies of reference biological drugs, developed as the patents for original biologicals expire. They are thus developed to replicate an original biological medicine just a generics are intended to replicate a chemically-synthesized medicine; however, there are important technical and regulatory differences between the two. Unlike chemical drugs, molecular identity cannot generally be established for any two biological drugs. Accordingly, their pharmacological properties cannot be assumed to be the same. This is due to the complexity of the production of biologicals and to the presence of minor natural variations in the molecular structure (collectively known as microheterogeneity). Further, biological production yields slightly different versions of the drug over time, particularly when changes are introduced in the production process. In this case the prechange and postchange versions of the biological are analyzed in what is called a comparability exercise. The comparable versions thus validated are considered not to have any significant differences at the clinical level. Likewise, biosimilars are not identical copies but comparable versions of the original biological drug, also validated through a comparability exercise, although of a much broader scope. Although current knowledge about biosimilars has increased significantly, they still arise a number of controversies and misconceptions, particularly regarding issues like extrapolation of indications, immunogenicity and substitution. This review deals with concepts and controversies in the biosimilar field.

Strengths, weaknesses and future challenges of biosimilars' development. An opinion on how to improve the knowledge and use of biosimilars in clinical practice.

Biosimilars started receiving the marketing authorization by European Medicine Agency since 2006. The development of biosimilars follows a well-defined step-wise approach, the so-called comparability exercise, which aims to compare non-clinical (mainly quality features and biological activity) and clinical (efficacy and safety profiles) features of new biosimilars with their respective reference products. Despite the undeniable advantages of such procedure, some concerns (such as the absence of switching studies or the evaluation of efficacy and safety in all therapeutic indications) still exist about its. In particular, the European regulatory framework on biosimilars approval does not include the conduction of switching studies demonstrating the interchangeability to be carried out before marketing authorization. This is one of the main aspects that negatively affects healthcare professionals' clinical decisions on switch. In order to achieve a better knowledge on safety and efficacy of biosimilar drugs, real world data should be collected and post-marketing efficacy and safety clinical studies (including those evaluating specific endpoints, therapeutic regimens and patients population), should be planned. also the conduction of well-designed switching studies is highly advisable, especially in the case of biosimilar drugs used in oncology settings. Lastly, considering the critical role of antidrug antibodies on efficacy/safety profile of biologic drugs, studies based on therapeutic drug monitoring would be useful in order to achieve treatment optimization. Implementing the above strategies could be helpful to fill the gap in knowledge observed in the present European biosimilar regulatory framework.

Pharmacokinetic and toxicology comparator testing of biosimilar drugs - Assessing need.

A key element in the development of a biosimilar molecule is the comparability of the biological activity/nonclinical similarity to the innovator drug. Although some regulatory guidelines are encouraging little or no in vivo testing, currently a common practice is to perform at least one toxicology and/or one pharmacokinetic (PK) study to assess if any different findings occur for in-life, clinical pathology and histopathological parameters or in exposure. An exercise was performed in which the results of such testing were evaluated. It was found that 10 PK comparison studies in the cynomolgus monkey across 4 monoclonal (Mab) classes showed similar exposure in all cases. In 17 toxicology comparison studies with 5 Mab classes performed in the same species and in 7 toxicology comparison studies with non-Mab biosimilars in the rat, no new/unexpected findings were seen and drug exposure measurement gave comparable values in all cases. Overall, although this work does not rule out possible utility of some in vivo testing (notably in the form of stand-alone PK testing) to confirm similar exposure between the 2 molecules tested, it is unclear what benefit can be gained from toxicology testing, especially if comparability has been demonstrated from physiochemical and in vitro characterisation.

From bioequivalence to biosimilars: How much do regulators dare?

The main advantage of an abbreviated licensing pathway is the possibility of extrapolating efficacy and safety data from an original medicinal product to a subsequent "copy" version, thereby reducing the clinical development programme in particular. For small-molecule chemically synthesized generics, such an abbreviated licensing pathway was established decades ago, whereas it was only more recently implemented for similar biological medicinal products, so-called biosimilars. Clinicians and patients have repeatedly expressed concerns about the efficacy and safety of biosimilars, especially in 'extrapolated' indications for which no own clinical data have been generated. Generic drugs usually contain well-defined active ingredients whose "identity" with that of the originator, the so-called reference product, is easily verifiable. Biological substances are generally more complex and difficult to characterize. They are produced in living organisms and therefore naturally exhibit some intrinsic variability, i.e. microheterogeneity. Since the chosen expression system and the manufacturing conditions influence the quality characteristics of a biological substance, mostly its posttranslational modifications such as the glycosylation pattern, it is unlikely that two independent manufacturing processes can achieve completely identical biologicals. A biosimilar, especially if it is a glycoprotein, can therefore, at best, be highly similar to the reference product. It seems that the not-identical-but-(highly)-similar-paradigm for biosimilars is often not well understood and causes confusion. However, while at first glance an abridged approval pathway for biosimilars appears to be daring, it is in fact based on sound scientific reasoning. A biosimilar applicant has to provide a considerably larger package of comparative data than a generic applicant to ensure that the biosimilar can indeed rely, for the purpose of licensing, on the efficacy and safety experience gained with the reference product. While for a generic, the demonstration of similar in vitro dissolution and in vivo bioavailability (so-called 'bioequivalence') is sufficient to conclude therapeutic equivalence with the reference product, for a biosimilar, comparable physicochemical, biological and functional characteristics as well as efficacy and safety/immunogenicity with the reference product must be demonstrated. In addition, unlike generics, any extrapolation to other indications of the reference product must be scientifically justified. More than 10 years of successful clinical experience with biosimilars in the EU support the credibility of the scientific principles guiding the biosimilar concept. So far, there has been no need for either withdrawal of an approved biosimilar or for additional labelling because of efficacy or safety concerns.

Concepts and Challenges of Biosimilars in Breast Cancer: The Emergence of Trastuzumab Biosimilars.

With the development of anti-human epidermal growth factor receptor 2 (HER2) monoclonal antibodies, trastuzumab-based therapy has become the standard of care among patients with early or advanced HER2-positive breast cancer. However, real-world data have shown that up to a half of patients do not receive trastuzumab or any other HER2-targeted agent, mainly due to high treatments costs. The prospect of a more enlarged access to trastuzumab treatment lies in the use of biosimilars, as the European and the US patent of the reference products has or will soon expire. Biosimilars are biologics highly similar in terms of quality characteristics, biological activity, safety and efficacy to already approved biologics. The biosimilarity of any European Union (EU)-approved biosimilar is guaranteed based on the comprehensive comparability exercise which includes comparative analytical, non-clinical and clinical studies. In the matter of biosimilars' interchangeability and substitution, the European Medicines Agency (EMA) and US Food and Drug Administration (FDA) have adopted different positions, triggering various discussions on the potential immunogenicity and efficacy in individual patients. As more biosimilars are gaining approval, the present review aims to offer concise information for oncologists and pharmacists about the production, approval, interchangeability, and substitution policies of biosimilars used in breast cancer therapy, with a special focus on trastuzumab.

Virus-like particle-based human vaccines: quality assessment based on structural and functional properties.

Human vaccines against three viruses use recombinant virus-like particles (VLPs) as the antigen: hepatitis B virus, human papillomavirus, and hepatitis E virus. VLPs are excellent prophylactic vaccine antigens because they are self-assembling bionanoparticles (20 to 60 nm in diameter) that expose multiple epitopes on their surface and faithfully mimic the native virions. Here we summarize the long journey of these vaccines from bench to patients. The physical properties and structural features of each recombinant VLP vaccine are described. With the recent licensure of Hecolin against hepatitis E virus adding a third disease indication to prophylactic VLP-based vaccines, we review how the crucial quality attributes of VLP-based human vaccines against all three disease indications were assessed, controlled, and improved during bioprocessing through an array of structural and functional analyses.