Considerations of critical quality attributes in the analytical comparability assessment of biosimilar products.

Based on experience in clinical trial approvals and marketing authorizations for biosimilar products in Korea, we suggest principles for the analytical comparability assessment of biosimilar products with respect to regulatory considerations. The composition and manufacturing processes of biosimilar products can differ from those of the reference product depending on the information available for the reference product and the time of product development; however, the analytical characteristics of biosimilar products should be highly similar to those of the reference product. Although manufacturing an identical product in terms of the quality profile is nearly impossible due to the high molecular weight and complex structure of biological products, the developer of the biosimilar product should attempt to establish a quality level as similar to that of the reference product as possible. When comparing the similarity of quality attributes, the criticality of the quality attributes and the characteristics of orthogonal quality attributes need to be considered carefully. Based on the results from the analytical comparability assessment, the comparability results of non-clinical and clinical studies should be evaluated before claiming biosimilarity to the reference product. In this review, we focus on quality attribute evaluation based on our regulatory experience.

Report of the International Regulatory Forum on Human Cell Therapy and Gene Therapy Products.

The development of human cell therapy and gene therapy products has progressed internationally. Efforts have been made to address regulatory challenges in the evaluation of quality, efficacy, and safety of the products. In this forum, updates on the specific challenges in quality, efficacy, and safety of products in the view of international development were shared through the exchange of information and opinions among experts from regulatory authorities, academic institutions, and industry practitioners. Sessions identified specific/critical points to consider for the evaluation of human cell therapy and gene therapy products that are different from conventional biological products; common approaches and practices among regulatory regions were also shared. Certain elements of current international guidelines might not be appropriate to be applied to these products. Further, international discussion on the concept of potency and in vivo tumorigenicity studies, among others, is needed. This forum concluded that the continued collective actions are expected to promote international convergence of regulatory approaches of the products. The Pharmaceuticals and Medical Devices Agency and Japanese Society for Regenerative Medicine jointly convened the forum with support from the National Institutes of Biomedical Innovation, Health and Nutrition. Participants at the forum include 300 experts in and outside of Japan.

Case studies on clinical evaluation of biosimilar monoclonal antibody: scientific considerations for regulatory approval.

The objective of this paper is to provide considerations based on comprehensive case studies important for regulatory evaluation of monoclonal antibodies as similar biotherapeutic products (SBPs) with a special emphasis on clinical aspects. Scientific principles from WHO Guidelines on SBPs were used as a basis for the exercise. Working groups consisted of regulators, manufacturers and academia. The following topics were discussed by the working groups: clinical criteria for biosimilarity, extrapolation approach and the overall regulatory decision making process. In order to determine typical pitfalls in the design of a SBP clinical programme and evaluate the gap of knowledge, amongst different industry and regulatory stakeholders on the appraisal of the data arising from SBP clinical studies, we have presented two fictional but realistic clinical case studies. The first case consists of the fictional development programme for an infliximab SBP candidate. The second case describes clinical studies proposed for a fictional rituximab SBP candidate. In the first scenario a highly similar quality profile has been taken forward into clinical studies whereas there was an important residual difference in functional attributes for the rituximab SBP candidate. These case studies were presented at the WHO implementation workshop for the WHO guidelines on evaluation of similar biotherapeutic products held in Seoul, Republic of Korea, in May 2014. The goal was to illustrate the interpretation of the clinical data arising from studies with SBP candidates and elicit knowledge gaps in clinical assessment. This paper reflects the outcome of the exercise and discussions held in Seoul and offers an analysis of the case studies as a learning opportunity on clinical development and evaluation of SBPs.

The role of the quality assessment in the determination of overall biosimilarity: a simulated case study exercise.

A determination of biosimilarity is based on a thorough characterization and comparison of the quality profiles of a similar biotherapeutic product and its reference biotherapeutic product. Although the general principles on the role of the quality assessment in a biosimilar evaluation are widely understood and agreed, detailed discussions have not been published yet. We try to bridge this gap by presenting a case study exercise based on fictional but realistic data to highlight key principles of an evaluation to determine the degree of similarity at the quality level. The case study comprises three examples for biosimilar monoclonal antibody candidates. The first describes a highly similar quality profile whereas the second and third show greater differences to the reference biotherapeutic product. The aim is to discuss whether the presented examples can be qualified as similar and which additional studies may be helpful in enabling a final assessment. The case study exercise was performed at the WHO implementation workshop for the WHO guidelines on quality assessment of similar biotherapeutic products held in Xiamen, China, in May 2012. The goal was to illustrate the interpretation of the comparative results at the quality level, the role of the quality assessment in the entire biosimilarity exercise and its influence on the clinical evaluation. This paper reflects the outcome of the exercise and discussion from Xiamen.

Improved protocols for histamine sensitization testing of acellular pertussis vaccines.

The histamine sensitization test is a widely used method for measuring the residual toxicity of pertussis toxin in acellular pertussis vaccines. Although it has been used as a routine assay for decades, the current protocols are difficult to standardize because the test results vary considerably and are based on several factors, including mouse strain, age and sex. In this study, we observed that mice of strains CD1, ddY and C57/BL6 were sufficiently sensitive to pertussis toxin among six mice strains tested and that aged male mice were more sensitive to pertussis toxin than younger or female mice. Using this animal model, we showed pertussis toxin dose-dependent responses in the two histamine sensitization test protocols based on either lethal end-point determination or mouse rectal temperature measurement. Sensitivity to pertussis toxin was further enhanced by the addition of lipopolysaccharide in both methods. With these improvements, pertussis toxin activity can be estimated more accurately and reproducibly using a reduced number of animals.

Retrospective analysis of the results of acellular pertussis vaccine toxicity tests performed in Korea.

Specific toxicity test is a major quality control test for acellular pertussis (aP) vaccines performed by manufacturers and regulatory authorities. The 'mouse body weight gain test (MWGT)', the 'leukocytosis-promoting test (LPT)' and the 'histamine sensitization test (HIST)' have been conducted to check the specific toxicity of all batches of aP vaccines used in Korea through the national quality control program, which requires a lot of animals, labor and time. In this study, test results obtained in the past 9 y from a total of 258 lots of aP vaccines were examined retrospectively to evaluate the three test methods. A pairwise comparison of the test results indicated a good correlation between LPT and HIST, whereas MWGT showed no correlation with either LPT or HIST. Moreover, the reversion to toxicity was higher than the residual toxicity in the majority of lots tested by HIST, which indicated that the histamine-sensitizing toxicity, although rated within a safe range, increased during the vaccine storage. Thus, the vaccine safety test results accumulated in the past might be useful for the improvement of test protocols.

WHO informal consultation on regulatory evaluation of therapeutic biological medicinal products held at WHO Headquarters, Geneva, 19-20 April 2007.

This report reflects the discussion and conclusions of an informal consultation held on 19-20 April 2007 at the World Health Organization concerning the regulatory evaluation of therapeutic biological medicinal products. The objectives of this meeting were to discuss the current status of so-called "similar" biological medicinal products (biosimilars) and to review regulatory pathways and challenges in evaluating the quality, safety and efficacy of these products. Biosimilars are products that are subject to licensing with a reduced data package due to a proven 'similarity' to the licensed reference product. The meeting was attended by experts in biotherapeutics from regulatory agencies, industry and academia representing 16 countries worldwide. Dr. Elwyn Griffiths (Canada) acted as Chairman and Dr. James Robertson (UK) was the Rapporteur. The meeting strongly focused on the usage of biosimilars and the current regulatory situation in many different countries. The application of International Nonproprietary Names (INN) to biosimilars, their potential immunogenicity, and WHO international standards and reference materials were also discussed, alongside presentations from the innovator and generic manufacturing industries. The consultation recognized the importance of the terminology as well as a definition of biosimilars for future considerations of these products. However, achieving a global consensus on the terminology for these new challenging products was not attempted at the Consultation, and it was decided that a future WHO working group should act on this issue as a next step. For purposes of this meeting report only, the term 'biosimilars' is temporarily used to refer to this category of products. It became clear that biotherapeutics authorized on the basis of a reduced data package are available and being used in some countries, with more appearing on the market. The existence of divergent approaches to the regulatory oversight of biosimilars in different countries revealed a need for defining regulatory expectations for these products at the global level. While many countries are following the guideline developed within the EU for quality aspects, discrepancies remain regarding the non-clinical and clinical studies of these products. The Consultation recommended that the WHO should develop a guideline in this area in order to provide a framework for the development of regulatory pathways for these products worldwide. For this purpose, agreement on the scope, definition and terminology of these products was deemed necessary. The interchangeability and substitution of products were also flagged as areas in need of harmonization. A WHO working group should be established to develop a guideline that would promote global consensus on the regulation of biosimilars, assist in their registration and enhance the availability of safe and effective biosimilar products worldwide.

Effects of sugar additives on protein stability of recombinant human serum albumin during lyophilization and storage.

Few researches on the protein stabilization of recombinant human serum albumin (rHSA) have been done. In the present study, we assessed the impact of sugar lyoprotectants on the protein stability of lyophilized rHSA (65 KDa) in the solid state. For the assessment, rHSA was formulated with sucrose and trehalose, respectively, alone or in combination with mannitol, which were lyophilized and stored at 35 degrees C. Degradation and aggregation of the resulting lyophilized formulations was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Induction of amorphous state by the lyophilactants with rHSA was determined by differential scanning calorimetry (DSC). The protein secondary structure of the rHSA in the formulations was analyzed by Fourier transform infrared spectroscopy (FT-IR). Results from SDS-PAGE analysis displayed that mannitol formulation caused aggregation resulting in a few bands that were greater than 65 KDa, whereas sucrose and trehalose formulations revealed no such aggregation. However, the aggregation of the protein decreased when mannitol was combined with sucrose or trehalose. DSC measurement supported the electrophoresis data showing that sucrose and trehalose formed complete amorphous state, but mannitol induced a partial amorphous state. These data indicate during lyophilization the most effective protein protection against aggregation was provided by sucrose and trehalose. The protection lasted during 4 months storage at 35 degrees C. FT-IR analysis displayed that the sucrose formulation inhibited deamidation. In conclusion, our data suggest that sucrose and trehalose as additives seems to be sufficient to protect from lyophilization of rHSA protein and also maintain its stability in the solid state during storage.