An in-depth examination of fatty acid solubility limits in biotherapeutic protein formulations containing polysorbate 20 and polysorbate 80

A comparison of Polysorbates and Alternative Surfactants for Interfacial Stress Protection and Mitigation of Fatty Acid Particle Formation in the Presence of an Esterase

The hydrolysis of polysorbate surfactants in large molecule drug product formulations caused by residual host cell proteins presents numerous stability concerns for pharmaceuticals. The fatty acids (FA) released by polysorbate hydrolysis can nucleate into particulates or challenge the conformational stability of the proteinaceous active pharmaceutical ingredient (API). The loss of intact polysorbate may also leave the Drug Product (DP) vulnerable to interfacial stresses. Polysorbate 20 and 80 are available in several different quality grades (Multi-compendial, Super Refined, Pure Lauric Acid (PLA)/Pure Oleic Acid (POA)). All variations of polysorbate as well as three alternative surfactants: Brij L23, Brij O20 and Poloxamer 188 were compared for their ability to protect against air-water interfacial stresses as well as their risk for developing particulates when in the presence of lipoprotein lipase (LPL) (Pseudomonas). Results show a meaningful difference in the timing and morphology of FA particle formation depending on the type of polysorbate used. All grades of polysorbate, while susceptible to hydrolysis, still offered sufficient protection to interfacial stresses, even when hydrolyzed to concentrations as low as 0.005 % (w/v). Alternative surfactants that lack an ester bond were resistant to lipase degradation and showed good protection against shaking stress.

High-Throughput Fluorometric Assay For Quantifying Polysorbate In Biopharmaceutical Products Using Micelle Activated Fluorescence Probe N-Phenyl-1-Naphthylamine

PURPOSE

Polysorbates are among the most used surfactants in biopharmaceutical products containing proteins. Our work aims to develop a high-throughput fluorometric assay to further diversify the analytical toolbox for quantification of PSs.

METHOD

The assay leverages the micelle activated fluorescence signal from N-Phenyl-1-Naphthylamine (NPN). The development and optimization of assay parameters were guided by the pre-defined analytical target profile. Furthermore, NMR was used to probe the interaction between protein, PS80 and NPN in the measurement system and understand protein interference.

RESULTS

All assay parameters including excitation and emission wavelengths, standard curve, NPN concentration, and incubation time have been optimized and adapted to a microplate format, making it compatible with automated solutions that will be pursued in the near future to drive consistency and efficiency in our workflows. The specificity, accuracy, and precision of the assay have been demonstrated through a case study. Furthermore, NMR results provided additional insight into the change of the interaction dynamics between PS80 and NPN as the protein concentration increases. The results indicate minimal interaction between the protein and PS80 at lower concentration. However, when the concentration exceeds 75 mg/mL, there is a significant interaction between the protein and PS-80 micelle and monomer.

CONCLUSION

A high-throughput fluorometric assay has been developed for quantification of polysorbates in biopharmaceutical samples including in-process samples, drug substance and drug product. The assay reported herein could serve as a powerful analytical tool for polysorbate quantification and control, complementing the widely used liquid chromatography with charged aerosol detection method.

Stress-mediated polysorbate 20 degradation and its potential impact on therapeutic proteins

PURPOSE

Polysorbates are the most commonly used surfactants in formulations to stabilize therapeutic proteins against interfacial stresses. Polysorbates can undergo oxidative or enzyme-mediated hydrolytic degradation to produce free fatty acids (FFAs) and subvisible particles in formulations. To determine which product related variables contribute to PS20 degradation, we investigated the effects of storage temperature, formulation, pH, presence of hydrolytic enzymes, and specific fatty acid composition on different grades of PS20 in relation to their PS20 degradation profile and consequently the quality of protein drug products.

METHODS

Bevacizumab and T-DM1 were reformulated in the freshly prepared therapeutic protein formulations containing either compendial PS20 or non-compendial PS20 with high % lauric acid and spiked with exogenous esterase or lipase. The release of FFAs and formation of particles were monitored at 4°C and 37°C. Protein quality was assessed for secondary structures, purity, and biological activity.

RESULTS

Hydrolytic release of FFAs and formation of subvisible particles were found to be dependent on grades of PS20, types of enzymes used, incubation temperature, and pH. Esterase- or lipase-mediated degradation of PS20 and formation of subvisible particles in drug formulation showed no significant impact on the biological activity and stability of therapeutic proteins against degradation or aggregation.

CONCLUSIONS

Our study suggests that degradation of PS20 and formation of FFA particles depend on the fatty acid composition of PS20, types of hydrolytic enzymes, pH, and temperature. The presence of FFA subvisible particles showed no significant impact on the purity and biological activity of the therapeutic proteins under the tested conditions.

Intranasal delivery of thin-film freeze-dried monoclonal antibodies using a powder nasal spray system

Monoclonal antibodies (mAbs) administered intranasally as dry powders can be potentially applied for the treatment or pre-exposure prevention of viral infections in the upper respiratory tract. However, a method to transform the mAbs from liquid to dry powders suitable for intranasal administration and a device that can spray the dry powders to the desired region of the nasal cavity are needed to fully realize the potentials of the mAbs. Herein, we report that thin-film freeze-dried mAb powders can be sprayed into the posterior nasal cavity using Aptar Pharma's Unidose (UDS) Powder Nasal Spray System. AUG-3387, a human-derived mAb that neutralizes the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was used in the present study. First, we prepared thin-film freeze-dried AUG-3387 powders (i.e., TFF AUG-3387 powders) from liquid formulations containing different levels of mAbs. The TFF AUG-3387 powder with the highest solid content (i.e., TFF AUG-3387C) was then chosen for further characterization, including the evaluation of the plume geometry, spray pattern, and particle size distribution after the powder was sprayed using the UDS Powder Nasal Spray. Finally, the deposition patterns of the TFF AUG-3387C powder sprayed using the UDS Powder delivery system were studied using 3D-printed nasal replica casts based on the CT scans of an adult and a child. It is concluded that it is feasible to intranasally deliver mAbs as dry powders by transforming the mAbs into dry powders using thin-film freeze-drying and then spraying the powder using a powder nasal spray system.

Monitoring polysorbate 80 degradation in protein solutions using Total Holographic Characterization

The degradation of polysorbate surfactants can limit the shelf life of biologic pharmaceutical products. Polysorbate is susceptible to degradation via either oxidation or hydrolysis pathways which releases free fatty acids (FFA) and other complex polymers. Degradants from Polysorbate 80 (PS80) can form particles and impact drug product quality. PS80 degradation products appear at low concentrations, and their refractive indexes are similar to that of the buffer, making them very challenging to detect. Furthermore, aggregates of FFA are similar in size and refractive index to protein aggregates adding complexity to characterizing these particles in protein solutions. Total Holographic Characterization (THC) is used in this work to characterize FFA particles of oleic acid and linoleic acid, the two most common degradation products of PS80. We demonstrate that the characteristic THC profile of the FFA oleic acid emulsion droplets can be used to monitor the degradation of PS80. THC can detect oleic acid at a concentration down to less than 100 ng/mL. Using the characteristic THC signal of oleic acid as a marker, the degradation of PS80 in protein solutions can be monitored quantitatively even in the presence of other contaminants of the same size, including silicone oil emulsion droplets and protein aggregates.

Illuminating a biologics development challenge: systematic characterization of CHO cell-derived hydrolases identified in monoclonal antibody formulations

Monoclonal antibodies (mAb) and other biological drugs are affected by enzymatic polysorbate (PS) degradation that reduces product stability and jeopardizes the supply of innovative medicines. PS represents a critical surfactant stabilizing the active pharmaceutical ingredients, which are produced by recombinant Chinese hamster ovary (CHO) cell lines. While the list of potential PS-degrading CHO host cell proteins (HCPs) has grown over the years, tangible data on industrially relevant HCPs are still scarce. By means of a highly sensitive liquid chromatography-tandem mass spectrometry method, we investigated seven different mAb products, resulting in the identification of 12 potentially PS-degrading hydrolases, including the strongly PS-degrading lipoprotein lipase (LPL). Using an LPL knockout CHO host cell line, we were able to stably overexpress and purify the remaining candidate hydrolases through orthogonal affinity chromatography methods, enabling their detailed functional characterization. Applying a PS degradation assay, we found nine mostly secreted, PS-active hydrolases with varying hydrolytic activity. All active hydrolases showed a serine-histidine-aspartate/glutamate catalytical triad. Further, we subjected the active hydrolases to pH-screenings and revealed a diverse range of activity optima, which can facilitate the identification of residual hydrolases during bioprocess development. Ultimately, we compiled our dataset in a risk matrix identifying PAF-AH, LIPA, PPT1, and LPLA2 as highly critical hydrolases based on their cellular expression, detection in purified antibodies, active secretion, and PS degradation activity. With this work, we pave the way toward a comprehensive functional characterization of PS-degrading hydrolases and provide a basis for a future reduction of PS degradation in biopharmaceutical drug products.

Enzymatic degradation pattern of polysorbate 20 impacts interfacial properties of monoclonal antibody formulations

Polysorbate 20 (PS20) is widely used to maintain protein stability in biopharmaceutical formulations. However, PS20 is susceptible to hydrolytic degradation catalyzed by trace amounts of residual host cell proteins present in monoclonal antibody (mAb) formulations. The resulting loss of intact surfactant and the presence of PS20 degradation products, such as free fatty acids (FFAs), may impair protein stability. In this study, two hydrolytically-active immobilized lipases, which primarily targeted either monoester or higher-order ester species in PS20, were used to generate partially-degraded PS20. The impact of PS20 degradation pattern on critical micelle concentration (CMC), surface tension, interfacial rheology parameters and agitation protection was assessed. CMC was slightly increased upon monoester degradation, but significantly increased upon higher-order ester degradation. The PS20 degradation pattern also significantly impacted the dynamic surface tension of a mAb formulation, whereas changes in the equilibrium surface tension were mainly caused by the adsorption of FFAs onto the air-water interface. In an agitation protection study, monoester degradation resulted in the formation of soluble mAb aggregates and proteinaceous particles, suggesting that preferential degradation of PS20 monoester species can significantly impair mAb stability. Additional mAbs should be tested in the future to assess the impact of the protein format.

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.

How enzymatic hydrolysis of polysorbate 20 influences colloidal protein stability

Polysorbates (PS) are esters of ethoxylated sorbitol anhydrides of different composition and are widely used surfactants in biologics. PSs are applied to increase protein stability and concomitant shelf-life via shielding against e.g., interfacial stresses. Due to the presence of specific lipolytic host cell protein (HCP) contaminations in the drug substance, PSs can be degraded via enzymatic hydrolysis. Surfactant hydrolysis leads to the formation of degradants, such as free fatty acids that might form fatty acid particles. In addition, PS degradation may reduce surfactant functionality and thus reduce the protection of the active pharmaceutical ingredient (API). Although enzymatic degradation was observed and reported in the last years, less is known about the relationship between certain polysorbate degradation patterns and the increase of mechanical and interfacial stress towards the API. In this study, the impact of specifically hydrolyzed polysorbate 20 (PS20) towards the stabilization of two monoclonal antibodies (mAbs) during accelerated shaking stress conditions was investigated. The results show that a specific enzymatic degradation pattern of PS20 can influence the colloidal stability of biopharmaceutical formulations. Furthermore, the kinetics of the appearance of visual phenomena, opalescence, and particle formation depended on the polysorbate degradation fingerprint as induced via the presence of surrogate enzymes. The current case study shows the importance of focusing on specific polysorbate ester fractions to understand the overall colloidal protein stabilizing effect. The performed study gives first insight into the functional properties of PS and helps to evaluate the impact of PS degradation in the formulation development of biopharmaceuticals in general.

Image Classification of Degraded Polysorbate, Protein and Silicone Oil Sub-Visible Particles Detected by Flow-Imaging Microscopy in Biopharmaceuticals Using a Convolutional Neural Network Model

Degradation of polysorbates in biopharmaceutical formulations can induce the formation of sub-visible particles (SvPs) in the form of free-fatty acids (FFAs) and potentially protein aggregates. Flow-imaging microscopy (FIM) is one of the most common techniques for enumerating and characterizing the SvPs, allowing for collection of image data of the SvPs in the size ranges of two to several hundred micrometers. The vast amounts of data obtained with FIM do not allow for rapid manual characterization by an experienced analyst and can be ambiguous. In this work, we present the application of a custom convolutional neural network (CNN) for classification of SvP images of FFAs, proteinaceous particles and silicon oil droplets, by FIM. The network was then used to predict the composition of artificially pooled test samples of unknown and labeled data with varying compositions. Minor misclassifications were observed between the FFAs and proteinaceous particles, considered tolerable for application to pharmaceutical development. The network is considered to be suitable for fast and robust classification of the most common SvPs found during FIM analysis.

Screening techniques for monitoring the sub-visible particle formation of free fatty acids in biopharmaceuticals

Free fatty acid (FFA) particles that originate from the enzymatic hydrolysis of polysorbate (PS) via co-purified host cell proteins generally appear abruptly in drug products during real-time (long-term) storage. Efforts were taken to understand the kinetics of FFA particle formation, aiming for a mitigation strategy. However, it is rather challenging particularly in the sub-visible particle (SVP) range, due to either the insufficient sensitivity of the analytical techniques used or the interference of the formulation matrices of proteinaceous drug products. In this study, we examined the feasibility of Raman microscopy, backgrounded membrane imaging (BMI) and total holographic characterization (THC) on the detection of FFA sub-visible particles (SVPs). The results indicate that THC is the most sensitive technique to track their occurrence during the course of PS hydrolysis. Moreover, with this technique we are able to distinguish different stages of FFA particle formation in the medium. In addition, a real time stability study of a biopharmaceutical was analyzed, demonstrating the viability of THC to monitor SVPs in a real sample and correlate it to the visible particles (VPs) occurrence.

Development of UPLC-UV-ELSD Method for Fatty Acid Profiling in Polysorbate 80 and Confirmation of the Presence of Conjugated Fatty Acids by Mass Spectrometry, UV Absorbance and Proton Nuclear Magnetic Resonance Spectroscopy

Polysorbate 80 (PS80), a chemical substance composed of sorbitol, ethylene glycol, and fatty acids, is commonly used in pharmaceutical drug products to stabilize formulations. However, recent studies have demonstrated that PS80 may hydrolyze over time and the released free fatty acids (FFAs) may lead to particle formation. Naming conventions of fatty acids in current pharmacopeia and in products' certificates of analysis (CoA) of PS80 do not typically distinguish between isomeric species of fatty acids in PS80. Thus, methods to fully characterize the fatty acid species present in PS80 raw materials are needed to enhance quality control strategies of pharmaceuticals using PS80. Here, extended effort is taken to characterize fatty acids in hydrolyzed PS80 raw materials and elucidate the identities of isomeric fatty acid species. In this work, a method was developed and optimized for separation and detection of fatty acids in alkaline hydrolyzed PS80 raw materials using ultra performance liquid chromatography (UPLC) with ultra-violet (UV) detection and evaporative light scattering detection (ELSD). Fatty acids not specified in the current pharmacopeias were detected in PS80 raw material by the developed LC-UV-ELSD method including conjugated forms of linoleic and linolenic fatty acid species. Their identities were orthogonally confirmed by retention time agreement with analytical standards, accurate mass by high resolution mass spectrometry, UV absorbance, and proton nuclear magnetic resonance spectroscopy. The detected conjugated fatty acids are theoretically more hydrophobic and less soluble than their unconjugated counterparts and may increase the propensity of PS80 to form particles upon hydrolysis. This work highlights the need for better quality control of PS80 raw material, as it may eventually play a critical role in product quality of therapeutic proteins.

Study of Oncolytic Virus Preservation and Formulation

In recent years, oncolytic viruses (OVs) have emerged as an effective means of treating cancer. OVs have multiple oncotherapeutic functions including specifically infecting and lysing tumor cells, initiating immune cell death, attacking and destroying tumor angiogenesis and triggering a broad bystander effect. Oncolytic viruses have been used in clinical trials and clinical treatment as drugs for cancer therapy, and as a result, oncolytic viruses are required to have long-term storage stability for clinical use. In the clinical application of oncolytic viruses, formulation design plays a decisive role in the stability of the virus. Therefore, this paper reviews the degradation factors and their degradation mechanisms (pH, thermal stress, freeze-thaw damage, surface adsorption, oxidation, etc.) faced by oncolytic viruses during storage, and it discusses how to rationally add excipients for the degradation mechanisms to achieve the purpose of maintaining the long-term stability of oncolytic viral activity. Finally, the formulation strategies for the long-term formulation stability of oncolytic viruses are discussed in terms of buffers, permeation agents, cryoprotectants, surfactants, free radical scavengers, and bulking agent based on virus degradation mechanisms.

Characterization of Recombinantly-Expressed Hydrolytic Enzymes from Chinese Hamster Ovary Cells: Identification of Host Cell Proteins that Degrade Polysorbate

Enzymatic hydrolysis of polysorbate in drug products is a major challenge for the biopharmaceutical industry. Polysorbate hydrolysis caused by host cell proteins (HCPs) co-purified during bioprocessing can reduce the protective effects of the surfactant for the active pharmaceutical ingredient and cause the accumulation of low-solubility degradation products over the long-term storage. The identities of such HCPs are elusive due to their extremely low concentrations after the efficient purification processes of most biopharmaceuticals. In this work, 20 enzymes-selected for their known or putative hydrolytic activity and potential to degrade polysorbate-were recombinantly expressed, purified, and characterized via orthogonal methods. First, these recombinant HCPs were assessed for hydrolytic activity against a fluorogenic esterase substrate in a recently-developed, high-throughput assay. Second, these HCPs were screened for hydrolytic activity against polysorbate in a representative mAb formulation. Third, HCPs that displayed hydrolytic activities in the first two assays were subjected to more detailed characterization of their enzyme kinetics against polysorbates. Finally, these HCPs were evaluated for substrate specificity towards different sub-species of polysorbates. This work provides critical new insights for targeted LC-MS/MS approaches for identification of relevant polysorbate-degrading enzymes and supports improvements to remove such HCPs, including knockouts or targeted removal during purification.

Formulation mitigations for particle formation induced by enzymatic hydrolysis of polysorbate 20 in protein-based drug products: insights from a full-factorial longitudinal study

Hydrolytic degradation of the polysorbate 20 (PS20) surfactant in protein-based liquid formulations releases free fatty acids (FFAs), which can accumulate to form particles in drug products during real-time (long-term) storage. To identify formulation conditions that mitigate the risk of particle formation, we conducted a longitudinal study using purified recombinant monoclonal antibody (mAb) formulated in 24 conditions. In this real-time stability study at 5 °C, three key formulation parameters—mAb concentration, initial PS20 concentration, and pH—were varied across representative ranges in a full-factorial design. A longitudinal regression analysis was used to evaluate the effects of these parameters and their interactions on PS20 degradation (via measurements of PS20, FFAs, and PS20 ester distribution) and on particle formation (via visible particle observations and subvisible particle counts). The time-dependent onset of visible particles trended with the rise in subvisible particle counts and FFA levels and fall in PS20 concentration. In the ranges studied here, lower mAb concentration and higher initial PS20 concentration delayed the onset of particles, whereas pH had a negligible effect. These observations were consistent with the general trends predicted by our previously published FFA solubility model. Taken together, these findings highlight the complex relationships between formulation parameters, PS20 degradation, and particle formation.

Industry Perspective on the Use and Characterization of Polysorbates for Biopharmaceutical Products Part 2: Survey Report on Control Strategy Preparing for the Future

Polysorbate (PS) 20 and 80 are the main surfactants used to stabilize biopharmaceutical products. Industry practices on various aspects of PS based on a confidential survey and following discussions by 16 globally acting major biotechnology companies is presented in two publications. Part 1 summarizes the current practice and use of PS during manufacture 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.¹ The current part 2 of the survey focusses on understanding, monitoring, prediction, and mitigation of PS degradation pathways in order to propose an effective control strategy. The results of the survey and extensive cross-company discussions are put into relation with currently available scientific literature.

Poloxamer 188 as surfactant in biological formulations - An alternative for polysorbate 20/80?

Surfactants are used to stabilize biologics. Particularly, polysorbates (Tween® 20 and Tween® 80) dominate the group of surfactants in protein and especially antibody drug products. Since decades drug developers rely on the ethoxylated sorbitan fatty acid ester mixtures to stabilize sensitive molecules such as proteins. Reasons are (i) excellent stabilizing properties, and (ii) well recognized safety and tolerability profile of these polysorbates in humans, especially for parenteral applications. However, over the past decade concerns regarding the stability of these two polysorbates were raised. The search of alternatives with preferably less reservations concerning degradation and product quality reducing issues leads, among others, to poloxamer 188 (e.g. Kolliphor® P188), a nonionic triblock-copolymer surfactant. This review sums up our current knowledge related to the characterization and physico-chemical properties of poloxamer 188, its analytics and stability properties for biological formulations. Furthermore, the advantages and disadvantages as a suitable polysorbate-alternative for the stabilization of biologics are discussed.

A Mechanistic Understanding of Monoclonal Antibody Interfacial Protection by Hydrolytically Degraded Polysorbate 20 and 80 under IV Bag Conditions

PURPOSE

Polysorbates (PS) contain polyoxyethylene (POE) sorbitan/isosorbide fatty acid esters that can partially hydrolyze over time in liquid drug products to generate degradants and a remaining intact PS fraction with a modified ester distribution. The degradants are composed of free fatty acids (FFAs) --primarily lauric acid for PS20 and oleic acid for PS80-- and POE head groups. We previously demonstrated that under IV bag agitation conditions, mAb1 (a surface-active IgG4) aggregation increased with increasing amounts of degradants for PS20 but not for PS80. The purpose of this work is to understand the mechanism behind this observation.

METHODS

The surface tension of the remaining intact PS fraction without degradants was modeled and compared with that of enzymatically degraded PS solutions. Next, mAb1 aggregation in saline was measured in the presence of laurate and oleate salts during static storage. Lastly, colloidal and conformational stability of mAb1 in the presence of these salts was investigated through differential scanning fluorimetry and dynamic light scattering under IV bag solution conditions.

RESULTS

The surface tension was primarily influenced by FFAs rather than the modified ester distribution of the remaining intact PS. MAb1 bulk aggregation increased in the presence of laurate but not oleate salts. Both salt types increased the melting temperature of mAb1 indicating FFA-mAb1 interactions. However, only laurate salt increased mAb1 self-association potentially explaining the higher aggregation propensity in its presence.

CONCLUSION

Our results help explain the observed differences between hydrolytically degraded PS20 and PS80 in affecting mAb1 aggregation under IV bag agitation conditions.

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.

Effect of Fatty Acid Composition in Polysorbate 80 on the Stability of Therapeutic Protein Formulations

Purpose

Polysorbate excipients are commonly used as surfactants to stabilize therapeutic proteins in formulations. Degradation of polysorbates could lead to particle formation and instability of the drug formulation. We investigated how the fatty acid composition of polysorbate 80 impacts the degradation profile, particle formation, and product stability under stress conditions.

Methods

Two polysorbate 80-containing therapeutic protein formulations were reformulated with either Polysorbate 80 NF synthesized from a fatty acid mixture that contains mainly oleic acid (≥58%) or a version of polysorbate 80 synthesized with high oleic acid (>98%). Stress conditions, including high temperature and esterase spiking, were applied and changes to both the polysorbate and the therapeutic protein product were investigated for stability, purity, innate immune response and biological activity.

Results

The addition of esterase and storage at 37°C led to significant hydrolysis of the polysorbate and increases in sub-visible particle formation for both polysorbates tested. The fatty acid composition of polysorbate 80 did not directly alter the stability profile of either therapeutic protein as measured by size exclusion chromatography, or significantly impact innate immune response or biological activity. However, formulations with Polysorbate 80 NF showed greater propensity for sub-visible particle formation under stress conditions.

Conclusions

These results suggest that composition of fatty acids in polysorbate 80 may be a promoter for sub-visible particulate formation under the stress conditions tested but may not impact protein aggregation or biological activity.

Assessing the polysorbate degradation fingerprints and kinetics of lipases - how the activity of polysorbate degrading hydrolases is influenced by the assay and assay conditions

Two of the most widely used surfactants to stabilize biologicals against e.g. interfacial stresses are polysorbate 20 (PS20) and polysorbate 80 (PS80). In recent years, numerous cases of hydrolytic polysorbate (PS) degradation in liquid formulations of biopharmaceuticals have been observed. Concomitant with the degradation of PSs, formulated proteins become inherently instable and more susceptible to aggregation. Furthermore, poorly soluble fatty acids (FA) are released from the PSs, which might lead to FA precipitation and the formation of visible and subvisible particles. Therefore, possible particle inducing factors have to be monitored closely. The major root cause of hydrolytic PS degradation in biologicals is the presence of enzymatic active host cell proteins (HCP), like lipases and esterases, which are co-purified with the active pharmaceutical ingredient. Such contaminants can be detected via their hydrolytic activity, either using ester-based substrates or PS itself. However, each approach has its up- and downsides, which makes the comparison of the results from other publications difficult. It was therefore the aim of the present study to investigate the impact of lipase specificities on the assay readouts. This study evaluates three different surrogate (model) lipases with distinctively different degradation kinetics and substrate specificities using specific analytical methods. The analytical panel contains on one hand two lipase activity assays with ester-based substrates, either detecting the release of para-nitrophenol or 4-methylumbelliferone, and on the other hand two PS-based monitoring analyses (fluorescence micelle assay and reverse phase high performance liquid chromatography - charged aerosol detection), which detect hydrolytic "activity" directly in the target substrate. Thereby, strengths and weaknesses of each assay are discussed, and recommendations are made for the respective use cases. Our results show that the determined lipase activities vary not only from assay to assay, but also significantly for the lipase tested, thus showing a different degradation fingerprint in the RP-HPLC-CAD chromatogram. This demonstrates that a comprehensive monitoring approach is essential to assess potential HCP contaminations.

Metal-Induced Fatty Acid Particle Formation Resulting from Hydrolytic Polysorbate Degradation

The occurrence of visible particles over the shelf-life of biopharmaceuticals is considered a potential safety risk for parenteral administration. In many cases, particle formation resulted from the accumulation of fatty acids released by the enzymatic hydrolysis of the polysorbate surfactant by co-purified host cell proteins. However, particle formation can occur before the accumulated fatty acids exceed their expected solubility limit. This early onset of particle formation is driven by nucleation phenomena e.g. the presence of metal cations that promote the formation and growth of fatty acid particles. To further characterize and understand this phenomenon, we assessed the potential of different metal cations to induce fatty acid particle formation using a dynamic light scattering assay. We demonstrated that the presence of trace amounts of multivalent cations, in particular trivalent cations such as aluminum and iron, may act as nucleation seed in the process of particle formation. Finally, we developed a mitigation strategy for metal-induced fatty acid particles that deploys a chelator to reduce the risk of particle formation in biopharmaceutical formulations.

Evaluating a Modified High Purity Polysorbate 20 Designed to Reduce the Risk of Free Fatty Acid Particle Formation

PURPOSE

To evaluate a modified high purity polysorbate 20 (RO HP PS20)-with lower levels of stearate, palmitate and myristate esters than the non-modified HP PS20-as a surfactant in biopharmaceutical drug products (DP). RO HP PS20 was designed to provide functional equivalence as a surfactant while delaying the onset of free fatty acid (FFA) particle formation upon hydrolytic degradation relative to HP PS20.

METHODS

Analytical characterization of RO HP PS20 raw material included fatty acid ester (FAE) distribution, higher order ester (HOE) fraction, FFA levels and trace metals. Functional assessments included 1) vial and intravenous bag agitation; 2) oxidation via a placebo and methionine surrogate study; and 3) hydrolytic PS20 degradation studies to evaluate FFA particle formation with and without metal nucleation.

RESULTS

Interfacial protection and oxidation propensity were comparable between the two polysorbates. Upon hydrolytic degradation, FFA particle onset was delayed in RO HP PS20. The delay was more pronounced when HOEs of PS20 were preferentially degraded. Furthermore, the hydrolytic degradants of RO HP PS20 formed fewer particles in the presence of spiked aluminum.

CONCLUSION

This work highlights the criticality of having tighter control on long chain FAE levels of PS20 to reduce the occurrence of FFA particle formation upon hydrolytic degradation and lower the variability in its onset. By simultaneously meeting compendial PS20 specifications while narrowing the allowable range for each FAE and shifting its composition towards the shorter carbon chain species, RO HP PS20 provides a promising alternative to HP PS20 for biopharmaceutical DPs.

Polysorbate Degradation and Particle Formation in a High Concentration mAb: Formulation Strategies to Minimize Effect of Enzymatic Polysorbate Degradation

Polysorbate (PS) 20 and 80 are the most common surfactants in monoclonal antibody (mAb) drug product (DP) formulations. Residual host cell proteins (HCP) present at extremely low concentrations in DP formulations can maintain enough enzymatic activity to degrade PS surfactants. Over time, the hydrolysis of surfactant causes the accumulation of minimally soluble free fatty acids resulting in precipitation and formation of subvisible and visible particulates. This manuscript summarizes the investigation of a batch of high concentration (>100 mg/mL) mAb DP where subvisible particles formed abruptly after prolonged storage at 5C°. The work also summarizes the effectiveness of different strategies for managing host cell proteins and fatty acid particles. The concentration and fatty acid composition of polysorbates were found to be significant factors in particle development. Solubilizers and alternative surfactants were all shown to be effective means of preventing particle formation. Lipase inhibitors proved to be a simple means to identify the problem but are more difficult to utilize as a solution.

Hydrolytic polysorbate 20 degradation - Sensitive detection of free fatty acids in biopharmaceuticals via UPLC-QDa analytics with isolator column

The enzymatic hydrolysis of polysorbates, e.g. induced by specific host cell proteins in biologics, is a known risk factor regarding the potential particle formation in the product over time. One of the root causes for this observation is an increase in free fatty acids (FA) within the formulation, which indicates the need for convenient monitoring of FA release. This study presents a novel UPLC-QDa based method to evaluate the content of the FAs esterified to polysorbate 20 (PS20) after hydrolysis. The presented method is label-free, i.e. independent of elaborate fluorophore-labeling and able to directly measure the ionized FAs. Furthermore, the method allows the determination of released FAs as percentage of ester bond hydrolysis and as absolute concentration expressed in ng/mL. Additionally, we describe for the first time in FA analytics the application of an isolator column, to remove trace levels of FAs present in the eluents to improve the sensitivity of the method. Lastly, the capabilities of the newly developed method are proven in case studies with three different monoclonal antibodies, which display characteristic FA release patterns in PS20-containing formulations. In summary, we developed a reliable, sensitive method for FA quantification in biologics, which could also be used as a predictive tool, considering FA solubility, regarding the formation of particles.

A Comprehensive Assessment of All-Oleate Polysorbate 80: Free Fatty Acid Particle Formation, Interfacial Protection and Oxidative Degradation

PURPOSE

Enzymatic polysorbate (PS) degradation and resulting free fatty acid (FFA) particles are detrimental to biopharmaceutical drug product (DP) stability. Different types and grades of polysorbate have varying propensity to form FFA particles. This work evaluates the homogenous all-oleate (AO) PS80 alongside heterogeneous PS20 and PS80 grades in terms its propensity to form FFA particles and other important attributes like interfacial protection and oxidation susceptibility.

METHODS

FFA particle formation rates were compared by degrading PS using non-immobilized hydrolases and fast degrading DP formulations. Interfacial protection of monoclonal antibodies (mAbs) was assessed by agitation studies in saline using non-degraded and degraded PS. Several antioxidants were assessed for their ability to mitigate AO PS80 oxidation and subsequent mAb oxidation by a 40°C placebo stability study and a 2, 2'-Azobis (2-amidinopropane) dihydrochloride stress model, respectively.

RESULTS

Visible and subvisible particles were significantly delayed in AO PS80 formulations compared with heterogeneous PS20 and PS80 formulations. Non-degraded AO PS80 was less protective of mAbs against the air-water interface compared with heterogeneous PS20. Interfacial protection by AO PS80 improved upon degradation owing to high surface activity of FFAs. Diethylenetriaminepentaacetic acid (DTPA) completely mitigated AO PS80 oxidation unlike L-methionine and N-Acetyl-DL-Tryptophan. However, DTPA did not mitigate radical mediated mAb oxidation.

CONCLUSION

AO PS80 is a promising alternative to reduce FFA particle formation compared with other PS types and grades. However, limitations observed here---such as lower protection against interfacial stresses and higher propensity for oxidation---need to be considered in assessing the risk/benefit ratio in using AO PS80.