High-throughput screening of excipients intended to prevent antigen aggregation at air-liquid interface

Combined Effect of Shaking Orbit and Vial Orientation on the Agitation-Induced Aggregation of Proteins

Orbital shaking in a glass vial is a commonly used forced degradation test to evaluate protein propensity for agitation-induced aggregation. Vial shaking in horizontal orientation has been widely recommended to maximize the air-liquid interface area while ensuring solution contact with the stopper. We evaluated the impact of shaking orbit diameter and frequency, and glass vial orientation (horizontal versus vertical) on the aggregation of three proteins prepared in surfactant-free formulation buffers. As soon as an orbit-specific frequency threshold was reached, an increase in turbidity was observed for the three proteins in vertical orientation only when using a 3 mm agitation orbit, and in horizontal orientation only when using a 30 mm agitation orbit. Orthogonal analyses confirmed turbidity was linked to protein aggregation. The most turbid samples had a visually more homogeneous appearance in vertical than in horizontal orientation, in line with the predicted dispersion of air and liquid phases obtained from computational fluid dynamics agitation simulations. Both shaking orbits were used to assess the performance of nonionic surfactants. We show that the propensity of a protein to aggregate in a vial agitated in horizontal or vertical orientation depends on the shaking orbit, and confirm that Brij® 58 and FM1000 prevent proteins from agitation-induced aggregation at lower concentrations than polysorbate 80.

Freeze-drying of few microliters of antibody formulations to implement 384-wells homogeneous instant assays

Enzyme-linked immunosorbent assay protocols have traditionally complex workflows with several intensive wash steps. Analytical tools with both shorter time-to-result and hands-on-time using smaller sample and assays reagents volumes are now investigated. In this context, fluorescence resonance energy transfer (FRET)-based assays are emerging as one of the most promising analytical tools in high-throughput screening (HTS). These immunoassays allow fast quantification of antigens at the nano-gram level in a final assay volume of only a few μL. We used a homogeneous time-resolved FRET (called HTRF) assay to develop a freeze-dried screening and ready-to-use format with only one rehydration step called "instant assay". To assure optimal performance of the developed homogeneous instant assay, we investigated the critical quality attributes by studying the functionality and stability of the critical reagents and fluorophores. The cyclic adenosine 3'-5'-monophosphate (cAMP) was selected as the antigen target. We tested various formulations (with different buffers, sugars, bulking reagents, surfactants and co-solvants) combined with a slow freezing and the use of an aluminium plate holder during the freeze-drying of few microliter of bioreagents. The optimized freeze-drying procedure permits to preserve more than 70% of Ab recognition properties. The developed off-the-shelf homogeneous FRET immunoassay allows direct and fast quantification of cAMP at a nanogram level.

A systematic review of commercial high concentration antibody drug products approved in the US: formulation composition, dosage form design and primary packaging considerations

Three critical aspects that define high concentration antibody products (HCAPs) are as follows: 1) formulation composition, 2) dosage form, and 3) primary packaging configuration. HCAPs have become successful in the therapeutic sector due to their unique advantage of allowing subcutaneous self-administration. Technical challenges, such as physical and chemical instability, viscosity, delivery volume limitations, and product immunogenicity, can hinder successful development and commercialization of HCAPs. Such challenges can be overcome by robust formulation and process development strategies, as well as rational selection of excipients and packaging components. We compiled and analyzed data from US Food and Drug Administration-approved and marketed HCAPs that are ≥100 mg/mL to identify trends in formulation composition and quality target product profile. This review presents our findings and discusses novel formulation and processing technologies that enable the development of improved HCAPs at ≥200 mg/mL. The observed trends can be used as a guide for further advancements in the development of HCAPs as more complex antibody-based modalities enter biologics product development.

Miniaturized Forced Degradation of Therapeutic Proteins and ADCs by Agitation-Induced Aggregation Using Orbital Shaking of Microplates

Microplate-based formulation screening is a powerful approach to identify stabilizing excipients for therapeutic proteins while reducing material requirements. However, this approach is sometimes not representative of studies conducted in relevant container closures. The present study aimed to identify critical parameters for a microplate-based orbital shaking method to screen biotherapeutic formulations by agitation-induced aggregation. For this purpose, an in-depth methodological study was conducted using different shakers, microplates, and plate seals. Aggregation was monitored by size exclusion chromatography, turbidity, and backgrounded membrane imaging. Both shaker quality and liquid-seal contact had substantial impacts on aggregation during shaking and resulted in non-uniform sample treatment when parameters were not suitably selected. The well volume to fill volume ratio (V_well/V_fill) was identified as an useful parameter for achieving comparable aggregation levels between different microplate formats. An optimized method (2400 rpm [a_c 95 m/s²], V_fill 60-100 µL [V_well/V_fill 6-3.6], 24 h, RT, heat-sealed) allowed for uniform sample treatment independent of surface tension and good agreement with vial shaking results. This study provides valuable guidance for miniaturization of shaking stress studies in biopharmaceutical drug development, facilitating method transfer and comparability between laboratories.

A review of Formulations of Commercially Available Antibodies

This review identified 126 commercially available antibodies approved globally between 1986 and February 2021 including 10 antibody drug conjugates, 16 biosimilars, and 3 antibody fragments. Prior to 2014 there were ≤ 5 approved each year, but after 2014 there have been ≥ 7 approved each year with the years 2017, 2019 and 2020 having the most at 17 each. A total of 136 products were identified of which 36 are lyophilized powders and 100 are solutions. The routes of administration are mainly subcutaneous or intravenous infusion with three intravenous bolus, two intravitreal, and one intramuscular. The subcutaneous products are ready-to-use solutions or reconstituted lyophilized powders that do not require dilution while most intravenous products are concentrates that require dilution into saline or another intravenous fluid prior to infusion. Most are packaged in single-dose units and the exception of multi-use is Herceptin® and its biosimilars. The package configurations are vials, prefilled autoinjectors, or prefilled syringes. A typical antibody formulation contains an antibody, an excipient to adjust tonicity or osmolality for solutions or a lyoprotectant for lyophilized powders, a buffer, and a surfactant. The ionic tonicity-adjusting excipient is mainly sodium chloride and the non-ionic osmolality-adjusting excipients include sucrose, trehalose, mannitol, maltose, and sorbitol. The lyoprotectants are trehalose and sucrose. The pH range is 4.8-8.0 and the buffers or pH-modifying agents include histidine, citrate, succinate, acetate, phosphate, glutamate, adipic acid, aspartic acid, lactic acid, tromethamine, and 2-(N-morpholino)-ethanesulfonic acid. The surfactants include mostly polysorbate 20 or polysorbate 80, with four containing poloxamer 188, and one that does not contain a surfactant but contains PEG 3350. One product does not contain a buffer, and 12 do not contain a surfactant. The viscosity-lowering excipients are sodium chloride and the amino acids arginine, glycine, proline, and lysine. Arginine may also function to adjust ionic strength and minimize aggregation. Human serum albumin is used in 2 products for intravenous infusion. Other excipients include methionine as an anti-oxidant, and EDTA or DTPA as chelating agents. The maximum volume of subcutaneous injection is 15 mL administered over 3-5 minutes, but the typically volume is 0.5-2 mL. Five fixed-dose combinations have recently been approved and four contain hyaluronidase to assist the large volume subcutaneous injection of up to 15 mL, while one is a fixed-dose combination for intravenous with three antibodies. Prefilled autoinjectors and syringes are becoming more common and many come affixed with a needle of 27-gauge or 29-gauge, while a few have a 26-gauge or a 30-gauge needle. Recent advancements include hyaluronidase to assist the large subcutaneous injection volume of 5-15 mL, fixed-dose combinations, buffer-free formulation, and smaller subcutaneous injection volume (0.1 mL).

Purification of viable peripheral blood mononuclear cells for biobanking using a robotized liquid handling workstation

Background

The purification of peripheral blood mononuclear cells (PBMCs) by means of density gradient (1.07 g/mL) centrifugation is one of the most commonly used methods in diagnostics and research laboratories as well as in biobanks. Here, we evaluated whether it was possible to set up an automated protocol for PBMC purification using a programmable liquid handling robotized workstation (Tecan, Freedom EVO 150). We selected a population composed of 30 subjects for whom it was possible to dispose of two ethylenediaminetetraacetic acid (EDTA) vacutainer tubes containing unfractionated peripheral blood. The purification of PBMCs was performed in parallel using automated and manual workflows.

Results

An automated workflow using the Freedom EVO 150 liquid handling workstation was generated for the isolation of PBMCs. This protocol allowed blood dilution in Dulbecco’s phosphate-buffered saline (DPBS), stratification onto the density gradient, and the collection of PBMC rings after centrifugation. The comparison between the automated and manual methods revealed no significant differences after separation in terms of total mononuclear cell enrichment, red blood cell contamination, or leucocyte formula, including the percentage of lymphoid subpopulations as B, T and natural killer (NK) lymphocytes.

Conclusions

Our results show that it is possible to set up an automated protocol for the isolation of PBMCs using a robotized liquid handling workstation. This automated protocol provided comparable results to the routinely used manual method. This automatic method could be of interest for those working in biobanking or industries involved in diagnostics and therapeutics field, to avoid operator-dependent errors as well as procedures standardization.

Automated Gravimetric Calibration to Optimize the Accuracy and Precision of TECAN Freedom EVO Liquid Handler

High-throughput screening technologies are increasingly integrated into the formulation development process of biopharmaceuticals. The performance of liquid handling systems is dependent on the ability to deliver accurate and precise volumes of specific reagents to ensure process quality. We have developed an automated gravimetric calibration procedure to adjust the accuracy and evaluate the precision of the TECAN Freedom EVO liquid handling system. Volumes from 3 to 900 µL using calibrated syringes and fixed tips were evaluated with various solutions, including aluminum hydroxide and phosphate adjuvants, β-casein, sucrose, sodium chloride, and phosphate-buffered saline. The methodology to set up liquid class pipetting parameters for each solution was to split the process in three steps: (1) screening of predefined liquid class, including different pipetting parameters; (2) adjustment of accuracy parameters based on a calibration curve; and (3) confirmation of the adjustment. The run of appropriate pipetting scripts, data acquisition, and reports until the creation of a new liquid class in EVOware was fully automated. The calibration and confirmation of the robotic system was simple, efficient, and precise and could accelerate data acquisition for a wide range of biopharmaceutical applications.

Understanding the relationship between biotherapeutic protein stability and solid-liquid interfacial shear in constant region mutants of IgG1 and IgG4

Relative stability of therapeutic antibody candidates is currently evaluated primarily through their response to thermal degradation, yet this technique is not always predictive of stability in manufacture, shipping, and storage. A rotating disk shear device is proposed that produces defined shear conditions at a known solid–liquid interface to measure stability in this environment. Five variants of IgG1 and IgG4 antibodies were created using combinations of two discrete triple amino acid sequence mutations denoted TM and YTE. Antibodies were ranked for stability based on shear device output (protein decay coefficient, PDC), and compared with accelerated thermal stability data and the melting temperature of the CH2 domain (T_m1) from differential scanning calorimetry to investigate technique complimentarity. Results suggest that the techniques are orthogonal, with thermal methods based on intramolecular interaction and shear device stability based on localized unfolding revealing less stable regions that drive aggregation. Molecular modeling shows the modifications’ effects on the antibody structures and indicates a possible role for Fc conformation and Fab-Fc docking in determining suspended protein stability. The data introduce the PDC value as an orthogonal stability indicator, complementary to traditional thermal methods, allowing lead antibody selection based on a more full understanding of process stability. © 2013 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:437–444, 2014

Immunogenicity of therapeutic proteins: influence of aggregation

The elicitation of anti-drug antibodies (ADA) against biotherapeutics can have detrimental effects on drug safety, efficacy, and pharmacokinetics. The immunogenicity of biotherapeutics is, therefore, an important issue. There is evidence that protein aggregation can result in enhanced immunogenicity; however, the precise immunological and biochemical mechanisms responsible are poorly defined. In the context of biotherapeutic drug development and safety assessment, understanding the mechanisms underlying aggregate immunogenicity is of considerable interest. This review provides an overview of the phenomenon of protein aggregation, the production of unwanted aggregates during bioprocessing, and how the immune response to aggregated protein differs from that provoked by non-aggregated protein. Of particular interest is the nature of the interaction of aggregates with the immune system and how subsequent ADA responses are induced. Pathways considered here include 'classical' activation of the immune system involving antigen presenting cells and, alternatively, the breakdown of B-cell tolerance. Additionally, methods available to screen for aggregation and immunogenicity will be described. With an increased understanding of aggregation-enhanced immune responses, it may be possible to develop improved manufacturing and screening processes to avoid, or at least reduce, the problems associated with ADA.

Alternative computational protocols for supercharging protein surfaces for reversible unfolding and retention of stability

Reengineering protein surfaces to exhibit high net charge, referred to as “supercharging”, can improve reversibility of unfolding by preventing aggregation of partially unfolded states. Incorporation of charged side chains should be optimized while considering structural and energetic consequences, as numerous mutations and accumulation of like-charges can also destabilize the native state. A previously demonstrated approach deterministically mutates flexible polar residues (amino acids DERKNQ) with the fewest average neighboring atoms per side chain atom (AvNAPSA). Our approach uses Rosetta-based energy calculations to choose the surface mutations. Both protocols are available for use through the ROSIE web server. The automated Rosetta and AvNAPSA approaches for supercharging choose dissimilar mutations, raising an interesting division in surface charging strategy. Rosetta-supercharged variants of GFP (RscG) ranging from −11 to −61 and +7 to +58 were experimentally tested, and for comparison, we re-tested the previously developed AvNAPSA-supercharged variants of GFP (AscG) with +36 and −30 net charge. Mid-charge variants demonstrated ∼3-fold improvement in refolding with retention of stability. However, as we pushed to higher net charges, expression and soluble yield decreased, indicating that net charge or mutational load may be limiting factors. Interestingly, the two different approaches resulted in GFP variants with similar refolding properties. Our results show that there are multiple sets of residues that can be mutated to successfully supercharge a protein, and combining alternative supercharge protocols with experimental testing can be an effective approach for charge-based improvement to refolding.

Virus-like particle formulation optimization by miniaturized high-throughput screening

Virus-like particles (VLPs) are non-infectious and immunogenic virus-mimicking protein assemblies that are increasingly researched as vaccine candidates. Stability against aggregation is an important determinant dictating the viability of a pipeline VLP product, making multivariable stability data highly desirable especially in early product development stages. However, comprehensive formulation studies are challenging due to low sample availability early in developability assessment. This issue is exacerbated by industry-standard analytical techniques which are low-throughput and/or sample-consuming. This study presents a miniaturized high-throughput screening (MHTS) methodology for VLP formulation by integrating dynamic light scattering (DLS) and asymmetrical flow field-flow fractionation (AF4) in a formulation funnel analysis. Using only 2 μg of sample and 100 s per measurement, a DLS plate reader was deployed to effectively pre-screen a large experimental space, allowing a smaller set of superior formulation conditions to be interrogated at high-resolution with AF4. The stabilizing effects of polysorbate 20, sucrose, trehalose, mannitol and sorbitol were investigated. MHTS data showed that addition of 0.5% w/v polysorbate 20 together with either 40% w/v sucrose or 40% w/v sorbitol could stabilize VLPs at elevated temperatures up to 58 °C. AF4 data further confirmed that the formulation containing 40% w/v sorbitol and 0.5% w/v polysorbate 20 effectively protected VLPs during freeze-thawing and freeze-drying, increasing recoveries from these processes by 80 and 50 percentage points, respectively. The MHTS strategy presented here could be used to rapidly explore a large formulation development space using reduced amounts of sample, without sacrificing the analytical resolution needed for quality control. Such a method paves the way for rapid formulation development and could potentially hasten the commercialization of new VLP vaccines.

Advancements in high throughput biophysical technologies: applications for characterization and screening during early formulation development of monoclonal antibodies

The formulation development of monoclonal antibodies is extremely challenging, due to the diversity and complexity contained within this class of molecules. The physical and chemical properties of a monoclonal antibody dictate the behavior of the protein drug during manufacturing, storage and clinical administration. In the past few years, the use of high throughput technologies has been widely adapted to delineate unique properties of individual immunoglobulin G's (IgG's) important for their development. Numerous screening techniques have been designed to reveal physical and chemical characteristics of a protein relevant to stability under production, formulation and delivery conditions. In addition, protein stability under accelerated stresses has been utilized to predict long-term storage behavior for monoclonal antibodies in the formulation. In this review, we summarize the recent advancements in the field of biophysical technology, with a specific focus on the techniques that can be directly applied to the formulation development of monoclonal antibodies. Several case studies are also presented here to provide examples of combining existing biophysical methods with high throughput screening technology in the formulation development of monoclonal antibody drugs.