Colloidal Instability Fosters Agglomeration of Subvisible Particles Created by Rupture of Gels of a Monoclonal Antibody Formed at Silicone Oil-Water Interfaces

The effect of glass container surface silanol density on monoclonal antibody formulation stability after application of mechanical shock

This study investigates the effect of silanol density on the surface of glass containers on the stability of monoclonal antibody (mAb) formulations subjected to mechanical stress. By calcining Type I glass containers at different temperatures, we altered the concentration of silanols on the glass surface and examined its impact on the stability of protein formulations under mechanical stress. Contact angle measurements and Fourier Transform Infrared (FTIR) spectroscopy indicated that silanol formation influences the hydrophilicity of the surface. Additionally, mAb solutions filled in Type I glass containers with varying silanol densities were repeatedly dropped from a height of 0.5 m to simulate mechanical stress during transport. The results demonstrated that increasing surface silanol density reduces protein monomer loss and the formation of protein aggregates and subvisible particles. Furthermore, protein aggregates and subvisible particles formed by dropping did not activate the complement in human serum in vitro. Adjusting the silanol density on the glass container surface offers an economical and environmentally friendly approach to improving the stability of mAb formulations during transportation.

Real-Time Observation of Protein Aggregation at Liquid-Liquid Interfaces in a Microfluidic Device

A droplet microfluidic device to capture in real-time protein aggregation at liquid-liquid interfaces is described. In contrast to conventional methods, typically characterized by a lag time between the application of interfacial stress and the measurement of protein aggregation, here protein adsorption, the formation of a viscoelastic protein layer, aggregation, and shedding of protein particles into solution is simultaneously monitored. The device is applied to analyze the stability of antibody formulations over a wide range of concentrations (1-180 mg mL-1) at the silicone oil (SO)-water interface under controlled mechanical deformation. The adsorption onto oil droplets induces the formation of a viscoelastic protein layer on a subsecond timescale, which progressively restricts the relaxation of the droplets within the chip. Upon mechanical rupture, the protein layer releases particles in solution. The rate of particle formation increases strongly with concentration, similar to the bulk viscosity. Concentrations above 120 mg mL-1 lead to aggregation in seconds and drastically decrease the mechanical perturbations required to shed protein particles in solution. These results are important for the development of formulations at high-protein concentrations (>100 mg mL-1) and indicate that particular attention should be given to interface-induced particle formation in this concentration range. In this context, low-volume microfluidic platforms allow the assessment of protein physical instabilities early in development and represent attractive tools to optimize antibody stability and formulation design consuming limited amounts of material.

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.

Pharmaceutical proteins at the interfaces and the role of albumin

A critical measure of the quality of pharmaceutical proteins is the preservation of native conformations of the active pharmaceutical ingredients. Denaturation of the active proteins in any step before administration into patients could lead to loss of potency and/or aggregation, which is associated with an increased risk of immunogenicity of the products. Interfacial stress enhances protein instability as their adsorption to the air-liquid and liquid-solid interfaces are implicated in the formation of denatured proteins and aggregates. While excipients in protein formulations have been employed to reduce the risk of aggregation, the roles of albumin as a stabilizer have not been reviewed from practical and theoretical standpoints. The amphiphilic nature of albumin makes it accumulate at the interfaces. In this review, we aim to bridge the knowledge gap between interfacial instability and the influence of albumin as a surface-active excipient in the context of reducing the immunogenicity risk of protein formulations.

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.

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.

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.

Antibodies Adsorbed to the Air-Water Interface Form Soft Glasses

When monoclonal antibodies are exposed to an air-water interface, they form aggregates, which negatively impacts their performance. Until now, the detection and characterization of interfacial aggregation have been difficult. Here, we exploit the mechanical response imparted by interfacial adsorption by measuring the interfacial shear rheology of a model antibody, anti-streptavidin immunoglobulin-1 (AS-IgG1), at the air-water interface. Strong viscoelastic layers of AS-IgG1 form when the protein is adsorbed from the bulk solution. Creep experiments correlate the compliance of the interfacial protein layer with the subphase solution pH and bulk concentration. These, along with oscillatory strain amplitude and frequency sweeps, show that the viscoelastic behavior of the adsorbed layers is that of a soft glass with interfacial shear moduli on the order of 10-3 Pa m. Shifting the creep compliance curves under different applied stresses forms master curves consistent with stress-time superposition of soft interfacial glasses. The interfacial rheology results are discussed in the context of the interface-mediated aggregation of AS-IgG1.

Mechanism of Protein-PDMS Visible Particles Formation in Liquid Vial Monoclonal Antibody Formulation

Visible particles (VPs) formation in liquid monoclonal antibody formulations is a critical quality issue. Formulations that include poloxamer 188 (PX188) as a surfactant are prone to the formation of VPs comprising aggregated complexes of protein and polydimethylsiloxane (PDMS; silicone oil) derived from primary containers. However, the mechanisms through which these VPs form are complicated and remain to be fully elucidated. This study demonstrates for the first time the dominant spot and pathway of protein-PDMS VP formation in a particular liquid vial formulation. Specifically, when a vial sealed with a PDMS-coated stopper is stored in an upright position under conditions whereby the antibody solution has become well-adhered to the stopper and an air phase exists in the vicinity, protein-PDMS aggregates form on the stopper and are then desorbed into the drug solution to be detected as VPs. Here, we evaluated the effects of several factors on VP formation: adhesion of the drug solution to the stopper, storage orientation, silicone coating on the stopper, vial material, and hydrophobicity of PX188. Remarkably, we found that changing any one of the factors could significantly affect VP formation. Our findings are instructive for better understanding the mechanisms of VP formation in vial products and can provide strategies for VP mitigation in biotherapeutics.

Surface-Induced Protein Aggregation and Particle Formation in Biologics: Current Understanding of Mechanisms, Detection and Mitigation Strategies

Protein stability against aggregation is a major quality concern for the production of safe and effective biopharmaceuticals. Amongst the different drivers of protein aggregation, increasing evidence indicates that interactions between proteins and interfaces represent a major risk factor for the formation of protein aggregates in aqueous solutions. Potentially harmful surfaces relevant to biologics manufacturing and storage include air-water and silicone oil-water interfaces as well as materials from different processing units, storage containers, and delivery devices. The impact of some of these surfaces, for instance originating from impurities, can be difficult to predict and control. Moreover, aggregate formation may additionally be complicated by the simultaneous presence of interfacial, hydrodynamic and mechanical stresses, whose contributions may be difficult to deconvolute. As a consequence, it remains difficult to identify the key chemical and physical determinants and define appropriate analytical methods to monitor and predict protein instability at these interfaces. In this review, we first discuss the main mechanisms of surface-induced protein aggregation. We then review the types of contact materials identified as potentially harmful or detected as potential triggers of proteinaceous particle formation in formulations and discuss proposed mitigation strategies. Finally, we present current methods to probe surface-induced instabilities, which represent a starting point towards assays that can be implemented in early-stage screening and formulation development of biologics.

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.

Risk Mitigation of Plunger-Stopper Displacement under Low Atmospheric Pressure by establishing Design Space for Filling-Stoppering Process of Prefilled Syringes: A Design of Experiment (DoE) Approach

There is a concern that low atmospheric pressure typically encountered during shipment could result in plunger-stopper displacement in prefilled syringes impacting sterility and container closure integrity (CCI) of drug product¹. In this work, following DoE principles we first investigated the impact of filling and stoppering operating parameters on creation of bubble height as performance parameters among others in nominal 1 mL and 2.25 mL Type I glass prefilled syringes (PFSs) with staked needle and rigid needle shield (RNS). Bubble height ranging from <2.0 mm to >15.0 mm were produced in syringes by filling water and vacuum stoppering at operating vacuum pressure ranging from 400 mbar to 950 mbar using a pilot scale filling-stoppering machine. We found that for a particular nominal fill volume in prefilled syringe, as the stoppering vacuum pressure increased, bubble height decreased resulting in plunger-stopper placed closer to the fill level. Subsequently, syringes with varying bubble size were exposed to reduced atmospheric pressure ranging from 628 Torr to 293 Torr bracketing the low pressure recommended by ASTM D4169 standard to qualify shipping containers for transportation of drug products. We found inverse linear correlation between bubble height and plunger-stopper displacement under low atmospheric pressure. However, plunger-stopper displacement increased exponentially as atmospheric pressure decreased. The results suggest that air bubble size in filled glass syringes should be minimized in order to mitigate sterility and container closure integrity (CCI) risk to drug product in prefilled syringes.

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.

Targeted antitumor comparison study between dopamine self-polymerization and traditional synthesis for nanoparticle surface modification in drug delivery

To improve the therapeutic efficacy of anticancer agents and extend their application, mussel-inspired chemical modifications have attracted considerable attention. Surface modification based on polydopamine (PDA) has been a facile and versatile method to immobilize biomolecules on substrates for targeted drug delivery. To better analyze pharmaceutical differences between PDA-based surface modification and traditional synthesis methods, we prepared two kinds of folate (FA)-targeted nanoparticles (NPs) loaded with paclitaxel (PTX). The resultant PTX-PDA-FA NPs and PTX-FA NPs represented PDA and synthesis strategies, respectively. PTX-PDA-FA NPs and PTX-FA NPs have been characterized. The particle size of PTX-PDA-FA NPs was smaller than that of PTX-FA NPs. The two kinds of NPs both exhibited long-rod morphology, good colloidal stability and sustained slow drug release. Cytotoxicityin vitrowas evaluated, and antitumor efficacy was investigated against 4T1 tumor-bearing mice. The tumor targeting therapeutic index of PTX-PDA-FA NPs and PTX-FA NPs showed equivalent superior specificity compared to nontargeted groups, which indicated that FA successfully attached to the surface of NPs by the PDA method and that the antitumor effect was equivalent to that of FA-modified NPs prepared by the chemical synthesis method. These results further indicated that PDA, as a simple and effective chemical surface modification platform, could be developed and applied in targeted delivery systems.

Adsorption and Aggregation of Monoclonal Antibodies at Silicone Oil-Water Interfaces

Monoclonal antibody (mAb) therapies are rapidly growing for the treatment of various diseases like cancer and autoimmune disorders. Many mAb drug products are sold as prefilled syringes and vials with liquid formulations. Typically, the walls of prefilled syringes are coated with silicone oil to lubricate the surfaces during use. MAbs are surface-active and adsorb to these silicone oil-solution interfaces, which is a potential source of aggregation. We studied formulations containing two different antibodies, mAb1 and mAb2, where mAb1 aggregated more when agitated in the presence of an oil-water interface. This directly correlated with differences in surface activity of the mAbs, studied with interfacial tension, surface mass adsorption, and interfacial rheology. The difference in interfacial properties between the mAbs was further reinforced in the coalescence behavior of oil droplets laden with mAbs. We also looked at the efficacy of surfactants, typically added to stabilize mAb formulations, in lowering adsorption and aggregation of mAbs at oil-water interfaces. We showed the differences between poloxamer-188 and polysorbate-20 in competing with mAbs for adsorption to interfaces and in lowering particulate and overall aggregation. Our results establish a direct correspondence between the adsorption of mAbs at oil-water interfaces and aggregation and the effect of surfactants in lowering aggregation by competitively adsorbing to these interfaces.

A Rapid, Small-Volume Approach to Evaluate Protein Aggregation at Air-Water Interfaces

Non-native protein aggregation is a common concern for biopharmaceuticals. A given protein may aggregate through a variety of mechanisms that depend on solution and physico-chemical stress conditions. A thorough evaluation of aggregation behavior for a protein under all conditions of interest is necessary to ensure drug safety and efficacy. This work introduces a rapid, small-volume approach to evaluate protein aggregation propensity upon exposure to air-water interfaces (AWI). A microtensiometer apparatus is used to aerate a small volume of a protein solution with microbubbles for short periods of time (≤10 s). Sub-visible particles that form are captured and analyzed using backgrounded membrane imaging. This allows one to capture all particles in the solution while being sample sparing. The surface-mediated aggregation of two model monoclonal antibodies (MAbs) and a globular protein (aCgn) was tested as a function of pH and temperature. Temperature had a negligible effect under the rapid interface turnover time scales with this technique. Electrostatic protein-protein interactions, mediated by pH changes, were more influential for particle formation via AWI. Nonionic surfactants substantially reduced particle formation for all MAb solutions, but not aCgn. The results are contrasted with expectations when exposing samples to much larger air-water interfacial stress.

In-Use Interfacial Stability of Monoclonal Antibody Formulations Diluted in Saline i.v. Bags

The use of monoclonal antibodies (mAbs) for the treatment of a variety of diseases is rapidly growing each year. Many mAbs are administered intravenously using i.v. bags containing 0.9% NaCl (normal saline). We studied the aggregation propensity of these antibody solutions in saline and compared it with a low ionic strength formulation buffer. The mAb studied in this work is prone to aggregate, and is known to form a viscoelastic network at the air-solution interface. We observed that this interfacial elasticity increased when formulated in saline. In the bulk, the mAbs exhibited a tendency to self-associate that was higher in saline. We also studied the aggregation of the mAbs in the presence of polysorbate-20, typically added to formulations to mitigate interfacial aggregation. We observed that with surfactants, the presence of salt in the buffer led to a greater mAb adsorption at the interface and resulted in the formation of more particulate aggregates. Our results show that the addition of salt to the buffer led to differences in the interfacial aggregation in mAb formulations, showing that stress studies used to screen for mAb aggregation intended for i.v. administration should be performed in conditions representative of their intended route of administration.

Using First Principles to Link Silicone Oil/Formulation Interfacial Tension With Syringe Functionality in Pre-Filled Syringes Systems

Numerous interactions can arise at the interface between the glass barrel/silicone oil coating/aqueous formulation in pre-filled syringes that can affect the functionality of the medical device. In this study, the Young-Dupré equation was applied at these interfaces to correlate the interfacial tension between the silicone oil coating and aqueous formulation to the functionality of the syringe. It was shown that lower silicone oil/drug product formulation interfacial tension led to an increase in the glide force of the syringe. The relationship between glide force profiles and silicone oil thickness after injection was also investigated and the data revealed that the silicone oil was removed at the end of the syringe barrel when the formulation contains polysorbate 80.

Critical analysis of techniques and materials used in devices, syringes, and needles used for intravitreal injections

Intravitreal injections have become the most commonly performed intraocular treatments worldwide. Because intravitreal injections may induce severe adverse events, such as infectious and noninfectious endophthalmitis, cataract, ocular hypertension, vitreous hemorrhage, or retinal detachment, appropriate awareness of the materials and techniques used are essential to reduce these sight-threatening complications. This review provides insights into the needles, syringes, silicone oil coating, sterilization methods, devices to assist intravitreal injections, scleral piercing techniques using needles, syringe handling, anesthesia, and safety issues related to materials and techniques. It is paramount that physicians be aware of every step involved in intravitreal injections and consider the roles and implications of all materials and techniques used. The ability to understand the theoretical and practical circumstances may definitely lead to state-of-the-art treatments delivered to patients. The most important practical recommendations are: choosing syringes with as little silicone oil as possible, or, preferably, none; avoiding agitation of syringes; awareness that most biologics (e.g., antiangiogenic proteins) are susceptible to changes in molecular properties under some conditions, such as agitation and temperature variation; understanding that improper materials and techniques may lead to complications after intravitreal injections, e.g., inflammation; and recognizing that some devices may contribute to an enhanced, safer, and faster intravitreal injection technique.

Anti-GPC3 Antibody Tagged Cationic Switchable Lipid-Based Nanoparticles for the Co-Delivery of Anti-miRNA27a And Sorafenib in Liver Cancers

PURPOSE

The immediate plasma metabolism and development of chemo-resistance (single agent) severely hampers the clinical effectiveness of Sorafenib (SRF) in liver cancer therapy. MicroRNA27a inhibition is a promising biological strategy for breast cancer therapy.

METHODS

In this study, we aimed to prepare SRF and anti-miRNA27a-loaded anti-GPC3 antibody targeted lipid nanoparticles to enhance the therapeutic efficacy against liver cancers. In this study, we have employed a unique cationic switchable lipid (CSL) as a mean to encapsulate miRNA as well as to confer pH-responsiveness to the nanocarrier system.

RESULTS

The G-S27LN was nanosized and offered a pH-responsive release of SRF from the carrier system and we have demonstrated the specific affinity of G-S27LN towards the GPC3-overexpressed HepG2 cancer cells. Anti-microRNA27a significantly increased the protein expression of FOXO1 and PPAR-γ which are crucial components involved in proliferation and apoptosis of tumor cells. Combination of SRF and anti-miRNA27a (G-S27LN) resulted in significantly lower cell viability with a marked increase in the apoptosis cell proportion compared to that of free SRF indicating the synergistic anticancer effect. Animal studies in liver cancer xenograft model demonstrated significant suppression of tumor burden, reduced tumor cell and elevated TUNEL positive apoptosis with no toxicity concerns in animals treated with G-S27LN formulation.

CONCLUSION

The CSL-based G-S27LN efficiently co-delivered anti-microRNA27a and SRF and therefore represents a promising therapy to treat liver cancer. This study also brings forth a platform strategy for the effective treatment of number of other advanced cancers.

Science and art of protein formulation development

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

Biocorona formation contributes to silver nanoparticle induced endoplasmic reticulum stress

Prior research has demonstrated cells exposed to silver nanoparticles (AgNPs) undergo endoplasmic reticulum (ER) stress leading to cellular apoptosis and toxicity, however, the fundamental mechanism underlying AgNP-induced ER stress is unknown. We hypothesize the biophysical interactions between AgNPs and adsorbed proteins lead to misfolded proteins to elicit an ER stress response. Our investigation examined rat aortic endothelial cells (RAEC) exposed to 20 or 100 nm AgNPs with or without a biocorona (BC) consisting of bovine serum albumin (BSA), high density lipoprotein (HDL) or fetal bovine serum (FBS) to form a complex BC. The presence of a BC consisting of BSA or FBS proteins significantly reduced uptake of 20 nm and 100 nm AgNPs in RAEC. Western blot analysis indicated robust activation of the IREα and PERK pathways in RAEC exposed to 20 nm despite the reduction in uptake by the presence of a BC. This was not observed for the 100 nm AgNPs. Hyperspectral darkfield microscopy qualitatively confirmed that the preformed BC was maintained following uptake by RAEC. Transmission electron microscopy demonstrated a size dependent effect on the sub-cellular localization of AgNPs. Overall, these results suggest that AgNP size, surface area and BC formation governs the induction of ER stress and alterations in intracellular trafficking.

Steric Repulsion Forces Contributed by PEGylation of Interleukin-1 Receptor Antagonist Reduce Gelation and Aggregation at the Silicone Oil-Water Interface

Silicone oil, used as a lubricating coating in pharmaceutical containers, has been implicated as a cause of therapeutic protein aggregation. After adsorbing to silicone oil-water interfaces, proteins may form interfacial gels, which can be transported into solution as insoluble aggregates if the interfaces are perturbed. Mechanical interfacial perturbation of both monomeric recombinant human interleukin-1 receptor antagonist (rhIL-1ra) and PEGylated rhIL-1ra (PEG rhIL-1ra) in siliconized syringes resulted in losses of soluble monomeric protein. However, the loss of rhIL-1ra was twice that for PEG rhIL-1ra; even though in solution, PEG rhIL-1ra had a lower ΔG_unf and exhibited a more perturbed tertiary structure at the interface. Net protein-protein interactions in solution for rhIL-1ra were attractive but increased steric repulsion because of PEGylation led to net repulsive interactions for PEG rhIL-1ra. Attractive interactions for rhIL-1ra were associated with increases in intermolecular β-sheet content at the interface, whereas no intermolecular β-sheet structures were observed for adsorbed PEG rhIL-1ra. rhIL-1ra formed interfacial gels that were 5 times stronger than those formed by PEG rhIL-1ra. Thus, the steric repulsion contributed by the PEGylation resulted in decreased interfacial gelation and in the reduction of aggregation, in spite of the destabilizing effects of PEGylation on the protein's conformational stability.

Hyaluronic Acid Layer-By-Layer (LbL) Nanoparticles for Synergistic Chemo-Phototherapy

PURPOSE

The aim of this study was to design hyaluronic acid (HA) layer-by-layer (LbL) nanoparticles, which carried paclitaxel (PTX) and Indocyanine green (ICG) to both tumor cells and tumor associated cells to achieve synergistic chemo-photothermal therapeutic effect.

METHODS

The LbL-engineered nanoparticles (PDIH) were prepared by dopamine self-polymerization on PTX nanocrystal to form thin, surface-adherent polydopamine (PDA) films, which subsequently absorbed ICG and HA. The tumor cell and tumor associated cell targeting and antitumor efficacy of PDIH were investigated both in vitro an in vivo using 4 T1 murine mammary cancer cell lines and mice bearing orthotopic 4 T1 breast tumor.

RESULTS

PDIH presented a long-rod shape in TEM and showed enhanced photothermal effect and cytotoxicity upon NIR laser irradiation both in vitro and in vivo. PDIH also displayed high target ability to CD44 overexpressed tumor cells and tumor associated cells mediated by HA. In vivo antitumor study indicated that PDIH therapeutic strategy could achieve remarkable antitumor efficacy.

CONCLUSION

PDIH showed excellent tumor-targeting property and chemo-photothermal therapeutic efficacy.

Protein Nanoparticles Promote Microparticle Formation in Intravenous Immunoglobulin Solutions During Freeze-Thawing and Agitation Stresses

In this study, we investigated the potential roles of nanoparticles (<100 nm) and submicron (100-1000 nm) particles in the formation of microparticles (>1000 nm) in protein formulations under some pharmaceutically relevant stress conditions. Exposure of intravenous immunoglobulin solutions to the interface-associated stresses of freeze-thawing or agitation resulted in relatively large increases in microparticle concentrations, which depended directly on the levels of pre-existing nano- and submicron particles. Thus, agglomeration of nanoparticles and submicron particles appears to play a role in microparticle formation under these stresses. In contrast, increases in microparticle concentrations during quiescent incubation at elevated temperatures were independent of the initial nano- and submicron particle concentrations in solution.

Biodistribution and Pharmacokinetic Evaluations of a Novel Taxoid DHA-SBT-1214 in an Oil-in-Water Nanoemulsion Formulation in Naïve and Tumor-Bearing Mice

PURPOSE

The main purpose of this study was to formulate an oil-in-water nanoemulsion of a next generation taxoid DHA-SBT-1214 and evaluate its biodistribution and pharmacokinetics.

METHODS

DHA-SBT-1214 was encapsulated in a fish oil containing nanoemulsion using a high pressure homogenization method. Following morphological characterization of the nanoemulsions, qualitative and quantitative biodistribution was evaluated in naïve and cancer stem cell-enriched PPT-2 human prostate tumor bearing mice.

RESULTS

DHA-SBT-1214 was successfully encapsulated up to 20 mg/ml in the nanoemulsion formulation and had an average oil droplet size of 200 nm. Using a DiR near infra-red dye encapsulated nanoemulsion, we have shown the delivery of nanoemulsion to mouse tumor region. By quantitative analysis, DHA-SBT-1214 encapsulated nanoemulsion demonstrated improved pharmacokinetic properties in plasma and different tissues as compared to its solution form. Furthermore, the nanoemulsions were stable and had slower in vitro drug release compared to its solution form.

CONCLUSIONS

The results from this study demonstrated effective encapsulation of the drug in a nanoemulsion and this nanoemulsion showed sustained plasma levels and enhanced tumor delivery relative to the solution form.

Protein Adsorption and Layer Formation at the Stainless Steel-Solution Interface Mediates Shear-Induced Particle Formation for an IgG1 Monoclonal Antibody

Passage of specific protein solutions through certain pumps, tubing, and/or filling nozzles can result in the production of unwanted subvisible protein particles (SVPs). In this work, surface-mediated SVP formation was investigated. Specifically, the effects of different solid interface materials, interfacial shear rates, and protein concentrations on SVP formation were measured for the National Institute of Standards and Technology monoclonal antibody (NISTmAb), a reference IgG1 monoclonal antibody (mAb). A stainless steel rotary piston pump was used to identify formulation and process parameters that affect aggregation, and a flow cell (alumina or stainless steel interface) was used to further investigate the effect of different interface materials and/or interfacial shear rates. SVP particles produced were monitored using flow microscopy or flow cytometry. Neutron reflectometry and a quartz crystal microbalance with dissipation monitoring were used to characterize adsorption and properties of NISTmAb at the stainless steel interface. Pump/shear cell experiments showed that the NISTmAb concentration and interface material had a significant effect on SVP formation, while the effects of interfacial shear rate and passage number were less important. At the higher NISTmAb concentrations, the adsorbed protein became structurally altered at the stainless steel interface. The primary adsorbed layer remained largely undisturbed during flow, suggesting that SVP formation at high NISTmAb concentration was caused by the disruption of patches and/or secondary interactions.

Cilostazol-Loaded Poly(ε-Caprolactone) Electrospun Drug Delivery System for Cardiovascular Applications

PURPOSE

The study discusses the value of electrospun cilostazol-loaded (CIL) polymer structures for potential vascular implant applications.

METHODS

Biodegradable polycaprolactone (PCL) fibers were produced by electrospinning on a rotating drum collector. Three different concentrations of CIL: 6.25%, 12.50% and 18.75% based on the amount of polymer, were incorporated into the fibers. The fibers were characterized by their size, shape and orientation. Materials characterization was carried out by Fourier Transformed Infrared spectroscopy (FTIR), Raman spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In vitro drug release study was conducted using flow-through cell apparatus (USP 4).

RESULTS

Three-dimensional structures characterized by fibers diameter ranging from 0.81 to 2.48 μm were in the range required for cardiovascular application. DSC and XRD confirmed the presence of CIL in the electrospun fibers. FTIR and Raman spectra confirmed CIL polymorphic form. Elastic modulus values for PCL and the CIL-loaded PCL fibers were in the range from 0.6 to 1.1 GPa. The in vitro release studies were conducted and revealed drug dissolution in combination with diffusion and polymer relaxation as mechanisms for CIL release from the polymer matrix.

CONCLUSIONS

The release profile of CIL and nanomechanical properties of all formulations of PCL fibers demonstrate that the cilostazol loaded PCL fibers are an efficient delivery system for vascular implant application.

Improvement in Ocular Bioavailability and Prolonged Delivery of Tobramycin Sulfate Following Topical Ophthalmic Administration of Drug-Loaded Mucoadhesive Microparticles Incorporated in Thermosensitive In Situ Gel

PURPOSE

Conventional topical delivery in hyperacute bacterial conjunctivitis and endophthalmitis is associated with low drug bioavailability due to rapid precorneal clearance. Hence, in the present investigation, an attempt has been made to enhance ocular bioavailability of tobramycin sulfate by formulating drug-loaded microparticles dispersed in thermosensitive in situ gel.

METHODS

Microparticles prepared by emulsion-ionic gelation technique were characterized for drug loading, entrapment efficiency, particle size, surface morphology, and in vitro drug release. Consequently microparticles (F2 prepared with 1.5%w/v chitosan, 0.2%w/v tripolyphosphate, and drug, 30%w/w of polymer) with high drug loading and encapsulation efficiency were dispersed in thermosensitive in situ gel containing poloxamer 407 and varying percentage of chitosan. In situ gel containing drug-loaded microparticles were evaluated for gelation temperature, rheological behavior, mucoadhesive strength, in vitro drug release, in vitro permeation, ocular irritation, and bioavailability in aqueous humor of rabbits.

RESULTS

Formulation containing 17%w/v poloxamer 407 and 0.5%w/v chitosan (P2) gelled at 32°C ± 1.5°C gave pseudoplastic behavior. In vitro permeability of tobramycin from the formulation P2 was found 2-folds greater than eye drops. It also gave significantly higher aqueous humor concentration of tobramycin compared with eye drops with no signs of ocular irritation.

CONCLUSION

Thus, the formulation possesses high potential for treating ocular infections.