The similarity question for biologicals and non-biological complex drugs

Integrating Quantitative Methods & Modeling and Analytical Techniques in Reverse Engineering; A Cutting-Edge Strategy in Complex Generic Development

Generic drugs are crucial for healthcare, offering affordable alternatives to brand-name drugs. Complex generics, with intricate ingredients, are gaining increasing importance in managing chronic conditions. However, prior to the regulatory market approval, they must demonstrate similarity in active ingredients, formulations, strength, and administration routes to ensure bioequivalence. The primary constraint lies in demonstrating bioequivalence with the innovator drug using traditional methods includes a lack of advanced technologies, and standardized protocols for analysing complex products. Given the multifaceted nature of these products, a single methodology may not suffice to establish in vitro/in vivo bioequivalence. Recognizing this, the USFDA conducts several workshops aiming advancement of complex generic drug product development. Notably, these efforts highlight the need to use Quantitative Methods and Modeling (QMM) approaches to support generic product development. QMM is a scientific approach used to analyze data and simulate drug development processes, ensuring safe, effective, and similar formulations of generic drugs using mathematical, statistical, and computational tools. QMM facilitates the design of formulations and processes, establishes a framework for in vivo BE studies, and suggests alternative ways to demonstrate BE. Appropriate utilization of the QMM approach can reduce the need for unwanted in vivo studies and bolster in vitro approaches for generic product development. Furthermore, use of orthogonal analytical techniques to characterize and decode innovator drugs can provide valuable insights into product attributes. Integrating this data into QMM enables the assessment of critical material attributes, or critical process parameters, thus demonstrating sameness. The combined application of QMM and analytical techniques not only supports regulatory decisions but also enhances the success rate of complex generic drug products.

Dissimilar ferric derisomaltose formulations - In vitro comparisons between an originator and its intended similars

BACKGROUND

The complex nature of intravenous (IV) iron formulations makes manufacturing and characterising similars challenging. This study examined whether simple in vitro tests can distinguish the high-dose IV iron formulation, Monofer® (ferric derisomaltose [FDI]), from the first intended copies of FDI, Rapifer® (FDI intended similar A [FDIIS-A]) and Tosiron® (FDI intended similar B [FDIIS-B]), approved in India and Pakistan, respectively. Neither intended similar is available in Europe or the United States.

METHODS

Iron content, pH, density, non-volatile residue, carbohydrate content, molecular weight distribution, complex robustness (measured using acid hydrolysis half-life [t½]) and free (dialysable) iron content were examined. Mean results from three batches of FDIIS-A were compared with mean values calculated from three batches of Monofer®. Due to product withdrawal, only one batch of FDIIS-B was available for comparison with Monofer®.

RESULTS

Iron content was similar for all formulations (∼100 mg/mL). The chromatograms (obtained using gel permeation chromatography) of FDIIS-A and FDIIS-B differed from that of Monofer®. FDIIS-A was substantially less robust than Monofer® (t½: 15 h versus 40.3 h); t½ for FDIIS-B was not tested. Free iron content was substantially higher in FDIIS-A (0.091 % w/v) and FDIIS-B (1.0 % w/v) versus Monofer® (<0.003 % w/v). Where tested, remaining parameters varied between the formulations (insufficient sample quantities prevented all tests being conducted for all intended similars). For all tests, greater inter-batch variability was seen for FDIIS-A versus Monofer®.

CONCLUSIONS

Simple in vitro tests demonstrated that, aside from total iron content, the first intended similars of FDI bear little resemblance to their originator drug. It is clear that the efficacy and safety profile of Monofer® cannot be extrapolated to the two intended similars. The results call for increased regulatory scrutiny of intended IV iron similars.

Adult and pediatric relapsing multiple sclerosis phase II and phase III trial design and their primary end points: A systematic review

No systematic review of trial designs in patients with relapsing multiple sclerosis (RMS) was reported. This systematic review was conducted on the trial designs and primary end points (PEs) of phase II and III trials intended to modify the natural course of the disease in patients with RMS. The purpose of the study is to explore trends/topics and discussion points in clinical trial design and PE, comparing them to regulatory guidelines and expert recommendations. Three trial registration systems, ClinicalTrials.gov, the EU Clinical Trials Register, and the Japan Registry of Clinical Trials, were used and 60 trials were evaluated. The dominant clinical trial design was a randomized controlled parallel-arms trial and other details were as follows: in adult phase III confirmatory trials (n = 32), active-controlled double-blind trial (DBT) (53%) and active-controlled open-label assessor-masking trial (16%); in adult phase II dose-finding trials (n = 9), placebo- and active-controlled DBT (44%), placebo-controlled DBT (22%), and placebo-controlled add-on DBT (22%); and in pediatric phase III confirmatory trials (n = 8), active-controlled DBT (38%) and active-controlled open-label non-masking trial (25%). The most common PEs were as follows: in adult confirmatory trials, annual relapse rate (ARR) (56%) and no evidence of disease activity-3 (NEDA-3) (13%); in adult dose-finding trials, the cumulative number of T1 gadolinium-enhancing lesions (56%), combined unique active lesions (22%), and overall disability response score (22%); and in pediatric confirmatory trials, ARR (38%) and time to first relapse (25%). It was suggested that some parts of the regulatory guidelines and expert recommendations need to be revised.

Applying a risk assessment guided evaluation for verifying comprehensive two-dimensional gas chromatography to analyse complex pharmaceuticals

The reliability of analytical results is critical and indispensable when applied in regulated environments such as the pharmaceutical industry. Therefore, analytical workflows must be validated. However, validation guidelines are often designed for quantitative targeted analysis and rarely apply to qualitative untargeted approaches. In this study, we employ a risk assessment approach to identify critical parameters which might influence the qualitative results derived by online derivatisation - comprehensive two-dimensional gas chromatography coupled to a high-resolution time-of-flight mass spectrometer (GC × GC-HR-ToF-MS) for the analysis of the active pharmaceutical ingredient (API) sodium bituminosulfonate (SBS). To show the complexity and feasibility of such an approach, we focus on investigating three potential risk factors: sample preparation, vapourability, and the thermal stability of sulfonates. Through the individual evaluation of these potential risk factors due to the application of sample preparation approaches and thermal gravimetric analysis (TGA), we demonstrate the high derivatisation efficiency and repeatability of the online derivatisation method and confirm the absence of derivatisation-induced side reactions. In addition, we also show the potential thermal instability of an incompletely derivatised API. To address the limitation of these individual assessments, we applied a holistic evaluation step with negative electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry (ESI( -) FT-ICR MS) as an orthogonal technique. This confirms that most of the API is detected via the presented GC-based method. Thereby, we demonstrated the practical feasibility of the risk assessment-based approach to ensure the validity of the qualitative data for a complex untargeted method.

Understanding Biosimilar Insulins - Development, Manufacturing, and Clinical Trials

BACKGROUND

A wave of expiring patents for first-generation insulin analogues has created opportunities in the global insulin market for highly similar versions of these products, biosimilar insulins. Biologics are generally large, complex molecules produced through biotechnology in a living system, such as a microorganism, plant cell, or animal cell. Since manufacturing processes of biologics vary, biosimilars cannot be exact copies of their reference product but must exhibit a high degree of functional and structural similarity. Biosimilarity is proven by analytical approaches in comparative assessments, preclinical cell-based and animal studies, as well as clinical studies in humans facilitating the accumulation of evidence across all assessments. The approval of biosimilars follows detailed regulatory pathways derived from those of their reference products and established by agencies such as the European Medicines Agency and the US Food and Drug Administration. Regulatory authorities impose requirements to ensure that biosimilars meet high standards of quality, safety, and efficacy and are highly similar to their reference product.

PURPOSE

This review aims to aid clinical understanding of the high standards of development, manufacturing, and regulation of biosimilar insulins.

METHODS

Recent relevant studies indexed by PubMed and regulatory documents were included.

CONCLUSIONS

Driven by price competition, the emergence of biosimilar insulins may help expand global access to current insulin analogues. To maximize the impact of the advantage for falling retail costs of biosimilar insulins compared with that of reference insulins, healthcare professionals and insulin users must gain further awareness and confidence.

Exploiting Pharma 4.0 Technologies in the Non-Biological Complex Drugs Manufacturing: Innovations and Implications

The pharmaceutical industry has entered an era of transformation with the emergence of Pharma 4.0, which leverages cutting-edge technologies in manufacturing processes. These hold tremendous potential for enhancing the overall efficiency, safety, and quality of non-biological complex drugs (NBCDs), a category of pharmaceutical products that pose unique challenges due to their intricate composition and complex manufacturing requirements. This review attempts to provide insight into the application of select Pharma 4.0 technologies, namely machine learning, in silico modeling, and 3D printing, in the manufacturing process of NBCDs. Specifically, it reviews the impact of these tools on NBCDs such as liposomes, polymeric micelles, glatiramer acetate, iron carbohydrate complexes, and nanocrystals. It also addresses regulatory challenges associated with the implementation of these technologies and presents potential future perspectives, highlighting the incorporation of digital twins in this field of research as it seems to be a very promising approach, namely for the optimization of NBCDs manufacturing processes.

A place for biosimilars in the changing multiple sclerosis treatment landscape

BACKGROUND

The treatment paradigm for multiple sclerosis (MS), particularly relapsing-remitting MS, is heavily reliant on biologic disease-modifying therapies (DMTs). However, the current cost of treatment acts as a significant barrier to access for patients. Over the next few years exclusivity periods for key biologic medicines used in MS are likely to end, opening the door for biosimilar medicines to enter the market.

METHODS

In this review, we discuss what biosimilar medicines are, and how the existing experience with biosimilar medicines across multiple therapy areas can inform the assimilation of biosimilar medicines into the MS treatment landscape in Europe and the US.

RESULTS

There is currently a lack of knowledge and awareness around the distinctions and similarities between small molecules, non-biological complex drugs, and biological medicines, as well as the different categories of follow-on successor medicines. These include biosimilar medicines that offer a matching efficacy and safety profile to the reference biologic. Understanding and recognition of the stringency of the approval pathways required for drug categories such as biosimilars are key in building confidence in treatment outcomes. For example, biosimilar medicines are sometimes perceived only as 'copies' of their reference biologic despite undergoing an extensive approval process requiring that no clinically meaningful differences are observed between the biosimilar medicine and the reference medicine. For MS, introduction of biosimilar medicines in the future will enable more people with MS to receive effective treatment, and also expand access to biologic DMTs in MS. Experiences from the use of biosimilars in multiple therapy areas have shown us that this can result in cost-saving benefits for a healthcare system. Introduction of biosimilar medicines in other therapy areas has also demonstrated the importance of appropriate, accurate education and information for their successful integration into clinical practice.

CONCLUSION

In order to realize optimized treatment outcomes in MS in coming years and to find the appropriate place for biosimilar medicines in the changing MS landscape, it is essential that clinicians and people with MS understand the fundamentals of biosimilars, their potential benefits and consistency of treatment provided by a biosimilar medicine, given the matching efficacy and safety profile to its reference medicine. As evidenced in other therapy areas, biosimilar medicines may reduce key barriers to access by providing a cost-effective alternative to the MS treatment arsenal, while providing the same treatment outcomes as reference biologics.

An Analytical Method for Determination of Total Iron in Pharmaceuticalgrade Intravenous Iron Colloidal Complexes by Redox-Potentiometry

BACKGROUND

Iron carbohydrate complexes are colloidal dispersions made up of polynuclear Fe(III)-oxyhydroxide cores surrounded by a carbohydrate shell that stabilizes the complex in iron colloidal formulations. The current study provides an improved method that is precise, accurate, and linear for quantifying total iron in most Iron Carbohydrate Colloid Drug Products.

METHODS

Redox iodometry with a potentiometric determination is used to evaluate total iron in intravenous formulations. The visual indicator approach is more prone to fluctuations at endpoint calculations. Hence, the voltage potential approach is widely accepted as it is more accurate and sensitive. It tracks the actual change in activity that coincides with the equivalence point that is finally considered an endpoint. The principle is based on the idea that ferric iron in formulation reduces to ferrous iron in the presence of the iodide, which oxidizes to iodine. The released iodine is titrated using sodium thiosulfate.

RESULTS

The proposed method was precise, with %RSD (relative standard deviation) not more than 1. The method was linear between 80% and 120%, with a linear regression of 0.999. The percent recovery ranged from 98.20 to 99.98 for the concentration ranges of 80-120. The method's robustness was checked by various analysts using different reagent grades.

CONCLUSION

The proposed potentiometric determination method was precise, accurate, linear, and sensitive. The method was successfully validated, and the total iron content determined for commercial batches agrees with the iron claim on the label. Therefore, this method can be adapted widely for total iron content determination in any Intravenous formulation currently available on the market. The proposed method is more accessible at the Quality Control facilities on an industrial scale.

Quality by Design (QbD) Approach in Marketing Authorization Procedures of Non-Biological Complex Drugs: A Critical Evaluation

The emergence of innovator-driven complex drug products, such as Non-Biological Complex Drugs (NBCDs), has provided disruptive advances in the Nanotechnology and Biotechnology fields. However, the design and development of NBCDs can be particularly challenging due to some unresolved scientific and regulatory challenges associated with the pharmaceutical quality assessment. The application of a more holistic, systematic, integrated science and risk-based approach, such as Quality by Design (QbD), is essential to address key scientific, technological, and regulatory constraints in the research and development of the NBCDs. The deeper product and process understanding derived from the implementation of the QbD approach ensures consistent, reliable, and high-quality pharmaceutical products. Furthermore, this approach promotes innovation and continuous improvement in the entire product lifecycle. Regulatory authorities highly recommend QbD-based submissions to successfully translate NBCDs from laboratory-scale research to the pharmaceutical market with the required quality, safety, and efficacy standards. The main aim of this article is to obtain a comprehensive and in-depth investigation into the state of implementation of the QbD approach in the pharmaceutical development and marketing authorization of NBCDs in Europe and the United States, through the analysis of the available data from their regulatory dossiers. In addition, it aims to understand and discuss how the QbD approach is used and implemented for complex drug products in the pharmaceutical industry, highlighting the gaps and challenges involved with its implementation. An analysis is held regarding QbD's advantages in terms of knowledge growth, regulatory flexibility, and the speed of development based on big data science, along with the reduction of regulatory failures and market withdrawals.

Regulatory Science Approach in Pharmaceutical Development of Follow-On Versions of Non-Biological Complex Drug Products

Scientific and technological breakthroughs in the field of Nanotechnology have been a driving force throughout the development and approval of Non-Biological Complex Drugs (NBCDs). However, the fast-growing expansion of NBCDs and the emergence of their follow-on versions have brought with them several scientific, technological, and regulatory challenges. The definition of NBCDs is still not officially recognized by the regulatory authorities, and there is no dedicated regulatory pathway addressing the particular features of NBCDs and their follow-on versions. The lack of clear and consistent regulatory guidance documents in this field, as well as, the inconsistency across different regulatory agencies, impact negatively on the acceptance and enormous potential of these drug products. Patient access to high-quality NBCDs follow-on versions may be compromised by regulatory uncertainty resulting from the use of different regulatory approaches across the globe, as well as within the same class of products. Accordingly, there is a real need to develop a specific regulatory pathway compliant with the complexity of NBCDs and their follow-on versions or, alternatively, make better use of available regulatory pathways. The main goal of the review is to deeply investigate and provide a critical overview of the regulatory landscape of NBCDs and follow-on versions currently adopted by the regulatory authorities. The dissemination of knowledge and discussion in this field can contribute to clarifying regulations, policies, and regulatory approaches to complex generics, thereby filling regulatory and scientific gaps in the establishment of therapeutic equivalence.

Future perspectives for advancing regulatory science of nanotechnology-enabled health products

The identification of regulatory challenges for nanotechnology-enabled health products, followed by discussions with the involved stakeholders, is the first step towards a strategic planning of how such challenges can be successfully addressed in the future. In order to better understand whether the identified regulatory needs are sector-specific for health products or might also hinder the progress in other domains, the REFINE consortium reached out to communities representing other sectors that also exploit the potential of nanotechnology, i.e. industrial chemicals, food and cosmetics. Through a series of trans-sectorial workshops, REFINE partners identified common as well as sector-specific challenges and discussed possible ways forward. Potential solutions lie in a more strengthen collaboration between regulatory and research communities resulting in a targeted production and exploitation of academic data for the regulatory decision-making. Furthermore, a coordinated use of knowledge sharing platforms and databases, trans-sectorial standardisation activities and harmonisation of regulatory activities between geographical regions are possible ways forward, in line with the upcoming European political initiatives such as the Chemical Strategy for Sustainability (CSS). Finally, we also discuss the perspectives for further development and sustainability of methods and tools developed in the REFINE project.

Health status improvement with ferric carboxymaltose in heart failure with reduced ejection fraction and iron deficiency

AIM

Intravenous ferric carboxymaltose (FCM) has been shown to improve overall quality of life in iron-deficient heart failure with reduced ejection fraction (HFrEF) patients at a trial population level. This FAIR-HF and CONFIRM-HF pooled analysis explored the likelihood of individual improvement or deterioration in Kansas City Cardiomyopathy Questionnaire (KCCQ) domains with FCM versus placebo and evaluated the stability of this response over time.

METHODS AND RESULTS

Changes versus baseline in KCCQ overall summary score (OSS), clinical summary score (CSS) and total symptom score (TSS) were assessed at weeks 12 and 24 in FCM and placebo groups. Mean between-group differences were estimated and individual responder analyses and analyses of response stability were performed. Overall, 760 (FCM, n = 454) patients were studied. At week 12, the mean improvement in KCCQ OSS was 10.6 points with FCM versus 4.8 points with placebo (least-square mean difference [95% confidence interval, CI] 4.36 [2.14; 6.59] points). A higher proportion of patients on FCM versus placebo experienced a KCCQ OSS improvement of ≥5 (58.3% vs. 43.5%; odds ratio [95% CI] 1.81 [1.30; 2.51]), ≥10 (42.4% vs. 29.3%; 1.73 [1.23; 2.43]) or ≥15 (32.1% vs. 22.6%; 1.46 [1.02; 2.11]) points. Differences were similar at week 24 and for CSS and TSS domains. Of FCM patients with a ≥5-, ≥10- or ≥15-point improvement in KCCQ OSS at week 12, >75% sustained this improvement at week 24.

CONCLUSION

Treatment of iron-deficient HFrEF patients with intravenous FCM conveyed clinically relevant improvements in health status at an individual-patient level; benefits were sustained over time in most patients.

[Knowledge and perceptions of biosimilar medicines by health professionals in Tunisia]

INTRODUCTION

Biosimilar drugs occupy a strategic place in the global pharmaceutical market. However, there are brakes on their use. The objective of our study is to assess the knowledge and perceptions of healthcare professionals on biosimilar drugs in a developing country.

MATERIAL AND METHODS

This is a prospective survey via an anonymous 18-question multiple-choice questionnaire developed and published online through the "Google Forms" application over a period of one month. This questionnaire is intended for Tunisian pharmacists and doctors of all ranks.

RESULTS

A total of 240 health professionals responded to this questionnaire, including 158 pharmacists and 82 physicians. Among them, 73 are not informed about the biosimilar drugs and were excluded from the rest of the questionnaire. Questions regarding the definition of biosimilar drugs and their differences from generic drugs obtained the best rate of 76 % of correct answers. In contrast, the questions that generated the most errors mainly concerned the regulation of biosimilar drugs. Participants felt that they were under-informed about biosimilar drugs in 65 % of the cases. In addition, 92 % were in favor of the development of this class of drugs and 85 % estimated significant to very significant savings related to their use.

CONCLUSION

Our study confirms the lack of information of pharmacists and physicians on biosimilar drugs. Sensitization of healthcare professionals on the safety and effectiveness of the use of these drugs seems to be necessary in order to allow their development.

A pragmatic regulatory approach for complex generics through the U.S. FDA 505(j) or 505(b)(2) approval pathways

The diverse nature of complex drug products poses challenges for the development of regulatory guidelines for generic versions. While complexity is not new in medicines, the technical capacity to measure and analyze data has increased. This requires a determination of which measurements and studies are relevant to demonstrate therapeutic equivalence. This paper describes the views of the NBCD Working Group and provides pragmatic solutions for approving complex generics by making best use of existing U.S. Food and Drug Administration's abbreviated approval pathways 505(j) and 505(b)(2). We argue that decisions on the appropriateness of submitting a 505(j) or 505(b)(2) application can build on the FDA's complex drug product classification as well as the FDA's much applauded guidance document for determining whether to submit an ANDA or a 505(b)(2) application. We hope that this paper contributes to the discussions to increase the clarity of regulatory approaches for complex generics, as well as the predictability for complex generic drug developers, to facilitate access to much‐needed complex generics and to promote the sustainability of the healthcare system.

Highway to Success—Developing Advanced Polymer Therapeutics

Polymer therapeutics are advancing as an important class of drugs. Polymers have already demonstrated their value in extending the half‐life of proteins. They show great potential as delivery systems for improving the therapeutic index of drugs, via biophysical targeting and more recently with more precision targeting. They are also important for intracellular delivery of nucleic acid based drugs. The same frameworks that have been successfully applied to improve the small molecule drug development can be adopted. This approach together with improved pathophysiological disease knowledge and critical developability considerations, imperative given the size and complexity of polymer therapeutics, provides a structured framework that should improve their clinical translation and exploit their functionality and potential. Progress in understanding the right target, gaining the right tissue and cell exposure, ensuring the right safety, selecting the right patient population is discussed. The right commercial considerations are outlined and the need for a multi‐disciplinary approach is emphasized. Crucial developability factors together with scientific and technical advancements to enable pharmaceutical development of a quality robust product are addressed. It is argued that by applying this structured approach to their design and development, polymer therapeutics will continue to grow and develop as important next generation medicines.

Influence of bound dodecanoic acid on the reconstitution of albumin nanoparticles from a lyophilized state

The development of reference standards for nanoparticle sizing allows for cross laboratory studies and effective transfer of particle sizing methodology. To facilitate this, these reference standards must be stable upon long-term storage. Here, we examine factors that influence the properties of cross-linked albumin nanoparticles, fabricated with an ethanol desolvation method, when reconstituted from a lyophilized state. We demonstrate, with nanoparticle tracking analysis, no significant changes in mean particle diameter upon reconstitution of albumin nanoparticles fabricated with bovine serum albumin loaded with dodecanoic acid, when compared to nanoparticles fabricated with a fatty acid-free BSA. We attribute this stability to the modulation of nanoparticle charge-charge interactions at dodecanoic acid specific binding locations. Furthermore, we demonstrate this in a lyophilized state over six months when stored at − 80 °C. We also show that the reconstitution process is readily transferable between technicians and laboratories and further confirm our finding with dynamic light scattering analysis.

Probabilistic modeling of an injectable aqueous crystalline suspension using influence networks

Probabilistic modeling using influence networks is an efficient, intuitive, and easy to communicate strategy in the development of complex pharmaceutical products. This study was aimed to use a risk-based approach to explore the complex interactions between product and process design parameters affecting size and shape of the particles in injectable aqueous crystalline suspensions (ACS). Based on a risk assessment, a design of experiments (DOE) was applied to evaluate the most important parameters, i.e., four critical material attributes and two critical process parameters. A model hydrophobic drug (carbamazepine) was milled and homogenized in a multistep process (dispersion and milling steps). The final formulations were characterized with automated at-line image analysis of thousands of individual particles. The particle size and shape distributions were summarized with descriptive parameters, and the relationship of these parameters and the DOE was modeled using influence networks (INs). This approach was compared and contrasted with a classical modeling approach based on multivariate linear regression (MVLR). INs had a superior visual interpretation capability of the complex and multivariate ACS system making the risk-based decision making more accessible. The probability and causality were included in the IN, i.e., the relationships between size and shape. Moreover, IN allowed to incorporate prior knowledge in a systematic way by implementing a 'black and white list'. An IN based model was created with the following model performance: a mean absolute percentage error of 1.7% and 1.1% for the size and 6.2% and 5.0% for the shape, respectively for dispersed and milled ACS. Parameters with the highest and lowest probability to control the critical quality attributes of ACS could be identified. Consequently, the parameter settings giving the optimum particle size and shape could be predicted using a Monte Carlo simulation to calculate the probability of success including the uncertainty of the model. The cubic MVLR model for the size of milled ACS was comparable to the IN in terms of the mean absolute percentage error, i.e., 1.1%. However, IN was more efficient in visualizing the complex and multivariate data set, including all the critical quality attributes and formulation/process parameters of the ACS at the same time. Moreover, the prior knowledge used in probabilistic modeling of IN could be systematically documented.

Electron microscopy-based semi-automated characterization of aggregation in monoclonal antibody products

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Size-based quantification of small heterogeneous proteins using electron microscopy.

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Electron microscopy as an orthogonal tool for characterizing protein aggregates.

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Quick assessment of small heterogeneous proteins via softEM, a GUI-based algorithm.

Aggregation is a critical parameter for protein-based therapeutics, due to its impact on the immunogenicity of the product. The traditional approach towards characterization of such products is to use a collection of orthogonal tools. However, the fact that none of these tools is able to completely classify the distribution and physical characteristics of aggregates, implies that there exists a need for additional analytical methods. We report one such method for characterization of heterogeneous population of proteins using transmission electron microscopy. The method involves semi-automated, size-based clustering of different protein species from micrographs. This method can be utilized for quantitative characterization of heterogeneous populations of antibody/protein aggregates from TEM images of proteins, and may also be applicable towards other instances of protein aggregation.

Evaluation of Therapeutic Equivalence for the Follow-On Version of Intravenously Administered Non-Biological Complex Drugs

The interchangeability evaluation for generic drugs formulated as intravenous injections normally only requires assessments of pharmaceutical equivalence (PE) when the medicinal products are simple small-molecule drugs. However, intravenously administered non-biological complex drugs (NBCDs), such as liposomes, microsphere suspension, or fat emulsion, have inherent passive disposition selectivity due to their special formulations, thereby the in vivo drug performances are improved. Because of the complexity in formulation, the in vitro pharmaceutical investigations of follow-on NBCDs are more complicated than those required for generic small-molecule drugs. In addition to qualitative and quantitative sameness of the active and inactive ingredients, it is required to comparatively study the static and kinetic microscopic particle-related physiochemical properties of the follow-on NBCDs versus the reference products. Moreover, for complex formulations that have a significant impact on the biodistribution of the drug compound, an in vivo bioequivalence (BE) study is also important. Since NBCDs that demonstrated bioequivalence through the conventional BE approach have been found inequivalent in efficacy or safety to the reference products, pivotal BE studies for follow-on NBCDs are required to take both encapsulated/total drug and free drug as the analytes to address release kinetics and biodistribution of the active pharmacological ingredient in the body. This manuscript reviews the 26 U.S. FDA published product-specific guidelines for intravenous injections. In general, these NBCDs can be stratified into four groups according to their release kinetics and ability of bio-membrane penetration. Group 1 consists of seven small-molecule, non-complex drugs; group 2 included four NBCDs with either microscale particle size or rapid dissolution property; group 3 include five loosely packed NBCDs (fat emulsions) and one quickly released ophthalmic liposomal drug; and the last group contains four cytotoxic liposomal or protein-bound NBCDs and five iron carbohydrate complexes. The requirements of the corresponding guidelines range from simple proof of PE between the test and the reference products, to a collection of studies that demonstrate the key manufacturing process (e.g. liposome loading), the particle- or vehicle-wise static and kinetic physiological characterizations, the dissolution test, and BE evaluation of both total/encapsulated drug form and free drug form between the follow-on NBCDs and their reference products. Such studies are challenging in implementation. Therefore, a variety of alternative approaches are proposed in this article.

Nanomedicines and Nanosimilars: Looking for a New and Dynamic Regulatory "Astrolabe" Inspired System

The application of the nanotechnology in medicine and pharmaceutics opens new horizons in therapeutics. Several nanomedicines are in the market and an increasing number is in clinical trials. But which is the advantage of the medicines in nanoscale? The scientists and the regulatory authorities agree that the size and consequently the physiochemical/biological properties of nanomaterials play a key role in their safety and effectiveness. Additionally, all of them agree that a new scientific-based regulatory landscape is required for the establishment of nanomedicines in the market. The aim of this review is to investigate the parameters that the scientists and the regulatory authorities should take into account in order to build up a dynamic regulatory landscape for nanomedicines. For this reason, we propose an "astrolabe-like system" as the guide for establishing the regulatory approval process. Its function is based on the different physicochemical/biological properties in comparison to low molecular weight drugs.

Assessing the Similarity between Random Copolymer Drug Glatiramer Acetate by Using LC-MS Data Coupling with Hypothesis Testing

The full characterization of nonbiological complex drugs (NBCDs) is not possible, but analytical approaches are of urgent need to evaluate the similarity between different lots and compare with their follow-up versions. Here, we propose a hypothesis testing-based approach to assess the similarity/difference between random amino acid copolymer drugs using liquid chromatography mass spectrometry (LC-MS) analysis. Two glatiramer acetate (GA) drugs, commercially available Copaxone and in-house synthesized SPT, and a negative control were digested by Lys-C and followed by HILIC-MS analysis. After retention time alignment and feature identification, 1627 features matched to m/z values in an elemental composition database were considered as derived from active drug ingredients. A hypothesis testing approach, the sum of squared deviations test, was developed to process high-dimensional data derived from LC-MS spectra. The feasibility of this approach was first demonstrated by testing 5 versus 5 lots of Copaxone and Copaxone versus SPT, which suggested a significant similarity by obtaining the estimated 95th percentile of the distribution of the estimator (ρ̂_(95%)) at 0.0056 (p-value = 0.0026) and 0.0026 (p-value < 0.0001), respectively. In contrast, the ρ̂ was 0.036 (p-value = 1.00), while comparing Copaxone and the negative control, implying a lack of similarity. We further synthesized nine stable isotope-labeled peptides to validate the proposed amino acid sequences in the database, demonstrating the correctness in sequence identification. The quantitation variations in our analytical procedures were determined to be 6.8-7.7%. This approach was found to have a great potential for evaluating the similarity between generic NBCDs and listed reference drugs, as well as to monitor the lot-to-lot variation.

Nanomedicines - Tiny particles and big challenges

After decades of research, nanotechnology has been used in a broad array of biomedical products including medical devices, drug products, drug substances, and pharmaceutical-grade excipients. But like many great achievements in science, there is a fine balance between the risks and opportunities of this new technology. Some materials and surface structures in the nanosize range can exert unexpected toxicities and merit a more detailed safety assessment. Regulatory agencies such as the United States Food and Drug Administration or the European Medicines Agency have started dealing with the potential risks posed by nanomaterials. Considering that a thorough characterization is one of the key aspects of controlling such risks this review presents the regulatory background of nanosafety assessment and provides some practical advice on how to characterize nanomaterials and drug formulations. Further, the challenges of how to maintain and monitor pharmaceutical quality through a highly complex production processes will be discussed.

The Breakthrough of Biosimilars: A Twist in the Narrative of Biological Therapy

The coming wave of patent expiries of first generation commercialized biotherapeutical drugs has seen the global market open its doors to close copies of these products. These near perfect substitutes, which are termed as “biosimilars”, do not need to undergo intense clinical trials for their approval. However, they are mandated to produce identical similarity from their reference biologics in terms of clinical safety and efficacy. As such, these biosimilar products promise to foster unprecedented access to a wide range of life-saving biologics. However, seeing this promise be fulfilled requires the development of biosimilars to be augmented with product trust, predictable regulatory frameworks, and sustainable policies. It is vital for healthcare and marketing professionals to understand the critical challenges surrounding biosimilar use and implement informed clinical and commercial decisions. A proper framework of pharmacovigilance, education, and scientific exchange for biologics and biosimilars would ensure a dramatic rise in healthcare access and market sustainability. This paper seeks to collate and review all relevant published intelligence of the health and business potential of biosimilars. In doing so, it provides a visualization of the essential steps that are required to be taken for global biosimilar acceptance.

Perception of hematologists and oncologists about the biosimilars: A prospective Tunisian study based on a survey

INTRODUCTION

Biosimilar drugs have significantly shaken the global pharmaceutical market through a better access to the health care services. The aim of this study is to establish a state of play in Tunisia based on the knowledge and perceptions of doctors on biosimilars in order to identify the problems related to these drugs and to propose solutions for improvement.

MATERIALS AND METHODS

In our study, we conducted a prospective, descriptive survey using a questionnaire, destinated to oncologists and hematologists with different grades, from both public and private sectors and from several regions. The questions focused on physicians' general knowledge of biosimilars and their comparison with reference on safety, quality, efficacy, and indication. Finally, we explored the proportion of physicians who are favorable to the policy encouraging biosimilar use.

RESULTS

One hundred and seven doctors among 150 answered the questionnaire; 57% were oncologists and 43% were hematologists. About one over five physicians defines biosimilar as a chemical drug. About 29% do not differentiate between a biosimilar and a generic one. A percentage of 68 believe that a biosimilar can have all the indications of its reference following complementary clinical studies. On the other side, 68.2% support the policy encouraging these drugs. Last, only 3.7% of the practitioners believe that they are well informed about biosimilars.

DISCUSSION

Our results are comparable to other surveys described in the literature. However, this is the first study that targets oncologists and hematologists specifically.

CONCLUSION

Our study showed a lack of information from oncologists and hematologists about biosimilars in Tunisia. Thus, health authorities should carry out training programs on biosimilars and introduce clear and effective legislation in order to allow better access to health care services.

Pharmacokinetics of ferric bepectate-a new intravenous iron drug for treating iron deficiency

IV iron is indicated in clinical conditions, where rapid anaemia alleviation and repletion of iron stores are required. The acute toxicity of IV iron is ascribed to the presence of labile iron in plasma. Thus, shorter plasma residence time might improve the safety profile, even for compounds holding‐on the iron tightly. In this single‐centre, open‐label, single‐dose escalation study, we evaluated the elimination kinetics of ferric bepectate (FBP) compared to those of ferric carboxymaltose (FCM). Thirty‐three iron‐depleted anaemic patients who had undergone cardiac surgery were included and received 200, 500 or 1500 mg FBP or 500 mg FCM. Plasma drug curves were subjected to model‐free analysis. Because saturation kinetics was found, a compartmental model with limited elimination capacity was applied. Urinary iron excretion was also analysed. The initial non‐compartmental analysis revealed an increasing AUC/dose ratio for FBP. For both drugs, the central distribution compartment corresponded to plasma volume, and elimination followed Michaelis‐Menten saturation kinetics. Maximal elimination rates (V_max) were 224 mg/h and 81 mg/h for FBP 500 mg and FCM 500 mg, respectively; drug concentrations at half V_max (K_m), 99 mg/L and 212 mg/L, respectively; and terminal plasma half‐life (T½), 3.05 h and 8.96 h, respectively. Both drugs were equally effective in eliciting an early ferritin rise. Urinary iron excretion was measurable in all patients receiving FCM but not in those receiving FBP, which was well tolerated. Intravenous iron drugs are subject to capacity‐limited elimination with different saturation thresholds. Urinary iron excretion can be used as a surrogate for labile plasma iron.

Differences between intravenous iron products: focus on treatment of iron deficiency in chronic heart failure patients

Iron deficiency is the leading cause of anaemia and is highly prevalent in patients with chronic heart failure (CHF). Iron deficiency, with or without anaemia, can be corrected with intravenous (i.v.) iron therapy. In heart failure patients, iron status screening, diagnosis, and treatment of iron deficiency with ferric carboxymaltose are recommended by the 2016 European Society of Cardiology guidelines, based on results of two randomized controlled trials in CHF patients with iron deficiency. All i.v. iron complexes consist of a polynuclear Fe(III)‐oxyhydroxide/oxide core that is stabilized with a compound‐specific carbohydrate, which strongly influences their physico‐chemical properties (e.g. molecular weight distribution, complex stability, and labile iron content). Thus, the carbohydrate determines the metabolic fate of the complex, affecting its pharmacokinetic/pharmacodynamic profile and interactions with the innate immune system. Accordingly, i.v. iron products belong to the new class of non‐biological complex drugs for which regulatory authorities recognized the need for more detailed characterization by orthogonal methods, particularly when assessing generic/follow‐on products. Evaluation of published clinical and non‐clinical studies with different i.v. iron products in this review suggests that study results obtained with one i.v. iron product should not be assumed to be equivalent to other i.v. iron products that lack comparable study data in CHF. Without head‐to‐head clinical studies proving the therapeutic equivalence of other i.v. iron products with ferric carboxymaltose, in the highly vulnerable population of heart failure patients, extrapolation of results and substitution with a different i.v. iron product is not recommended.

Quality Comparison of Biosimilar and Copy Filgrastim Products with the Innovator Product

Purpose

Filgrastim, a recombinant human granulocyte-colony stimulating factor, is widely used to treat congenital and acquired neutropenia. Following patent expiration of the innovator filgrastim product, biosimilar filgrastim products have been approved in the EU and shown to be comparable with the innovator with respect to quality, safety and efficacy. In less regulated markets, copy filgrastim products are available but data about their quality are scarce. In the present study, we provide a head-to-head comparative study on the quality of biosimilar and copy filgrastim products.

Methods

Innovator filgrastim product, Neupogen®, two EU-licensed biosimilars, Zarzio® and Tevagrastim®, and two copy filgrastim products, Biocilin® and PDgrastim®, were subjected to peptide mapping, circular dichroism spectroscopy, fluorescence spectroscopy, sodium dodecyl sulfate polyacrylamide gel electrophoresis, high performance size-exclusion chromatography, reversed-phase ultra-performance liquid chromatography, endotoxin test, flow imaging microscopy and in vitro potency assay.

Results

Zarzio® and Tevagrastim® have comparable quality to Neupogen®, while Biocilin® showed a significantly lower and PDgrastim® a higher specific activity. Moreover, PDgrastim® showed a higher level of impurities and a lower thermo stability than the other products.

Conclusions

Except for the deviating specific activities of the two copy filgrastim products, we found no substantial differences in product quality between the filgrastim products studied.

Nanomedicine safety in preclinical and clinical development: focus on idiosyncratic injection/infusion reactions

Injection/infusion reactions to nanopharmaceuticals (and particulate drug carriers) are idiosyncratic and well documented. The molecular basis of nanoparticle-mediated injection reactions is debatable, with two hypotheses as front-runners. The first is complement-activation-related 'pseudoallergy', where a causal role for nanoparticle-mediated complement activation in injection/infusion reactions is considered. However, the second hypothesis (the rapid phagocytic response hypothesis) states a transitional link from robust clearance of nanoparticles (NPs) from the blood by strategically placed responsive macrophages to adverse hemodynamic and cardiopulmonary reactions, regardless of complement activation. Here, I critically examine and discuss these hypotheses. Current experimentally derived evidence appears to be more in support of the rapid phagocytic response hypothesis than of the 'pseudoallergy' hypothesis.

Follow-on products for treatment of multiple sclerosis in Latin America: An update

Both proprietary and non-proprietary medicines are expected to undergo rigorous pre-approval testing and both should meet stringent health authority regulatory requirements related to quality to obtain approval. Non-proprietary (also known as copy or generic) medicines, which base their authorization and use on the proprietary documentation and label, are often viewed as a means to help lower cost and thus increase patient access. If these medicines fail to meet quality standards, such as good manufacturing practice and bioequivalence (in humans), they are then defined as substandard copies and can pose serious risks to patients in terms of safety and efficacy. Availability of this type of compounds is more prevalent in regions where health authorities do not enforce registration regulations as stringent as those of the Food and Drug Administration, European Medicines Agency, or World Health Organization, including preestablished quality standard requirements. This article focuses on non-proprietary medicines for multiple sclerosis, that are not identical to proprietary versions and could thus fail to meet efficacy or have different impact on the safety of patients with multiple sclerosis.

Desafios ao controle da qualidade de medicamentos no Brasil

Resumo Introdução O desenvolvimento científico e tecnológico, assim como a adoção de políticas públicas voltadas à redução do custo dos medicamentos, tem ampliado o acesso da população a alternativas terapêuticas, as quais incluem medicamentos genéricos, biossimilares, nanomedicamentos e complexos não biológicos. As categorias já comercializadas exigem procedimentos próprios para a garantia de sua qualidade, eficácia terapêutica e segurança. Nesse contexto, o presente estudo procura realizar uma avaliação do cenário atual no Brasil sobre esse tema, apontando para situações que certamente terão de ser enfrentadas em um futuro próximo. Metodologia Foi realizado um levantamento de dados nas bases eletrônicas MEDLINE, PubMed e SCIELO, buscando artigos originais, tanto em português quanto em inglês, indexados retrospectivamente até 1999. Foram utilizados termos de busca relevantes em língua portuguesa e inglesa. Mais de 50 artigos científicos foram encontrados. Resultados e Discussão A maioria dos artigos avaliados aponta problemas tanto na fabricação quanto no controle de medicamentos genéricos e biossimilares, seja no mercado internacional, seja no nacional. No entanto, novas formas medicamentosas estão sendo criadas e necessitam do desenvolvimento de legislação e de metodologias específicas para a garantia da qualidade desses produtos. Uma avaliação do atual sistema brasileiro de registro e controle da qualidade aponta falhas e, especialmente, falta de uma farmacovigilância mais bem estruturada e ativa no país. Conclusão O atual cenário demonstra que os órgãos responsáveis no país necessitam rever a atual sistemática utilizada na fabricação e controle de medicamentos e aprimorá-la, bem como se preparar para o enfrentamento de outras demandas, algumas ainda mais complexas, que já se encontram em desenvolvimento.

A Comprehensive Review on Copemyl®

Economic sustainability is of paramount importance in the rapidly evolving therapeutic scenario of multiple sclerosis (MS). Glatiramoids are a class of drugs whose forefather, glatiramer acetate, has been used as a disease modifying drug (DMD) in patients with MS for over 20 years. Its patent expired in 2015; new versions of such drug are nowadays available on the market, potentially contributing to lowering prices and enhancing a better allocation of economic resources. In this review, we analyze the recommendations underlying the approval of both generic drugs and biosimilars by regulatory authorities, and we provide methodological tools to contextualize the design of studies on these new classes of drugs. We examine in more detail the preclinical and clinical data of Copemyl^®, a new member of the glatiramoid class, focusing on its biological and immunological properties and illustrating randomized controlled trials that led to its authorization.

The Botanical Drug Substance Crofelemer as a Model System for Comparative Characterization of Complex Mixture Drugs

Crofelemer is a botanical polymeric proanthocyanidin that inhibits chloride channel activity and is used clinically for treating HIV-associated secretory diarrhea. Crofelemer lots may exhibit significant physicochemical variation due to the natural source of the raw material. A variety of physical, chemical, and biological assays were used to identify potential critical quality attributes (CQAs) of crofelemer, which may be useful in characterizing differently sourced and processed drug products. Crofelemer drug substance was extracted from tablets of one commercial drug product lot, fractionated, and subjected to accelerated thermal degradation studies to produce derivative lots with variations in chemical and physical composition potentially representative of manufacturing and raw material variation. Liquid chromatography, UV absorbance spectroscopy, mass spectrometry, and nuclear magnetic resonance analysis revealed substantial changes in the composition of derivative lots. A chloride channel inhibition cell-based bioassay suggested that substantial changes in crofelemer composition did not necessarily result in major changes to bioactivity. In 2 companion papers, machine learning and data mining approaches were applied to the analytical and biological data sets presented herein, along with chemical stability data sets derived from forced degradation studies, to develop an integrated mathematical model that can identify CQAs which are most relevant in distinguishing between different populations of crofelemer.

A review of the literature analyzing benefits and concerns of infliximab biosimilar CT-P13 for the treatment of rheumatologic diseases: focus on interchangeability

The introduction of biological agents drastically changed the treatment paradigm of inflammatory arthritides, ameliorating the natural history of the diseases but concomitantly increasing the drug costs due to the manufacturing process. On this concern, biosimilar drugs may represent a valid option for reducing this elevated cost and increasing the availability of these highly effective treatments. Recently, CT-P13, the first biosimilar of infliximab, has been approved with the same indications established for the reference product (RP), and its daily use is progressively increasing. However, the experience with biosimilar drugs in the field of rheumatology is still limited, raising potential doubts and concerns on their correct management in real-life settings. Comparability analysis between CT-P13 and its RP was evaluated in equivalence randomized controlled trials (RCTs) - PLANETRA and PLANETAS - performed on patients with rheumatoid arthritis and axial spondylitis, respectively. CT-P13 and RP showed similar profile in terms of quality, biological activity, safety, immunogenicity, and efficacy. However, the interchangeability between infliximab RP and its biosimilar still represents the most challenging issue because of a lack of a long-lasting experience. To date, reassuring preliminary data on this topic were reported in open-label extensions of PLANETRA and PLANETAS RCTs and in ongoing real-life observational studies. These findings, taken all together, significantly affect the landscape of biosimilar regulatory pathways and strongly support CT-P13 introduction as a great opportunity for expanding the accessibility to these very effective and high-cost therapies.

Biosimilars in rheumatology: understanding the rigor of their development

This article examines the current landscape of biosimilar development in rheumatology. As misperceptions about biosimilars exist regarding their comparability to the reference products for clinical use, we review the development paradigm with the goal of improving rheumatologists' understanding of the rigor with which biosimilars are developed. With an emphasis on European Union and US markets, it gives an overview of some of the challenges and issues related to biosimilar development that need to be considered by rheumatologists in this increasingly growing therapeutic space.

Scientific and Regulatory Considerations for Generic Complex Drug Products Containing Nanomaterials

In the past few decades, the development of medicine at the nanoscale has been applied to oral and parenteral dosage forms in a wide range of therapeutic areas to enhance drug delivery and reduce toxicity. An obvious response to these benefits is reflected in higher market shares of complex drug products containing nanomaterials than that of conventional formulations containing the same active ingredient. The surging market interest has encouraged the pharmaceutical industry to develop cost-effective generic versions of complex drug products based on nanotechnology when the associated patent and exclusivity on the reference products have expired. Due to their complex nature, nanotechnology-based drugs present unique challenges in determining equivalence standards between generic and innovator products. This manuscript attempts to provide the scientific rationales and regulatory considerations of key equivalence standards (e.g., in vivo studies and in vitro physicochemical characterization) for oral drugs containing nanomaterials, iron-carbohydrate complexes, liposomes, protein-bound drugs, nanotube-forming drugs, and nano emulsions. It also presents active research studies in bridging regulatory and scientific gaps for establishing equivalence of complex products containing nanomaterials. We hope that open communication among industry, academia, and regulatory agencies will accelerate the development and approval processes of generic complex products based on nanotechnology.

What do oncologists need to know about biosimilar products?

Many biologic products have improved the outcomes of cancer patients, but the costs can substantially burden healthcare systems. Biosimilar products can potentially reduce drug costs and increase patient access to beneficial treatments. Approval of a biosimilar product relies on the demonstration of "comparability" or "no clinically meaningful differences" as compared to its reference biologic product. Biosimilar products for erythropoietin, granulocyte colony-stimulating factor, trastuzumab, and rituximab are already available, and the regulatory processes in various countries are constantly evolving. It is important that oncologists be familiar with the potential issues surrounding the clinical use of biosimilar products. In this review article, we provide background information about biosimilar products and their regulatory approval processes, followed by a discussion of individual biosimilar drugs.

The regulator’s perspective: How should new therapies and follow-on products for MS be clinically evaluated in the future?

Background:

Although there is still no cure for multiple sclerosis (MS), the introduction of several innovative drugs with modes of action different from that of the existing drug arsenal and the progress in monitoring disease progression by imaging and using biomarkers are currently causing a knowledge surge. This provides opportunities for improving patient disease management. New therapies are also under development and pose challenges to the regulatory bodies regarding the optimal design of clinical trials with more patient-focused clinical endpoints. Moreover, with the upcoming patent expiry of some of the key first-line MS treatments in Europe, regulatory bodies will also face the challenge of recommending marketing authorisation for generic and abridged versions based on appropriate requirements for demonstrating equality/similarity to the innovator’s product.

Objective:

The goal of this article is to improve the understanding of the relevant guidance documents of the European Medicines Agency (EMA) on clinical investigation of medicinal products and to highlight the issues that the agency will need to clarify regarding follow-on products of first-line MS treatments.

Conclusion:

Today, it is clear that close collaboration between patients, healthcare professionals, regulatory bodies and industry is crucial for developing new safe and effective drugs, which satisfy the needs of MS patients.

Biosimilarity Assessments of Model IgG1-Fc Glycoforms Using a Machine Learning Approach

Biosimilarity assessments are performed to decide whether 2 preparations of complex biomolecules can be considered "highly similar." In this work, a machine learning approach is demonstrated as a mathematical tool for such assessments using a variety of analytical data sets. As proof-of-principle, physical stability data sets from 8 samples, 4 well-defined immunoglobulin G1-Fragment crystallizable glycoforms in 2 different formulations, were examined (see More et al., companion article in this issue). The data sets included triplicate measurements from 3 analytical methods across different pH and temperature conditions (2066 data features). Established machine learning techniques were used to determine whether the data sets contain sufficient discriminative power in this application. The support vector machine classifier identified the 8 distinct samples with high accuracy. For these data sets, there exists a minimum threshold in terms of information quality and volume to grant enough discriminative power. Generally, data from multiple analytical techniques, multiple pH conditions, and at least 200 representative features were required to achieve the highest discriminative accuracy. In addition to classification accuracy tests, various methods such as sample space visualization, similarity analysis based on Euclidean distance, and feature ranking by mutual information scores are demonstrated to display their effectiveness as modeling tools for biosimilarity assessments.

Correlating the Impact of Well-Defined Oligosaccharide Structures on Physical Stability Profiles of IgG1-Fc Glycoforms

As part of a series of articles in this special issue describing 4 well-defined IgG1-Fc glycoforms as a model system for biosimilarity analysis (high mannose-Fc, Man5-Fc, GlcNAc-Fc and N297Q-Fc aglycosylated), the focus of this work is comparisons of their physical properties. A trend of decreasing apparent solubility (thermodynamic activity) by polyethylene glycol precipitation (pH 4.5, 6.0) and lower conformational stability by differential scanning calorimetry (pH 4.5) was observed with reducing size of the N297-linked oligosaccharide structures. Using multiple high-throughput biophysical techniques, the physical stability of the Fc glycoproteins was then measured in 2 formulations (NaCl and sucrose) across a wide range of temperatures (10°C-90°C) and pH (4.0-7.5) conditions. The data sets were used to construct 3-index empirical phase diagrams and radar charts to visualize the regions of protein structural stability. Each glycoform showed improved stability in the sucrose (vs. salt) formulation. The HM-Fc and Man5-Fc displayed the highest relative stability, followed by GlcNAc-Fc, with N297Q-Fc being the least stable. Thus, the overall physical stability profiles of the 4 IgG1-Fc glycoforms also show a correlation with oligosaccharide structure. These data sets are used to develop a mathematical model for biosimilarity analysis (as described in a companion article by Kim et al. in this issue).