Assessment of Structural and Functional Comparability of Biosimilar Products: Trastuzumab as a Case Study

Assessment of change in the basic variants composition of trastuzumab during dilution in saline for administration

Postproduction handling of drug products during preparation or clinical use may affect the structure and efficacy of the drug and perhaps remain unnoticed. Since chemical modifications can impact the product's structure, stability, and biological activity, this study investigates the impact of elevated temperature and subtle shift in pH on the drug product post-dilution in saline. The mAb sample diluted in saline for administration was stressed at elevated temperature and slightly acidic pH condition. Extended stability studies were performed and monitored for size and charge heterogeneity. Size heterogeneity shows no significant changes, whereas charge heterogeneity shows an increase in basic variants and a reduction in main species. Further, basic variants were isolated and characterized to identify the type and site of chemical modification. Intact mass analysis and peptide mapping identify that the basic variants were attributed mainly to the isomerization of HC Asp102 into iso-Asp or its succinimide intermediate. Four basic variants were found to exhibit similar structural properties as the main and control samples. However, basic variants showed reduced binding affinity to HER2 receptor, while there was no significant difference in FcRn binding. The results indicate that modification in the HC Asp102, which is present in the CDR, affects antigen binding and thus can influence the potency of the drug product. Hence, with the conventional stability studies required to license the drug product, including in-use or extended stability studies to mimic the postproduction handling would be desirable.

Machine learning tool as an enabler for rapid quantification of monoclonal antibodies N-glycans using fluorescence detector

Liquid chromatography-mass spectrometry (LC-MS) is widely used for identification and quantification of N-glycans of monoclonal antibodies (mAbs), owing to its high sensitivity and accuracy. However, its resource-intensive nature necessitates the development of rapid and cost-effective orthogonal analysis approaches. This study aims to develop an online method utilizing the Extreme Gradient Boosting (XGBoost) machine learning (ML) algorithm for real time quantification of InstantPC labelled N-glycans by Liquid Chromatography (LC) - fluorescence detector (FLD). The LC-FLD profile is pre-processed for baseline correction and noise reduction prior to fed to the machine learning (ML) algorithm. The algorithm has been successfully tested for commercial and inhouse developed mAbs and validated using LC-MS quantification as reference. The LC-FLD-ML model predicted values were at par with the LC-MS values with root mean square error of <0.5 and R2 of >0.95. The average errors using ML model (1.80 %) was reduced by a minimum of 28 % and 40 % for origin (1.5 %) and manual (1.07 %) based integration, respectively. The approach reduces the data analysis time per sample by ~70 % (from ~5 min to ~1.5 min), thereby offering a time and resource efficient orthogonality with LC-MS for quantification of N-glycans in mAbs.

LC-MS Characterization and Stability Assessment Elucidate Correlation Between Charge Variant Composition and Degradation of Monoclonal Antibody Therapeutics

Aggregation stability of monoclonal antibody (mAb) therapeutics is influenced by many critical quality attributes (CQA) such as charge and hydrophobic variants in addition to environmental factors. In this study, correlation between charge heterogeneity and stability of mAbs for bevacizumab and trastuzumab has been investigated under a variety of stresses including thermal stress at 40 °C, thermal stress at 55 °C, shaking (mechanical), and low pH. Size- and charge-based heterogeneities were monitored using analytical size exclusion chromatography (SEC) and cation exchange chromatography (CEX), respectively, while dynamic light scattering was used to assess changes in hydrodynamic size. CEX analysis revealed an increase in cumulative acidic content for all variants of both mAbs post-stress treatment attributed to increased deamidation. Higher charge heterogeneity was observed in variants eluting close to the main peak than the ones eluting further away (25-fold and 42-fold increase in acidic content for main and B1 of bevacizumab and 19-fold for main of trastuzumab, respectively, under thermal stress; 50-fold increase in acidic for main and B1 of bevacizumab and 10% rise in basic content of main of trastuzumab under pH stress). Conversely, variants eluting far away from main exhibit greater aggregation as compared to close-eluting ones. Aggregation kinetics of variants followed different order for the different stresses for both mAbs (2nd order for thermal and pH stresses and 0th order for shaking stress). Half-life of terminal charge variants of both mAbs was 2- to 8-fold less than main indicating increased degradation propensity.

Impact of Excipient Extraction and Buffer Exchange on Recombinant Monoclonal Antibody Stability

The foundation of a biosimilar manufacturer's regulatory filing is the demonstration of analytical and functional similarity between the biosimilar product and the pertinent originator product. The excipients in the formulation may interfere with characterization using typical analytical and functional techniques during this biosimilarity exercise. Consequently, the producers of biosimilar products resort to buffer exchange to isolate the biotherapeutic protein from the drug product formulation. However, the impact that this isolation has on the product stability is not completely known. This study aims to elucidate the extent to which mAb isolation via ultrafiltration-diafiltration-based buffer exchange impacts mAb stability. It has been demonstrated that repeated extraction cycles do result in significant changes in higher-order structure (red-shift of 5.0 nm in fluorescence maxima of buffer exchanged samples) of the mAb and also an increase in formation of basic variants from 19.1 to 26.7% and from 32.3 to 36.9% in extracted innovator and biosimilar Tmab samples, respectively. It was also observed that under certain conditions of tertiary structure disruptions, Tmab could be restabilized depending on formulation composition. Thus, mAb isolation through extraction with buffer exchange impacts the product stability. Based on the observations reported in this paper, we recommend that biosimilar manufacturers take into consideration these effects of excipients on protein stability when performing biosimilarity assessments.

Taurine, a Naturally Occurring Amino Acid, as a Physical Stability Enhancer of Different Monoclonal Antibodies

Degradation of therapeutic monoclonal antibodies (mAbs) is a major concern as it affects efficacy, shelf-life, and safety of the product. Taurine, a naturally occurring amino acid, is investigated in this study as a potential mAb stabilizer with an extensive analytical characterization to monitor product degradation. Forced degradation of trastuzumab biosimilar (mAb1)-containing samples by thermal stress for 30 min resulted in high-molecular-weight species by more than 65% in sample without taurine compared to the sample with taurine. Samples containing mAb1 without taurine also resulted in higher Z-average diameter, altered protein structure, higher hydrophobicity, and lower melting temperature compared to samples with taurine. The stabilizing effect of taurine was retained at different mAb and taurine concentrations, time, temperatures, and buffers, and at the presence of polysorbate 80 (PS80). Even the lowest taurine concentration (10 mM) considered in this study, which is in the range of taurine levels in amino acid injections, resulted in enhanced mAb stability. Taurine-containing samples resulted in 90% less hemolysis than samples containing PS80. Additionally, mAb in the presence of taurine showed enhanced stability upon subjecting to stress with light of 365 nm wavelength, combination of light and H2O2, and combination of Fe2+ and H2O2, as samples containing mAb without taurine resulted in increased degradation products by more than 50% compared to samples with taurine upon subjecting to these stresses for 60 min. In conclusion, the presence of taurine enhanced physical stability of mAb by preventing aggregate formation, and the industry can consider it as a new mAb stabilizer.

Multi-attribute method (MAM) to assess analytical comparability of adalimumab biosimilars

Adalimumab drug product (Humira ®), the first fully human monoclonal antibody (mAb) approved by FDA in 2002, led the top ten list of best-selling mAbs in 2018 and has been the most profitable drug in the world. With the expiration of patent protection in Europe in 2018 and in United States by 2023, the landscape is changing as up to 10 adalimumab biosimilars are expected to enter the market in the US. Biosimilars offer the potential to lower costs on health care systems and increase patient accessibility. The analytical similarity of seven different adalimumab biosimilars was accomplished in the present study using the multi-attribute method (MAM), a LC-MS based peptide mapping technique that allows for primary sequence assessment and evaluation of multiple quality attributes including deamidation, oxidation, succinimide formation, N- and C- terminal composition and detailed N-glycosylation analysis. In the first step, characterization of the most relevant post-translational modifications of a reference product was attained during the discovery phase of MAM. During the second step, as part of the MAM targeted monitoring phase, adalimumab batch-to batch variability was evaluated to define statistical intervals for the establishment of similarity ranges. The third step describes biosimilarity evaluation of predefined quality attributes and new peak detection for the assessment of any new or modified peak compared to the reference product. This study highlights a new perspective of the MAM approach and its underlying power for biotherapeutic comparability exercises in addition to analytical characterization. MAM offers a streamlined comparability assessment workflow based on high-confidence quality attribute analysis using high-resolution accurate mass mass spectrometry (HRAM MS) and the capability to detect any new or modified peak compared to the reference product.

Assessment of structural and functional similarity of biosimilar products: Bevacizumab as a case study

The antiangiogenic drug bevacizumab is a blockbuster therapeutic pharmaceutical product that is used to treat many different types of cancer including kidney, colon, rectum, lung, and breast cancer. As a result, multiple biosimilars have been approved across the various regulatory jurisdictions in India (>20 in number till date). The rapidly growing market and acceptance of biosimilars was the motivation to perform comparability study of bevacizumab biosimilars that are presently available in the Indian market. A comprehensive analytical and functional biosimilarity assessment has been performed to examine and compare innovator product of bevacizumab (Avastin-innovator product, Roche Products (India) Pvt Ltd) and six biosimilars that are being marketed in India (Abevmy from Mylan Pharmaceuticals Pvt Ltd, Bevazza from Lupin Ltd, Bryxta from Zydus Cadila, Krabeva from Biocon, Ivzumab from RPG Life Sciences Ltd, and Advamab from Alkem Laboratories Ltd). Physiochemical characterization of drug products was performed with respect to their primary structure (intact mass, reduced mass, peptide mapping by LC-MS), higher order structure (secondary structure by FTIR, Far-UV-CD, and tertiary structure by Near-UV-CD, intrinsic fluorescence spectroscopy), impurity profile (SE-HPLC, SEC-MALS, extrinsic fluorescence: size heterogenicity, degradation, stability; DLS: hydrodynamic radius; WCX-HPLC: charge variants analysis) and post-translational modifications by measuring reduced glycans through fluorescence dye analysis. Functional characterization was performed by SPR and cell proliferation assay. Further, chemometrics based quantitative evaluation of biosimilarity has been performed by combining the data obtained from analytical characterization platform. The analysis of the analytical, functional and chemometric results revealed significant levels of similarity, with biosimilar4 being the sole exception. Despite being within product specifications, Biosimilar4 displayed significant deviations with respect to critical quality attributes, including a lower proportion of monomer content, a larger percentage of basic charge variant species, and a lower proportion of aglycosylated glycoform.

Optimization of medium with perfusion microbioreactors for high density CHO cell cultures at very low renewal rate aided by design of experiments

A novel approach of design of experiment (DoE) is developed for the optimization of key substrates of the culture medium, amino acids, and sugars, by utilizing perfusion microbioreactors with 2 mL working volume, operated in high cell density continuous mode, to explore the design space. A mixture DoE based on a simplex-centroid is proposed to test multiple medium blends in parallel perfusion runs, where the amino acids concentrations are selected based on the culture behavior in presence of different amino acid mixtures, and using targeted specific consumption rates. An optimized medium is identified with models predicting the culture parameters and product quality attributes (G0 and G1 level N-glycans) as a function of the medium composition. It is then validated in runs performed in perfusion microbioreactor in comparison with stirred-tank bioreactors equipped with alternating tangential flow filtration (ATF) or with tangential flow filtration (TFF) for cell separation, showing overall a similar process performance and N-glycosylation profile of the produced antibody. These results demonstrate that the present development strategy generates a perfusion medium with optimized performance for stable Chinese hamster ovary (CHO) cell cultures operated with very high cell densities of 60 × 106 and 120 × 106  cells/mL and a low cell-specific perfusion rate of 17 pL/cell/day, which is among the lowest reported and is in line with the framework recently published by the industry.

Taking the individual bias out of examining comparability of biosimilars: A case study on monoclonal antibody therapeutics

Biosimilar manufacturers need to perform analytical and functional similarity assessments against the reference product. Successful demonstration allows for an abbreviated clinical path, thereby translating to affordable biosimilars. Current practices for regulatory concurrence on analytical similarity data are based on chart visualization and open to individual (human) bias. Here, we present a novel, chemometric approach for assessing biosimilarity that aims to simplify assessment and eliminate individual bias from decision making through application of weighted principal component analysis. Through the proposed approach, chemical information across the analytical characterization platform and drug products can be collated into a single plot for quantitative biosimilarity assessment. The proposed one-plot analysis offers a holistic visualization of 1) inter-product variability (w.r.t reference product) in cases where multiple batches per product have been investigated and 2) intra-product variability for each critical quality attribute (CQA) wherein information from orthogonal tools can be incorporated within the same plot. This allows for numerical grading of similarity for biosimilars of any given reference product. Although the proposed statistical approach is novel, it builds on standardized measures of CQA, criticality, and analytical procedures, thus making this approach easy to incorporate within the existing regulatory framework.

On Replication in Biopharmaceutical Analysis

The landscape of biopharmaceutical analysis features different analytical requirements in terms of instrumentation and type of analysis (QC, RTRT, and in-process). One of the questions that often crops up for routine analysis is “How much replication is enough?” Should all the samples be run in triplicate irrespective of the type of analysis, or does the type of analysis (such as charge or size variants) have any bearing on the number of optimal replicates?

Establishing Analytical and Functional Comparability for Biosimilars

A biosimilar is a drug product that has been deemed to be highly similar to its off-patent reference product in terms of purity, molecular structure, and bioactivity. Approvals to such products are granted on the basis of unambiguous demonstration of “no clinically meaningful differences” between the reference and the intended biosimilar. For a successful biosimilar approval, establishing analytical and functional biosimilarity across all relevant critical quality attributes is an essential prerequisite. This critical activity is performed using a combination of orthogonal, high-resolution tools that can accurately quantitate the minor differences that exist. In this article, we review key findings from some of the recent biosimilarity assessments that we have published on biosimilars of granulocyte-colony-stimulating factor (G-CSF), insulin glargine, rituximab, and trastuzumab.

Optimized Methods for Analytical and Functional Comparison of Biosimilar mAb Drugs: A Case Study for Avastin, Mvasi, and Zirabev

Bevacizumab is a humanized therapeutic monoclonal antibody used to reduce angiogenesis, a hallmark of cancer, by binding to VEGF-A. Many pharmaceutical companies have developed biosimilars of Bevacizumab in the last decade. The official reports provided by the FDA and EMA summarize the analytical performance of biosimilars as compared to the originators without giving detailed analytical procedures. In the current study, several key methods were optimized and reported for analytical and functional comparison of bevacizumab originators (Avastin, Altuzan) and approved commercial biosimilars (Zirabev and Mvasi). This case study presents a comparative analysis of a set of biosimilars under optimized analytical conditions for the first time in the literature. The chemical structure of all products was analyzed at intact protein and peptide levels by high-resolution mass spectrometry; the major glycoforms and posttranslational modifications, including oxidation, deamidation, N-terminal PyroGlu addition, and C-terminal Lys clipping, were compared. The SPR technique was used to reveal antigen and some receptor binding kinetics of all products, and the ELISA technique was used for C1q binding affinity analysis. Finally, the inhibition performance of the samples was evaluated by an MTS-based proliferation assay in vitro. Major glycoforms were similar, with minor differences among the samples. Posttranslational modifications, except C-terminal Lys, were determined similarly, while unclipped Lys percentage was higher in Zirabev. The binding kinetics for VEGF, FcRn, FcγRIa, and C1q were similar or in the value range of originators. The anti-proliferative effect of Zirabev was slightly higher than the originators and Mvasi. The analysis of biosimilars under the same conditions could provide a new aspect to the literature in terms of the applied analytical techniques. Further studies in this field would be helpful to better understand the inter-comparability of the biosimilars.

Trastuzumab in breast cancer treatment: the Era of biosimilars

BACKGROUND

The discovery of trastuzumab as anti-HER2 therapy markedly improved disease control and the survival rates of patients with HER2+ breast cancer. However, as trastuzumab is considered a complex molecule, the cost of production is usually elevated, which significantly affects health budgets and limits the treatment access for patients who live in underdeveloped countries. Recently, trastuzumab production became more accessible and sustainable due to the patents' expiration, allowing biosimilar versions of trastuzumab to be developed.

OBJECTIVE

Our main goal was to shed more light on the uses of biosimilars in breast cancer treatment, emphasizing trastuzumab.

METHOD

An integrative review was carried out in the PubMed, Scielo, Web of Science, and SCOPUS databases using the terms "biosimilar," "breast cancer," "monoclonal antibody," and "trastuzumab." The time range included scientific articles published from 2015 to 2021.

RESULTS AND DISCUSSION

The bibliographic survey showed the complexities in biological medicine manufacturing and how the monoclonal antibody's therapy with trastuzumab improved the patients' life expectancy, revolutionizing HER2+ breast cancer treatment. Nonetheless, despite its benefits, trastuzumab generates certain restrictions, especially from the economic perspective. Trastuzumab biosimilars have high selectivity and rarely cause adverse effects compared to conventional chemotherapy.

CONCLUSION

This study shows that trastuzumab biosimilars improve patients' accessibility to breast cancer treatment through a safe and effective therapy compared to the drug reference.

Analytical Similarity Assessment of Biosimilars: Global Regulatory Landscape, Recent Studies and Major Advancements in Orthogonal Platforms

Biopharmaceuticals are one of the fastest-growing sectors in the biotechnology industry. Within the umbrella of biopharmaceuticals, the biosimilar segment is expanding with currently over 200 approved biosimilars, globally. The key step towards achieving a successful biosimilar approval is to establish analytical and clinical biosimilarity with the innovator. The objective of an analytical biosimilarity study is to demonstrate a highly similar profile with respect to variations in critical quality attributes (CQAs) of the biosimilar product, and these variations must lie within the range set by the innovator. This comprises a detailed comparative structural and functional characterization using appropriate, validated analytical methods to fingerprint the molecule and helps reduce the economic burden towards regulatory requirement of extensive preclinical/clinical similarity data, thus making biotechnological drugs more affordable. In the last decade, biosimilar manufacturing and associated regulations have become more established, leading to numerous approvals. Biosimilarity assessment exercises conducted towards approval are also published more frequently in the public domain. Consequently, some technical advancements in analytical sciences have also percolated to applications in analytical biosimilarity assessment. Keeping this in mind, this review aims at providing a holistic view of progresses in biosimilar analysis and approval. In this review, we have summarized the major developments in the global regulatory landscape with respect to biosimilar approvals and also catalogued biosimilarity assessment studies for recombinant DNA products available in the public domain. We have also covered recent advancements in analytical methods, orthogonal techniques, and platforms for biosimilar characterization, since 2015. The review specifically aims to serve as a comprehensive catalog for published biosimilarity assessment studies with details on analytical platform used and critical quality attributes (CQAs) covered for multiple biotherapeutic products. Through this compilation, the emergent evolution of techniques with respect to each CQA has also been charted and discussed. Lastly, the information resource of published biosimilarity assessment studies, created during literature search is anticipated to serve as a helpful reference for biopharmaceutical scientists and biosimilar developers.

Unexplored Excipients in Biotherapeutic Formulations: Natural Osmolytes as Potential Stabilizers Against Thermally Induced Aggregation of IgG1 Biotherapeutics

Monoclonal antibodies (mAbs), while incredibly successful, are prone to a variety of degradation pathways, the most significant of which is aggregation. One of the most commonly used strategy to overcome protein aggregation is addition of excipients to the formulation. Osmolytes such as trehalose, sucrose, and glycine are widely used. In this paper, we explore potential use of naturally occurring osmolytes such as betaine, sarcosine, ectoine, and hydroxyectoine for reducing aggregation of mAb therapeutics. Experimentation has been performed on two IgG1 mAbs via accelerated stability studies. A variety of analytical tools have been used for monitoring the impact, dynamic light scattering (DLS) for colloidal stability, Fourier transform infrared (FTIR) spectroscopy and fluorescence spectroscopy for conformational stability and the higher order structure (HOS), and differential scanning calorimetry (DSC) for thermal stability. No significant impact of osmolyte addition was observed on protein structure, on comparative Fc receptor (FcRn) binding, and on biocompatibility as per our hemolytic assay. Our results rank the osmolytes’ stabilizing trend to be sarcosine > betaine > hydroxyectoine > ectoine. Sarcosine emerged as the most successful osmolyte rendering highest degree of protection against aggregation. Our data support the prospect of using these osmolytes as successful excipients for mAb formulations.

Biosimilars accessible in the market for the treatment of cancer

Biosimilars are the biological product clinically identical to a biologic reference standard regarding their strength, purity, and safety. A large segment of biosimilars has been developed for the treatment of cancer. This review aims to discuss various facets of biosimilars and explicates on biosimilars accessible in the market for cancer clinical intervention. It also illustrates the outcomes of recent clinical trial studies concerning biosimilars. Further, it also crosstalk the safety profiles, regulatory approval requirements, and allied challenges therein. The work will be of significant interest to researchers working in the field of biologics and biosimilars.

Raman spectroscopy for in situ, real time monitoring of protein aggregation in lyophilized biotherapeutic products

Quality of biotherapeutic products is of paramount importance for ensuring patient safety. Analytical tools that can facilitate rapid quality assessment of the therapeutic product at the point of care are very much in demand. In this article, we apply chemometrics based analysis of Raman spectra towards quantitative prediction of protein aggregation in lyophilized biotherapeutic products. Two commercially available therapeutic proteins, erythropoietin (EPO) and human growth hormone (HGH), have been used to demonstrate the applicability of the proposed approach. Thermally induced protein aggregation was monitored by size exclusion chromatography as well as Raman spectroscopy with a 785 nm wavelength laser. Partial least square (PLS) regression was used to analyse the Raman spectra and create a model for quantitative determination of aggregate. Satisfactory performance was observed with both EPO and HGH with R² of 0.91 and 0.94, cross-validation correlation coefficient of 0.85 and 0.89, and Root Mean Square Error computed from cross calibration (RMSEcv) of 5.25 and 1.92, respectively. The developed approach can enable rapid and accurate assessment of aggregation in lyophilized samples of biotherapeutic products. The study also demonstrates novel use of Raman spectroscopy for protein quantification through a vial.

Comparative analytical profiling of bevacizumab biosimilars marketed in India: a national control laboratory study

In this study, analytical profiling of the bevacizumab (BVZ) biosimilars (N = 3) approved in India were evaluated for charge heterogeneity, isoelectric focusing, aggregation and in vitro potency analysis. The charge variants were characterized using high performance cation-exchange chromatography (CEX-HPLC), capillary zone electrophoresis (CZE) and capillary isoelectric focusing (cIEF). cIEF was also used for estimation of isoelectric point (pI value). In addition, aggregate analysis was done using size exclusion high performance chromatography (SEC-HPLC). The cell-based inhibition of proliferation assay using HUVEC cells, indirect ELISA and Western blot were performed for in vitro biological activity. In addition of cell-based cytotoxicity assay was also performed and found no cytotoxic effect on both HuT78 and WIL2S cells by bevacizumab biosimilars. The significant variations in acidic (p < 0.0001) and basic variants (p < 0.0001), pI value (p = 0.0035), aggregates (p = 0.0306) of biosimilars were found as compared to innovator product; however, cell-based potency analysis (p = 0.6047) and indirect ELISA (p = 0.1611) have shown no significant difference in the biological activity. The banding patterns of all biosimilars in western blot were found similar to the innovator product. The comparatively higher basic variants in the biosimilars were attributing to the high pI value of biosimilars to that of innovator product, although these variations were not affecting the biological activity of the biosimiars. This is a unique study, wherein the independent analysis by a National Control Laboratory (NCL) will not only help the National Regulatory Authority (NRA) to assess the quality and consistency in manufacturing of BVZ biosimilars marketed in India but also facilitate the uptake of BVZ biosimilars, and sustainable access to new medicines against the anti-angiogenic therapy.