Survey of Data Package and Sample Size of Comparative Clinical Studies for Biosimilar Developments from PMDA Assessments

BACKGROUND

The Japanese biosimilar guideline requires that the sponsors conduct clinical studies such as comparative pharmacokinetic (PK), pharmacodynamic (PD), or efficacy studies. In each biosimilar development, the sponsors consider the clinical data package, and thus clinical data packages vary among biosimilar developments.

OBJECTIVES

The aim of this study was to elucidate the clinical data packages for the biosimilars approved in Japan. The details of clinical data packages and sample size for the regulatory approvals of biosimilars in Japan was reported.

METHODS

We surveyed the clinical data packages and sample size based on the Pharmaceuticals and Medical Devices Agency (PMDA) website review reports between 2009 and 2023.

RESULTS

Twenty-four biosimilars have been approved based on the comparative PK and efficacy studies, 10 biosimilars have been approved based on the comparative PK/PD study, and one biosimilar has been approved based on the comparative efficacy study. Regarding the sample size, comparative PK studies were conducted in healthy volunteers or patients for up to 300 cases, although the majority enrolled only 1-100 cases (68.1%, 32/47). Comparative PD studies enrolling 1-30, 31-60, and 61-90 cases totaled 4, 7, and 4 cases, respectively. Finally, comparative efficacy studies enrolling 1-300, 301-600, and 601-900 totaled 6, 10, and 11 cases, respectively. In particular, the oncology and rheumatology areas were the first and second disease areas recruiting 601-900 patients.

CONCLUSION

Large numbers of patients were enrolled to conduct a comparative efficacy study. Efficient biosimilar development should be considered on the basis of the accumulation of scientific understanding of comparable features of biosimilars and their development.

The bioequivalence study design recommendations for immediate-release solid oral dosage forms in the international pharmaceutical regulators programme participating regulators and organisations: differences and commonalities

Bioequivalence (BE) studies are considered the standard for demonstrating that the performance of a generic drug product in the human body is sufficiently similar to that of its comparator product. The objective of this article is to describe the recommendations from participating Bioequivalence Working Group for Generics (BEWGG) members of the International Pharmaceutical Regulators Programme (IPRP) regarding the conduct and acceptance criteria for BE studies of immediate release solid oral dosage forms. A survey was conducted among BEWGG members regarding their BE recommendations and requirements related to study subjects, study design, sample size, single or multiple dose administration, study conditions (fasting or fed), analyte to be measured, selection of product strength, drug content, handling of endogenous substances, BE acceptance criteria, and additional design aspects. All members prefer conducting single dose cross-over designed studies in healthy subjects with a minimum of 12 subjects and utilizing the parent drug data to assess BE. However, differences emerged among the members when the drug's pharmacokinetics and pharmacodynamics become more complex, such that the study design (e.g., fasting versus fed conditions) and BE acceptance criteria (e.g., highly variable drugs, narrow therapeutic index drugs) may be affected. The survey results and discussions were shared with the ICH M13 Expert Working Group (EWG) and played an important role in identifying and analyzing gaps during the harmonization process. The draft ICH M13A guideline developed by the M13 EWG was endorsed by ICH on 20 December 2022, under Step 2.

Historical Overview of Regulatory Approvals and PMDA Assessments for Biosimilar Products in Japan During 2009-2022

A biosimilar product is defined as "a biological product that is highly similar to an existing, approved biological product (known as originator or reference product) in terms of structure, function, quality, and clinical efficacy and safety". Recently, biosimilar products have been actively developed around the world, and part of the reason for this is to combat the rapid growth of medical expenses in many countries, including Japan, the United States (US), and Europe. The use of biosimilar products has been promoted as a measure to address this issue. The review of marketing authorization applications for biosimilar products in Japan is conducted by the Pharmaceuticals and Medical Devices Agency (PMDA), which reviews the comparability of the quality, efficacy, and safety based on the data submitted by the applicants. As of December 2022, 32 biosimilar products have been approved in Japan. Through this process, the PMDA has gained much experience and knowledge regarding the development and regulatory approval of biosimilar products; however, details of the regulatory approvals for biosimilar products in Japan have not been reported until now. Therefore, in this article, we present the details of regulatory history and revised guidelines for approval of biosimilar products in Japan, questions and answers, other relevant notifications, and consideration for comparability evaluations for analytical, non-clinical, and clinical studies. In addition, we provide details about the approval history, number, and types of biosimilar products that have been approved between 2009 and 2022 in Japan.

First Approval of Generic Mometasone Furoate Nasal Suspension Spray in Japan: Similarities and Differences Between Japan and the USA

The Ministry of Health, Labour and Welfare (MHLW) in Japan approved the first generic version of Nasonex in February 2018. The Pharmaceuticals and Medical Devices Agency requires in vitro, pharmacokinetic, and pharmacodynamic or clinical endpoint data to approve generic nasal spray drug products. However, the MHLW has not published basic principle for approving nasal generic drug products. Therefore, this article summarizes the data used for the approval of the first generic Nasonex based on publicly available data. Additionally, we compare the bioequivalence evaluations regarding the human studies based on the generic version of Nasonex between Japan and the USA.

A Survey of the Criteria Used for the Selection of Alternative Comparator Products by Participating Regulators and Organizations of the International Pharmaceutical Regulators Programme

The safety and efficacy of a generic product are partly based on demonstrating bioequivalence to the innovator product; however, when the innovator product is no longer available as a comparator product, a survey conducted within the Bioequivalence Working Group for Generics (BEWGG) of the International Pharmaceutical Regulators Programme (IPRP) indicated that the criteria for selecting an alternative comparator product varies. For most members of the BEWGG, an existing marketed generic that was approved based on a comparison with the locally registered innovator product can be used, contingent on criteria that ranges from allowing any generic to be used, to allowing only specific criteria-defined generics to be used. Notwithstanding the acceptability of a generic as an alternative comparator, it is not always the preferred comparator for several jurisdictions. Some jurisdictions require the use of a locally sourced alternative innovator comparator (e.g., the same medicinal ingredient manufactured by a different company) or a foreign innovator comparator. Unlike the other members of the BEWGG, the European Union (EU) has no such options available, rather mechanisms are in place to allow manufacturers to develop a new comparator. The criteria described herein regarding the use of an alternative comparator product can also be applied to scenarios where a specific strength of a series of strengths or an innovative fixed dose combination are discontinued. The results of the survey demonstrate that while criteria for selecting alternative comparator products are not harmonized among the BEWGG participants, the common concern for all jurisdictions is to select a comparator product that meets the safety and efficacy standards of the original innovator product.

Requirements for Additional Strength Biowaivers for Modified Release Solid Oral Dosage Forms in International Pharmaceutical Regulators Programme Participating Regulators and Organisations: Differences and Commonalities

This article describes an overview of waivers of in vivo bioequivalence studies for additional strengths in the context of the registration of modified release generic products and is a follow-up to the recent publication for the immediate release solid oral dosage forms. The current paper is based on a survey among the participating members of the Bioequivalence Working Group for Generics (BEWGG) of the International Pharmaceutical Regulators Program (IPRP) regarding this topic. Most jurisdictions consider the extrapolation of bioequivalence results obtained with one (most sensitive) strength of a product series as less straightforward for modified release products than for immediate release products. There is consensus that modified release products should demonstrate bioequivalence not only in the fasted state but also in the fed state, but differences exist regarding the necessity of additional multiple dose studies. Fundamental differences between jurisdictions are revealed regarding requirements on the quantitative composition of different strengths and the differentiation of single and multiple unit dosage forms. Differences in terms of in vitro dissolution requirements are obvious, though these are mostly related to possible additional comparative investigations rather than regarding the need for product-specific methods. As with the requirements for immediate release products, harmonization of the various regulations for modified release products is highly desirable to conduct the appropriate studies from a scientific point of view, thus ensuring therapeutic equivalence.

A Survey of the Regulatory Requirements for the Waiver of In Vivo Bioequivalence Studies of Generic Products in Certain Dosage Forms by Participating Regulators and Organisations of the International Pharmaceutical Regulators Programme

The requirements to waive in vivo bioequivalence studies for immediate release solid oral dosage forms based on the Biopharmaceutics Classifications System (BCS) are well known, and biowaivers[1] for other types of oral dosage forms based on pre-defined criteria may also be acceptable. Similarly, biowaivers for dosage forms such as injectable products may also be allowed if certain criteria are met. The current paper summarises the biowaiver requirements for oral solutions and suspensions, soft gelatin capsules and injectable products (intravenous injections, subcutaneous and intramuscular injections, emulsions for injection and micellar solutions for injection) among the participants of the Bioequivalence Working Group for Generics (BEWGG) of the International Pharmaceutical Regulators Programme (IPRP). A review of the requirements indicated that there was a trend towards convergence when the dosage form became less complex; however, the most common approach used by each of the jurisdictions was a case-by-case approach given that most jurisdictions do not have well defined guidelines to support all possible scenarios. Even in the simplest case of intravenous solutions, the acceptability of qualitative changes in excipients differ between the IPRP members.  Notwithstanding the differences, the dissemination of the information is a first step towards regulatory convergence regarding biowaivers for certain dosage forms and should be useful for pharmaceutical companies currently developing generic medicinal products for IPRP jurisdictions.  

Modernization and Strengthening of Bioequivalence Guidelines in Japan

Until now, human bioequivalence (BE) studies were conducted based on the revised 'Guideline for Bioequivalence Studies of Generic Products' issued in 2012 by the Ministry of Health, Labour and Welfare (MHLW) in Japan. However, revisions of BE guidelines were required to account for the globalization of pharmaceutical development, new technology, and scientific rationales over the last 8 years. Therefore, the MHLW published the revised 'Guideline for Bioequivalence Studies of Generic Products' in 2020. In this article, we introduce the main revised contents, such as the addition of a fed-state BE study, reconsideration of the pilot study and add-on study, acceptance of foreign subjects in a BE study, and clarification of the requirement of a reference product. Furthermore, we compare the BE evaluations of generic oral solid dosage forms with those of the Pharmaceuticals and Medical Devices Agency (PMDA), the US Food and Drug Administration (FDA), and the European Medicines Agency (EMA).

Current Regulation for Bioequivalence Evaluations of Generic Ophthalmic Dosage Forms in Japan

In Japan, the revised version of bioequivalence (BE) evaluations for generic drug products was made available in 2012; however, the scope of this guideline is mainly oral solid dosage forms. Other dosage forms have to be discussed regarding how to evaluate BE by applicants and regulators during consultation meetings or the review process. Recently, there has been an increase in developing generic drug products in various dosage forms in Japan. Therefore, the Pharmaceuticals and Medical Devices Agency (PMDA) must strengthen their efforts to establish methodologies for BE evaluations for various dosage forms, including those of ophthalmic drugs. In 2016, the Japanese Ministry of Health, Labour and Welfare (MHLW) issued "The basic principles of bioequivalence evaluations of generic ophthalmic aqueous solutions." This document presents recommendations for clinical endpoint BE studies or biowaiver options to evaluate the BE of generic ophthalmic aqueous solutions. However, this document has brought other issues to the forefront, such as the lack of feasibility of human BE studies for certain indications. Therefore, the PMDA, Japan Ophthalmic Pharmaceutical Manufacturer's Association, and BE experts discussed these issues for 2 years, which led to an update by MHLW in 2018 entitled "The basic principles of bioequivalence evaluations of generic ophthalmic dosage forms." This document describes methodologies for evaluating the BE of ophthalmic dosage forms including suspensions. This article introduces recently approved generic products of ophthalmic dosage forms in Japan, the basic principle of which was issued in 2018, and compares the BE evaluations between the PMDA and U.S. Food and Drug Administration.

A Survey of the Regulatory Requirements for the Acceptance of Foreign Comparator Products by Participating Regulators and Organizations of the International Generic Drug Regulators Programme

The acceptance of foreign comparator products is the most limiting factor for the development and regulatory assessment of generic medicines marketed globally. Bioequivalence studies have to be repeated with the local comparator products of each jurisdiction because it is unknown if the comparators of the different countries are the same product, with the consequent duplication of efforts by regulators and industry alike. The regulatory requirements on the acceptability of foreign comparator products of oral dosage forms differ between countries participating in the Bioequivalence Working Group for Generics of the International Pharmaceutical Regulators Programme. Brazil, Colombia, the European Union member States, Japan, Mexico, South Korea and the United States only accept bioequivalence studies with their local comparator. In contrast, Australia, Canada, New Zealand, Singapore, South Africa, Switzerland and Taiwan accept studies with foreign comparators under certain conditions. Canada limits its use to highly soluble drugs with a wide therapeutic range in immediate release products. Australia requires a comparison of the quantitative composition. In contrast, there are fewer restrictions on the acceptance of foreign comparators in New Zealand, Singapore, South Africa, Switzerland and Taiwan. For the WHO Prequalification of Medicines and for developing generics of the essential medicines the WHO lists comparators from different countries. In conclusion, there is currently no consensus amongst regulators on the acceptability of foreign comparator products.

The Requirements for Additional Strength Biowaivers for Immediate Release Solid Oral Dosage Forms in International Pharmaceutical Regulators Programme Participating Regulators and Organisations: Differences and Commonalities

In relation to the registration of generic products, waivers of in vivo bioequivalence studies (biowaivers) are considered in three main cases: certain dosage forms for which bioequivalence is self-evident (e.g. intravenous solutions), biowaivers based on the Biopharmaceutics Classification System and biowaivers for additional strengths with respect to the strength for which in vivo bioequivalence has been shown. The objective of this article is to describe the differences and commonalities in biowaivers for additional strengths of immediate release solid oral dosage forms between the participating members of the International Pharmaceutical Regulators Program (IPRP). The requirements are based on five main aspects; the pharmacokinetics of the drug substance, the manufacturing process, the qualitative and quantitative composition of the different strengths, and the comparative dissolution profiles. For the pharmacokinetic aspects, many regulators/agencies have the same requirements. All strengths must be manufactured with the same process, although a few regulators/agencies accept small differences. In relation to the formulation aspects, the data required breaks down into three major approaches based initially on one of those of the EU, the USA or Japan, but there are some differences in these three major approaches with some country specific interpretations. Most regulators/agencies also have the same requirements for the dissolution data, though there are some notable exceptions.

Comparison of Generic Drug Reviews for Marketing Authorization between Japan and Canada

Purpose

Generic drugs are assuming an increasingly important role in sustaining modern healthcare systems, as the cost of healthcare, including drug usage, is gradually expanding around the world. To date, published articles comparing generic drug reviews between different countries are scarce.

Objective

The objective of this study was to examine generic drug reviews in Japan and Canada.

Methods

We surveyed generic drug reviews from Japan and Canada and compared the following points: general matter (application types, type of partial change or Supplement to an Abbreviated New Drug Submission, application and approval numbers, review period, application format, review report, responsibility for review), bioequivalence studies for solid oral dosage forms, and bioequivalence guidelines, guidance, or basic principles regarding various dosage forms.

Results

This survey described the many similarities and differences in generic drug reviews between the two countries and points that should be improved to promote better generic drug reviews. In particular, regulations for the definition of the same or different active pharmaceutical ingredients (APIs) are similar for both authorities.

Conclusions

The results clarified the future challenges of generic drug reviews, and the differences highlighted by this survey will be important considerations for the future. This is the first article to present and discuss the details of generic drug reviews between Japan and Canada.

A Survey of the Regulatory Requirements for BCS-Based Biowaivers for Solid Oral Dosage Forms by Participating Regulators and Organisations of the International Generic Drug Regulators Programme

Purpose:  The Biopharmaceutics Classification System (BCS) based biowaiver is a scientific model which enables the substitution of in vivo bioequivalence studies with in vitro data as evidence of therapeutic equivalence subject to certain conditions. Despite being based on the same principles, BCS-based biowaivers are interpreted and regulated differently among international regulatory agencies. In this survey, the Bioequivalence Working Group (BEWG) of the International Generic Drug Regulators Programme (IGDRP) compared the criteria for BCS-based biowaivers applied by the participating regulators and organisations. Methods:  Differences and similarities regarding solubility, permeability, dissolution, excipients and fixed-dose combination products, were identified and compared in a detailed survey of each participant’s criteria for BCS-based biowaivers. These criteria were determined based upon the participants’ respective regulatory guidance documents, policies and practices. Results: This review has, with the exception of two participants who do not accept BCS-based biowaivers, revealed that most IGDRP participants interpret the BCS principles and conditions similarly but notable differences exist in the application of these principles.  Conclusion: Although many similarities exist, this review identifies several opportunities for greater convergence of regulatory requirements amongst the surveyed jurisdictions. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page

Bioequivalence Evaluations of Generic Dry Powder Inhaler Drug Products: Similarities and Differences Between Japan, USA, and the European Union

In Japan, the development of generic oral dry powder inhaler (DPI) drug products for marketing approval has recently increased. The Pharmaceuticals and Medical Devices Agency (PMDA) considers the required data for each drug product in the consultation meeting. However, guidelines for DPI drug products have been published by the US Food and Drug Administration and the European Medicines Agency. Recently, the basic principles of bioequivalence evaluations of generic DPI drug products were published in March 2016 by the Ministry of Health, Labour and Welfare. The document mainly outlines the current understanding regarding the bioequivalence evaluations of generic DPI drug products based on knowledge from PMDA consultation meetings. In this review, we compared the bioequivalence evaluations of DPI drug products among Japan, USA, and the European Union and discuss future development of generic DPI drug products in Japan.

Similarities and Differences of International Practices and Procedures for the Regulation for Active Substance Master Files/Drug Master Files of Human Use: Moving Toward Regulatory Convergence

Purpose. A gap analysis survey of international practices for Active Substance Master Files (ASMFs)/Drug Master Files (DMFs) of human use was conducted as a project of the ASMF/DMF working group of the International Generic Drug Regulators Pilot (IGDRP) to identify similarities and differences among ASMF/DMF procedures of 10 IGDRP members and 2 observers. Methods. We conducted a questionnaire survey and compared the following aspects: overall ASMF/DMF procedures, submission requirements for ASMFs/DMFs, assessment processes for ASMFs/DMFs, the technical requirements for active pharmaceutical ingredients (APIs), generation of assessment reports for ASMFs/DMFs, procedures for changing ASMF/DMF details, and Good Manufacturing Practice (GMP) inspection/certification of API manufacturers. Twelve organizations participated in this project: the Brazilian Health Surveillance Agency (Anvisa), the European Union (EU), Health Canada (HC), the Singapore Health Sciences Authority (HSA), the South African Medicines Control Council (MCC), the South Korean Ministry of Food and Drug Safety (MFDS), the Japanese Pharmaceuticals and Medical Devices Agency (PMDA), the Swiss Agency for Therapeutic Products (Swissmedic), the Taiwan Food and Drug Administration (TFDA), the Australian Therapeutic Goods Administration (TGA), the European Directorate for the Quality of Medicines & HealthCare (EDQM) (Observer) and the Prequalification Team (PQT) of the World Health Organization (WHO), which includes the PQT–Medicines (Observer). Results. Although there were many similarities among the participating agencies surveyed, there were also differences that should be discussed such as assessment processes of ASMFs/DMFs and Technical requirements for APIs. Conclusions. These differences revealed by this survey will be key considerations in order to facilitate the filing of ASMFs/DMFs globally and to establish a framework for sharing and utilizing information related to ASMFs/DMFs among IGDRP members in the future. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Similarities and Differences of International Practices and Procedures for the Regulation for Active Substance Master Files/Drug Master Files of Human Use: Moving Toward Regulatory Convergence

Purpose. A gap analysis survey of international practices for Active Substance Master Files (ASMFs)/Drug Master Files (DMFs) of human use was conducted as a project of the ASMF/DMF working group of the International Generic Drug Regulators Pilot (IGDRP) to identify similarities and differences among ASMF/DMF procedures of 10 IGDRP members and 2 observers. Methods. We conducted a questionnaire survey and compared the following aspects: overall ASMF/DMF procedures, submission requirements for ASMFs/DMFs, assessment processes for ASMFs/DMFs, the technical requirements for active pharmaceutical ingredients (APIs), generation of assessment reports for ASMFs/DMFs, procedures for changing ASMF/DMF details, and Good Manufacturing Practice (GMP) inspection/certification of API manufacturers. Twelve organizations participated in this project: the Brazilian Health Surveillance Agency (Anvisa), the European Union (EU), Health Canada (HC), the Singapore Health Sciences Authority (HSA), the South African Medicines Control Council (MCC), the South Korean Ministry of Food and Drug Safety (MFDS), the Japanese Pharmaceuticals and Medical Devices Agency (PMDA), the Swiss Agency for Therapeutic Products (Swissmedic), the Taiwan Food and Drug Administration (TFDA), the Australian Therapeutic Goods Administration (TGA), the European Directorate for the Quality of Medicines & HealthCare (EDQM) (Observer) and the Prequalification Team (PQT) of the World Health Organization (WHO), which includes the PQT–Medicines (Observer). Results. Although there were many similarities among the participating agencies surveyed, there were also differences that should be discussed such as assessment processes of ASMFs/DMFs and Technical requirements for APIs. Conclusions. These differences revealed by this survey will be key considerations in order to facilitate the filing of ASMFs/DMFs globally and to establish a framework for sharing and utilizing information related to ASMFs/DMFs among IGDRP members in the future. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Regulation of Generic Drugs in Japan: the Current Situation and Future Prospects

Generic drugs are interchangeable with original proprietary drugs, as they have the same active pharmaceutical ingredients, dosage forms, strength, quality, indications, effects, directions, and dosage. The cost of generic drugs is lower than original drugs, because the developmental cost is lower. The expansion of medical expenses is an important issue in many countries, including Japan, the USA, and Europe, and promotion of generic drugs has been demanded to solve this issue in Japan. Generic drug approval review in Japan is conducted by the Pharmaceuticals and Medical Devices Agency (PMDA), which reviews the equivalence of the original drugs from the viewpoint of quality, efficacy, and safety, based on documentation submitted by the generic drug applicants. However, the details of the generic drug review in Japan have not been reported. In this report, we introduce the application types, the number of applications and approvals, and the review timeline of generic drugs in Japan. In addition, we discuss recent consultations and future prospects.

Characterization of N-glycan heterogeneities of erythropoietin products by liquid chromatography/mass spectrometry and multivariate analysis

RATIONALE

Glycan heterogeneity on recombinant human erythropoietin (rEPO) product is considered to be one of the critical quality attributes, and similarity tests of glycan heterogeneities are required in the manufacturing process changes and developments of biosimilars. A method for differentiating highly complex and diverse glycosylations is needed to evaluate comparability and biosimilarity among rEPO batches and products manufactured by different processes.

METHODS

The glycan heterogeneities of nine rEPO products (four innovator products and five biosimilar products) were distinguished by multivariate analysis (MVA) using the peak area ratios of each glycan to the total peak area of glycans in mass spectra obtained by liquid chromatography/mass spectrometry (LC/MS) of N-glycans from rEPOs.

RESULTS

Principal component analysis (PCA) using glycan profiles obtained by LC/MS proved to be a useful method for differentiating glycan heterogeneities among nine rEPOs. Using PC values as indices, we were able to visualize and digitalize the glycan heterogeneities of each rEPO. The characteristic glycans of each rEPO were also successfully identified by orthogonal partial least-squares discrimination analysis (OPLS-DA), an MVA method, using the glycan profile data.

CONCLUSIONS

PCA values were useful for evaluating the relative differences among the glycan heterogeneities of rEPOs. The characteristic glycans that contributed to the differentiation were also successfully identified by OPLS-DA. PCA and OPLS-DA based on mass spectrometric data are applicable for distinguishing glycan heterogeneities, which are virtually indistinguishable on rEPO products.

Rapid evaluation for heterogeneities in monoclonal antibodies by liquid chromatography/mass spectrometry with a column-switching system

The development of therapeutic antibodies has grown over the last several years. Most of the recombinant monoclonal antibodies (mAbs) produced by mammalian cells are glycoproteins. Glycosylation of the mAbs can be associated with effector functions, such as antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity, as well as immunogenicity and clearance. Thus, mAb glycan heterogeneity is a significant characteristic associated with the safety and efficacy of the products. Therefore, glycan heterogeneity should be evaluated during research and development (R&D) and during development of mAbs manufacturing processes to identify the process parameters that affect glycan heterogeneity and to enhance understanding of the manufacturing process. There is an increasing need for a rapid, easy, and automated evaluation method for glycan heterogeneity. Liquid chromatography/mass spectrometry (LC/MS) is a method that can be used to analyze glycoforms. LC/MS is marked by the ability to measure the oligosaccharide composition of each glycoform, whereas other general methods, such as capillary electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and ion-exchange chromatography, cannot. However, a laborious off-line purification of mAbs is required to evaluate glycan heterogeneities. In this study, we demonstrate the use of a rapid, easy, and automated evaluation system for mAb glycoforms by LC/MS. This LC/MS system uses a column-switching system equipped with 2 columns, a protein A affinity column and a reversed-phase column (desalting column). We devised 2 column-switching systems: one that targeted intact mAbs (system 1) and one that targeted the light and heavy chains of the mAbs (system 2). Our results show that the proposed systems are applicable as a tool to evaluate the glycoforms in several situations, including the research, development, and production processes of mAbs. Additionally, we hope that our systems are useful as process analytical technology (PAT) for molecular heterogeneities containing glycoforms of mAbs in implementation of quality by design (QbD).

Overexpression of heat shock protein 70 restores the structural stability and functional defects of temperature-sensitive mutant of large T antigen at nonpermissive temperature

The effects of heat shock protein 70 (Hsp70), a molecular chaperone, on the degradation and functional alterations of a mutant large T antigen induced by a nonpermissive temperature were examined. In this study, mouse tracheal epithelial TM02-3 cells harboring temperature-sensitive simian virus 40 large T antigen and stable TM02-3 cells overexpressing human Hsp70 and/or Hsp40 were used. Although the temperature shift from 33 degrees C (permissive temperature) to 39 degrees C (nonpermissive temperature) induced increases in the endogenous chaperones including Hsp70 and Hsp40, degradation of the T antigen, activation of the p53-p21(waf1) pathway, and an arrest of cell growth were observed in the mock cells. In contrast, these changes induced by the temperature shift were partially but significantly prevented in stable cells overexpressing human Hsp70 and/or Hsp40. A combination of Hsp70 and Hsp40 was the most effective, suggesting that Hsp40 may cooperate with Hsp70. Moreover, immunocytochemical observation indicated that human Hsp70 was expressed in the cytoplasm at 33 degrees C, but it colocalized with T antigen in the nucleus at 39 degrees C. These results suggest that overexpressed Hsp70 translocates from the cytoplasm to nucleus, and significantly restores the structural stability and functional defects of mutant large T antigen in the cells.

New gastric epithelial cell lines from mice transgenic for temperature-sensitive simian virus 40 large T antigen show distinct types of cell differentiation

AIM

To develop conditionally immortalized gastric mucosal cell lines that show distinct types of cell differentiation from transgenic mice harboring temperature-sensitive simian virus 40 (tsSV40) large T antigen.

METHODS

Gastric mucosal cells from the transgenic mice were cultured at a permissive temperature (33 degrees C), and proliferative cells were then cloned by colony formation.

RESULTS

Eight gastric cell lines showed epithelial-like morphology and grew at 33 degrees C. Three different types of the cell lines have been established: (1) MGE12-1, MGE3-2, and MGE509 cells expressing mRNAs for pit cell markers (gastric mucin and cathepsin E); (2) MGE02, MGE503, and MGE511 cells expressing mRNAs for pit and zymogenic (pepsinogen F) cell markers, and (3) MGE507 and MGE727 cells expressing mRNAs for pit, zymogenic, and parietal (H,K-ATPase alpha-subunit) cell markers. Moreover, the TaqMan assay showed that mRNA levels of mucin, H,K-ATPase alpha-subunit, and pepsinogen F were influenced by nonpermissive temperature (39 degrees C) in MGE503 and MGE727 cells.

CONCLUSION

These gastric epithelial cell lines seem to reflect different stages of development of gastric mucosal cells.

Requirement for lysine-19 of the yeast mitochondrial ATPase inhibitor for the stability of the inactivated inhibitor-F1Fo complex at higher pH

The ATPase inhibitor is a regulatory subunit of mitochondrial ATP synthase. In this study, the role of Lys19 of the yeast ATPase inhibitor was examined by site-directed mutagenesis. Two amino acids (Gln and Glu) were substituted for the Lys19. The purified mutant inhibitor (Lys19-->Gln) had similar ATPase inhibitory activity to that of the wild-type inhibitor at pH 6.5, but was less active at pH 7.4. ATP synthesis in mutant mitochondria was normally activated by the addition of ADP and succinate, but the inactivated ATPase complex in the mutant mitochondria was activated more readily than that in control cells by raising pH. These results show that Lys19 of the yeast ATPase inhibitor is not essential for ATPase inhibitory activity, but increases the stability of the inhibitor-F1Fo complex at higher pH.

Heparin coupling in inhibition of calcification of vascular bioprostheses

Inhibitory effect of heparin coupling on calcification of bioprosthetic vascular grafts of different origin was studied. Heparin-bonded (Hep) and 0.625% glutaraldehyde-cross-linked (GA) segments of porcine thoracic aorta (AO), pulmonary artery (PA), jugular vein (JV) and rabbit aorta (RA) were implanted subcutaneously in weanling rats for 5 months. Heparin bonding is ineffective in prevention of calcification of JV (Hep: Ca, 159 +/- 32.26 mg g-1; GA: Ca, 193.55 +/- 17.81; p = 0.075) and RA (Hep: Ca, 150.17 +/- 14.78; GA: Ca, 192.12 +/- 26.61; p = 0.015). Calcium content of heparin-coupled PA and AO was significantly less when compared with their GA-treated counterparts. Calcification inhibition was achieved to a greater extent in heparin-bonded PA (Hep: Ca = 22.62 +/- 5.72, GA: Ca = 115.99 +/- 21.91, p < 0.0001) than in the AO coupled to heparin (Hep: Ca = 63.77 +/- 22.75, GA: Ca = 150.40 +/- 35.21, p < 0.0001). Elastin fibers were the predominant site of calcification in all explanted vascular grafts. Heparin-bonded porcine pulmonary artery is seemed to be the best among all vascular bioprostheses in this study.

In vitro and in vivo calcification of vascular bioprostheses

Efficacy of different chemical treatments on calcification of vascular graft in vitro and in vivo was studied. Culture medium-filled rat aortas were separately treated in 0.2% glutaraldehyde and epoxy compound, and photooxidized in 0.01% methylene blue for a shorter period (group 1). Another group of rat aortas were separately treated in the same chemicals for a longer period (group 2). All fresh and treated aortas of both groups were cultured for 21 days in an organ culture medium and implanted (except for group 1) in weanling rats for five months. Histology and immunohistochemistry revealed that differently treated aortas of group 1 grow and calcify, and the smooth muscle cells between elastin fibers are the primary site of calcium deposition. In contrast, differently treated aortas of group 2 neither grew, nor did calcify in the medium except the epoxy compound cross-linked aorta of group 2 which did not grow but did calcify. Untreated aorta did not calcify. All fresh and differently treated aortic homografts calcified severely in rats. Our whole arterial segment-calcification system would be useful for analyzing the molecular and cellular mechanisms of both bioprosthetic and atherosclerotic calcification of vascular graft. New anticalcification technique is the only hope for better outcome of future vascular bioprostheses.

Inhibitory effect of photooxidation on intimal and medial thickening of saphenous vein

BACKGROUND

The inhibitory effect of short-term photooxidation on medial and neointimal proliferation of human saphenous vein was investigated.

METHODS

Culture medium-filled surgically prepared saphenous vein segments were photooxidized in 0.01% methylene blue solution for 5 minutes. Photooxidized and nonphotooxidized saphenous veins were checked for viability of endothelial cells by culturing vein segments for 21 days followed by histologic and immunohistochemical studies.

RESULTS

Endothelial cells of saphenous vein segments remained unaffected after photooxidation. Both the intima and media of nonphotooxidized veins became highly cellular and thickened because of the proliferation and migration of smooth muscle cells. Like precultured fresh saphenous vein, intimal (0.031+/-0.017 mm; p=0.0067) and medial thicknesses (0.702+/-0.123 mm; p < 0.0001) and proliferating cell nuclear antigen-positive cell count (14+/-8/mm2; p=0.0005) of cultured photooxidized veins were significantly less than those of cultured nonphotooxidized veins (intimal thickness, 0.059+/-0.041 mm; medial thickness, 0.997+/-0.228 mm; proliferating cell nuclear antigen positive cell count, 34+/-16/mm2.

CONCLUSIONS

Methylene blue-induced short-term photooxidation is effective in inhibition of intimal and medial thickening of saphenous vein.

Valved conduit in the descending thoracic aorta in juvenile sheep: a useful, cost-effective model for accelerated calcification study in systemic circulation

To evaluate the efficacy of any new anticalcificant in bioprostheses, a cost-effective and easy circulatory model is proposed. Calcification of 0.625% glutaraldehyde-treated porcine aortic valved conduits implanted in the descending thoracic aorta in 11 juvenile sheep for 5 months was compared with that of leaflets of glutaraldehyde-treated porcine aortic valve implanted subcutaneously in 3-week-old male Wistar rats for the same period. Cusps of valved conduits (Ca, 205.41 +/- 16.24 mg g(-1)) in sheep and aortic valve leaflets in rats (Ca, 235.21 +/- 45.25 mg g(-1)) (P = 0.0299) were severely calcified. Morphological characteristics of calcification of all explants were virtually identical. This model provides a model for testing calcification that lies between the subcutaneous weanling rat model and orthotopic whole valve replacement on the left side of the heart. It is less costly and easier to perform than the latter, but does provide exposure to the bloodstream under pressure, which the rat model does not.

Prevention of calcification in glutaraldehyde-treated porcine aortic and pulmonary valves

BACKGROUND

The problem of calcification in porcine aortic (AVs) and pulmonary (PVs) valves and its relationship to glutaraldehyde (GA) is of current interest. We proposed an anticalcification treatment to develop noncalcifying porcine AVs and PVs.

METHODS

Porcine AVs and PVs were cross-linked in GA. Partially degraded heparin was coupled to the GA-treated AVs and PVs through intermediate surface-bound substrate containing amino groups. Control AVs and PVs were cross-linked in 0.625% GA but had no heparin coupling. All specimens were implanted subdermally in 3-week-old rats for 5 months for calcification studies.

RESULTS

Control AVs (Ca, 233.69 +/- 42.61 mg/g) and PVs (Ca, 181.48 +/- 4.06 mg/g) were severely calcified. Coupling of partially degraded heparin revealed complete prevention of calcification in GA-treated AVs (Ca, 0.73 +/- 0.27) and PVs (Ca, 1.125 +/- 0.22 mg/g) implanted subcutaneously in weanling rats for 5 months.

CONCLUSIONS

The proposed anticalcification treatment is effective in preventing calcification of GA-treated AVs and PVs implanted subcutaneously in weanling rats for 5 months.

Heparin in calcification prevention of porcine pericardial bioprostheses

Calcific degeneration is the main cause of failure of glutaraldehyde-treated xenograft heart valve substitutes implanted in humans. Coupling of heparin through an intermediate surface-bound substrate containing amino groups showed complete prevention of calcification of glutaraldehyde-treated porcine pericardium implanted subdermally in weanling rats for 5 months (heparin bonded pericardium: calcium, 0.625 +/- 0.24 mg g(-1); glutaraldehyde-only-treated pericardium: calcium, 228.32 +/- 37.39 mg g(-1); P < 0.0001). Conceivably, inactivation of unpaired aldehyde moieties present in bioprostheses after exposure to glutaraldehyde by amino compounds followed by blocking the potential binding sites of the graft with a surface modifying agent like heparin would be the key steps in the prevention of calcification and degeneration of glutaraldehyde-treated biological tissue grafts.

New-generation valved conduit: an experimental study

OBJECTIVE

An ideal valved conduit to repair complex congenital heart defects is yet to be developed. In this study we have evaluated the merits of our newly developed calcification-free biologic valve incorporated in a compatible conduit of biologic origin in an animal model.

METHODS

Porcine aortic valves and main pulmonary arteries were cross-linked in glutaraldehyde, followed by coupling to partially degraded heparin through an intermediate surface-bound substrate containing amino groups. Because commercially available valves are treated only with glutaraldehyde, control aortic valves and main pulmonary arteries were cross-linked in 0.625% glutaraldehyde. Valved conduits were fabricated from main pulmonary arteries, which were sewn to the aortic and ventricular ends of aortic valves. Valved conduits were examined for calcification and other pathologic changes after being implanted in the descending thoracic aorta in juvenile sheep for 5 months.

RESULTS

Severe calcification was noticed in all layers of cusps (calcium, 231.86 +/- 17.90 mg/gm) and aortic wall (calcium, 123.24 +/- 24.72 mg/gm) of aortic valves and main pulmonary arteries (calcium, 135.43 +/- 26.63 mg/gm) of valved conduits treated with 0.625% glutaraldehyde. Cusps (calcium, 1.28 +/- 0.22 mg/gm) of the aortic valve of heparin-bonded conduits did not calcify at all. Only sparse calcific deposits were noticed in the medial layer of the aortic wall (calcium, 25.90 +/- 22.79 mg/gm) of aortic valves and main pulmonary arteries (calcium, 9.64 +/- 10.79 mg/gm) of the valved conduits coupled to heparin.

CONCLUSION

Heparin coupling is effective in preventing calcification of glutaraldehyde cross-linked valved conduits implanted in the systemic circulation of juvenile sheep.

Apico-aortic shunt: a support technique during surgery on the descending thoracic aorta

To find out whether apico-aortic shunt may become an alternative support technique during surgery on the descending thoracic aorta, performance between apico-aortic shunt and aorto-aortic shunt was compared. In 5 sheep weighing 20-25 kg, apico-aortic shunt and aorto-aortic shunt were instituted with covalently bonded heparin coated polyvinyl tube (internal diameter 5 mm). After clamping the descending thoracic aorta, apico-aortic shunt and aorto-aortic shunt were opened for 30 minutes each. Proximal pressure was elevated to 200 mmHg and distal pressure was fallen to 55 mmHg after clamping the descending thoracic aorta. Opening of apico-aortic shunt and aorto-aortic shunt decreased proximal pressure to 178 +/- 14.8 and 173 +/- 12.0 mmHg, respectively (p = 0.57), and raised distal pressure to 82.4 +/- 7.8 and 90.0 +/- 3.5 mmHg, respectively (p = 0.83). The baseline blood flow of the descending thoracic aorta was 1.4-1.5 l/min. Apico-aortic shunt and aorto-aortic shunt were 0.76 +/- 0.16 and 0.80 +/- 0.22 l/min, respectively (p = 0.67). Blood gas tension, pH and BE measurement showed no significant change and difference between apico-aortic shunt and aorto-aortic shunt, and before and after clamping the descending thoracic aorta. Using apico-aortic shunt, interposition of bioprosthetic valved conduit in the descending thoracic aorta in 10 sheep was successfully performed without paraplegia and any other complications. We concluded that apico-aortic shunt may become an alternative support technique during surgery on the descending thoracic aorta in some specific situations.

Is the dog a useful model for accelerated calcification study of cardiovascular bioprostheses?

Chitosan posttreatment has been shown to be effective in prevention of calcification of the glutaraldehyde treated bovine pericardium when implanted subdermally in rats for 12 weeks. The efficacy of chitosan posttreatment in complete calcium mitigation of the glutaraldehyde treated porcine aortic valves implanted in the right side of the heart in dogs was well-documented in our previous study. In this study, an attempt has been made to evaluate the merit of the chitosan posttreatment in prevention of calcification of the glutaraldehyde (GA) treated porcine aortic valved conduits in the systemic circulation in dogs for a period of 5 months. Eleven mongrel dogs underwent left thoracotomy. Porcine aortic valved conduits treated with 0.625% GA (n = 5) and GA-chitosan (n = 6) were implanted in the descending thoracic aortas of the dogs for 5 months. Gross histological observations showed no calcification in either the 0.625% GA treated or in the GA-chitosan treated valved conduits at 5 months. This was confirmed by results of quantitative analyses for calcium in each explant. There was no significant difference in calcium content between the GA only (Ca, 0.43 +/- 0.26 mg/g) and GA-chitosan treated (Ca, 0.51 +/- 0.19 mg/g; p = 0.5959) valved conduits. This study suggests that the dog is not a suitable model for evaluating the efficacy of a calcium mitigating agent in bioprostheses implanted in systemic circulation.

Mitral regurgitation caused by mitral paraannular cyst

A case of mitral regurgitation (MR) caused by mitral paraannular cyst is reported. A 37-year-old woman on maintenance hemodialysis was admitted to Akita University Hospital because of congestive heart failure. Echocardiography revealed mitral paraannular cyst, which caused coaptation failure of the mitral leaflets and significant MR. She underwent decapsulation of the cyst followed by mitral valve replacement. Postoperative echocardiography showed no recurrence of the cyst three years after surgery. Although mitral annular calcification has been described as a cause of MR in patients with uremia, a report of a solitary intracardiac cyst which causes significant MR is quite rare.