Biophysical study of bevacizumab structure and bioactivity under thermal and pH-stresses

Aggregation of therapeutic monoclonal antibodies due to thermal and air/liquid interfacial agitation stress: Occurrence, stability assessment strategies, aggregation mechanism, influencing factors, and ways to enhance stability

Therapeutic proteins, such as monoclonal antibodies (mAbs) are known to undergo stability related issues during various stages of product life cycle resulting in the formation of aggregates and fragments. Aggregates of mAb might result in reduced therapeutic activity and could cause various adverse immunogenic responses. Sample containing mAb undergo aggregation due to various types of stress factors, and there is always a continuous interest among researchers and manufacturers to determine the effect of different factors on the stability of mAb. Thermal stress and air/liquid interfacial agitation stress are among two of the common stress factors to which samples containing mAb are exposed to during various stages. Initial part of this review articles aims to provide a generalized understanding of aggregation of mAb such as size ranges of aggregates, aggregate types, stress factors, analytical techniques, permissible aggregate limits, and stability assessment methods. This article further aims to explain different aspects associated with aggregation of mAb in liquid samples due to thermal and air/liquid interfacial agitation stress. Under each stress category, the occurrence of stress during product life cycle, type of aggregates formed, mechanism of aggregation, strategies used by various researchers to expose mAb containing samples to stress, different factors affecting aggregation, fate of aggregates in human body fluids, and strategies used to enhance mAb stability has been explained in detail. The authors hope that this article provides a detailed understanding about stability of mAb due to thermal and air/liquid interfacial stress with relevance to product life cycle from manufacturing to administration into patients.

Stability of Protein Pharmaceuticals: Recent Advances

There have been significant advances in the formulation and stabilization of proteins in the liquid state over the past years since our previous review. Our mechanistic understanding of protein-excipient interactions has increased, allowing one to develop formulations in a more rational fashion. The field has moved towards more complex and challenging formulations, such as high concentration formulations to allow for subcutaneous administration and co-formulation. While much of the published work has focused on mAbs, the principles appear to apply to any therapeutic protein, although mAbs clearly have some distinctive features. In this review, we first discuss chemical degradation reactions. This is followed by a section on physical instability issues. Then, more specific topics are addressed: instability induced by interactions with interfaces, predictive methods for physical stability and interplay between chemical and physical instability. The final parts are devoted to discussions how all the above impacts (co-)formulation strategies, in particular for high protein concentration solutions.'

Chitosan surface modification modulates the mucoadhesive, permeation and anti-angiogenic properties of gellan gum/bevacizumab nanoparticles

Bevacizumab (BVZ) was the first monoclonal antibody approved by the FDA and has shown an essential advance in the antitumor therapy of colorectal cancer (CRC), however, the systemic action of BVZ administered intravenously can trigger several adverse effects. The working hypothesis of the study was to promote the modulation of the mucoadhesion properties and permeability of the BVZ through the formation of nanoparticles (NPs) with gellan gum (GG) with subsequent surface modification with chitosan (CS). NPs comprising BVZ and GG were synthesized through polyelectrolyte complexation, yielding spherical nanosized particles with an average diameter of 264.0 ± 2.75 nm and 314.0 ± 0.01 nm, polydispersity index of 0.182 ± 0.01 e 0.288 ± 0.01, and encapsulation efficiency of 29.36 ± 0.67 e 60.35 ± 0.27 mV, for NPs without (NP_BVZ) and with surface modification (NP_BVZ + CS). The results showed a good ability of nanoparticles with surface modification to modulate the NPs biological properties.

177Lu-Labeled Iron Oxide Nanoparticles Functionalized with Doxorubicin and Bevacizumab as Nanobrachytherapy Agents against Breast Cancer

The use of conventional methods for the treatment of cancer, such as chemotherapy or radiotherapy, and approaches such as brachytherapy in conjunction with the unique properties of nanoparticles could enable the development of novel theranostic agents. The aim of our current study was to evaluate the potential of iron oxide nanoparticles, coated with alginic acid and polyethylene glycol, functionalized with the chemotherapeutic agent doxorubicin and the monoclonal antibody bevacizumab, to serve as a nanoradiopharmaceutical agent against breast cancer. Direct radiolabeling with the therapeutic isotope Lutetium-177 (177Lu) resulted in an additional therapeutic effect. Functionalization was accomplished at high percentages and radiolabeling was robust. The high cytotoxic effect of our radiolabeled and non-radiolabeled nanostructures was proven in vitro against five different breast cancer cell lines. The ex vivo biodistribution in tumor-bearing mice was investigated with three different ways of administration. The intratumoral administration of our functionalized radionanoconjugates showed high tumor accumulation and retention at the tumor site. Finally, our therapeutic efficacy study performed over a 50-day period against an aggressive triple-negative breast cancer cell line (4T1) demonstrated enhanced tumor growth retention, thus identifying the developed nanoparticles as a promising nanobrachytherapy agent against breast cancer.

Intravitreal implants manufactured by supercritical foaming for treating retinal diseases

Chronic retinal diseases, such as age-related macular degeneration (AMD), are a major cause of global visual impairment. However, current treatment methods involving repetitive intravitreal injections pose financial and health burdens for patients. The development of controlled drug release systems, particularly for biological drugs, is still an unmet need in prolonging drug release within the vitreous chamber. To address this, green supercritical carbon dioxide (scCO2) foaming technology was employed to manufacture porous poly(lactic-co-glycolic acid) (PLGA)-based intravitreal implants loaded with dexamethasone. The desired implant dimensions were achieved through 3D printing of customised moulds. By varying the depressurisation rates during the foaming process, implants with different porosities and dexamethasone release rates were successfully obtained. These implants demonstrated controlled drug release for up to four months, surpassing the performance of previously developed implants. In view of the positive results obtained, a pilot study was conducted using the monoclonal antibody bevacizumab to explore the feasibility of this technology for preparing intraocular implants loaded with biologic drug molecules. Overall, this study presents a greener and more sustainable alternative to conventional implant manufacturing techniques, particularly suited for drugs that are susceptible to degradation under harsh conditions.

Analytical Techniques for the Characterization and Quantification of Monoclonal Antibodies

Monoclonal antibodies (mAbs) are a fast-growing class of biopharmaceuticals. They are widely used in the identification and detection of cell makers, serum analytes, and pathogenic agents, and are remarkably used for the cure of autoimmune diseases, infectious diseases, or malignancies. The successful application of therapeutic mAbs is based on their ability to precisely interact with their appropriate target sites. The precision of mAbs rely on the isolation techniques delivering pure, consistent, stable, and safe lots that can be used for analytical, diagnostic, or therapeutic applications. During the creation of a biologic, the key quality features of a particular mAb, such as structure, post-translational modifications, and activities at the biomolecular and cellular levels, must be characterized and profiled in great detail. This implies the requirement of powerful state of the art analytical techniques for quality control and characterization of mAbs. Until now, various analytical techniques have been developed to characterize and quantify the mAbs according to the regulatory guidelines. The present review summarizes the major techniques used for the analyses of mAbs which include chromatographic, electrophoretic, spectroscopic, and electrochemical methods in addition to the modifications in these methods for improving the quality of mAbs. This compilation of major analytical techniques will help students and researchers to have an overview of the methodologies employed by the biopharmaceutical industry for structural characterization of mAbs for eventual release of therapeutics in the drug market.

Structural and functional analysis of broad pH and thermal stable protease from Penicillium aurantiogriseum URM 4622

This study aimed to better characterize a recently purified stable extracellular alkaline peptidase produced by Penicillium aurantiogriseum (URM 4622) through fluorescence spectroscopy, far-UV circular dichroism, kinetic and thermodynamic models to understand its' structure-activity and denaturation. Fluorescence data showed that changing pH leads to tryptophan residues exposure to more hydrophilic environments at optimum activity pH 9.0 and 10.0. When thermally treated, it displayed less unfolding at these pH values, along with 4-fold less photoproducts formation than at neutral pH. Different pH CD spectra showed more β-sheet (21.5-43.0%) than α-helix (1-6.2%). At pH9.0, more than 2-fold higher α-helix content than any other pH. The melting temperature (T_m) was observed between 50 and 60 °C at all pH studied, with lower T_m at pH 9.0-11.0 (54.9-50.3 °C). The protease displayed two phase transition, with two energies of denaturation, and a 4-fold higher thermal stability (ΔH°_m) than reports for other microorganism's proteases. An irreversible folding transition occurs between 50 and 60 °C. It displayed energies of denaturation suggesting higher thermal stability than reported for other microorganism's proteases. These results help elucidating the applicability of this new stable protease.

Application of ultraviolet, visible, and infrared light imaging in protein-based biopharmaceutical formulation characterization and development studies

Imaging is increasingly more utilized as analytical technology in biopharmaceutical formulation research, with applications ranging from subvisible particle characterization to thermal stability screening and residual moisture analysis. This review offers a comprehensive overview of analytical imaging for scientists active in biopharmaceutical formulation research and development, where it presents the unique information provided by the ultraviolet (UV), visible (Vis), and infrared (IR) sections in the electromagnetic spectrum. The main body of this review consists of an outline of UV, Vis, and IR imaging techniques for several (bio)physical properties that are commonly determined during protein-based biopharmaceutical formulation characterization and development studies. The review concludes with a future perspective of applied imaging within the field of biopharmaceutical formulation research.

ATR-FTIR spectroscopy and spectroscopic imaging to investigate the behaviour of proteins subjected to freeze-thaw cycles in droplets, wells, and under flow

Biopharmaceuticals are used to treat a range of diseases from arthritis to cancer, however, since the advent of these highly specific, effective drugs, there have been challenges involved in their production. The most common biopharmaceuticals, monoclonal antibodies (mAbs), are vulnerable to aggregation and precipitation during processing. Freeze thaw cycles (FTCs), which can be required for storage and transportation, can lead to a substantial loss of product, and contributes to the high cost of antibody production. It is therefore necessary to monitor aggregation levels at susceptible points in the production pathway, such as during purification and transportation, thus contributing to a fuller understanding of mAb aggregation and providing a basis for rational optimisation of the production process. This paper uses attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and spectroscopic imaging to investigate the effect of these potentially detrimental FTCs on protein secondary structure in both static wells and under flowing conditions, using lysozyme as a model protein. The results revealed that the amount of protein close to the surface of the ATR crystal, and hence level of aggregates, increased with increasing FTCs. This was observed both within wells and under flow conditions, using conventional ATR-FTIR spectroscopy and ATR-FTIR spectroscopic imaging. Interestingly, we also observed changes in the Amide I band shape indicating an increase in β-sheet contribution, and therefore an increase in aggregates, with increasing number of FTCs. These results show for the first time how ATR-FTIR spectroscopy can be successfully applied to study the effect of FTC cycles on protein samples. This could have numerous broader applications, such as in biopharmaceutical production and rapid diagnostic testing.

LC-MS based case-by-case analysis of the impact of acidic and basic charge variants of bevacizumab on stability and biological activity

The present study investigates the impact of charge variants on bevacizumab's structure, stability, and biological activity. Five basic and one acidic charge variants were separated using semi-preparative cation exchange chromatography using linear pH gradient elution with purity > 85%. Based on the commercial biosimilar product's composition, two basic variants, one acidic and the main bevacizumab product, were chosen for further investigation. Intact mass analysis and tryptic peptide mapping established the basic variants' identity as those originating from an incomplete clipping of either one or both C-terminal lysine residues in the heavy chain of bevacizumab. Based on peptide mapping data, the acidic variant formation was attributed to deamidation of asparagine residue (N84), oxidation of M258, and preservation of C-terminal lysine residue, located on the heavy chain of bevacizumab. None of the observed charge heterogeneities in bevacizumab were due to differences in glycosylation among the variants. The basic (lysine) variants exhibited similar structural, functional, and stability profiles as the bevacizumab main product. But it was also noted that both the variants did not improve bevacizumab's therapeutic utility when pooled in different proportions with the main product. The acidic variant was found to have an equivalent secondary structure with subtle differences in the tertiary structure. The conformational difference also translated into a ~ 62% decrease in biological activity. Based on these data, it can be concluded that different charge variants behave differently with respect to their structure and bioactivity. Hence, biopharmaceutical manufacturers need to incorporate this understanding into their process and product development guidelines to maintain consistency in product quality.

ATR-FTIR spectroscopy and spectroscopic imaging for the analysis of biopharmaceuticals

Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy is a label-free, non-destructive technique that can be applied to a vast range of biological applications, from imaging cancer tissues and live cells, to determining protein content and protein secondary structure composition. This review summarises the recent advances in applications of ATR-FTIR spectroscopy to biopharmaceuticals, the application of this technique to biosimilars, and the current uses of FTIR spectroscopy in biopharmaceutical production. We discuss the use of ATR-FTIR spectroscopic imaging to investigate biopharmaceuticals, and finally, give an outlook on the possible future developments and applications of ATR-FTIR spectroscopy and spectroscopic imaging to this field. Throughout the review comparisons will be made between FTIR spectroscopy and alternative analytical techniques, and areas will be identified where FTIR spectroscopy could perhaps offer a better alternative in future studies. This review focuses on the most recent advances in the field of using ATR-FTIR spectroscopy and spectroscopic imaging to characterise and evaluate biopharmaceuticals, both in industrial and academic research based environments.

3D printing of drug-loaded multi-shell rods for local delivery of bevacizumab and dexamethasone: A synergetic therapy for retinal vascular diseases

The clinical therapy for retinal vascular diseases requires repeated intravitreal injections of drugs owing to their short half-life, which imposes health and economic burdens on patients. Therefore, it is necessary to develop an advanced drug delivery system that can prolong the drug activity and minimize secondary complications. In this study, we developed a core/shell drug-loaded rod (drug rod) to deliver two types of drugs (bevacizumab (BEV) and dexamethasone (DEX)) from a single implant. The coaxial printing technique allowed BEV and DEX to be released with different kinetics at the same site by using a polymeric shell and a hydrogel core, respectively. The suggested printing technique facilitates the production of drug rods with various dimensions and drug concentrations, and the multi-layered design allows to adjust the release profile of dual drug-delivery system. The rod was injected in rat vitreous less invasively using a small-gauge needle. Further, we validated the efficacy of the implanted drug rods in inhibiting inflammatory responses and long-term suppression of neovascularization compared to the conventional intravitreal injection of BEV in animal model, indicating that the drug rods can be an alternative therapeutic approach for the treatment of various types of retinal vascular diseases.

Specific and high-resolution identification of monoclonal antibody fragments detected by capillary electrophoresis-sodium dodecyl sulfate using reversed-phase HPLC with top-down mass spectrometry analysis

In recent years, capillary electrophoresis-sodium dodecyl sulfate (cSDS) has been widely used for high resolution separation and quantification of the fragments and aggregates of monoclonal antibodies (mAbs) to ensure the quality of mAb therapeutics. However, identification of the low-molecular-weight (LMW) and high-molecular-weight (HMW) species detected in cSDS electropherograms has been based primarily on the approximate MWs calculated from standard curves using known MW standards and correlations with fragments and aggregates identified by other methods. It is not easy to collect sufficient amounts of H/LMW species from cSDS for analysis by orthogonal methods and the direct coupling of cSDS with mass spectrometry (MS) is very difficult due to interference from SDS. In this study, we describe the precise identification of H/LMW species detected by cSDS using reversed-phase high performance liquid chromatography (RP-HPLC) coupled with top-down tandem MS analysis. The H/LMW species were first identified by on-line RP-HPLC MS analysis and the RP-HPLC fractions were then analyzed by cSDS to connect the identified H/LMW species with the peaks in the cSDS electropherogram. With this method, 58 unique H/LMW species were identified from an immunoglobulin G1 (IgG1) mAb. The identified fragments ranged from 10 kDa single chain fragments to 130 kDa triple chain fragments, including some with post-translational modifications. This is the first study to clearly identify the antibody fragments, including the exact clipping sites, observed in cSDS electropherograms. The methodology and results presented here should be applicable to most other IgG1 mAbs.

Nanoparticles provide long-term stability of bevacizumab preserving its antiangiogenic activity

Bevacizumab is one of the most common monoclonal antibodies used to treat cancer due to its antiangiogenic role. However, the frequent parenteral administrations are not attractive for the patient adhesion to the therapy. Nanoencapsulation of bevacizumab might be a useful alternative to increase administration intervals, due to controlled release properties. To achieve a long-term bevacizumab stability into PLGA nanoparticles, we developed an optimized and validated lyophilization protocol. The co-encapsulation of trehalose and bevacizumab into PLGA nanoparticles, associated to their lyophilization with external 10% (w/v) of trehalose, allowed maintenance of the physical-chemical characteristics of nanoparticles and bevacizumab secondary and tertiary structure. More relevant, the antiangiogenic activity of bevacizumab was kept over 6 months of storage while formulated with this protocol. No significant differences were found upon 6 months of storage at 4 °C and 25 °C/60% HR, and minor differences were observed for storage at 40 °C/75% HR, bringing to our knowledge, the first successfully report for monoclonal antibody storage at room temperature, without losing its structural and functional features. Our results served as starting point to understand the monoclonal antibody-based nanoparticle behavior over time, creating an innovative approach for a long-term monoclonal antibody stability.

STATEMENT OF SIGNIFICANCE

Nanoencapsulation of monoclonal antibodies has boost the interest of researchers as an alternative to the current antibody-based therapy, changing the route of administrations through controlled release of monoclonal antibodies. Despite good results have been achieved with nanoencapsulation process, no strategy has still found concerning a long-term stability of nanoparticles and monoclonal antibodies. In this study, the aim was to find out a validated and optimized method that allows a long-term stability of nanoparticles and antibodies. Over 6 months of storage, an optimized nanosystem was considered stable for both nanoparticles and antibody structure, at 4 °C and 25 °C, resulting the first successfully report for monoclonal antibody storage at room temperature.