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

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.

Investigation on the Combined Effect of Hydroxypropyl Beta-Cyclodextrin (HPβCD) and Polysorbate in Monoclonal Antibody Formulation

Monoclonal antibodies require careful formulation due to their inherent stability limitations. Polysorbates are commonly used to stabilize mAbs, but they are prone to degradation, which results in unwanted impurities. KLEPTOSE® HPβCD (hydroxypropyl beta-cyclodextrin) has functioned as a stable stabilizer for protein formulations in our previous research. The current study investigates the collaborative impact of combining polysorbates and HPβCD as excipients in protein formulations. The introduction of HPβCD in formulations showed it considerably reduced aggregation in two model proteins, bevacizumab and ipilimumab, following exposure to various stress conditions. The diffusion interaction parameter revealed a reduction in protein-protein interactions by HPβCD. In bevacizumab formulations, the subvisible particle counts per 0.4 mL of samples in commercial formulations vs. formulations containing both HPβCD and polysorbates subjected to distinct stressors were as follows: agitation, 87,308 particles vs. 15,350 particles; light, 25,492 particles vs. 6765 particles; and heat, 1775 particles vs. 460 particles. Isothermal titration calorimetry (ITC) measurement indicated a weak interaction between PS 80 and HPβCD, with a KD value of 74.7 ± 7.5 µM and binding sites of 5 × 10-3. Surface tension measurements illustrated that HPβCD enhanced the surface activity of polysorbates. The study suggests that combining these excipients can improve mAb stability in formulations, offering an alternative for the biopharmaceutical industry.

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.

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.

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.

All-in-one stability indicating polysorbate 20 degradation root-cause analytics via UPLC-QDa

Polysorbates (PS) are the most frequently used surfactants to stabilize biologicals. Ironically, these excellent stabilizing non-ionic surfactants have inherent structural properties, which lead to instabilities of their own. Such PS degradation can be triggered by multiple root-causes, like chemical and enzymatic hydrolysis or oxidative degradation. This can on the one hand reduce the concentration of surface-active PS and on the other hand lead to the formation of unfavorable degradants, like poorly soluble free fatty acids (FFA), which may phase separate and form visible FFA particles. Due to the potential criticality of PS degradation in biopharmaceutical formulations, various analytics have been established in recent years not only to monitor the PS content but also to evaluate specific PS markers and crucial degradants. However, in most cases sample preparations and several analytical assays have to be conducted to obtain a comprehensive picture of potential PS degradation root-causes. Here we show a novel approach for PS degradation UPLC-QDa based root-cause analytics, which utilizes previously established analytics for (i) most relevant polysorbate 20 (PS20) esters, (ii) PS20 free fatty acids and (iii) a newly developed method for the evaluation of PS20 specific oxidation markers. Thereby, this triad of analytical methods uses the same sample preparation and detector, which reduces the overall necessary effort, time investment and sample volume. Furthermore, the innovative PS20 oxidation marker method allows to quantify specific concentrations of the determined markers by external calibration and possible perception of oxidative degradation processes prior to relevant losses of PS20 esters, which could serve as an early indication during formulation development. The applicability of this method set was verified using several PS20 containing stress samples, which cover the most relevant root-causes, including acidic and alkaline hydrolysis, enzyme mediated hydrolysis, oxidative AAPH stress and Fe2+/H2O2 mediated degradation as well as autoxidation via long-term storage at elevated temperatures. Overall, this analytical setup has shown to deliver in-depth data about PS20 degradation, which can be used to narrow down the causative stress without the necessity of fundamentally different methods. Therefore, it can be seen as all-in-one solution during sometimes troublesome development of biopharmaceutical formulations, that supports the elucidation of the PS degradation mechanism(s) and thus establish mitigation strategies.

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.

Evaluation of the In-Use Stability of Monoclonal Antibody IV Admixtures Prepared from Drug Products Containing Polysorbate 20 Degraded by Host-Cell Lipases

Host-cell lipases can be present in monoclonal antibody drug products and can degrade polysorbates present in the formulations as stabilizers. We hypothesized that the in-use stability of the IV admixture prepared from such a drug product might be impacted by decreasing levels of polysorbate 20. Host-cell lipase activity has, in fact, been observed during development of one of our therapeutic monoclonal antibody drug products. Throughout the course of the product shelf life, polysorbate 20 levels decreased but no other quality attributes of the drug product were impacted. An experimental approach was developed to simulate how the prepared IV admixture in-use stability is affected as polysorbate 20 concentration in the drug product decreased over the shelf life, and from that a minimum level of polysorbate 20 required in the drug product was determined to estimate the in-use stability of the IV admixture as the polysorbate 20 in the drug product degrades. The results indicate that although the observed degradation of polysorbate 20 does not affect quality attributes of this drug product, in-use stability of the IV admixture as a function of polysorbate degradation can be impacted and should be assessed to ensure sufficient quality.

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.

Application of Formulation Principles to Stability Issues Encountered During Processing, Manufacturing, and Storage of Drug Substance and Drug Product Protein Therapeutics

The field of formulation and stabilization of protein therapeutics has become rather extensive. However, most of the focus has been on stabilization of the final drug product. Yet, proteins experience stress and degradation through the manufacturing process, starting with fermentaition. This review describes how formulation principles can be applied to stabilize biopharmaceutical proteins during bioprocessing and manufacturing, considering each unit operation involved in prepration of the drug substance. In addition, the impact of the container on stabilty is discussed as well.

Comparative Stability Study of Polysorbate 20 and Polysorbate 80 Related to Oxidative Degradation

The surfactants polysorbate 20 (PS20) and polysorbate 80 (PS80) are utilized to stabilize protein drugs. However, concerns have been raised regarding the degradation of PSs in biologics and the potential impact on product quality. Oxidation has been identified as a prevalent degradation mechanism under pharmaceutically relevant conditions. So far, a systematic stability comparison of both PSs under pharmaceutically relevant conditions has not been conducted and little is known about the dependence of oxidation on PS concentration. Here, we conducted a comparative stability study to investigate (i) the different oxidative degradation propensities between PS20 and PS80 and (ii) the impact of PS concentration on oxidative degradation. PS20 and PS80 in concentrations ranging from 0.1 mg⋅mL-1 to raw material were stored at 5, 25, and 40 °C for 48 weeks in acetate buffer pH 5.5 and water, respectively. We observed a temperature-dependent oxidative degradation of the PSs with strong (40 °C), moderate (25 °C), and weak/no degradation (5 °C). Especially at elevated temperatures such as 40 °C, fast oxidative PS degradation processes were detected. In this case study, a stronger degradation and earlier onset of oxidation was observed for PS80 in comparison to PS20, detected via the fluorescence micelle assay. Additionally, degradation was found to be strongly dependent on PS concentration, with significantly less oxidative processes at higher PS concentrations. Iron impurities, oxygen in the vial headspaces, and the pH values of the formulations were identified as the main contributing factors to accelerate PS oxidation.

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.

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.

A fast and sensitive high-throughput assay to assess polysorbate-degrading hydrolytic activity in biopharmaceuticals

Hydrolysis of polysorbate in biopharmaceutical products has been ascribed to the enzymatic activity from trace levels of residual host cell proteins. In recent years, significant efforts to identify the causative enzymes typically used elaborate, material-intensive and time-consuming approaches. Therefore, the lack of fast and sensitive assays to monitor their activity remains a major bottleneck for supporting process optimization and troubleshooting activities where time and sample throughput are crucial constraints. To address this bottleneck, we developed a novel Electrochemiluminescence-based Polysorbase Activity (EPA) assay to measure hydrolytic activities in biotherapeutics throughout the drug substance manufacturing process. By combining the favorable features of an in-house designed surrogate substrate with a well-established detection platform, the method yields fast (∼36 h turnaround time) and highly sensitive readouts compatible with high-throughput testing. The assay capability for detecting substrate conversion in a precise and reliable manner was demonstrated by extensive qualification studies and by employing a number of recombinant hydrolases associated with polysorbate hydrolysis. In addition, high assay sensitivity and wide applicability were confirmed for in-process pool samples of three different antibody products by performing a head-to-head comparison between this method and an established liquid chromatography - mass spectrometry based assay for the quantification of free fatty acids. Overall, our results suggest that this new approach is well-suited to resolve differences in hydrolytic activity through all stages of purification.

A highly sensitive and robust LC-MS platform for host cell protein characterization in biotherapeutics

Host cell proteins (HCPs) are a major class of process-related impurities that need to be closely monitored during the production of biotherapeutics. Mass spectrometry (MS) has emerged as a promising tool for HCP analysis due to its specificity for individual HCP's identification and quantitation. However, utilization of MS as a routine characterization tool is still limited due to the time-consuming procedures, non-standardized instrumentation and methodologies, and the limited sensitivity compared to the enzyme-linked immunosorbent assays (ELISA). In this study, we introduced a sensitive (limit of detection (LOD) at 1-2 ppm) and robust HCP profiling platform method with suitable precision and accuracy that can be readily adopted to antibodies and other biotherapeutic modalities without the need for HCP enrichment. The NIST mAb and multiple in-house antibodies were analyzed, and results were benchmarked with other reported studies. In addition, a targeted analysis method with optimized sample preparation for absolute quantitation of lipases was developed and qualified with an LOD of 0.6 ppm and precision of <15%, which can be further improved to an LOD of 5 ppb by using the nano-flow LC.

Methods for addressing host cell protein impurities in biopharmaceutical product development

The high demand for monoclonal antibody (mAb) therapeutics in recent years has resulted in significant efforts to improve their costly manufacturing process. The high cost of manufacturing mAbs derives mainly from the purification process, which contributes to 50%-80% of the total manufacturing cost. One of the main challenges facing industry at the purification stage is the clearance of host cell proteins (HCPs) that are produced and often co-purified with the desired mAb product. One of the issues HCPs can cause is the degradation of the final mAb protein product. In this review, techniques are considered that can be used at different stages (upstream and downstream) of mAb manufacture to improve HCP clearance. In addition to established techniques, many new approaches for HCP removal are discussed that have the potential to replace current methods for improving HCP reduction and thereby the quality and stability of the final mAb product.

Ceramic hydroxyapatite chromatography plays a critical role in bispecific antibody purification process for impurity removal

Background

Significant challenges exist in downstream purification of bispecific antibodies (BsAbs) due to the complexity of BsAb architecture. A unique panel of mispaired species can result in a higher level of product-related impurities. In addition to process-related impurities such as host cell proteins (HCPs) and residual DNA (resDNA), these product-related impurities must be separated from the targeted BsAb product to achieve high purity. Therefore, development of an efficient and robust chromatography purification process is essential to ensure the safety, quality, purity and efficacy of BsAb products that consequently meet regulatory requirements for clinical trials and commercialization.

Methods

We have developed a robust downstream BsAb process consisting of a mixed-mode ceramic hydroxyapatite (CHT) chromatography step, which offers unique separation capabilities tailored to BsAbs, and assessed impurity clearance.

Results

We demonstrate that the CHT chromatography column provides additional clearance of low molecular weight (LMW) and high molecular weight (HMW) species that cannot be separated by other chromatography columns such as ion exchange for a particular BsAb, resulting in ≥98% CE-SDS (non-reduced) purity. Moreover, through Polysorbate-80 (PS-80) spiking and LC-MS HCP assessments, we reveal complete clearance of potential PS-80-degrading HCP populations in the CHT eluate product pool.

Conclusions

In summary, these results demonstrate that CHT mixed-mode chromatography plays an important role in separation of product- and process-related impurities in the BsAb downstream process.

Blueprint for antibody biologics developability

Large-molecule antibody biologics have revolutionized medicine owing to their superior target specificity, pharmacokinetic and pharmacodynamic properties, safety and toxicity profiles, and amenability to versatile engineering. In this review, we focus on preclinical antibody developability, including its definition, scope, and key activities from hit to lead optimization and selection. This includes generation, computational and in silico approaches, molecular engineering, production, analytical and biophysical characterization, stability and forced degradation studies, and process and formulation assessments. More recently, it is apparent these activities not only affect lead selection and manufacturability, but ultimately correlate with clinical progression and success. Emerging developability workflows and strategies are explored as part of a blueprint for developability success that includes an overview of the four major molecular properties that affect all developability outcomes: 1) conformational, 2) chemical, 3) colloidal, and 4) other interactions. We also examine risk assessment and mitigation strategies that increase the likelihood of success for moving the right candidate into the clinic.

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.

Alternative Excipients for Protein Stabilization in Protein Therapeutics: Overcoming the Limitations of Polysorbates

Given their safety and efficiency in protecting protein integrity, polysorbates (PSs) have been the most widely used excipients for the stabilization of protein therapeutics for years. In recent decades, however, there have been numerous reports about visible or sub-visible particles in PS-containing biotherapeutic products, which is a major quality concern for parenteral drugs. Alternative excipients that are safe for parenteral administration, efficient in protecting different protein drugs against various stress conditions, effective in protein stabilization in high-concentrated liquid formulations, stable under the storage conditions for the duration of the product's shelf-life, and compatible with other formulation components and the primary packaging are highly sought after. The aim of this paper is to review potential alternative excipients from different families, including surfactants, carbohydrate- and amino acid-based excipients, synthetic amphiphilic polymers, and ionic liquids that enable protein stabilization. For each category, important characteristics such as the ability to stabilize proteins against thermal and mechanical stresses, current knowledge related to the safety profile for parenteral administration, potential interactions with other formulation components, and primary packaging are debated. Based on the provided information and the detailed discussion thereof, this paper may pave the way for the identification or development of efficient excipients for biotherapeutic protein stabilization.

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.

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.

The measurement and control of high-risk host cell proteins for polysorbate degradation in biologics formulation

Nonionic surfactant polysorbates, including PS-80 and PS-20, are commonly used in the formulation of biotherapeutic products for both preventing surface adsorption and acting as stabilizer against protein aggregation. Trace levels of residual host cell proteins (HCPs) with lipase or esterase enzymatic activity have been shown to degrade polysorbates in biologics formulation. The measurement and control of these low abundance, high-risk HCPs for polysorbate degradation are an industry-wide challenge to achieve desired shelf life of biopharmaceuticals in liquid formulation, especially for high-concentration formulation product development. Here, we reviewed the challenges, recent advances, and future opportunities of analytical method development, risk assessment, and control strategies for polysorbate degradation during formulation development with a focus on enzymatic degradation. Continued efforts to advance our understanding of polysorbate degradation in biologics formulation will help develop high-quality medicines for patients.

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.