Impact of Polysorbate 80 Grade on the Interfacial Properties and Interfacial Stress Induced Subvisible Particle Formation in Monoclonal Antibodies

Correlating Differences in the Surface Activity to Interface-Induced Particle Formation in Different Protein Modalities: IgG mAb Versus Fc-Fusion Protein

The propensity of protein-based biologics to form protein particles during bioprocessing can be related to their interfacial properties. In this study, we compare the surface activity and interfacial film properties of two structurally different biologics, an IgG and Fc-fusion, in the absence and presence of interfacial dilatational stresses, and correlate these differences to their tendency to form interface-induced protein particles. Our results show that interface-induced particle formation is protein-dependent, with the Fc-fusion demonstrating greater interfacial stability. This observation can be correlated with faster adsorption kinetics of the Fc-fusion protein, and formation of a less incompressible film at the air-liquid interface. The addition of polysorbate 80 (PS80), commonly added to mitigate protein particle formation, led to a surfactant-dominant interface for quiescent conditions and coadsorption of protein and surfactant for the Fc-fusion when exposed to interfacial stress. On the other hand, for the IgG molecule, the surface always remained surfactant dominant. Image analysis demonstrated that PS80 was more effective in mitigating particle formation for the IgG than Fc-fusion. This suggests that a surfactant-dominant interface is necessary to prevent interface-induced protein particle formation. Further, while PS80 is effective in mitigating particle formation in the IgG formulation, it may not be the best choice for other protein modalities.

Understanding the Impact of Combined Hydrodynamic Shear and Interfacial Dilatational Stress, on Interface-Mediated Particle Formation for Monoclonal Antibody Formulations

During biomanufacturing, several unit operations expose solutions of biologics to multiple stresses, such as hydrodynamic shear forces due to fluid flow and interfacial dilatational stresses due to mechanical agitation or bubble collapse. When these stresses individually act on proteins adsorbed to interfaces, it results in an increase in protein particles in the bulk solution, a phenomenon referred to as interface-induced protein particle formation. However, an understanding of the dominant cause, when multiple stresses are acting simultaneously or sequentially, on interface-induced protein particle formation is limited. In this work, we established a unique set-up using a peristaltic pump and a Langmuir-Pockels trough to study the impact of hydrodynamic shear stress due to pumping and interfacial dilatational stress, on protein particle formation. Our experimental results together demonstrate that for protein solutions subjected to various combinations of stress (i.e., interfacial and hydrodynamic stress in different sequences), surface pressure values during adsorption and when subjected to compression/dilatational stresses, showed no change, suggesting that the interfacial properties of the protein film are not impacted by pumping. The concentration of protein particles is an order of magnitude higher when interfacial dilatational stress is applied at the air-liquid interface, compared to solutions that are only subjected to pumping. Furthermore, the order in which these stresses are applied, have a significant impact on the concentration of protein particles measured in the bulk solution. Together, these studies conclude that for biologics exposed to multiple stresses throughout bioprocessing and manufacturing, exposure to air-liquid interfacial dilatational stress is the predominant mechanism impacting protein particle formation at the interface and in the bulk solution.

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.'

Study of Monoclonal Antibody Aggregation at the Air-Liquid Interface under Flow by ATR-FTIR Spectroscopic Imaging

Throughout bioprocessing, transportation, and storage, therapeutic monoclonal antibodies (mAbs) experience stress conditions that may cause protein unfolding and/or chemical modifications. Such structural changes may lead to the formation of aggregates, which reduce mAb potency and may cause harmful immunogenic responses in patients. Therefore, aggregates need to be detected and removed or ideally prevented from forming. Air-liquid interfaces, which arise during various stages of bioprocessing, are one of the stress factors causing mAb aggregation. In this study, the behavior of an immunoglobulin G (IgG) at the air-liquid interface was investigated under flow using macro attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic imaging. This chemically specific imaging technique allows observation of adsorption of IgG to the air-liquid interface and detection of associated secondary structural changes. Chemical images revealed that IgG rapidly accumulated around an injected air bubble under flow at 45 °C; however, no such increase was observed at 25 °C. Analysis of the second derivative spectra of IgG at the air-liquid interface revealed changes in the protein secondary structure associated with increased intermolecular β-sheet content, indicative of aggregated IgG. The addition of 0.01% w/v polysorbate 80 (PS80) reduced the amount of IgG at the air-liquid interface in a static setup at 30 °C; however, this protective effect was lost at 45 °C. These results suggest that the presence of air-liquid interfaces under flow may be detrimental to mAb stability at elevated temperatures and demonstrate the power of ATR-FTIR spectroscopic imaging for studying the structural integrity of mAbs under bioprocessing conditions.

Using Passive Microrheology to Measure the Evolution of the Rheological Properties of NIST mAb Formulations during Adsorption to the Air-Water Interface

The development of novel protein-based therapeutics, such as monoclonal antibodies (mAbs), is often limited due to challenges associated with maintaining the stability of these formulations during manufacturing, storage, and clinical administration. An undesirable consequence of the instability of protein therapeutics is the formation of protein particles. MAbs can adsorb to interfaces and have the potential to undergo partial unfolding as well as to form viscoelastic gels. Further, the viscoelastic properties may be correlated with their aggregation potential. In this work, a passive microrheology technique was used to correlate the evolution of surface adsorption with the evolution of surface rheology of the National Institute of Standards and Technology (NIST) mAb reference material (NIST mAb) and interface-induced subvisible protein particle formation. The evolution of the surface adsorption and interfacial shear rheological properties of the NIST mAb was recorded in four formulation conditions: two different buffers (histidine vs phosphate-buffered saline) and two different pHs (6.0 and 7.6). Our results together demonstrate the existence of multiple stages for both surface adsorption and surface rheology, characterized by an induction period that appears to be purely viscous, followed by a sharp increase in protein molecules at the interface when the film rheology is viscoelastic and ultimately a slowdown in the surface adsorption that corresponds to the formation of solid-like or glassy films at the interface. When the transitions between the different stages occurred, they were dependent on the buffer/pH of the formulations. The onset of these transitions can also be correlated to the number of protein particles formed at the interface. Finally, the addition of polysorbate 80, an FDA-approved surfactant used to mitigate protein particle formation, led to the interface being surfactant-dominated, and the resulting interface remained purely viscous.

Correlating Surface Activity with Interface-Induced Aggregation in a High-Concentration mAb Solution

Interface-induced aggregation resulting in protein particle formation is an issue during the manufacturing and storage of protein-based therapeutics. High-concentration formulations of therapeutic proteins are even more prone to protein particle formation due to increased protein-protein interactions. However, the dependence of interface-induced protein particle formation on bulk protein concentration is not understood. Furthermore, the formation of protein particles is often mitigated by the addition of polysorbate-based surfactants. However, the details of surfactant-protein interactions that prevent protein particle formation at high concentrations remain unclear. In this work, a tensiometer technique was used to evaluate the surface pressure of an industrially relevant mAb at different bulk concentrations, and in the absence and presence of a polysorbate-based surfactant, polysorbate 20 (PS20). The adsorption kinetics was correlated with subvisible protein particle formation at the air-water interface and in the bulk protein solution using a microflow imaging technique. Our results showed that, in the absence of any surfactant, the number of subvisible particles in the bulk protein solutions increased linearly with mAb concentration, while the number of protein particles measured at the interface showed a logarithmic dependence on bulk protein concentration. In the presence of surfactants above the critical micelle concentration (CMC), our results for low-concentration mAb solutions (10 mg/mL) showed an interface that is surfactant-dominated, and particle characterization results showed that the addition of the surfactant led to reduced particle formation. In contrast, for the highest concentration (170 mg/mL), coadsorption of proteins and surfactants was observed at the air-water interface, even for surfactant formulations above CMC and the surfactant did not mitigate subvisible particle formation. Our results taken together provide evidence that the ratio between the surfactant and mAb molecules is an important consideration when formulating high-concentration mAb therapeutics to prevent unwanted aggregation.

The Effects of Excipients on Freeze-dried Monoclonal Antibody Formulation Degradation and Sub-Visible Particle Formation during Shaking

PURPOSES

We previously reported an unexpected phenomenon that shaking stress could cause more protein degradation in freeze-dried monoclonal antibody (mAb) formulations than liquid ones (J Pharm Sci, 2022, 2134). The main purposes of the present study were to investigate the effects of shaking stress on protein degradation and sub-visible particle (SbVP) formation in freeze-dried mAb formulations, and to analyze the factors influencing protein degradation during production and transportation.

METHODS

The aggregation behavior of mAb-X formulations during production and transportation was simulated by shaking at a rate of 300 rpm at 25°C for 24 h. The contents of particles and monomers were analyzed by micro-flow imaging, dynamic light scattering, size exclusion chromatography, and ultraviolet - visible (UV-Vis) spectroscopy to compare the protective effects of excipients on the aggregation of mAb-X.

RESULTS

Shaking stress could cause protein degradation in freeze-dried mAb-X formulations, while surfactant, appropriate pH, polyol mannitol, and high protein concentration could impact SbVP generation. Water content had little effect on freeze-dried protein degradation during shaking, as far as the water content was controlled in the acceptable range as recommended by mainstream pharmacopoeias (i.e., less than 3%).

CONCLUSIONS

Shaking stress can reduce the physical stability of freeze-dried mAb formulations, and the addition of surfactants, polyol mannitol, and a high protein concentration have protective effects against the degradation of model mAb formulations induced by shaking stress. The experimental results provide new insight for the development of freeze-dried mAb formulations.

Small-angle x-ray scattering investigation of the integration of free fatty acids in polysorbate 20 micelles

A critical quality attribute for liquid formulations is the absence of visible particles. Such particles may form upon polysorbate hydrolysis resulting in release of free fatty acids into solution followed by precipitation. Strategies to avoid this effect are of major interest for the pharmaceutical industry. In this context, we investigated the structural organization of polysorbate micelles alone and upon addition of the fatty acid myristic acid (MA) by small-angle x-ray scattering. Two complementary approaches using a model of polydisperse core-shell ellipsoidal micelles and an ensemble of quasiatomistic micelle structures gave consistent results well describing the experimental data. The small-angle x-ray scattering data reveal polydisperse mixtures of ellipsoidal micelles containing about 22-35 molecules per micelle. The addition of MA at concentrations up to 100 μg/mL reveals only marginal effects on the scattering data. At the same time, addition of high amounts of MA (>500 μg/mL) increases the average sizes of the micelles indicating that MA penetrates into the surfactant micelles. These results together with molecular modeling shed light on the polysorbate contribution to fatty acid solubilization preventing or delaying fatty acid particle formation.

Not the Usual Suspects: Alternative Surfactants for Biopharmaceuticals

Therapeutically relevant proteins naturally adsorb to interfaces, causing aggregation which in turn potentially leads to numerous adverse consequences such as loss of activity or unwanted immunogenic reactions. Surfactants are ubiquitously used in biotherapeutics drug development to oppose interfacial stress, yet, the choice of the surfactant is extremely limited: to date, only polysorbates (PS20/80) and poloxamer 188 are used in commercial products. However, both surfactant families suffer from severe degradation and impurities of the raw material, which frequently increases the risk of particle generation, chemical protein degradation, and potential adverse immune reactions. Herein, we assessed a total of 40 suitable alternative surfactant candidates and subsequently performed a selection through a three-gate screening process employing four protein modalities encompassing six different formulations. The screening is based on short-term agitation-induced aggregation studies coupled to particle analysis and surface tension characterization, followed by long-term quiescence stability studies connected to protein purity measurements and particle analysis. The study concludes by assessing the surfactant's chemical and enzymatic degradation propensity. The candidates emerging from the screening are de novo α-tocopherol-derivatives named VEDG-2.2 and VEDS, produced ad hoc for this study. They display protein stabilization potential comparable or better than polysorbates together with an increased resistance to chemical and enzymatic degradation, thus representing valuable alternative surfactants for biotherapeutics.

Comparison of Protein Particle Formation in IgG1 mAbs Formulated with PS20 Vs. PS80 When Subjected to Interfacial Dilatational Stress

Polysorbates (PS) are nonionic surfactants that are commonly included in protein formulations to mitigate the formation of interfacial stress-induced protein particles and thus increase their long-term storage stability. Nonetheless, factors that dictate the efficiency of different polysorbates in mitigating protein particle formation, especially during the application of interfacial stresses, are often ill defined. Here, we used a Langmuir trough to determine the surface activity of two IgG1 monoclonal antibodies formulated with two different polysorbates (PS20 and PS80) when subjected to interfacial dilatational stress. Interfacial properties of these formulations were then correlated with characterization of subvisible protein particles measured by micro-flow imaging (MFI). Both mAbs, when formulated in PS20, demonstrate faster adsorption kinetics and higher surface activity compared to PS80 or surfactant-free formulations. Compression/expansion results suggest that when exposed to interfacial dilatational stresses, both mAb/PS20 formulations display interfacial properties of PS20 alone. In contrast, interfacial properties of both mAb/PS80 formulations suggest mAbs and PS80 are co-adsorbed to the air-water interface. Further, MFI analysis of the interface and the bulk solution confirms that PS20 is more effective than PS80 at mitigating the formation of larger particles in the bulk solution in both mAbs. Concomitantly, the efficiency of PS to prevent interface-induced protein particle formation also depended on the protein's inherent tendency to aggregate at a surfactant-free interface. Together, the studies presented here highlight the importance of determining the interfacial properties of mAbs, surfactants, and their combinations to make informed formulation decisions about the choice of surfactant.

End-to-End Approach to Surfactant Selection, Risk Mitigation, and Control Strategies for Protein-Based Therapeutics

A survey performed by the AAPS Drug Product Handling community revealed a general, mostly consensus, approach to the strategy for the selection of surfactant type and level for biopharmaceutical products. Discussing and building on the survey results, this article describes the common approach for surfactant selection and control strategy for protein-based therapeutics and focuses on key studies, common issues, mitigations, and rationale. Where relevant, each section is prefaced by survey responses from the 22 anonymized respondents. The article format consists of an overview of surfactant stabilization, followed by a strategy for the selection of surfactant level, and then discussions regarding risk identification, mitigation, and control strategy. Since surfactants that are commonly used in biologic formulations are known to undergo various forms of degradation, an effective control strategy for the chosen surfactant focuses on understanding and controlling the design space of the surfactant material attributes to ensure that the desired material quality is used consistently in DS/DP manufacturing. The material attributes of a surfactant added in the final DP formulation can influence DP performance (e.g., protein stability). Mitigation strategies are described that encompass risks from host cell proteins (HCP), DS/DP manufacturing processes, long-term storage, as well as during in-use conditions.

Developability Assessments of Monoclonal Antibody Candidates to Minimize Aggregation During Large-Scale Ultrafiltration and Diafiltration (UF-DF) Processing

Therapeutic proteins are subjected to a variety of stresses during manufacturing, storage or administration, that often lead to undesired protein aggregation and particle formation. Ultrafiltration-diafiltration (UF-DF) processing of monoclonal antibodies (mAbs) is one such manufacturing step that has been shown to result in such physical degradation. In this work, we explore the use of different analytical techniques and lab-scale setups as methodologies to predict and rank-order the aggregation potential of four different mAbs during large-scale UF-DF processing. In the first part of the study, a suite of biophysical techniques was applied to assess differences in their inherent bulk protein properties including conformational and colloidal stability in a PBS buffer. Additionally, the inherent interfacial properties of these mAbs in PBS were measured using a Langmuir trough technique. In the next part of the study, several different scale-down lab models were evaluated including a lab bench-scale UF-DF setup, mechanical stress (shaking/stirring) studies in vials, and application of interfacial dilatational stress using a Langmuir trough to assess protein particle formation in different UF-DF processing buffers. Taken together, our results demonstrate the ability of a Langmuir-trough methodology to accurately predict the mAb instability profile observed during large scale UF-DF processing.

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.

Assessment of Cavitation Intensity in Accelerating Syringes of Spring-Driven Autoinjectors

PURPOSE

Cavitation is an undesired phenomenon that may occur in certain types of autoinjectors (AIs). Cavitation happens because of rapid changes of pressure in a liquid, leading to the formation of small vapor-filled cavities, which upon collapsing, can generate an intense shock wave that may damage the device container and the protein drug molecules. Cavitation occurs in the AI because of the syringe-drug relative displacement as a result of the syringe's sudden acceleration during needle insertion and the ensuing pressure drop at the bottom of the container. Therefore, it's crucial to analyze the potential effect of cavitation on AI. The goal of the current study is to investigate the effects of syringe and AI design parameters such as air gap size, syringe filling volume, fluid viscosity, and drive spring force (syringe acceleration) on the risk and severity of cavitation.

METHODS

A model autoinjector platform is built to record the syringe and cavitation dynamics which we use to estimate the cavitation intensity in terms of extension rate and to study the effects of design parameters on the severity of cavitation.

RESULTS

Our results show the generation of an intense shock wave and a high extension rate upon cavitation collapse. The induced extension rate increases with syringe acceleration and filling volume and decreases with viscosity and air gap size.

CONCLUSION

The most severe cavitation occurred in an AI device with the larger drive spring force and the syringe of a smaller air gap size filled with a less viscous fluid and a larger filling volume.

Polysorbate 80-Induced Anaphylactoid Reaction and the Effects on Cardiovascular Function: Dose Threshold and Species Comparison

Polysorbate 80 (PS80) is commonly used in pre-clinical formulations. The dose threshold for cardiovascular (CV) changes and hypersensitivity reaction in the dog was assessed and compared to other species. PS80 was administered by intravenous (IV) bolus (.5, 1 mg/kg), IV infusion (.3, .5, 1, 3 mg/kg), subcutaneous (SC) injection (5, 10, 15 mg/kg) and oral gavage (10 mg/kg) to dogs with CV monitoring. Monkeys and minipigs received PS80 by IV infusion at 3 mg/kg. Plasma histamine concentration was measured following PS80 IV infusion and with diphenhydramine pre-treatment in dogs only. In dogs, PS80 was not associated with CV changes at doses up to 15 mg/kg SC and 10 mg/kg oral, but decreased blood pressure and increased heart rate with IV bolus at ≥ .5 mg/kg and IV infusion at ≥ 1.0 mg/kg and decreased body temperature with IV infusion at 3 mg/kg was observed. Transient edema and erythema were noted with all administration routes, in all three species including doses that were devoid of CV effects. In monkeys and minipigs, PS80 did not induce CV, cutaneous or histamine concentration changes. These results suggest that mild, transient skin changes occur following PS80 administration at doses that are not associated with CV effects in the dogs. In dogs, the cardiovascular effect threshold was <.5 mg/kg for IV bolus, .3 mg/kg for IV infusion, 15 mg/kg for SC injection, and 10 mg/kg for oral administration. Monkey and minipig were refractory to PS80-induced histamine release at 3 mg/kg by IV infusion over 15 minutes.

Industry perspective on the use and characterization of polysorbates for biopharmaceutical products Part 1: Survey report on current state and common practices for handling and control of polysorbates

Polysorbates (PS) are widely used as a stabilizer in biopharmaceutical products. Industry practices on various aspects of PS are presented in this part 1 survey report based on a confidential survey and following discussions by 16 globally acting major biotechnology companies. The current practice and use of PS during manufacture across their global manufacturing sites are covered in addition to aspects like current understanding of the (in)stability of PS, the routine QC testing and control of PS, and selected regulatory aspects of PS. The results of the survey and extensive cross-company discussions are put into relation with currently available scientific literature. Part 2 of the survey report (upcoming) will focus on understanding, monitoring, prediction, and mitigation of PS degradation pathways to develop an effective control strategy.

Evaluating the combined impact of temperature and application of interfacial dilatational stresses on surface-mediated protein particle formation in monoclonal antibody formulations

Formation of submicron and subvisible protein particles (0.1-100 μm) present a major obstacle during processing and storage of therapeutic proteins. While protein aggregation resulting in particle formation is well-understood in bulk solution, the mechanisms of aggregation due to interfacial stresses is less understood. Particularly, in this study, we focus on understanding the combined effect of temperature and application of interfacial dilatational stresses, on interface-induced protein particle formation, using two industrially relevant monoclonal antibodies (mAbs). The surface activity of Molecule C (MC) and Molecule B (MB) were measured at room temperature (RT) and 4°C in the absence and presence of interfacial dilatation stress using a Langmuir trough. These results were correlated with Micro-flow imaging (MFI) to characterize formation of subvisible protein particles at the interface and in the bulk solution. Our results show that the surface activity for both proteins is temperature dependent. However, the extent of the impact of temperature on the mechanical properties of the monomolecular protein films when subjected to dilatational stresses is protein dependent. Protein particle analysis provided evidence that protein particles formed in bulk solution originate at the interface and are dependent on both application of thermal stresses and interfacial dilatational stresses. In the absence of any interfacial stresses, more and larger protein particles were formed at the interface at RT than at 4°C. When mAb formulations are subjected to interfacial dilatational stresses, protein particle formation in bulk solution was found to be temperature dependent. Together our results validate that mAb solutions maintained at 4°C can lower the surface activity of proteins and reduce their tendency to form interface-induced protein particles both in the absence and presence of interfacial dilatational stresses.

Fatty Acids Can Induce the Formation of Proteinaceous Particles in Monoclonal Antibody Formulations

The presence of subvisible or visible particles in mAb formulations can pose significant challenges to pharmaceutical development as it can lead to reduced shelf life, batch rejection, and recalls. Among all type of particles, proteinaceous particles are the most concerning due to their potential role in immunogenicity. Nevertheless, the underlying mechanism for protein particle formation remains poorly understood. Past research highlighted the importance of interfaces and mechanical agitation in causing protein particle formation. Current research suggests that fatty acids, as impurities present in excipients or as a result of polysorbate degradation, can also induce protein assembly and promote particle formation. In this work, we assessed oleic and lauric acid for their impact on particle formation as each represents the main hydrolysis product of PS80 or PS20, respectively. It was found that co-existence of either fatty acids with 10 mg/mL mAb A can cause protein particles, with a similar morphology to those observed previously in mAb formulations. FTIR spectra showed that the particles are proteinaceous, heterogeneous in its composition, but contain corresponding fatty acids. Interestingly, it was found that oleic acid is significantly more effective in causing protein particles than lauric acid in these experiments. This suggests that PS20 containing formulations might have a lower likelihood to have protein particles compared to PS80 containing mAb formulations if hydrolysis of polysorbate were to occur. Lastly, the presence of 0.01% polysorbate in the mAb A formulation was able to fully mitigate the effect of fatty acids and reduce the protein particles significantly, suggesting a potential mechanism where interfacial action is involved. The present study can help to understand the root cause for protein particles in a mAb formulation where fatty acids are introduced because of polysorbate hydrolysis. With further work, it will help to shed light into product control strategy as well as design approaches for robust mAb products.

Advancing Structure Characterization of PS-80 by Charge-Reduced Mass Spectrometry and Software-Assisted Composition Analysis

The commercially available Polysorbate 80 (PS-80) is a highly heterogeneous product. It is a complex and structurally diverse mixture consisting of polymeric species containing polyoxyethylenes (POEs), fatty acid esters, with/or without a carbohydrate core. The core is primarily sorbitan, with some isosorbide and sorbitol. Depending on the sources of fatty acids and the degrees of esterification, multiple combinations of fatty acid esters are commonly observed. A number of POE intermediates, such as polyoxyethylene glycols, POE-sorbitans, POE-isosorbides, and an array of fatty acid esters from these intermediates remain in the raw material as well. The complex composition of PS-80 is difficult to control and poses a significant characterization challenge for its use in the pharmaceutical industry. Here, we present a novel solution for PS-80 characterization using ultra high-performance liquid chromatography coupled with charge-reduction high resolution mass spectrometry. Post column co-infusion of triethylamine focused the signal into mainly singly charged molecular ions and reduced the extent of in-source fragmentation, resulting in a simpler ion map and enhanced measurement of PS-80 species. The data processing workflow is designed to programmatically identify PS-80 component classes and reduce the burden of manually analyzing complex MS data. The 2-dimensional graphical representation of the data helps visualize these features. Together, these innovative methodologies enabled us to analyze components in PS-80 with unprecedented detail and shall be a useful tool to study formulation and stability of pharmaceutical preparations. The power of this approach was demonstrated by comparing the composition of PS-80 obtained from different vendors.