Physicochemical and functional comparability between the proposed biosimilar rituximab GP2013 and originator rituximab

Basic regulatory science behind drug substance and drug product specifications of monoclonal antibodies and other protein therapeutics

In this review, we focus on providing basics and examples for each component of the protein therapeutic specifications to interested pharmacists and biopharmaceutical scientists with a goal to strengthen understanding in regulatory science and compliance. Pharmaceutical specifications comprise a list of important quality attributes for testing, references to use for test procedures, and appropriate acceptance criteria for the tests, and they are set up to ensure that when a drug product is administered to a patient, its intended therapeutic benefits and safety can be rendered appropriately. Conformance of drug substance or drug product to the specifications is achieved by testing an article according to the listed tests and analytical methods and obtaining test results that meet the acceptance criteria. Quality attributes are chosen to be tested based on their quality risk, and consideration should be given to the merit of the analytical methods which are associated with the acceptance criteria of the specifications. Acceptance criteria are set forth primarily based on efficacy and safety profiles, with an increasing attention noted for patient-centric specifications. Discussed in this work are related guidelines that support the biopharmaceutical specification setting, how to set the acceptance criteria, and examples of the quality attributes and the analytical methods from 60 articles and 23 pharmacopeial monographs. Outlooks are also explored on process analytical technologies and other orthogonal tools which are on-trend in biopharmaceutical characterization and quality control.

Hydrophilic Interaction Liquid Chromatography at Subzero Temperature for Hydrogen-Deuterium Exchange Mass Spectrometry

Chromatographic separations at subzero temperature significantly improve the precision of back-exchange-corrected hydrogen-deuterium exchange mass spectrometry (HDX-MS) determinations. Our previously reported dual-enzyme HDX-MS analysis instrument used reversed phase liquid chromatography (RPLC) at -30 °C, but high backpressures limited flow rates and required materials and equipment rated for very high pressures. Here, we report the design and performance of a dual-enzyme HDX-MS analysis instrument comprising a RPLC trap column and a hydrophilic interaction liquid chromatography (HILIC) analytical column in a two-dimensional RPLC-HILIC configuration at subzero temperature. During operation at -30 °C, the HILIC column manifests greatly reduced backpressure, which enables faster analytical flow rates and the use of materials rated for lower maximum pressures. The average peptide eluted from a HILIC column during a 40 min gradient at -30 °C contained ≈13% more deuterium than peptides eluted from a tandem RPLC-RPLC apparatus using a conventional 8 min gradient at 0 °C. A subset of peptides eluted from the HILIC apparatus contained ≈24% more deuterium.

Recent advances in structural mass spectrometry methods in the context of biosimilarity assessment: from sequence heterogeneities to higher order structures

Biotherapeutics and their biosimilar versions have been flourishing in the biopharmaceutical market for several years. Structural and functional characterization is needed to achieve analytical biosimilarity through the assessment of critical quality attributes as required by regulatory authorities. The role of analytical strategies, particularly mass spectrometry-based methods, is pivotal to gathering valuable information for the in-depth characterization of biotherapeutics and biosimilarity assessment. Structural mass spectrometry methods (native MS, HDX-MS, top-down MS, etc.) provide information ranging from primary sequence assessment to higher order structure evaluation. This review focuses on recent developments and applications in structural mass spectrometry for biotherapeutic and biosimilar characterization.

Method validation and new peak detection for the liquid chromatography-mass spectrometry multi-attribute method

The multi-attribute method (MAM) is a liquid chromatography-mass spectrometry (LC-MS) peptide mapping technique that has been proposed as a replacement for several conventional quality control (QC) methods for therapeutic proteins. In addition to quantification of multiple product quality attributes (PQAs), MAM can also monitor impurities using a new peak detection (NPD) feature. Here, results are provided from method validation and NPD studies of an MAM approach applied to rituximab as a model monoclonal antibody (mAb). Twenty-one rituximab PQAs were monitored, including oxidation, pyroglutamination, deamidation, lysine clipping, and glycosylation. The PQA monitoring aspect of the method was validated according to ICH Guidance. Accuracy, precision, specificity, detection and quantitation limits, linearity, range, and robustness were demonstrated for this MAM approach with minimal issues. All PQAs were successfully validated except for several oxidation sites, which did not pass intermediate precision criteria. The variability found in oxidation measurements was attributed to artificial oxidation during sample preparation and could likely be alleviated through several approaches. The NPD aspect of the method was also evaluated. A spike-in approach was used to assess the limits of detection and quantitation (LOD/LOQ) of the NPD feature of MAM. For NPD, the peak intensity threshold was found to be the most critical parameter for accurate detection of impurities since a low threshold can result in false positives while a high threshold can obscure the detection of true peaks. Overall, the MAM approach presented and validated here has been demonstrated to be suitable for both targeted monitoring of rituximab PQAs and non-targeted detection of new peaks that represent impurities.

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.

REFLECT: prospective multicenter non-interventional study evaluating the effectiveness and safety of Sandoz rituximab (SDZ-RTX; Rixathon®) in combination with CHOP for the treatment of patients with previously untreated CD20-positive diffuse large B-cell lymphoma

Background

REFLECT is the first prospective study of Sandoz biosimilar rituximab (SDZ-RTX) in patients with diffuse large B-cell lymphoma (DLBCL).

Objective

To evaluate the 2-year effectiveness and safety of SDZ-RTX as first-line treatment for DLBCL.

Design

Real-world, multicenter, open-label, single-arm, non-interventional, post-approval study of SDZ-RTX in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in patients with treatment-naïve CD20‑positive DLBCL.

Methods

Treatment-naïve, CD20-positive adult patients (⩾18 years) with DLBCL eligible for therapy with R-CHOP were treated with SDZ-RTX-CHOP every 2 or 3 weeks for 6-8 cycles. The effectiveness of SDZ-RTX was measured by the complete response (CR) rate at the end of R-CHOP treatment, as assessed by the treating physician. Progression-free survival (PFS) was assessed at 24 months.

Results

A total of 169 patients [52.1% female, median (range) age 70 (24-94) years] with DLBCL were included in the full analysis set. At baseline, 19.5% and 24.3% of patients had Ann Arbor disease stage III or IV, respectively, and most patients (80.5%) had Eastern Cooperative Oncology Group Performance Status of 0 or 1. A total of 100 (59.2%) patients completed the 24-month observation period. In total, 110 [65.1%; 95% confidence interval (CI): 57.4-72.3] patients achieved CR as best response and 50 (29.6%; 95% CI: 22.8-37.1) patients achieved partial response. Overall best response rate was 94.7% (95% CI: 90.1-97.5). One-year PFS was 84.9% (95% CI: 78.2-89.6), while 2-year PFS was 78.5% (95% CI: 70.9-84.4); median PFS was not reached within the observational period. A total of 143 (84.6%) patients experienced ⩾1 adverse event, 53 (31.4%) of which were suspected to be related to study drug.

Conclusion

This real-world, 2-year study reconfirms that first-line treatment of CD20-positive DLBCL with R-CHOP using SDZ-RTX is effective and well tolerated.

Registration

N/A.

Current evidence of rituximab in the treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disorder of the central nervous system. The immunopathology of MS involves both T and B lymphocytes. Rituximab is one of the anti-CD20 monoclonal antibody therapies which deplete B-cells. Although some anti-CD20 therapies have been approved by the Food and Drug Administration for treatment of MS, rituximab is used off-label. Several studies have shown that rituximab has a good efficacy and safety in MS, including certain specific patient conditions such as treatment-naïve patients, treatment-switching patients, and the Asian population. However, there are still questions about the optimal dose and duration of rituximab in MS due to the different dosing regimens used in each study. Moreover, many biosimilars have become available at a lower cost with comparable physicochemical properties, pharmacokinetics, pharmacodynamics, efficacy, safety, and immunogenicity. Thus, rituximab may be considered as a potential therapeutic option for patients without access to standard treatment. This narrative review summarized the evidence of both original and biosimilars of rituximab in MS treatment including pharmacokinetics, pharmacodynamics, clinical efficacy, safety, and dosing regimen.

Study of the Stability of Sandoz Rituximab Biosimilar Rixathon®/Riximyo® When Subjected for up to 21 Days to Ambient Storage

Aim

The purpose of this study was to evaluate the extended physicochemical and biological stability of Sandoz Rixathon®/Riximyo® (SDZ-RTX) after exposure to out-of-fridge (OOF) conditions.

Materials and Methods

The impact of the short-term temperature excursion on stability parameters of SDZ-RTX was simulated by subsequently exposing the three batches of SDZ-RTX (100 and 500 mg) to OOF conditions, (I) 25 ± 2 °C/60 ± 5% relative humidity (RH) and (II) 30 ± 2 °C/65 ± 5% RH, for up to 21 days after more than the claimed 36-month shelf-life storage in long-term conditions (5 ± 3 °C). Analytical methods used included the cation exchange chromatography (CEX), size exclusion chromatography (SEC), and non-reducing capillary electrophoresis-sodium dodecyl sulfate (nrCE-SDS), as well as biological activity by complement-dependent cytotoxicity (CDC)-bioactivity as well as further methods, for example, related to identity and pharmacopoeia test methods.

Results

No notable changes were observed across all batches with respect to identity (charge and primary structure), pharmaceutical tests (clarity, visible and subvisible particles analytics, container appearance, degree of coloration, pH, osmolality, extractable volume, and container closure integrity testing), protein content by UV and microbiological parameters (sterility and bacterial endotoxins) under both OOF conditions. Only minor changes were observed for parameters evaluated via SEC, CEX, and nrCE-SDS. For potency (CDC-bioactivity) only one of the batches showed a relevant change. Even for these stability-indicating test methods, all analyzed parameters complied with the shelf-life specifications.

Conclusion

SDZ-RTX is safe for use even under worst-case conditions, for example, after subjecting it for up to 21 days at OOF conditions (25 ± 2 °C/60 ± 5% RH or 30 ± 2 °C/65 ± 5% RH) after the batches had reached an age that was already beyond the claimed shelf-life.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40268-022-00393-4.

Structural and Functional Analysis of CEX Fractions Collected from a Novel Avastin® Biosimilar Candidate and Its Innovator: A Comparative Study

Avastin^® is a humanized recombinant monoclonal antibody used to treat cancer by targeting VEGF-A to inhibit angiogenesis. SIMAB054, an Avastin^® biosimilar candidate developed in this study, showed a different charge variant profile than its innovator. Thus, it is fractionated into acidic, main, and basic isoforms and collected physically by Cation Exchange Chromatography (CEX) for a comprehensive structural and functional analysis. The innovator product, fractionated into the same species and collected by the same method, is used as a reference for comparative analysis. Ultra-Performance Liquid Chromatography (UPLC) ESI-QToF was used to analyze the modifications leading to charge heterogeneities at intact protein and peptide levels. The C-terminal lysine clipping and glycosylation profiles of the samples were monitored by intact mAb analysis. The post-translational modifications, including oxidation, deamidation, and N-terminal pyroglutamic acid formation, were determined by peptide mapping analysis in the selected signal peptides. The relative binding affinities of the fractionated charge isoforms against the antigen, VEGF-A, and the neonatal receptor, FcRn, were revealed by Surface Plasmon Resonance (SPR) studies. The results show that all CEX fractions from the innovator product and the SIMAB054 shared the same structural variants, albeit in different ratios. Common glycoforms and post-translational modifications were the same, but at different percentages for some samples. The dissimilarities were mostly originating from the presence of extra C-term Lysin residues, which are prone to enzymatic degradation in the body, and thus they were previously assessed as clinically irrelevant. Another critical finding was the presence of different glyco proteoforms in different charge species, such as increased galactosylation in the acidic and afucosylation in the basic species. SPR characterization of the isolated charge variants further confirmed that basic species found in the CEX analyses of the biosimilar candidate were also present in the innovator product, although at lower amounts. The charge variants’ in vitro antigen- and neonatal receptor-binding activities varied amongst the samples, which could be further investigated in vivo with a larger sample set to reveal the impact on the pharmacokinetics of drug candidates. Minor structural differences may explain antigen-binding differences in the isolated charge variants, which is a key parameter in a comparability exercise. Consequently, such a biosimilar candidate may not comply with high regulatory standards unless the binding differences observed are justified and demonstrated not to have any clinical impact.

Comparison of originator and biosimilar monoclonal antibodies using HRMS, Fc affinity chromatography, and 2D-HPLC

Due to the complex manufacturing process of therapeutic monoclonal antibodies, it is hardly possible to produce an identical copy of the original product (originator). Consequently, follow-on products (biosimilars) must demonstrate their efficacy being similar to the originator in terms of structure and function. During this process, a variety of analytical methods are required for this purpose. This study focuses on three particularly relevant analytical techniques: high-resolution mass spectrometry, fragment crystallisable (Fc) affinity chromatography, and two-dimensional peptide mapping. Each analytical method proved able to identify specific differences between originator and biosimilar. High-resolution mass spectrometry was used to characterize the glycan pattern. It was shown that a trastuzumab biosimilar did not have the G0:G0F sugar modification identified in the originator. The application of affinity chromatography to rituximab showed that originator and biosimilar interacted differently with the immobilized Fc receptor. Furthermore, 2D-HPLC peptide mapping demonstrated the influence of orthogonality of separation dimensions, leading to differentiation of a rituximab originator and biosimilar.

Chromatography at -30 °C for Reduced Back-Exchange, Reduced Carryover, and Improved Dynamic Range for Hydrogen-Deuterium Exchange Mass Spectrometry

For hydrogen-deuterium exchange mass spectrometry (HDX-MS) to have an increased role in quality control of biopharmaceuticals, H for D back-exchange occurring during protein analyses should be minimized to promote greater reproducibility. Standard HDX-MS analysis systems that digest proteins and separate peptides at pH 2.7 and 0 °C can lose >30% of the deuterium marker within 15 min of sample injection. This report describes the architecture and performance of a dual-enzyme, HDX-MS instrument that conducts liquid chromatography (LC) separations at subzero temperature, thereby reducing back-exchange and supporting longer LC separations with improved chromatographic resolution. LC separations of perdeuterated, fully reduced, iodoacetamide-treated BSA protein digest standard peptides were performed at 0, -10, -20, and -30 °C in ethylene glycol (EG)/H₂O mixtures. Analyses conducted at -20 and -30 °C produced similar results. After subtracting for deuterium retained in arginine side chains, the average peptide eluted during a 40 min gradient contained ≈16% more deuterium than peptides eluted with a conventional 8 min gradient at 0 °C. A subset of peptides exhibited ≈26% more deuterium. Although chromatographic peaks shift with EG concentration and temperature, the apparatus elutes unbroadened LC peaks. Electrospray ion intensity does not decline with increasing EG fraction. To minimize bias from sample carryover, the fluidic circuits allow flush and backflush cleaning of all enzyme and LC columns. The system can perform LC separations and clean enzyme columns simultaneously. Temperature zones are controlled ±0.058 °C. The potential of increased sensitivity by mixing acetonitrile with the analytical column effluent was also examined.

Elucidating chemical and disulfide heterogeneities in rituximab using reduced and non-reduced peptide mapping

Peptide mapping by liquid chromatography-mass spectrometry is the gold standard to characterize post-translational modifications and disulfide bonds. The structural integrity, heterogeneity, and quality of biotherapeutic proteins are evaluated via reduced and non-reduced peptide mapping methods. However, non-enzymatic artifacts are often induced during sample preparation when alkaline pH conditions are used. To minimize these artifacts, methods using various acidic pH conditions have been developed by multiple researchers. However, these may lead to missed and non-specific cleavages during the analysis. In this study, improved reduced and non-reduced peptide mapping method has been proposed to characterize endogenous chemical modifications and native disulfide bonds of monoclonal antibody -based products. Solubilization has been carried out at acidic pH conditions under high temperature, followed by the addition of tris (2-carboxyethyl) phosphine as a reducing agent and a low alkylating agent. It was observed that the non-enzymatic post-translational modifications and non-native disulfide scrambled peptides significantly reduced under trypsin plus Lys-C digestion conditions at acidic pH as compared to the traditional methods. The results demonstrate that the proposed peptide mapping method using trypsin plus Lys-C could identify and quantify various chemical and disulfide heterogeneities with minimal artifacts. This article is protected by copyright. All rights reserved.

Immunotherapy in indolent Non-Hodgkin's Lymphoma

Treatment of non-Hodgkin lymphoma (NHL) in general has improved over the years with the emergence of the monoclonal antibodies (MAB) therapy. NHL is divided into B cell NHL and T cell NHL. Treatment of NHL was based on the subtype of NHL and its staging. NHL is divided into aggressive and indolent NHL (iNHL). Subtypes of iNHL include: Follicular lymphoma (FL), Marginal zone lymphoma (MZL), Chronic lymphocytic leukemia/small-cell lymphocytic lymphoma (CLL/SLL), Gastric mucosa-associated lymphoid tissue (MALT) lymphoma, Lymphoplasmacytic lymphoma, Waldenström macroglobulinemia, Nodal marginal zone lymphoma (NMZL), Splenic marginal zone lymphoma (SMZL). Chemotherapy was the main stay treatment of iNHL until the emergence of Rituximab, anti-CD20 MAB targeting CD-20 surface cell antigens that are present on B-cells lymphoma and not on precursor cells, mainly efficacious in B cell iNHL, It became the mainstay treatment in follicular lymphoma (FL) as a single agent modality or in combination with chemotherapy. The anti-CD20 Rituximab played an important role in the development of the treatment of iNHL to become FDA approved in 1997. It was also proven effective in multiple other types of lymphoma. MAB through targeting the cell surface antigen leads to a direct or immune mediated cytotoxicity. This carries few side effects, including allergic reactions. Other than that, a resistance mechanism to rituximab emerged by inducing a failure in the apoptosis mechanism. Alternative mechanisms of resistance included the presence of soluble antigens that could act by binding to the antibody present before the drug itself can bind the lymphoma cell. Thus, the interest in immunotherapy grew further to explore the possibility of conjugating an immune mediated drug to a radio-sensitizing agent in order to enhance the selectivity of the drug. Here came the development of 90Y-ibritumomab tiuxetan and 131I-tositumomab. After it, humanized anti-CD20 emerged ofatumumab, IMMU106 (veltuzumab) in 2005, and ocrelizumab which are considered as second generation anti-CD20 and 3rd generation anti-CD20 include AME-133v (ocaratuzumab), PRO131921 and GA101 (obinutuzumab). Also multiple other agents emerged targeting different surface cell antigens like CD52 (alemtuzumab), CD22 (unconjugated epratuzumab and calicheamicin conjugated CMC-544 [inotuzumab ozogamicin]), CD80 (galiximab), CD2 (MEDI-507 [siplizumab]), CD30 (SGN-30 and MDX-060 [iratumumab], Brentuximab vedotin), CD40 (SGN-40), and CD79b (Polatuzumab). Other agents include MAB targeting T-Cells like mogamulizumab, Denileukin Diftitox and BiTEs or bispecific T cell engagers like Mosunetuzumab, Glofitamab, and Epcoritamab. Moreover, further studies came up to evaluate the role of immunotherapy in combination chemotherapy as a pathway to evade the resistance mechanisms. Side effects of the treatment were mainly infusion related adverse reactions, myelosuppression in conjugated forms leading to immunosuppression and subsequently to infectious complications. Another important aspect in immunotherapy is the half-lives of the medication which is an important factor that can influence the evaluation of the response. The MAB treatment showed important benefit in the treatment of iNHL and it continuously shows how rapidly it can develop to provide optimum care and benefit to patients with iNHL.

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.

Immunogenicity of Rituximab biosimilar GP2013 in chronic inflammatory rheumatic disorders in daily clinical practice

OBJECTIVE

To study in daily practice the risk of immunogenicity of patients treated with the biosimilar rituximab (RTX) GP2013 used for chronic inflammatory rheumatic disorders.

METHODS

A prospective monocentric routine care study was carried out between September 2018 and May 2021, including consecutive patients treated with the biosimilar RTX GP2013. Biosamples were taken before each infusion to quantify anti-RTX antibodies (ADAbs) and serum RTX trough levels by ELISA (Lisa Tracker Duo Rituximab, LTR005, Theradiag).

RESULTS

168 GP2013-treated patients were included (129 who switched from originator RTX and 39 originator RTX naïve). The analysis of 602 samples identified 15 patients (8%) with positive ADAbs including 6 and 9 with transient and persistent ADAbs, respectively. The switch from originator RTX to GP2013 did not increase the risk of immunogenicity, with an incidence rate of 0.8 for 100 patient years. The frequency of persistent ADAs was higher in non-RA patients (5/56, 9% vs. 4/112, 3.5%). Patients with positive persistent ADAbs were more frequently non-caucasian (7/9, 78%, vs. 56/159, 35%, p<0.01) and all had detectable circulating B cells (vs. 40% in ADAb-negative patients, P<0.001). ADAb positivity was not associated with disease activity or RTX discontinuation but patients with ADAb titers >100 ng/mL experienced reduced treatment efficacy or severe infusion-related reaction.

CONCLUSION

Within the study duration, the immunogenicity of GP2013 is a rare event affecting the pharmacodynamics of RTX. Although development of ADAbs had no impact on treatment discontinuation, possible harmful consequences may be observed in patients with high antibody levels.

Rituximab for the treatment of multiple sclerosis: a review

In the last decades, evidence suggesting the direct or indirect involvement of B cells on multiple sclerosis (MS) pathogenesis has accumulated. The increased amount of data on the efficacy and safety of B-cell-depleting therapies from several studies has suggested the addition of these drugs as treatment options to the current armamentarium of disease modifying therapies (DMTs) for MS. Particularly, rituximab (RTX), a chimeric monoclonal antibody directed at CD20 positive B lymphocytes resulting in cell-mediated apoptosis, has been demonstrated to reduce inflammatory activity, incidence of relapses and new brain lesions on magnetic resonance imaging (MRI) in patients with relapsing-remitting MS (RRMS). Additional evidence also demonstrated that patients with progressive MS (PMS) may benefit from RTX, which also showed to be well tolerated, with acceptable safety risks and favorable cost-effectiveness profile.Despite these encouraging results, RTX is currently approved for non-Hodgkin's lymphoma, chronic lymphocytic leukemia, several forms of vasculitis and rheumatoid arthritis, while it can only be administered off-label for MS treatment. Between Northern European countries exist different rules for using not licensed drug for treating MS. The Sweden MS register reports a high rate (53.5%) of off-label RTX prescriptions in relation to other annually started DMTs to treat MS patients, while Danish and Norwegian neurologists have to use other anti-CD20 drugs, as ocrelizumab, in most of the cases.In this paper, we review the pharmacokinetics, pharmacodynamics, clinical efficacy, safety profile and cost effectiveness aspects of RTX for the treatment of MS. Particularly, with the approval of new anti-CD20 DMTs, the recent worldwide COVID-19 emergency and the possible increased risk of infection with this class of drugs, this review sheds light on the use of RTX as an alternative treatment option for MS management, while commenting the gaps of knowledge regarding this drug.

Assessment of Functional Characterization and Comparability of Biotherapeutics: a Review

The development of monoclonal antibody (mAb) biosimilars is a complex process. The key to their successful development and commercialization is an in-depth understanding of the key product attributes that impact safety and efficacy and the strategies to control them. Functional assessment of mAb is a crucial part of the comparability of biopharmaceutical drugs. The development of a relevant and robust functional assay requires an interdisciplinary approach and sufficient flexibility to balance regulatory concerns as well as dynamics and variability during the manufacturing process. Although many advanced tools are available to study and compare the potency and bioactivity of the protein, most of these techniques suffer from major shortcomings that limit their routine use. These include the complexity of the task, establishment of the relevance of the chosen method with the mechanism of action (MOA) of the biosimilar, cost and extended time of analysis, and often the ambiguity in interpretation of the resulting data. To overcome or to address these challenges, the use of multiple orthogonal state-of-the-art techniques is a necessary prerequisite.

Quality similarity-driven development of biosimilar monoclonal antibodies

The number of approved and marketed biosimilar monoclonal antibodies has been increasing steeply in recent years in regulated markets. In contrast to small molecular generic drugs, structure and variant profile of biosimilar mAbs are not identical with those of the reference medicinal product. Biosimilarity is proven by using the "totality of evidence" approach, and it forms the basis of the approval process of biosimilars in regulated markets. This process includes a comprehensive quality similarity exercise. This step involves the evaluation of all physico-chemical and biological-functional characteristics. The present paper evaluates the analytical similarity approaches taken through the evaluation of quality attributes of recently approved biosimilar mAbs.

Continuous Feeding Reduces the Generation of Metabolic Byproducts and Increases Antibodies Expression in Chinese Hamster Ovary-K1 Cells

Chinese hamster ovary (CHO) cells are the most important host system used for monoclonal antibody (mAb) expression. Moreover, the fed-batch culture mode is the most widely used method to increase mAb expression in CHO cells by increasing the amount of feed. However, a high amount of culture feed results in the production of metabolic byproducts. In this work, we used a continuous feeding strategy to reduce metabolic byproducts and improve mouse–human chimeric anti-epidermal growth factor receptor vIII (EGFRvIII) antibody C12 expression in Chinese hamster ovary-K1 cells. Moreover, the effects of the feeding strategy on the cell culture and monoclonal antibody production were evaluated in chemically defined suspension cultures of recombinant CHO-K1 cells. Compared with bolus feeding methods, the continuous feeding method did not have any advantages when the feeding amount was low, but with a high feeding amount, the continuous feeding method significantly reduced the concentrations of lactate and NH₄⁺ in the later culture stage. At the end of the culture stage, compared with bolus feeding methods, the lactate and NH₄⁺ concentrations under the continuous feeding mode were reduced by approximately 45% and 80%, respectively. In addition, the antibody C12 expression level was also increased by almost 10%. Compared to the bolus feeding method, the antibody C12 produced by the continuous feeding method had a lower content of high-mannose glycoforms. Further analysis found that the osmolality of the continuous feeding method was lower than that of the typical fed-batch bolus feeding method. Conclusively, these results indicate that the continuous feeding method is very useful for reducing metabolic byproducts and achieving higher levels of mAb production.

Need for a risk-based control strategy for managing glycosylation profile for biosimilar products

INTRODUCTION

Monoclonal antibodies, though a popular class of therapeutics, are complex molecules that are manufactured using complex processes, making it nontrivial to maintain high level of batch-to-batch consistency in product quality. Glycosylation is a posttranslation modification that is widely considered a critical quality attribute (CQA) as its variations are known to impact the Fc effector functions of mAbs. With continuing rise of biosimilars, comparability of these products to the reference product with respect to glycosylation is a topic of immense interest.

AREAS COVERED

In this article, we focus on the various aspects related to this topic including criticality of the various glycosylated forms, as well as comparability of biosimilars with respect to glycosylation.

EXPERT OPINION

We propose that manufacturers should focus on those glycoforms that are present in larger amounts and are known to be critical with respect to the biotherapeutic's safety and efficacy. Such risk-based evaluation of glycoforms and their control would offer an optimal route to biosimilar manufacturers for a cost-effective approach toward product development without compromising on the safety and efficacy characteristics of the therapeutic. For mAbs lacking Fc effector function, devising stringent glycosylation control strategies can be bypassed, thereby simplifying process and product development.

Statistical Equivalence Testing of Higher-Order Protein Structures with Differential Hydrogen Exchange-Mass Spectrometry (HX-MS)

Hydrogen exchange-mass spectrometry (HX-MS) is widely recognized for its potential utility for establishing the equivalence of the higher-order structures of proteins, particularly in comparability and similarity contexts. However, recent progress in the statistical analysis of HX-MS data has instead placed an emphasis on significance testing to identify regions of proteins where there are significant differences in HX between two or more protein states. In the cases involving assessment of similarity or equivalence of the higher-order structure of different protein samples (e.g., biosimilars), significance testing of HX-MS data is unsuitable. To meet this need, we have adapted the univariate two one-sided test (TOST) equivalence testing method for HX-MS data. Equivalence acceptance criteria were determined using maximum deviations from randomized resampling of truly equivalent samples to define hybrid equivalence criteria (maximum deviation of true equivalents, MDTE). Application of the TOST-MDTE test on differential HX-MS measurements of wild-type and mutated maltose-binding proteins demonstrates that the equivalence testing method was fit-for-purpose. Three infliximab biosimilars (Remsima, Renflexis, and Inflectra) were found to be equivalent to their Remicade reference product based on differential HX-MS measurements, while 5% deglycosylated NIST mAb was not statistically equivalent to the unmodified NIST mAb reference.

Efficacy and safety of Sandoz biosimilar rituximab for active rheumatoid arthritis: 52-week results from the randomized controlled ASSIST-RA trial

OBJECTIVES

This report provides data for the extent of B cell depletion and recovery, efficacy, safety and immunogenicity of Sandoz rituximab (SDZ-RTX; GP2013; Rixathon®) compared with reference rituximab (Ref-RTX) up to week 52 of the ASSIST-RA study.

METHODS

Patients were randomized to SDZ-RTX or Ref-RTX in combination with methotrexate according to the RTX label. The primary endpoint was analysed at week 24. Responders (28-joint DAS [DAS28] decrease from baseline >1.2) at week 24 with residual disease activity (DAS28 ≥2.6) were eligible for a second treatment course between week 24 and 52. Endpoints after week 24 included change from baseline in peripheral B cells, DAS28, ACR 20% response rate (ACR20), Clinical and Simplified Disease Activity Indexes (CDAI, SDAI) and HAQ disability index (HAQ-DI). Safety and immunogenicity were assessed by the incidence of adverse events and antidrug antibodies.

RESULTS

Primary and secondary endpoints up to week 24 were met. Overall, 260/312 randomized patients completed treatment up to week 52. SDZ-RTX resulted in B cell concentrations over time similar to Ref-RTX. The efficacy of SDZ-RTX was similar to Ref-RTX up to week 52, as measured by DAS28, ACR20/50/70, CDAI, SDAI and HAQ-DI. Safety of SDZ-RTX was similar to Ref-RTX regarding frequency, type and severity of adverse events, which were consistent with the known Ref-RTX safety profile. The incidence of antidrug antibodies was low and transient similarly across treatment groups.

CONCLUSION

SDZ-RTX demonstrated similar B cell concentrations over time, efficacy, safety and immunogenicity to Ref-RTX over 52 weeks of the ASSIST-RA study.

Biosimilar or Not: Physicochemical and Biological Characterization of MabThera and Its Two Biosimilar Candidates

The development of therapeutic biosimilar antibodies has become an important driving force of the modern biopharmaceutical industry. In this study, physiochemical characteristics (amino acid sequence, intact/subunit molecular weight, isoelectric point, post-translation modification, and disulfide linkage pattern), purity (charge variants, high and low molecular weight variants), antigen binding activity, Fc receptor binding affinity and Fc-effector function (CDC and ADCC) were analyzed by using an extensive set of state-of-the-art and orthogonal analytical technologies to provide a comprehensive characterization of the innovative product rituximab and two biosimilar candidates. The similarity study showed that biosimilar candidate 1 (BC1) and the reference product (RP) MabThera had an identical protein amino acid sequences and highly similar primary structures along with similar purity, heterogeneity profiles, antigen binding activity, Fc receptor binding affinity, and Fc-effector functions. Biosimilar candidate 2 (BC2), which had an amino acid replacement at a constant region, a different N-glycosylation profiling, and purity, was not analytically similar to RP. Although BC2 showed improvement such as an increased level of afucose, another IgG1 allotype, and similar biological activities, it was not recommended to be applied as a biosimilar compound in drug registration because the biosimilar manufacturer must first show that its primary structure was identical to that of RP. Our physicochemical characterizations and bioassay comparability study provided a deepened understanding of the structure-function relationship of quality attributes.

Development, Validation, and Comparison of Two Mass Spectrometry Methods (LC-MS/HRMS and LC-MS/MS) for the Quantification of Rituximab in Human Plasma

Rituximab is a chimeric immunoglobulin G1-kappa (IgG1κ) antibody targeting the CD20 antigen on B-lymphocytes. Its applications are various, such as for the treatment of chronic lymphoid leukemia or non-Hodgkin’s lymphoma in oncology, and it can also be used in the treatment of certain autoimmune diseases. Several studies support the interest in therapeutic drug monitoring to optimize dosing regimens of rituximab. Thus, two different laboratories have developed accurate and reproductive methods to quantify rituximab in human plasma: one using liquid chromatography quadripolar tandem mass spectrometer (LC-MS/MS) and the other, liquid chromatography orbitrap tandem mass spectrometer (LC-MS/HRMS). For both assays, quantification was based on albumin depletion or IgG-immunocapture, surrogate peptide analysis, and full-length stable isotope-labeled rituximab. With LC-MS/MS, the concentration range was from 5 to 500 µg/mL, the within- and between-run precisions were <8.5%, and the limit of quantitation was 5 µg/mL. With LC-MS/HRMS, the concentration range was from 10 to 200 µg/mL, the within- and between-run accuracy were <11.5%, and the limit of quantitation was 2 µg/mL. Rituximab plasma concentrations from 63 patients treated for vasculitis were compared. Bland–Altman analysis and Passing–Bablok regression showed the interchangeability between these two methods. Overall, these methods were robust and reliable and could be applied to routine clinical samples.

Rituximab in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in diffuse large B-cell lymphoma

Background

Diffuse large B-cell lymphoma (DLBCL) is the most frequent non-Hodgkin lymphoma worldwide. The current standard of care is chemoimmunotherapy with an R-CHOP regimen. We aim to review the role of this regimen after two decades of being the standard of care.

Methods

A comprehensive literature review of DLBCL, including the epidemiology, trials defining R-CHOP as the standard of care, as well as dose intensification and dose reduction schemes. Additionally, we briefly review the development of rituximab biosimilars and the addition of targeted drugs to R-CHOP in clinical trials.

Discussion

R-CHOP cures approximately 70% of DLBCL patients. Dose-dense regimens do not show a benefit in response and increase toxicity. Dose reduction, particularly in elderly patients or with comorbidities, may be a treatment option. DLBCL constitutes a group of diseases that activate different biological pathways. Matching specific treatments to a defined genetic alteration is under development. Rituximab biosimilars have become available to a broader population, particularly in developing countries, where access to treatment is limited because of economic resources.

Conclusion

DLBCL landscape is heterogeneous. R-CHOP immunochemotherapy has been a standard of care for two decades and cures approximately 70% of cases. Molecular characterization of patients is evolving and may have critical therapeutic implications.

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.

Analytical comparability study of anti-CD20 monoclonal antibodies rituximab and obinutuzumab using a stability-indicating orthogonal testing protocol: Effect of structural optimization and glycoengineering

Glycoengineering and biosimilarity are the key factors for growing, promising and progressive approaches in monoclonal antibodies development. In this study, the physicochemical stability of anti-CD20 rituximab (RTX); originator and biosimilar was compared to its glycoengineered humanized version; obinutuzumab (OBZ). An orthogonal stability-indicating protocol using a set of validated bioanalytical techniques; size exclusion high performance liquid chromatography (SE-HPLC), reversed phase liquid chromatography (RP-HPLC), quantitative gel electrophoresis by TapeStation, receptor binding assay and dynamic light scattering (DLS) was used to investigate the effect of different stress factors on the pattern and kinetics of degradation. SE-HPLC results supported with spectral purity showed similar degradation extent with a different pattern of degradation between RTX and OBZ. A lower tendency to form degraded fragments and a relatively higher favorability for degradation through aggregate formation has been revealed in case of OBZ. Results were in agreement with those of DLS and receptor binding assay which showed specificity to the intact antibodies in the presence of their degradation products. Furthermore, results were additionally confirmed through denaturing quantitative gel electrophoresis which suggested reducible covalent bonds as the mechanism for aggregates formation. RP-HPLC results showed two oxidized forms via excessive oxidation of RTX and OBZ with nearly the same degradation percent. Comparability data of RTX and OBZ using the applied methodologies showed that although glycoengineering; carried out to enhance the therapeutic and biological activity of OBZ altered the pattern of degradation but did not significantly affect the overall stability. Results showed also consistent stability profile between the biosimilar and its originator RTX products.

Comparative Analysis of One-Dimensional Protein Fingerprint by Line Shape Enhancement and Two-Dimensional 1H,13C Methyl NMR Methods for Characterization of the Higher Order Structure of IgG1 Monoclonal Antibodies

The use of NMR spectroscopy has emerged as a premier tool to characterize the higher order structure of protein therapeutics and in particular IgG1 monoclonal antibodies (mAbs). Due to their large size, traditional 1H-15N correlation experiments have proven exceedingly difficult to implement on mAbs, and a number of alternative techniques have been proposed, including the one-dimensional (1D) 1H protein fingerprint by line shape enhancement (PROFILE) method and the two-dimensional (2D) 1H-13C methyl correlation-based approach. Both 1D and 2D approaches have relative strengths and weaknesses, related to the inherent sensitivity and resolution of the respective methods. To further increase the utility of NMR to the biopharmaceutical community, harmonized criteria for decision making in employing 1D and 2D approaches for mAb characterization are warranted. To this end, we have conducted an interlaboratory comparative study of the 1D PROFILE and 2D methyl methods on several mAbs samples to determine the degree to which each method is suited to detect spectral difference between the samples and the degree to which results from each correlate with one another. Results from the study demonstrate both methods provide statistical data highly comparable to one another and that each method is capable of complementing the limitations commonly associated with the other, thus providing a better overall picture of higher order structure.

Real-world use and acceptance of rituximab biosimilars in non-Hodgkin lymphoma in an oncologist network in Germany

Aim: Present real-world data for rituximab (biosimilar and reference)-containing regimens in extrapolated indications in non-Hodgkin lymphoma (NHL)/chronic lymphocytic leukemia (CLL). Patients & methods: Data collected from office-based oncologic practices in Germany (July 2017–June 2019). Results: Of 1741 patients, 1241 had NHL; 500 had CLL. Of 7595 therapy cycles, 28.3% used reference rituximab; 55.2% used rituximab biosimilars; 2.0% used subcutaneous rituximab; 14.5% used rituximab, not otherwise specified. Rituximab biosimilars were used across all indications; 57.3% of cycles were administered in extrapolated indications. Over 24 months, the proportion of rituximab prescriptions that were for biosimilars increased from 12.0 to 83.0%. Conclusion: Our real-world data in NHL and CLL depicts increasing use of rituximab biosimilars across multiple treatment protocols, including extrapolated indications.

Rituximab biosimilars for lymphoma in Europe

Introduction: The approval of rituximab, a monoclonal antibody targeting CD20, revolutionized the treatment of B-cell non-Hodgkin lymphomas and became an undisputed standard of care. However, as with all biologic medicines, the complex development and manufacturing process for rituximab have meant that the medicine attracts high treatment costs. Approved rituximab biosimilars have been comprehensively demonstrated to match the reference medicine. With the potential to increase access to biologic therapy, they have a key role in helping to improve patient outcomes in lymphoma care. Areas covered: In this review, we discuss the role of rituximab in the treatment of lymphoma. We explore development and regulatory requirements for biosimilar development and the potential impact of these medicines on access and sustainability. Focusing on biosimilars of rituximab, we examine in detail the evidence for biosimilarity for the two rituximab biosimilars that are approved in Europe and provide an overview of rituximab biosimilars currently in development. Expert opinion: We foresee a wider uptake of biosimilar medicines for lymphoma treatment over the next 5 years. The associated cost savings should be invested in broadening patient access to biological therapies, enabling wider use of more expensive treatment strategies and driving innovation in cancer care.

A consensus statement on the use of biosimilar medicines in hematology in Australia

Despite their availability for over a decade, the exact nature of biosimilar medicines is still poorly understood with paucity of clear treatment guidelines for their use in clinical practice in Australia. Although hematologists have had experience with biosimilars in the setting of supportive care, with the approval of the first biosimilar rituximab in hematological malignancies, it is important to revisit this topic. To inform the use of biosimilar medicines in clinical practice, we have developed a consensus statement from an Expert Panel of Australian hematologists, oncologists, and cancer pharmacists. These recommendations address the approach to use of biosimilar products in place of the corresponding reference medicine in a number of different clinical contexts. Our recommendations are based on the premise that biosimilar medicines can be considered therapeutically equivalent to their reference brand and used in a similar way to the reference product in any approved indication. We advocate for local approaches to the provision of patient information, dispensing of the intended brand and pharmacovigilance, to be developed in consultation with local hematologists and aim to improve confidence in the appropriate use of biosimilar medicines and their expected outcomes among hematologists.

Multifaceted assessment of rituximab biosimilarity: The impact of glycan microheterogeneity on Fc function

Biosimilars are poised to reduce prices and increase patient access to expensive, but highly effective biologic products. However, questions still remain about the degree of similarity and scarcity of information on biosimilar products from outside of the US/EU in the public domain. Thus, as an independent entity, we performed a comparative analysis between the innovator, Rituxan® (manufactured by Genentech/Roche), and a Russian rituximab biosimilar, Acellbia® (manufactured by Biocad). We evaluated biosimilarity of these two products by a variety of state-of-the-art analytical mass spectrometry techniques, including tandem MS mapping, HX-MS, IM-MS, and intact MS. Both were found to be generally similar regarding primary and higher order structure, though differences were identified in terms of glycoform distribution levels of C-terminal Lys, N-terminal pyroGlu, charge variants and soluble aggregates. Notably, we confirmed that the biosimilar had a higher level of afucosylated glycans, resulting in a stronger FcγIIIa binding affinity and increased ADCC activity. Taken together, our work provides a comprehensive comparison of Rituxan® and Acellbia®.

Scientific rationale underpinning the development of biosimilar rituximab in hematological cancers and inflammatory diseases

Sandoz rituximab (SDZ-RTX; Rixathon^®; GP2013), a rituximab biosimilar, was approved in June 2017 in Europe in all indications of reference rituximab. The stepwise SDZ-RTX development program generated extensive physicochemical, structural, functional, and biological data demonstrating a match with reference rituximab on all clinically relevant attributes. A focused clinical development program followed, in two indications selected for sensitivity to detect potential differences versus reference rituximab: rheumatoid arthritis (pivotal pharmacokinetics and efficacy evaluation) and follicular lymphoma (pivotal efficacy/safety evaluation). These trials demonstrated highly similar pharmacokinetics, pharmacodynamics, efficacy, safety, and immunogenicity profiles. The totality of evidence for biosimilarity for SDZ-RTX, combined with knowledge that B-cell depletion is common to each approved indication, allowed SDZ-RTX approval for use in all indications of reference rituximab.

Brief Report: Safety and Immunogenicity of Rituximab Biosimilar GP 2013 After Switch From Reference Rituximab in Patients With Active Rheumatoid Arthritis

OBJECTIVE

Comparable clinical efficacy of the rituximab (RTX) biosimilar GP2013 and reference RTX has been established in blinded randomized trials. However, when switching from a reference biologic to a biosimilar, potential safety implications are often an important consideration. Therefore, the aim of this study was to evaluate the safety of switching from reference RTX to RTX biosimilar GP2013 compared with treatment continuation with reference RTX in patients with rheumatoid arthritis (RA).

METHODS

In this multinational, randomized, double-blind, parallel-group safety study, 107 patients with RA who had previously received treatment (of any duration) with reference RTX as part of routine practice and who required continuation of treatment were randomized to receive either GP2013 or to continue treatment with reference RTX. All patients received a stable dosage of methotrexate and folic acid during the study. Study assessments included the incidence of hypersensitivity, infusion-related and anaphylactic reactions, immunogenicity (antidrug antibodies), and general safety.

RESULTS

Regardless of whether patients switched to GP2013 or continued treatment with reference RTX, the incidences of hypersensitivity (9.4% and 11.1%, respectively) and infusion-related reactions (11.3% and 18.5%, respectively) were similarly low. Only 1 patient (in the reference RTX group) developed antidrug antibodies to RTX after starting study treatment. No neutralizing antidrug antibodies were observed. Antidrug antibodies were not associated with adverse events (AEs). No clinically meaningful differences in the rate of AEs were observed between treatment groups.

CONCLUSION

No safety risks were detected when patients switched from reference RTX to GP2013. The safety profiles of patients in both treatment groups were similar, although the study was not powered for statistical testing of equivalence in safety.

2D J-correlated proton NMR experiments for structural fingerprinting of biotherapeutics

The higher order structure (HOS) of protein therapeutics is essential for drug safety and efficacy and can be evaluated by two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy at atomic resolution. ¹Hn-¹⁵N amide correlated and ¹H-¹³C methyl correlated NMR spectroscopies at natural isotopic abundance have been demonstrated as feasible on protein therapeutics as large as monoclonal antibodies and show great promise for use in establishing drug substance structural consistency across manufacturing changes and in comparing a biosimilar to an originator reference product. Spectral fingerprints from ¹Hn-¹Hα correlations acquired using 2D homonuclear proton-proton J-correlated NMR experiments provide a complementary approach for high-resolution assessment of the HOS of lower molecular weight (<25 kDa) protein therapeutics. Here, we evaluate different pulse sequences (COSY, TOCSY and TACSY) used to generate proton-proton J-correlated NMR spectral fingerprints and appraise the performance of each method for application to protein therapeutic HOS assessment and comparability.

Variability of Biologics and its Impact on Biosimilar Development

This symposium took place during the International Conference on Malignant Lymphoma (ICML) in Lugano, Switzerland, June 2019, and focussed on scientific aspects associated with development and approval of rituximab biosimilars in lymphoma. The symposium began with an overview presented by Dr Cornes detailing the urgent economic need for biosimilars to improve access to these biologic treatments in oncology and other therapy areas. Prof Schellekens, author of the first paper on biosimilars in 2002, discussed how regulatory strategies for biosimilars were shaped, and how these have evolved in the intervening years. Today, the emphasis of biosimilar development is placed on extensive analytical testing to demonstrate a match with the reference medicine at a fundamental level. Clinical testing plays a confirmatory role, removing any residual uncertainty regarding potential clinical differences between biosimilar and reference medicine. Dr Schiestl presented further detail on analytical perspectives on biosimilars. Development of biosimilars is complicated by the inherent variability of biological synthesis techniques employed in the manufacture of biologics. This variability is further increased by ongoing changes to manufacturing processes, which can result in changes in biological activity. Consistent quality is therefore a cornerstone of biosimilar development. Prof Jurczak provided a comprehensive overview of the factors that must be considered during clinical development of a biosimilar. Clinical trials for biosimilars have a confirmatory role in the development process, rather than the pivotal role played by clinical trials for reference medicines. Therefore, these trials have markedly different objectives compared with reference clinical trials, resulting in differences in the chosen endpoints. In biosimilar trials, response endpoints, which provide rapid and sensitive assessments of equivalence, are preferred to survival endpoints, which require large and lengthy trials for adequate evaluation. Prof Jurczak illustrated this using data from the Phase III clinical trials of the Sandoz rituximab biosimilar. In this trial, Sandoz rituximab demonstrated an equivalent response rate to reference rituximab. Increasing economic pressure on healthcare systems means that biosimilars are likely to play an increasing role in the treatment of cancer in coming years, requiring clinicians to increase their familiarity with these important medicines.

Interlaboratory Comparison of Hydrogen-Deuterium Exchange Mass Spectrometry Measurements of the Fab Fragment of NISTmAb

Hydrogen-deuterium exchange mass spectrometry (HDX-MS) is an established, powerful tool for investigating protein-ligand interactions, protein folding, and protein dynamics. However, HDX-MS is still an emergent tool for quality control of biopharmaceuticals and for establishing dynamic similarity between a biosimilar and an innovator therapeutic. Because industry will conduct quality control and similarity measurements over a product lifetime and in multiple locations, an understanding of HDX-MS reproducibility is critical. To determine the reproducibility of continuous-labeling, bottom-up HDX-MS measurements, the present interlaboratory comparison project evaluated deuterium uptake data from the Fab fragment of NISTmAb reference material (PDB: 5K8A ) from 15 laboratories. Laboratories reported ∼89 800 centroid measurements for 430 proteolytic peptide sequences of the Fab fragment (∼78 900 centroids), giving ∼100% coverage, and ∼10 900 centroid measurements for 77 peptide sequences of the Fc fragment. Nearly half of peptide sequences are unique to the reporting laboratory, and only two sequences are reported by all laboratories. The majority of the laboratories (87%) exhibited centroid mass laboratory repeatability precisions of ⟨ sLab⟩ ≤ (0.15 ± 0.01) Da (1σx̅). All laboratories achieved ⟨sLab⟩ ≤ 0.4 Da. For immersions of protein at THDX = (3.6 to 25) °C and for D2O exchange times of tHDX = (30 s to 4 h) the reproducibility of back-exchange corrected, deuterium uptake measurements for the 15 laboratories is σreproducibility15 Laboratories( tHDX) = (9.0 ± 0.9) % (1σ). A nine laboratory cohort that immersed samples at THDX = 25 °C exhibited reproducibility of σreproducibility25C cohort( tHDX) = (6.5 ± 0.6) % for back-exchange corrected, deuterium uptake measurements.

Conformational characterization of a novel anti-HER2 candidate antibody

Regulatory agencies establish that a broad physicochemical and biological characterization is necessary for the evaluation of comparability between a biosimilar candidate product and a reference commercial drug. Between them, conformational characterization of proteins is of vital importance to determine its folding and biological functions. In this work, the conformational features of a novel monoclonal antibody (called 5G4) were evaluated by means of circular dichroism spectroscopy and fluorescence. Secondary structure and thermal stability of mAbs were determined by circular dichroism in the far ultraviolet, while three-dimensional folding of proteins was analyzed by both circular dichroism in the near ultraviolet and intrinsic tryptophan fluorescence. In all experiments, Herceptin (Roche) was used as control. Both antibodies showed a composition of secondary structure predominantly of β-sheets (55–56%) and thermal stability of ~ 75°C, suggesting structural similarity. The three-dimensional folding of proteins was also similar due to the absorption spectra of the aromatic residues and the emission wavelength maxima by fluorescence were comparable. The values of the fluorescence attenuation constant (Stern-Volmer constant) for increasing concentrations of acrylamide were also similar, suggesting a degree of exposure of tryptophan residues similar, although it was slightly decreased for Herceptin. Our data permit to consider that 5G4 monoclonal antibody showed similar conformational characteristics when compared with Herceptin.

Effects of terminal galactose residues in mannose α1-6 arm of Fc-glycan on the effector functions of therapeutic monoclonal antibodies

Typical crystallizable fragment (Fc) glycans attached to the CH2 domain in therapeutic monoclonal antibodies (mAbs) are core-fucosylated and asialo-biantennary complex-type glycans, e.g., G2F (full galactosylation), G1aF (terminal galactosylation on the Man α1-6 arm), G1bF (terminal galactosylation on the Man α1-3 arm), and G0F (non-galactosylation). Terminal galactose (Gal) residues of Fc-glycans are known to influence effector functions such as antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity (CDC), but the impact of the G1F isomers (G1aF and G1bF) on the effector functions has not been reported. Here, we prepared four types of glycoengineered anti-CD20 mAbs bearing homogeneous G2F, G1aF, G1bF, or G0F (G2F mAb, G1aF mAb, G1bF mAb, or G0F mAb, respectively), and evaluated their biological activities. Interestingly, G1aF mAb showed higher C1q- and FcγR-binding activities, CDC activity, and FcγR-activation property than G1bF mAb. The activities of G1aF mAb and G1bF mAb were at the same level as G2F mAb and G0F mAb, respectively. Hydrogen–deuterium exchange/mass spectrometry analysis of dynamic structures of mAbs revealed the greater involvement of the terminal Gal residue on the Man α1-6 arm in the structural stability of the CH2 domain. Considering that mAbs interact with FcγR and C1q via their hinge proximal region in the CH2 domain, the structural stabilization of the CH2 domain by the terminal Gal residue on the Man α1-6 arm of Fc-glycans may be important for the effector functions of mAbs. To our knowledge, this is the first report showing the impact of G1F isomers on the effector functions and dynamic structure of mAbs.

Abbreviations: ABC, ammonium bicarbonate solution; ACN, acetonitrile; ADCC, antibody-dependent cell-mediated cytotoxicity; C1q, complement component 1q; CDC, complement-dependent cytotoxicity; CQA, critical quality attribute; Endo, endo-β-N-acetylglucosaminidase; FA, formic acid; Fc, crystallizable fragment; FcγR, Fcγ receptors; Fuc, fucose; Gal, galactose; GlcNAc, N-acetylglucosamine; GST, glutathione S-transferase; HER2, human epidermal growth factor receptor 2; HDX, hydrogen–deuterium exchange; HILIC, hydrophilic interaction liquid chromatography; HLB-SPE, hydrophilic-lipophilic balance–solid-phase extraction; HPLC, high-performance liquid chromatography; mAb, monoclonal antibody; Man, mannose; MS, mass spectrometry; PBS, phosphate-buffered saline; SGP, hen egg yolk sialylglycopeptides.

Practical Guidance on Biosimilars, With a Focus on Latin America: What Do Rheumatologists Need to Know?

BACKGROUND/HISTORICAL PERSPECTIVE

Availability of biologic disease-modifying antirheumatic drugs (bDMARDs) has improved clinical outcomes in rheumatoid arthritis, but it also increased the cost of treatment. Biosimilars, the regulated copies of biologic products, have a potential to reduce health care costs and expand access to treatment. However, because of a complex development process, biosimilars can be considered only those noninnovator biologics with satisfactory supporting evidence (ranging from structural to clinical), as outlined in the recommendations by the World Health Organization (WHO). In Latin America, a heterogeneous regulatory landscape and nonconsistent approval practices for biosimilars create decision-making challenges for practicing rheumatologists.

SUMMARY OF LITERATURE

Most Latin American countries either have adopted or are in the process of adopting guidelines for the approval of biosimilars. However, among several marketed bDMARDs in the region, currently there are only 2 products that could be considered true biosimilars, based on the WHO criteria. The rest can be considered only intended copies, whose safety and efficacy are not fully established. One such product had to be withdrawn from the market because of safety concerns.

CONCLUSIONS AND FUTURE DIRECTIONS

Practicing rheumatologists in Latin America need to understand the regulatory situation for biosimilars in their countries. When considering bDMARDs that are not innovator products, clinicians should use only those that have been approved according to the WHO recommendations. For clarification, local health authorities or professional associations should be contacted.

Structural and functional comparability study of anti-CD20 monoclonal antibody with reference product

Background

Cell surface protein, CD20, is extensively expressed on the surface of B cells. Antibodies targeting CD20 protein are being used to treat B-cell malignancies and B-cell mediated autoimmune diseases. Considering the cost of therapy with innovator monoclonal antibodies for these diseases, development of biosimilar products for the treatment of such diseases provides affordable solution to rising healthcare costs.

Materials and Methods

Reference products of rituximab (six batches) were procured and stored as per manufacturer's instructions. Cell lines used in bioassay were procured from American Type Culture Collection and all other reagents used for analysis were of analytical grade. Primary structure was studied by intact mass analysis, peptide fingerprinting, peptide mass fingerprinting and sequence coverage analysis. Higher order structure was studied by circular dichroism, ultraviolet-visible spectroscopy, fluorescence spectroscopy, and disulfide bridge analysis. Different isoforms of reference product and SB-02 were identified using capillary isoelectric focusing and capillary zone electrophoresis. Glycosylation was studied by N-glycan mapping using LC-ESI-MS, point of glycosylation, released glycan analysis using ultra performance liquid chromatography (UPLC). Product related impurities such as oligomer content analysis and oxidized impurities were studied using size exclusion chromatography and reverse phase high performance liquid chromatography, respectively.

Results and Conclusion

Here, we report physicochemical and biological characterizations of Sun Pharma’s proposed biosimilar (SB-02) to rituximab, a monoclonal anti-CD20 antibody approved for the treatment of non-Hodgkin’s lymphoma and chronic lymphocytic leukemia. SB-02 and rituximab exhibited indistinguishable primary as well as higher-order structure upon analyzing with the array of analytical and extended characterization methods according to statistical methods. The molecule also displayed comparability to reference product in post-translational modifications and charge heterogeneity. In functional bioassays, SB-02 demonstrated comparable potency with respect to reference product. Our results indicate highly similar quality profile between SB-02 and rituximab.