Impact of Excipient Extraction and Buffer Exchange on Recombinant Monoclonal Antibody Stability.

The foundation of a biosimilar manufacturer's regulatory filing is the demonstration of analytical and functional similarity between the biosimilar product and the pertinent originator product. The excipients in the formulation may interfere with characterization using typical analytical and functional techniques during this biosimilarity exercise. Consequently, the producers of biosimilar products resort to buffer exchange to isolate the biotherapeutic protein from the drug product formulation. However, the impact that this isolation has on the product stability is not completely known. This study aims to elucidate the extent to which mAb isolation via ultrafiltration-diafiltration-based buffer exchange impacts mAb stability. It has been demonstrated that repeated extraction cycles do result in significant changes in higher-order structure (red-shift of 5.0 nm in fluorescence maxima of buffer exchanged samples) of the mAb and also an increase in formation of basic variants from 19.1 to 26.7% and from 32.3 to 36.9% in extracted innovator and biosimilar Tmab samples, respectively. It was also observed that under certain conditions of tertiary structure disruptions, Tmab could be restabilized depending on formulation composition. Thus, mAb isolation through extraction with buffer exchange impacts the product stability. Based on the observations reported in this paper, we recommend that biosimilar manufacturers take into consideration these effects of excipients on protein stability when performing biosimilarity assessments.

Fc gamma receptor binding profile of anti-citrullinated protein antibodies in immune complexes suggests a role for FcγRI in the pathogenesis of synovial inflammation.

OBJECTIVES: Anti-citrullinated protein antibodies (ACPA) are highly specific for rheumatoid arthritis (RA). Here, we studied binding of ACPA-IgG immune complexes (IC) to individual Fc gamma receptors (FcγR) to identify potential effector mechanisms by which ACPA could contribute to RA pathogenesis. METHODS: ACPA-IgG1 and control IgG1(IgG1 depleted of ACPA-IgG1) were isolated from plasma and synovial fluid (SF) of RA patients by affinity chromatography using CCP2 peptides. Subsequently, IC were generated using fluorescently labelled F(ab')2 fragments against the F(ab')2 region of IgG, or by using citrullinated fibrinogen. IC were incubated with FcγR-transfected CHO cell lines or neutrophils from healthy donors. FcγR binding of IC was analysed by flow cytometry in the presence or absence of specific blocking antibodies. RESULTS: ACPA-IgG1 IC predominantly bound to FcγRI and FcγRIIIA on FcγR-transfected CHO cell lines, while much lower binding was observed to FcγRIIA and FcγRIIB. ACPA-IgG1 IC showed reduced binding to FcγRIIIA compared to control IgG1 IC, in line with enhanced ACPA-IgG1 Fc core-fucosylation. Neutrophils activated in vitro to induce de novo expression of FcγRI showed binding of ACPA-IgG IC, and blocking studies revealed that almost 30% of ACPA-IgG IC binding to activated neutrophils was mediated by FcγRI. CONCLUSIONS: Our studies show that ACPA-IgG1 IC bind predominately to activating FcγRI and FcγRIIIA, and highlight FcγRI expressed by activated neutrophils as relevant receptor for these IC. As neutrophils isolated from SF exhibit an activated state and express FcγRI in the synovial compartment, this IC-binding could contribute to driving disease pathogenesis in RA.

Aggregate Formation and Antibody Stability in Infusion Bags: The Impact of Manual and Robotic Compounding of Monoclonal Antibodies.

Monoclonal antibodies (mAbs) can be damaged during the aseptic compounding process, with aggregation being the most prevalent form of degradation. Protein aggregates represent one of several risk factors for undesired immunogenicity of mAbs, which can potentially lead to severe adverse drug reactions and less effective treatments. Since data on aggregate and particle formation by robotic compounding is missing, we aimed to compare the antibody stability between robotic- and manual compounding of mAbs with regard to formation of (sub)visible aggregates. Infliximab and trastuzumab were compounded into infusion bags with the APOTECAchemo robot or manually by nurses or pharmacy technicians. The products were analyzed by quantifying (sub)visible particles with nanoparticle tracking analysis, dynamic light scattering (DLS), light obscuration, micro-flow imaging, high pressure size exclusion chromatography (HP-SEC), and visual inspection. HP-SEC showed high percentages monomers in trastuzumab (99.4 % and 99.4 %) and infliximab (99.5 % and 99.6 %) infusion bags for both manual and robotic compounding, respectively. DLS indicated more consistent and reproducible results with robotic compounding, and confirmed monodisperse samples with a higher polydispersity index for manual compounding (0.16, interquartile range; IQR 0.14-0.18) compared to robotic compounding (0.12, IQR 0.11-0.15). This study shows that the studied compounding methods had a minor impact on the number of aggregates and particles, and that robotic compounding of mAbs provided at least similar quality as manual compounding.

Bacterial adhesion forces with substratum surfaces and the susceptibility of biofilms to antibiotics.

Biofilms causing biomaterial-associated infection resist antibiotic treatment and usually necessitate the replacement of infected implants. Here we relate bacterial adhesion forces and the antibiotic susceptibility of biofilms on uncoated and polymer brush-coated silicone rubber. Nine strains of Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa adhered more weakly to brush-coated silicone rubber (-0.05 ± 0.03 to -0.51 ± 0.62 nN) than to uncoated silicone rubber (-1.05 ± 0.46 to -5.1 ± 1.3 nN). Biofilms of weakly adhering organisms on polymer brush coatings remained in a planktonic state, susceptible to gentamicin, unlike biofilms formed on uncoated silicone rubber.

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.

The risk of biomaterial-associated infection after revision surgery due to an experimental primary implant infection.

The fate of secondary biomaterial implants was determined by bio-optical imaging and plate counting, after antibiotic treatment of biomaterials-associated-infection (BAI) and surgical removal of an experimentally infected, primary implant. All primary implants and tissue samples from control mice showed bioluminescence and were culture-positive. In an antibiotic treated group, no bioluminescence was detected and only 20% of all primary implants and no tissue samples were culture-positive. After revision surgery, bioluminescence was detected in all control mice. All the implants and 80% of all tissue samples were culture-positive. In contrast, in the antibiotic treated group, 17% of all secondary implants and 33% of all tissue samples were culture-positive, despite antibiotic treatment. The study illustrates that due to the BAI of a primary implant, the infection risk of biomaterial implants is higher in revision surgery than in primary surgery, emphasizing the need for full clearance of the infection, as well as from surrounding tissues prior to implantation of a secondary implant.

Hyaluronan-based dissolving microneedles with high antigen content for intradermal vaccination: Formulation, physicochemical characterization and immunogenicity assessment.

The purpose of this study was to optimize the manufacturing of dissolving microneedles (dMNs) and to increase the antigen loading in dMNs to investigate the effect on their physicochemical properties. To achieve this, a novel single-array wells polydimethylsiloxane mold was designed, minimizing antigen wastage during fabrication and achieving homogeneous antigen distribution among the dMN arrays. Using this mold, hyaluronan (HA)-based dMNs were fabricated and tested for maximal ovalbumin (OVA) content. dMNs could be fabricated with an OVA:HA ratio as high as 1:1 (w/w), without compromising their properties such as shape and penetration into the ex vivo human skin, even after storage at high humidity and temperature. High antigen loading did not induce protein aggregation during dMN fabrication as demonstrated by complementary analytical methods. However, the dissolution rate in ex vivo human skin decreased with increasing antigen loading. About 2.7 µg OVA could be delivered in mice by using a single array with an OVA:HA ratio of 1:3 (w/w). Intradermal vaccination with dMNs induced an immune response similar as subcutaneous injection and faster than after hollow microneedle injection. In conclusion, results suggest that (i) the polydimethylsiloxane mold design has an impact on the manufacturing of dMNs, (ii) the increase in antigen loading in dMNs affects the microneedle dissolution and (iii) dMNs are a valid alternative for vaccine administration over conventional injection.

Bacterial colonization of polymer brush-coated and pristine silicone rubber implanted in infected pockets in mice.

OBJECTIVES: Curing biomaterial-associated infection (BAI) frequently includes antibiotic treatment, implant removal and re-implantation. However, revision implants are at a greater risk of infection as they may attract bacteria from their infected surroundings. Polymer brush-coatings attract low numbers of bacteria, but the virtue of polymer brush-coatings in vivo has seldom been investigated. Here, we determine the possible benefits of polymer brush-coated versus pristine silicone rubber in revision surgery, using a murine model. METHODS: BAI was induced in 26 mice by subcutaneous implantation of silicone rubber discs with a biofilm of Staphylococcus aureus Xen29. During the development of BAI, half of the mice received rifampicin/vancomycin treatment. After 5 days, the infected discs were removed from all mice, and either a polymer brush-coated or pristine silicone rubber disc was re-implanted. Revision discs were explanted after 5 days, and the number of cfu cultured from the discs and the surrounding tissue was determined. RESULTS: None of the polymer brush-coated discs after antibiotic treatment appeared colonized by staphylococci, whereas 83% of the pristine silicone rubber discs were re-infected. Polymer brush-coated discs also showed reduced colonization rates in the absence of antibiotic treatment when compared with pristine silicone rubber discs. Tissue surrounding the discs was culture-positive in all cases. CONCLUSIONS: Polymer brush-coatings are less prone to re-infection than pristine silicone rubber when used in revision surgery, i.e. when implanted in a subcutaneous pocket infected by a staphylococcal BAI. Antibiotic pre-treatment during the development of BAI hardly had any effect in preventing the colonization of pristine silicone rubber.

Determination of the shear force at the balance between bacterial attachment and detachment in weak-adherence systems, using a flow displacement chamber.

We introduce a procedure for determining shear forces at the balance between attachment and detachment of bacteria under flow. This procedure can be applied to derive adhesion forces in weak-adherence systems, such as polymer brush coatings, which are currently at the center of attention for their control of bacterial adhesion and biofilm formation.

Bacterial adhesion and growth on a polymer brush-coating.

Biomaterials-related infections pose serious problems in implant surgery, despite the development of non-adhesive coatings. Non-adhesive coatings, like polymer brush-coatings, have so far only been investigated with respect to preventing initial bacterial adhesion, but never with respect to effects on kinetics of bacterial growth. Here, we compare adhesion and 20 h growth of three bacterial strains (Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa) on pristine and brush-coated silicone rubber in a parallel plate flow chamber. Brush-coatings were made using a tri-block copolymer of polyethylene oxide (PEO) and polypropylene oxide (PPO). Brush-coatings prevented adhesion of staphylococci to below 5 x 10(5)cm(-2) after 30 min, which is a 10-fold reduction compared to pristine silicone rubber. Biofilms grew on both brush-coated and pristine silicone rubber, while the viability of biofilms on brush-coatings was higher than on pristine silicone rubber. However, biofilms on brush-coatings developed more slowly and detached almost fully by high fluid shear. Brush-coating remained non-adhesive after S. epidermidis biofilm formation and subsequent removal whereas a part of its functionality was lost after removal of S. aureus biofilms. Adhesion, growth and detachment of P. aeruginosa were not significantly different on brush-coatings as compared with pristine silicone rubber, although here too the viability of biofilms on brush-coatings was higher. We conclude that polymer brush-coatings strongly reduce initial adhesion of staphylococci and delay their biofilm growth. In addition, biofilms on brush-coatings are more viable and easily removed by the application of fluid shear.

Universal Applicator for Digitally-Controlled Pressing Force and Impact Velocity Insertion of Microneedles into Skin.

Microneedle technologies have been developed for dermal drug and vaccine delivery, including hollow-, solid-, coated-, and dissolving microneedles. Microneedles have been made in many different geometries and of many different materials, all of which may influence their skin-penetrating ability. To ensure reproducible and effective drug and vaccine delivery via microneedles, the optimal insertion parameters should be known. Therefore, a digitally-controlled microneedle applicator was developed to insert microneedles into the skin via impact insertion (velocity) or via pressing force insertion. Six microneedle arrays with different geometries and/or materials were applied onto ex vivo human skin with varying velocities or pressing forces. Penetration efficiency and delivered antigen dose into the skin after application of microneedles were determined. In general, microneedles pierced the skin more efficiently when applied by impact application as compared to application via pressing force. However, the angle of application of the applicator on the skin can affect the velocity of the impact, influencing the penetration efficiency of microneedles. Regarding the antigen delivery into the skin, the delivered dose was increasing by increasing the velocity or pressure, and thus, increasing the penetration efficiency. These data demonstrate that an applicator is an important tool to determine optimal application conditions with ex vivo human skin.

Development of PLGA nanoparticle loaded dissolving microneedles and comparison with hollow microneedles in intradermal vaccine delivery.

Skin is an attractive but also very challenging immunisation site for particulate subunit vaccines. The aim of this study was to develop hyaluronan (HA)-based dissolving microneedles (MNs) loaded with PLGA nanoparticles (NPs) co-encapsulating ovalbumin (OVA) and poly(I:C) for intradermal immunisation. The NP:HA ratio used for the preparation of dissolving MNs appeared to be critical for the quality of MNs and their dissolution in ex vivo human skin. Asymmetrical flow field-flow fractionation and dynamic light scattering were used to analyse the NPs released from the MNs in vitro. Successful release of the NPs depended on the drying conditions during MN preparation. The delivered antigen dose from dissolving MNs in mice was determined to be 1 µg OVA, in NPs or as free antigen, by using near-infrared fluorescence imaging. Finally, the immunogenicity of the NPs after administration of dissolving MNs (NP:HA weight ratio 1:4) was compared with that of hollow MN-delivered NPs in mice. Immunization with free antigen in dissolving MNs resulted in equally strong immune responses compared to delivery by hollow MNs. However, humoral and cellular immune responses evoked by NP-loaded dissolving MNs were inferior to those elicited by NPs delivered through a hollow MN. In conclusion, we identified several critical formulation parameters for the further development of NP-loaded dissolving MNs.

Postproduction Handling and Administration of Protein Pharmaceuticals and Potential Instability Issues.

The safety and efficacy of protein pharmaceuticals depend not only on biological activity but also on purity levels. Impurities may be process related because of limitations in manufacturing or product related because of protein degradation occurring throughout the life history of a product. Although the pharmaceutical biotechnology industry has made great progress in improving bulk and drug product manufacturing as well as company-controlled storage and transportation conditions to minimize the level of degradation, there is less control over the many factors that may subsequently affect product quality after the protein pharmaceuticals are released and shipped by the manufacturer. Routine handling or unintentional mishandling of therapeutic protein products may cause protein degradation that remains unnoticed but can potentially compromise the clinical safety and efficacy of the product. In this commentary, we address some potential risks associated with (mis)handling of protein pharmaceuticals after release by the manufacturer. We summarize the environmental stress factors that have been shown to cause protein degradation and that may be encountered during typical handling procedures of protein pharmaceuticals in a hospital setting or during self-administration by patients. Moreover, we provide recommendations for improvements in product handling to help ensure the quality of protein pharmaceuticals during use.

Potential Issues With the Handling of Biologicals in a Hospital.

A master student, who surveyed the procedures in a hospital pharmacy with regard to the handling of biologicals, identified several issues that might have jeopardized product quality. This case may be a tip of the iceberg and illustrates the urgent need for a better education of end-users about how to handle biologicals.

A Flow Imaging Microscopy-Based Method Using Mass-to-Volume Ratio to Derive the Porosity of PLGA Microparticles.

The release of drugs from poly(lactic-co-glycolic acid) (PLGA) microparticles depends to a large extent on the porosity of the particles. Therefore, porosity determination of PLGA microparticles is extremely important during pharmaceutical product development. Currently, mercury intrusion porosimetry (MIP) is widely used despite its disadvantages, such as the need for a large amount of sample (several hundreds of milligrams) and residual toxic waste. Here, we present a method based on the estimation of the volume of a known mass (a few milligrams) of particles using micro-flow imaging (MFI) to determine microparticle batch porosity. Factors that are critical for the accuracy of this method (i.e., density of the suspending fluid, particle concentration, and postsample rinsing) were identified and measures were taken to minimize potential errors. The validity of the optimized method was confirmed by using nonporous polymethylmethacrylate microparticles. Finally, the method was employed for the analysis of 7 different PLGA microparticle batches with various porosities (4.0%-51.9%) and drug loadings (0%-38%). Obtained porosity values were in excellent agreement with the MIP-derived porosities. Altogether, the developed MFI-based method is a valuable tool for deriving the total volume of a known mass of PLGA particles and therewith their porosity.

Intradermal vaccination with hollow microneedles: A comparative study of various protein antigen and adjuvant encapsulated nanoparticles.

In this study, we investigated the potential of intradermal delivery of nanoparticulate vaccines to modulate the immune response of protein antigen using hollow microneedles. Four types of nanoparticles covering a broad range of physiochemical parameters, namely poly (lactic-co-glycolic) (PLGA) nanoparticles, liposomes, mesoporous silica nanoparticles (MSNs) and gelatin nanoparticles (GNPs) were compared. The developed nanoparticles were loaded with a model antigen (ovalbumin (OVA)) with and without an adjuvant (poly(I:C)), followed by the characterization of size, zeta potential, morphology, and loading and release of antigen and adjuvant. An in-house developed hollow-microneedle applicator was used to inject nanoparticle suspensions precisely into murine skin at a depth of about 120µm. OVA/poly(I:C)-loaded nanoparticles and OVA/poly(I:C) solution elicited similarly strong total IgG and IgG1 responses. However, the co-encapsulation of OVA and poly(I:C) in nanoparticles significantly increased the IgG2a response compared to OVA/poly(I:C) solution. PLGA nanoparticles and liposomes induced stronger IgG2a responses than MSNs and GNPs, correlating with sustained release of the antigen and adjuvant and a smaller nanoparticle size. When examining cellular responses, the highest CD8+ and CD4+ T cell responses were induced by OVA/poly(I:C)-loaded liposomes. In conclusion, the applicator controlled hollow microneedle delivery is an excellent method for intradermal injection of nanoparticle vaccines, allowing selection of optimal nanoparticle formulations for humoral and cellular immune responses.

No Touching! Abrasion of Adsorbed Protein Is the Root Cause of Subvisible Particle Formation During Stirring.

This study addressed the effect of contact sliding during stirring of a monoclonal antibody solution on protein aggregation, in particular, in the nanometer and micrometer size range. An overhead stirring set-up was designed in which the presence and magnitude of the contact between the stir bar and the container could be manipulated. A solution of 0.1 mg/mL of a monoclonal antibody (IgG) in phosphate buffered saline was stirred at 300 rpm at room temperature. At different time points, samples were taken and analyzed by nanoparticle tracking analysis, flow imaging microscopy, and size-exclusion chromatography. In contrast to non-contact-stirred and unstirred samples, the contact-stirred sample contained several-fold more particles and showed a significant loss of monomer. No increase in oligomer content was detected. The number of particles formed was proportional to the contact area and the magnitude of the normal pressure between the stir bar and the glass container. Extrinsic 9-(2,2-dicyanovinyl) julolidine fluorescence indicated a conformational change for contact-stirred protein samples. Presence of polysorbate 20 inhibited the formation of micron-sized aggregates. We suggest a model in which abrasion of the potentially destabilized, adsorbed protein leads to aggregation and renewal of the surface for adsorption of a fresh protein layer.

A Comprehensive Evaluation of Nanoparticle Tracking Analysis (NanoSight) for Characterization of Proteinaceous Submicron Particles.

Nanoparticle tracking analysis (NTA) has attracted great interest for application in the field of submicron particle characterization for biopharmaceuticals. It has the virtue of direct sample visualization and particle-by-particle tracking, but the complexity of method development has limited its routine applicability. We systematically evaluated data collection and processing parameters as well as sample handling methods using shake-stressed protein samples. The camera shutter and gain were identified as the key factors influencing NTA results. We also demonstrated that sample filtration was necessary for NTA analysis if there were high numbers of micron particles, whereas the choice of filter membrane was critical for data quality. Sample dilution into corresponding formulation buffer did not affect particle size distributions in our study. Finally, NTA analysis exhibited excellent repeatability in intraday comparison of multiple measurements on the same sample and interday comparison on different batches of samples. Shaking-induced protein aggregation could also be sensitively monitored by NTA. In conclusion, NTA analysis can be used as a robust stability-indicating method for the characterization of proteinaceous submicron particles and thereby complement other analytical methods, provided that consistent sample handling and parametric settings are established for the specific case study.