Surface Activity of a Monoclonal Antibody

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.'

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.

Oxidation of polysorbates - An underestimated degradation pathway?

To ensure the stability of biologicals over their entire shelf-life, non-ionic surface-active compounds (surfactants) are added to protect biologics from denaturation and particle formation. In this context, polysorbate 20 and 80 are the most used detergents. Despite their benefits of low toxicity and high biocompatibility, specific factors are influencing the intrinsic stability of polysorbates, leading to degradation, loss in efficacy, or even particle formation. Polysorbate degradation can be categorized into chemical or enzymatic hydrolysis and oxidation. Under pharmaceutical relevant conditions, hydrolysis is commonly originated from host cell proteins, whereas oxidative degradation may be caused by multiple factors such as light, presence of residual metal traces, peroxides, or temperature, which can be introduced upon manufacturing or could be already present in the raw materials. In this review, we provide an overview of the current knowledge on polysorbates with a focus on oxidative degradation. Subsequently, degradation products and key characteristics of oxidative-mediated polysorbate degradation in respect of different types and grades are summarized, followed by an extensive comparison between polysorbate 20 and 80. A better understanding of the radical-induced oxidative PS degradation pathway could support specific mitigation strategies. Finally, buffer conditions, various stressors, as well as appropriate mitigation strategies, reagents, and alternative stabilizers are discussed. Prior manufacturing, careful consideration and a meticulous risk-benefit analysis are highly recommended in terms of polysorbate qualities, buffers, storage conditions, as well as mitigation strategies.

Transportation of mAb Dosing Solution in Intravenous Bag: Impact of Manual, Vehicle, and Pneumatic Tube System Transportation Methods on Product Quality

Monoclonal antibody (mAb) products for intravenous (IV) administration generally require aseptic compounding with a commercial diluent within a pharmacy. The prepared dosing solution in the IV bag may be transported to the dosing location via manual, vehicular, pneumatic tube system (PTS), or a combination of these methods. In this study, the type and level of physical stresses associated with these three methods and their product quality impact for relatively sensitive and stable mAbs were assessed. Vibration was found to be the main stress associated with manual and vehicle transportation methods, although this was at a relatively low level (<1 GRMS/Root-Mean-Square Acceleration). Shock and drop events, at relatively low levels, were also observed with these methods. PTS transportation showed substantially more intense shock, vibration, and drop stresses and the measured levels were up to 91 G/force of acceleration or deceleration, 3.7 GRMS and 39 G, respectively. Using a foam padding insert for PTS transportation reduced the shock level considerably (91 G to 59 G). Transportation of mAb dosing solutions in IV bags via different methods including PTS transportation variables caused a small increase in the subvisible particle counts and there was no change in submicrometer particle distribution. No visible particles and no significant change to soluble aggregate levels were observed after transportation. Strategies such as removal of IV bag headspace prior to transport and in-line filtration poststress reduced the subvisible particles counts. All tested transportation conditions showed negligible impact on other product quality attributes tested. Removal of IV bag headspace prior to PTS transport prevented formation of micro air bubbles and foaming compared to the unaltered IV bag. This study shows examples where manual, vehicle, and PTS transport methods did not significantly impact product quality, and provides evidence that mAb products that are appropriately stabilized in the dosing solution (e.g., with a surfactant) can be transported via a PTS.

Existence of a superior polysorbate fraction in respect to protein stabilization and particle formation?

Biologicals including monoclonal antibodies are the current flagships in pharmaceutical industry. However, they are exposed to a multitude of destabilization conditions like for instance hydrophobic interfaces, leading to reduced biological activity. Polysorbates are commonly applied to effectively stabilize these active pharmaceutical ingredients against colloidal stress. Nevertheless, chemical instability of polysorbate via hydrolysis or oxidation results in degradation products that might form particles via phase separation. Polysorbates are mixtures of hundreds of individual components, and recently purer quality grades with reduced variations in the fatty acid composition are available. As the protective function of polysorbate itself is not completely understood, even less is known about its individual components, raising the question of the existence of a superior polysorbate species in respect to protein stabilization or degradation susceptibility. Here, we evaluated the protective function of four main fractions of polysorbate 20 (PS20) in agitation studies with monoclonal antibodies, followed by particle analysis as well as protein and polysorbate content determination. The commercially-available inherent mixtures PS20 high purity and PS20 all-laurate, as well as the fraction isosorbide-POE-monolaurate showed superior protection against mechanical-induced stress (visual inspection and turbidity) at the air-water interface in comparison to sole sorbitan-POE-monolaurate, -dilaurate, and -trilaurate. Fractions composed mainly of higher-order esters like sorbitan-POE-dilaurate and sorbitan-POE-trilaurate indicated high turbidities as indication for subvisible and small particles accompanied by a reduced protein monomer content after agitation. For the isosorbide-POE-monolaurates as well as for the inherent polysorbate mixtures no obvious differences in protein content and protein aggregation (SEC) were observed, reflecting the observations from visual appearance. However, absolute polysorbate concentrations vary drastically between different species in the actual formulations. As there are still open questions in respect to protein specificity or regarding mixtures versus individual components of PS20, further studies must be performed, to gain a better understanding of a "generalized" stabilizing effect of polysorbates on monoclonal antibodies. The knowledge of the characteristics of individual polysorbate species can have the potential to pave the way to superior detergents in respect to protein stabilization and/or degradation susceptibility.

Investigating the Orientation of an Interfacially Adsorbed Monoclonal Antibody and Its Fragments Using Neutron Reflection

Interfacial adsorption is a molecular process occurring during the production, purification, transport, and storage of antibodies, with a direct impact on their structural stability and subsequent implications on their bioactivities. While the average conformational orientation of an adsorbed protein can be readily determined, its associated structures are more complex to characterize. Neutron reflection has been used in this work to investigate the conformational orientations of the monoclonal antibody COE-3 and its Fab and Fc fragments at the oil/water and air/water interfaces. Rigid body rotation modeling was found to be suitable for globular and relatively rigid proteins such as the Fab and Fc fragments but less so for relatively flexible proteins such as full COE-3. Fab and Fc fragments adopted a 'flat-on' orientation at the air/water interface, minimizing the thickness of the protein layer, but they adopted a substantially tilted orientation at the oil/water interface with increased layer thickness. In contrast, COE-3 was found to adsorb in tilted orientations at both interfaces, with one fragment protruding into the solution. This work demonstrates that rigid-body modeling can provide additional insights into protein layers at various interfaces relevant to bioprocess engineering.

Novel trehalose-based excipients for stabilizing nebulized anti-SARS-CoV-2 antibody

COVID-19 is caused by the infection of the lungs by SARS-CoV-2. Monoclonal antibodies, such as sotrovimab, showed great efficiency in neutralizing the virus before its internalization by lung epithelial cells. However, parenteral routes are still the preferred route of administration, even for local infections, which requires injection of high doses of antibody to reach efficacious concentrations in the lungs. Lung administration of antibodies would be more relevant requiring lower doses, thus reducing the costs and the side effects. But aerosolization of therapeutic proteins is very challenging, as the different processes available are harsh and trigger protein aggregation and conformational changes. This decreases the efficiency of the treatment, and can increase its immunogenicity. To address those issues, we developed a series of new excipients composed of a trehalose core, a succinyl side chain and a hydrophobic carbon chain (from 8 to 16 carbons). Succinylation increased the solubility of the excipients, allowing their use at relevant concentrations for protein stabilization. In particular, the excipient with 16 carbons (C₁₆TreSuc) used at 5.6 mM was able to preserve colloidal stability and antigen-binding ability of sotrovimab during the nebulization process. It could also be used as a cryoprotectant, allowing storage of sotrovimab in a lyophilized form during weeks. Finally, we demonstrated that C₁₆TreSuc could be used as an excipient to stabilize antibodies for the treatment against COVID-19, by in vitro and in vivo assays. The presence of C₁₆TreSuc during nebulization preserved the neutralization capacity of sotrovimab against SARS-CoV-2 in vitro; an increase of its efficacy was even observed, compared to the non-nebulized control. The in vivo study also showed the wide distribution of sotrovimab in mice lungs, after nebulization with 5.6 mM of excipient. This work brings a solution to stabilize therapeutic proteins during storage and nebulization, making pulmonary immunotherapy possible in the treatment of COVID-19 and other lung diseases.

Protein-Surfactant and Protein-Protein Interactions During Freeze and Thaw: A Small-Angle Neutron Scattering Study of Lysozyme Solutions with Polysorbate and Poloxamer

Protein structural changes during freezing and subsequent thawing are of great importance to a variety of biopharmaceutical applications. In this work, we studied the influence of non-ionic surfactants (polysorbate 20 and poloxamer 188) on protein structural changes during freeze and thaw using lysozyme as a model protein. Small-angle neutron scattering was employed to characterize protein structures in both liquid and frozen solution states. The results show minimal impact of polysorbate 20 on lysozyme structures during freeze and thaw using practically relevant concentrations. Polysorbate 20 used at 0.04% (w/w) completely prevents freeze-induced aggregation of lysozyme. Poloxamer 188 seems to interact with lysozyme; when applied at high concentrations (10% w/w), such interaction prevents protein crowding or close packing typically associated with freeze concentration. Despite such interactions, lysozyme aggregation is observed with 10% (w/w) of poloxamer 188 during freezing, although the aggregation is reversed upon thawing.

Customer-centric product presentations for monoclonal antibodies

Delivering customer-centric product presentations for biotherapeutics, such as monoclonal antibodies (mAbs), represents a long-standing and paramount area of engagement for pharmaceutical scientists. Activities include improving experience with the dosing procedure, reducing drug administration-related expenditures, and ultimately shifting parenteral treatments outside of a controlled healthcare institutional setting. In times of increasingly cost-constrained markets and reinforced with the coronavirus pandemic, this discipline of "Product Optimization" in healthcare has gained momentum and changed from a nice-to-have into a must. This review summarizes latest trends in the healthcare ecosystem that inform key strategies for developing customer-centric products, including the availability of a wider array of sustainable drug delivery options and treatment management plans that support dosing in a flexible care setting. Three disease area archetypes with varying degree of implementation of customer-centric concepts are introduced to highlight relevant market differences and similarities. Namely, rheumatoid arthritis and inflammatory bowel disease, multiple sclerosis, and oncology have been chosen due to differences in the availability of subcutaneously dosed and ready-to-use self-administration products for mAb medicines and their follow-on biologics. Different launch scenarios are described from a manufacturer's perspective highlighting the necessity of platform approaches. To unfold the full potential of customer-centric care, value-based healthcare provider reimbursement schemes that incentivize the efficiency of care need to be broadly implemented.

Modification of Tubings for Peristaltic Pumping of Biopharmaceutics

Protein particle formation during peristaltic pumping of biopharmaceuticals is due to protein film formation on the inner tubing surface followed by rupture of the film by the roller movement. Protein adsorption can be prevented by addition of surfactants as well as by increasing the hydrophilicity of the inner surface. Attempts based on covalent surface coating were mechanically not stable against the stress of roller movement. We successfully incorporated surface segregating smart polymers based on a polydimethylsiloxane (PDMS) backbone and polyethylene glycol (PEG) side blocks in the tubing wall matrix. For this we applied an easy, reproducible and cost-effective process based on soaking of tubing in toluene containing the PDMS-PEG copolymer. With this tubing modification we could drastically reduce protein particle formation during peristaltic pumping of a monoclonal antibody and human growth hormone (HGH) formulation in silicone and thermoplastic elastomer-based tubing. The modification did not impact the tubing integrity during pumping while hydrophilicity was increased and protein adsorption was prevented. Free PDMS-PEG copolymer might have an additional stabilizing effect, but less than 50 ppm of the PDMS-PEG copolymer leached from the modified tubing during 1 h of pumping in the experimental setup. In summary, we present a new method for the modification of tubings which reduces protein adsorption and particle formation during any operation involving peristaltic pumping, e.g. transfer, filling, or tangential flow filtration.

A Novel MATLAB®-Algorithm-Based Video Analysis to Quantitatively Determine Solution Creeping in Intact Pharmaceutical Glass Vials

During the filling process of a biopharmaceutical drug product (DP), a liquid DP film might creep up the inner vial wall which is barely discernible, appears as milky-white haze after lyophilisation and is known as fogging. Creeping and fogging are mainly dependent on the primary packaging material surface and its hydration, vial preparation process as well as DP composition. The occurrence of both can impede visual inspection and might lead to DP rejection. Hence, our studies focused on the early detection of liquid solution and glass vial surface interaction directly after filling. For a fast and highly sensitive evaluation a novel video-based analysis was used. To our knowledge, this is the first time a MATLAB®-algorithm-based video analysis was applied to quantitatively determine creeping time-resolved. Furthermore, creeping in dependence of vial processing sites, surfactant type and concentration, filling temperature, and vial format were investigated. The results were verified using orthogonal conventional methods such as surface tension, wetting behaviour, and contact angle measurements, as well as ToF-SIMS, ICP-MS, and SEM. Additionally, the methods applied were assessed regarding their cross-validation capability. The observations indicate that the vial preparation process can have a pronounced impact on alteration of the glass vial surface and related creeping behaviour of the filled solution.

Differential Surface Adsorption Phenomena for Conventional and Novel Surfactants Correlates with Changes in Interfacial mAb Stabilization

Protein adsorption on surfaces can result in loss of drug product stability and efficacy during the production, storage, and administration of protein-based therapeutics. Surface-active agents (excipients) are typically added in protein formulations to prevent undesired interactions of proteins on surfaces and protein particle formation/aggregation in solution. The objective of this work is to understand the molecular-level competitive adsorption mechanism between the monoclonal antibody (mAb) and a commercially used excipient, polysorbate 80 (PS80), and a novel excipient, N-myristoyl phenylalanine-N-polyetheramine diamide (FM1000). The relative rate of adsorption of PS80 and FM1000 was studied by pendant bubble tensiometry. We find that FM1000 saturates the interface faster than PS80. Additionally, the surface-adsorbed amounts from X-ray reflectivity (XRR) measurements show that FM1000 blocks a larger percentage of interfacial area than PS80, indicating that a lower bulk FM1000 surface concentration is sufficient to prevent protein adsorption onto the air/water interface. XRR models reveal that with an increase in mAb concentration (0.5-2.5 mg/mL: IV based formulations), an increased amount of PS80 concentration (below critical micelle concentration, CMC) is required, whereas a fixed value of FM1000 concentration (above its relatively lower CMC) is sufficient to inhibit mAb adsorption, preventing mAb from co-existing with surfactants on the surface layer. With this observation, we show that the CMC of the surfactant is not the critical factor to indicate its ability to inhibit protein adsorption, especially for chemically different surfactants, PS80 and FM1000. Additionally, interface-induced aggregation studies indicate that at minimum surfactant concentration levels in protein formulations, fewer protein particles form in the presence of FM1000. Our results provide a mechanistic link between the adsorption of mAbs at the air/water interface and the aggregation induced by agitation in the presence of surfactants.

No ordinary proteins: Adsorption and molecular orientation of monoclonal antibodies

The interaction of monoclonal antibodies (mAbs) with air/water interfaces plays a crucial role in their overall stability in solution. We aim to understand this behavior using pendant bubble measurements to track the dynamic tension reduction and x-ray reflectivity to obtain the electron density profiles (EDPs) at the surface. Native immunoglobulin G mAb is a rigid molecule with a flat, "Y" shape, and simulated EDPs are obtained by rotating a homology construct at the surface. Comparing simulations with experimental EDPs, we obtain surface orientation probability maps showing mAbs transition from flat-on Y-shape configurations to side-on or end-on configurations with increasing concentration. The modeling also shows the presence of β sheets at the surface. Overall, the experiments and the homology modeling elucidate the orientational phase space during different stages of adsorption of mAbs at the air/water interface. These finding will help define new strategies for the manufacture and storage of antibody-based therapeutics.

4-Hydroxynonenal - A Toxic Leachable from Clinically Used Administration Materials

INTRODUCTION

The migration of chemicals from processing materials into biopharmaceuticals can lead to various problems. Leachables from administration materials, with no possibility of further clearance, are of particular concern. Released chemicals can be toxic or react with formulation components, thereby impacting product safety. Therapeutic proteins, which are susceptible to chemical modifications, have highest risk to be affected.

AIM

The aim of this study was to identify a previously unknown leachable compound from clinical administration sets, which was present above the applied generic safety threshold.

METHODS

Extracts of commonly used clinical administration sets were analyzed using a recently established specific assay allowing the identification and quantification of the α,β-unsaturated aldehyde 4-hydroxynonenal (HNE) in a drug product surrogate solution. HNE was quantified after derivatization with 2,4-dinitrophenylhydrazine (DNPH) and liquid extraction of the formed hydrazone by LC-MRM analysis.

RESULTS

Potentially genotoxic HNE was a leachable compound from all tested administration sets, in parts exceeding safety thresholds for genotoxicants. The HNE-releasing polymer was identified as PVC.

CONCLUSION

Clinical administration sets should be, like manufacturing materials and container closure systems, in the focus of routine leachables studies. Manufacturers of clinical administration sets should show responsibility to avoid the presence of safety concerning chemicals, like HNE.

4-Hydroxynonenal is An Oxidative Degradation Product of Polysorbate 80

INTRODUCTION

Polysorbates (PS) are used in biopharmaceuticals to stabilize therapeutic proteins. Oxidative degradation of (poly)unsaturated fatty acids (PUFAs) contained in PS was shown to lead to α,β-unsaturated carbonyls.

AIM

The n-6-PUFA linoleic acid accounts for up to 18% of all FAs contained in multi-compendial grade PS80. 4-Hydroxynonenal (HNE) is highly reactive towards nucleophilic amino acids, potentially leading to covalent protein modifications. This study tests whether HNE may be a pharmaceutically relevant PS80 peroxidation product.

METHODS

Since HNE was not directly detectable in the PS80 matrix by UV and MS, a new quantification method was established. After derivatization with 2,4-dinitrophenyl hydrazine (DNPH) and extraction of the formed hydrazone with a salting-out assisted liquid-liquid extraction, the HNE-DNPH adduct was analyzed by multiple reaction monitoring. Kinetic oxidation studies were conducted incubating PS80 in presence and absence of the antioxidant butylhydroxytoluene (BHT).

RESULTS

HNE was confirmed as PS80 degradant in oxidatively stressed samples. BHT was shown to prevent its formation.

CONCLUSION

HNE is a detectable PS80 degradation product raising questions about the potential impact on critical quality attributes of biopharmaceuticals formulated with PS80. Addition of BHT prevented HNE formation under oxidative stress. Consequently, BHT might be a valuable additive in PS used in biopharmaceuticals.

Effects of Hydrophobic Tail Length Variation on Surfactant-Mediated Protein Stabilization

Recently, protein therapeutics have gained significant attention as a result of their enhanced selectivity and diminished side effects compared to traditional small-molecule drugs. Despite their advantages, protein formulations typically suffer from stability issues because of aggregation and denaturation during production and storage, often resulting in detrimental immune responses. Surfactants can be used to stabilize and protect proteins in solution by preventing protein adsorption onto interfaces or by forming protective structures in solution. Herein, a detailed structure-activity relationship study is described, demonstrating the role that hydrophobic tail length plays in surfactant-mediated stabilization of the model therapeutic protein IgG. The FM1000 series, originating from a surfactant scaffold that allows for easy structure modulation, was synthesized by a simple 2-step procedure. First, phenylalanine was acylated with a variety of acyl chlorides of differing lengths to yield n-acyl phenylalanine, which was then coupled to Jeffamine M1000, a polyethylene glycol-based amine, to yield the final surfactant. With this FM1000 series, it was observed that the 14 carbon-long tail surfactant (14FM1000) was optimal at preventing IgG aggregation compared to surfactants with tails that were longer or shorter. Using a combination of dynamic surface tensiometry and quartz crystal microbalance with dissipation, it was hypothesized that 14FM1000 was able to prevent IgG adsorption, and therefore aggregation, by adsorbing appreciably onto surfaces quickly. 14FM1000 had the fastest rate of initial adsorption compared to the other surfactants studied. Short-tail surfactants were slow to and did not adsorb appreciably onto surfaces, allowing IgG adsorption. Although long-tail surfactants were also slow to adsorb, allowing IgG to adsorb and aggregate, their equilibrium adsorption was strong. Additionally, 14FM1000 was the most reversibly adsorbed surfactant, likely improving its ability to desorb and adsorb quickly to transient surfaces, therefore protecting the IgG at each new hydrophobic surface and preventing aggregation. By understanding the structure-activity relationship between surfactants and protein stabilization, we move toward more efficient design of future surfactants increasing the stability and utility of important protein therapeutics.

Degradation of polysorbates 20 and 80 catalysed by histidine chloride buffer

Polysorbates are amphiphilic, non-ionic surfactants, and they represent one of the key components of biopharmaceuticals. They serve as stabilisers, and their degradation can cause particle formation, which has been an industry-wide issue over the past decade. To determine the influence of the buffers most frequently used in biopharmaceuticals on polysorbate degradation, an accelerated stability study was carried out using placebo formulations containing 0.02% polysorbates and 20 mM buffers (pH 5.5, 6.5). These included histidine chloride, sodium citrate, sodium succinate and sodium phosphate buffers. The rate of polysorbate degradation was highest in histidine chloride buffer, and therefore we further focused on the mechanism here. The predominant degradation pathway of polysorbates in this buffer was ester hydrolysis, catalysed by the imidazole moiety of the histidine. Interestingly, the presence of therapeutic proteins in the formulations slowed histidine-catalysed degradation of polysorbates in 50% of cases, with negligible degradation seen otherwise. This emphasises the complex nature of the interactions between the components of biopharmaceutical drug products. Nonetheless, there are disadvantages of using histidine chloride buffers in biopharmaceuticals that contain polysorbates. Careful consideration should be given to selection of excipients used in parenteral formulations, whereby compatibility between buffer and surfactant is of key importance.

Competitive Surface Activity of Monoclonal Antibodies and Nonionic Surfactants at the Air-Water Interface Determined by Interfacial Rheology and Neutron Reflectometry

Interfacial stresses can destabilize therapeutic formulations containing monoclonal antibodies (mAbs), which is proposed to be a result of adsorption and aggregation at the air-water interface. To increase protein stability, pharmaceutical industries add surfactants, such as Polysorbate 20 (PS20), into protein formulations to minimize mAb adsorption at the interface but rarely quantify this process. We determine that mAb adsorption in surfactant-free solutions creates a monolayer with significant viscoelasticity, which can influence measurements of bulk mAb solution viscosity. In contrast, PS20 absorption leads to an interface with negligible interfacial viscosity that protects the air-water interface from mAb adsorption. These studies were performed through a combined study of surface tensiometry, interfacial rheology, capillary viscometry, and neutron reflectometry to determine the surface activity of a model surfactant, PS20, and mAb system, which can be useful for the successful formulation developments of biotherapeutics.

Armoring the Interface with Surfactants to Prevent the Adsorption of Monoclonal Antibodies

The pharmaceutical industry uses surface-active agents (excipients) in protein drug formulations to prevent the aggregation, denaturation, and unwanted immunological response of therapeutic drugs in solution as well as at the air/water interface. However, the mechanism of adsorption, desorption, and aggregation of proteins at the interface in the presence of excipients remains poorly understood. The objective of this work is to explore the molecular-scale competitive adsorption process between surfactant-based excipients and two monoclonal antibody (mAb) proteins, mAb-1 and mAb-2. We use pendant bubble tensiometry to measure the ensemble average adsorption dynamics of mAbs with and without the excipient. The surface tension measurements allow us to quantify the rate at which the molecules "race" to the interface in single-component and mixed systems. These results define the phase space, where coadsorption of both mAbs and excipients occurs onto the air/water interface. In parallel, we use X-ray reflectivity (XR) measurements to understand the molecular-scale dynamics of competitive adsorption, revealing the surface-adsorbed amounts of the antibody and excipient. XR has revealed that at a sufficiently high surface concentration of the excipient, mAb adsorption to the surface and subsurface domains was inhibited. In addition, despite the fact that both mAbs adsorb via a similar mechanistic pathway and with similar dynamics, a key finding is that the competition for the interface directly correlates with the surface activity of the two mAbs, resulting in a fivefold difference in the concentration of the excipient needed to displace the antibody.

Micellar Morphology of Polysorbate 20 and 80 and Their Ester Fractions in Solution via Small-Angle Neutron Scattering

Surfactants are commonly used in therapeutic protein formulations in biopharmaceuticals to impart protein stability; however, their solution morphology and the role of the individual components in these structurally heterogeneous commercial grade surfactants at physiologically and pharmaceutically relevant temperatures have not been investigated systematically. The micellar morphologies of Polysorbate 20 and Polysorbate 80 and their primary components monoester fractions, as well as the diester fractions, are evaluated at 4, 22°C, 40°C, and 50°C using small-angle neutron scattering to determine the aggregation number, radius of gyration, core radius, critical micelle concentration, shell thickness, and shell hydration. The sizes and aggregation numbers of the diester fractions of PS20 above 80°C and PS80 above 50°C exhibit significant changes in shape. The analysis of the small-angle neutron scattering data of PS20 confirms that the critical micellar concentration of the monoester fraction is significantly higher at 4°C compared to the diester fraction and their original material, all-laurate PS20. Overall, these experiments identify the dominant components responsible for the temperature-dependent behavior of these surfactants in pharmaceutical protein formulations.

Insights into virus inactivation by polysorbate 80 in the absence of solvent

Triton X-100 has long been used either alone or in combination with solvent to inactivate enveloped viruses in biopharmaceutical manufacturing. However, European Chemicals Agency (ECHA) officially placed Triton X-100 on the Annex XIV authorization list in 2017 because 4-(1,1,3,3-tetramethylbutyl) phenol, a degradation product of Triton X-100, is of harmful endocrine disrupting activities. As a result, any use of Triton X-100 in the European Economic Area would require an ECHA issued authorization after the sunset date of January 4, 2021. In search of possible replacements for Triton X-100, we discovered that polysorbate 80 (PS80) in absence of any solvents was able to effectively inactive enveloped viruses such as xenotropic murine leukemia virus and pseudorabies virus with comparable efficacy as measured by log reduction factors. Interestingly, PS80 did not show any virucidal activities in phosphate buffered saline (PBS) while achieving robust virus inactivation in cell-free Chinese hamster ovary (CHO) bioreactor harvests. This intriguing observation led us to speculate that virus inactivation by PS80 involved components in the cell-free CHO bioreactor harvests that were absent in PBS. Specifically, we hypothesized that esterase and/or lipases in the cell-free bioreactor harvests hydrolyzed PS80 to yield oleic acid, a known potent virucidal agent, which in turn inactivated viruses. This theory was confirmed using purified recombinant lysosomal phospholipase A2 isomer (rLPLA2) in PBS. Subsequent characterization work has indicated that virus inactivation by PS80 is effective and robust within temperature and concentration ranges comparable to those of Triton X-100. Similar to Triton X-100, virus inactivation by PS80 is dually dependent on treatment time and temperature. Unlike Triton X-100, PS80 inactivation does not correlate with concentrations in a simple manner. Additionally, we have demonstrated that PS20 exhibits similar virus inactivation activities as PS80. Based on the findings described in the current work, we believe that PS80 is potentially a viable replacement for Triton X-100 and can be used in manufacturing processes for wide spectrum of biopharmaceuticals to achieve desirable virus clearance. Finally, the advantages and disadvantages of using PS80 for virus inactivation are discussed in the contexts of GMP manufacturing.

Shocking Data on Parcel Shipments of Protein Solutions

An early-phase development shipping study was designed to interrogate the stability of liquid formulations under normal shipping conditions. Parcel shipments were made between Seattle, WA, and Indianapolis, IN, during 2018-2019. Each parcel contained a data recorder that tracked the shipment by GPS and measured shock and temperature. During the transport process, the parcels received up to 40 shock events with strengths ranging from 8 to 36G. After shipment, the formulations without polysorbate showed considerable increases in submicron and visible particles while little to no change occurred when polysorbate was present. Samples dropped repeatedly from a height of 18 inches to produce a shock of ∼25G caused visible particle formation with little increase in the subvisible particles, suggesting that other factors, such as vibration, in addition to the shock, were necessary to produce particle formation. These results provide a basis for further studies in the relationships between physical stability of mAbs and the challenges introduced by the shipment network, specifically shock and vibration. The findings indicate that the shock events as measured are repeatable and attributable to the layout of the sorting facility.

Science and art of protein formulation development

Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.

Monoclonal Antibody Interfaces: Dilatation Mechanics and Bubble Coalescence

Monoclonal antibodies (mAbs) are proteins that uniquely identify targets within the body, making them well-suited for therapeutic applications. However, these amphiphilic molecules readily adsorb onto air-solution interfaces where they tend to aggregate. We investigated two mAbs with different propensities to aggregate at air-solution interfaces. The understanding of the interfacial rheological behavior of the two mAbs is crucial in determining their aggregation tendency. In this work, we performed interfacial stress relaxation studies under compressive step strain using a custom-built dilatational rheometer. The dilatational relaxation modulus was determined for these viscoelastic interfaces. The initial value and the equilibrated value of relaxation modulus were larger in magnitude for the mAb with a higher tendency to aggregate in response to interfacial stress. We also performed single-bubble coalescence experiments using a custom-built dynamic fluid-film interferometer (DFI). The bubble coalescence times also correlated to the mAbs aggregation propensity and interfacial viscoelasticity. To study the influence of surfactants in mAb formulations, polyethylene glycol (PEG) was chosen as a model surfactant. In the mixed mAb/PEG system, we observed that the higher aggregating mAb coadsorbed with PEG and formed domains at the interface. In contrast, for the other mAb, PEG entirely covered the interface at the concentrations studied. We studied the mobility of the interfaces, which was manifested by the presence or the lack of Marangoni stresses. These dynamics were strongly correlated with the interfacial viscoelasticity of the mAbs. The influence of competitive destabilization in affecting the bubble coalescence times for the mixed mAb/PEG systems was also studied.

Effect of Polysorbate 20 and Polysorbate 80 on the Higher-Order Structure of a Monoclonal Antibody and Its Fab and Fc Fragments Probed Using 2D Nuclear Magnetic Resonance Spectroscopy

We examined how polysorbate 20 (PS20; Tween 20) and polysorbate 80 (PS80; Tween 80) affect the higher-order structure of a monoclonal antibody (mAb) and its antigen-binding (Fab) and crystallizable (Fc) fragments, using near-UV circular dichroism and 2D nuclear magnetic resonance (NMR). Both polysorbates bind to the mAb with submillimolar affinity. Binding causes significant changes in the tertiary structure of mAb with no changes in its secondary structure. 2D ¹³C-¹H methyl NMR indicates that with increasing concentration of polysorbates, the Fab region showed a decrease in crosspeak volumes. In addition to volume changes, PS20 caused significant changes in the chemical shifts compared to no changes in the case of PS80. No such changes in crosspeak volumes or chemical shifts were observed in the case of Fc region, indicating that polysorbates predominantly affect the Fab region compared to the Fc region. This differential effect of polysorbates on the Fab and Fc regions was because of the lesser thermodynamic stability of the Fab compared to the Fc. These results further indicate that PS80 is the preferred polysorbate for this mAb formulation, because it offers higher protection against aggregation, causes lesser structural perturbation, and has weaker binding affinity with fewer binding sites compared to PS20.

Knockout of a difficult-to-remove CHO host cell protein, lipoprotein lipase, for improved polysorbate stability in monoclonal antibody formulations

While the majority of host cell protein (HCP) impurities are effectively removed in typical downstream purification processes, a small population of HCPs are particularly challenging. Previous studies have identified HCPs that are challenging for a variety of reasons. Lipoprotein lipase (LPL)-a Chinese hamster ovary (CHO) HCP that functions to hydrolyze esters in triglycerides-was one of ten HCPs identified in previous studies as being susceptible to retention in downstream processing. LPL may degrade polysorbate 80 (PS-80) and polysorbate 20 (PS-20) in final product formulations due to the structural similarity between polysorbates and triglycerides. In this work, recombinant LPL was found to have enzymatic activity against PS-80 and PS-20 in a range of solution conditions that are typical of mAb formulations. LPL knockout CHO cells were created with CRISPR and TALEN technologies and resulting cell culture harvest fluid demonstrated significantly reduced polysorbate degradation without significant impact on cell viability when compared to wild-type samples. Biotechnol. Bioeng. 2017;114: 1006-1015. © 2016 Wiley Periodicals, Inc.

Surfactant Effects on Particle Generation in Antibody Formulations in Pre-filled Syringes

Protein aggregation and particle formation have been observed when protein solutions contact hydrophobic interfaces, and it has been suggested that this undesirable phenomenon may be initiated by interfacial adsorption and subsequent gelation of the protein. The addition of surfactants, such as polysorbate 20, to protein formulations has been proposed as a way to reduce protein adsorption at silicone oil-water interfaces and mitigate the production of aggregates and particles. In an accelerated stability study, monoclonal antibody formulations containing varying concentrations of polysorbate 20 were incubated and agitated in pre-filled glass syringes (PFS), exposing the protein to silicone oil-water interfaces at the siliconized syringe walls, air-water interfaces, and agitation stress. Following agitation in siliconized syringes that contained an air bubble, lower particle concentrations were measured in the surfactant-containing antibody formulations than in surfactant-free formulations. Polysorbate 20 reduced particle formation when added at concentrations above or below the critical micelle concentration (CMC). The ability of polysorbate 20 to decrease particle generation in PFS corresponded with its ability to inhibit gelation of the adsorbed protein layer, which was assessed by measuring the interfacial diffusion of individual antibody molecules at the silicone oil-water interface using total internal reflectance fluorescence (TIRF) microscopy with single-molecule tracking.