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The formulation of novel therapeutic proteins is a challenging task which aims at finding formulation conditions that will minimize protein degradation during long-term storage. One ...particularly important and difficult-to-predict protein degradation pathway is the so-called non-native aggregation. The qualitative and quantitative prediction of the latter has been a subject of extensive research over the past two decades. An increasing body of evidence shows that the widely-used short-term biophysical techniques cannot accurately rank formulation conditions in order of their effect on the aggregation during long-term storage of some therapeutic proteins, e.g. monoclonal antibodies. Here we suggest a novel approach for the selection of formulation conditions that will suppress the formation of protein aggregates during long-term storage. We postulate that conditions (i.e. pH, buffer type, ionic strength) that reduce the isothermal aggregation of various denaturant-induced partially folded protein species will be conditions that impede protein aggregation during long-term storage. To test our hypothesis, we developed an isothermal microdialysis-based unfolding/refolding assay, named ReFOLD, which we use to induce moderate aggregation of partially folded proteins. Next, we assessed the relative monomer yield after isothermal unfolding/refolding of two monoclonal antibodies, each formulated in 12 different conditions. Using the proposed approach, we were able to accurately rank the formulations in order of their effect on the amount of protein aggregates detected after storage for 12 months at 4 °C and 25 °C, while widely-used stability-indicating parameters like protein melting and aggregation onset temperatures failed to provide accurate predictive formulation rankings.
Here, we investigated the influence of the variable fragment (Fv) of IgG antibodies on the binding to the neonatal Fc receptor (FcRn) as well as on FcRn-dependent pharmacokinetics (PK). FcRn plays a ...key role in IgG homeostasis, and specific manipulation in the crystallizable fragment (Fc) is known to affect FcRn-dependent PK. Although the influence of the antigen-binding fragment (Fab) on FcRn interactions has been reported, the underlying mechanism is hitherto only poorly understood. Therefore, we analyzed the two IgG1 antibodies, briakinumab and ustekinumab, that have similar Fc parts but different terminal half-lives in human and systematically engineered variants of them with cross-over exchanges and varied charge distribution. Using FcRn affinity chromatography, molecular dynamics simulation, and in vivo PK studies in human FcRn transgenic mice, we provide evidence that the charge distribution on the Fv domain is involved in excessive FcRn binding. This excessive binding prevents efficient FcRn–IgG dissociation at physiological pH, thereby reducing FcRn-dependent terminal half-lives. Furthermore, we observed a linear correlation between FcRn column retention times of the antibody variants and the terminal half-lives in vivo. Taken together, our study contributes to a better understanding of the FcRn–IgG interaction, and it could also provide profound potential in FcRn-dependent antibody engineering of the variable Fab region.
Significance Therapeutic antibodies of the immunoglobulin G (IgG) isotype show a pharmacokinetic (PK) profile that is strongly mediated by the interaction with the neonatal Fc receptor (FcRn). Therefore, modulating the FcRn–IgG interaction allows altering PK characteristics of therapeutic antibodies. So far, engineering the crystallizable fragment (Fc) is known to affect PK, and, although the influence of the antigen binding fragment (Fab) on FcRn interactions has been reported, the underlying mechanism remains unknown. Here, we demonstrate that the charge distribution in the distal variable fragment (Fv) of IgGs is involved in excessive binding to the FcRn, thereby reducing FcRn-dependent terminal half-lives in vivo. These findings contribute to a better understanding of the FcRn–IgG interaction.
Aggregation is arguably the biggest challenge for the development of stable formulations and robust manufacturing processes of therapeutic proteins. In search of novel excipients inhibiting protein ...aggregation, cyclodextrins and their derivatives have been under examination for use in parenteral protein products since more than 20
years and significant research work has been accomplished highlighting the great potential of cyclodextrins as stabilizers of therapeutic proteins.
Oftentimes, the potential of cyclodextrins to inhibit protein aggregation has been attributed to their capability to incorporate hydrophobic residues on aggregation-prone proteins or on their partially unfolded intermediates into the hydrophobic cavity. In addition, also other mechanisms besides or even instead of complex formation play a role in the stabilization mechanism, e.g. non-ionic surfactant-like effects.
In this review a comprehensive overview of the available research work on the beneficial use of cyclodextrins and their derivatives in protein formulations, liquid as well as dried, is provided. The mechanisms of stabilization against different kinds of stress conditions, such as thermal or surface-induced, are discussed in detail.
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Prefilled syringes are a popular choice for the delivery of biopharmaceuticals. However, glass syringes might not be the optimal primary packaging material for all biopharmaceuticals. There is ...evidence that the necessary lubricant silicone oil in glass syringes can interact with proteins and can be shed from the surface into the product solution. In recent years, silicone oil-free polymer syringes were developed. Despite several advantages, however, a major shortcoming of these polymer systems is their relatively high gas permeability, which might be a limitation for the storage of oxygen sensitive biopharmaceuticals. So far, no long-term protein stability studies regarding such polymer systems have been published. In this study, 2 therapeutic proteins were stored in glass syringes and in silicone oil-free polymer syringes. In addition, polymer syringes stored in nitrogen-filled aluminum pouches or covered with oxygen-tight labels were included. Similar chemical protein stability was achieved at 4°C for all syringes. However, in contrast to the polymer syringes, high particle counts were observed in the glass syringes. Polymer syringes stored in nitrogen-filled aluminum pouches presented a promising alternative for the storage of biopharmaceuticals as they do not expose patients to silicone oil and silicone oil-protein aggregates.
Cake appearance is an important attribute of freeze-dried products, which may or may not be critical with respect to product quality (i.e., safety and efficacy). Striving for "uniform and elegant" ...cake appearance may continue to remain an important goal during the design and development of a lyophilized drug product. However, "sometimes" a non-ideal cake appearance has no impact on product quality and is an inherent characteristic of the product (due to formulation, drug product presentation, and freeze-drying process). This commentary provides a summary of challenges related to visual appearance testing of freeze-dried products, particularly on how to judge the criticality of cake appearance. Furthermore, a harmonized nomenclature and description for variations in cake appearance from the ideal expectation of uniform and elegant is provided, including representative images. Finally, a science and risk-based approach is discussed on establishing acceptance criteria for cake appearance.
The presence of particles is a major issue during therapeutic protein formulation development. Both proteinaceous and nonproteinaceous particles need to be analyzed not only due to the requirements ...of the Pharmacopeias but also to monitor the stability of the protein formulation. Increasing concerns about the immunogenic potential together with new developments in particle analysis make a comparative description of established and novel analytical methods useful. Our review aims to provide a comprehensive overview on analytical methods for the detection and characterization of visible and subvisible particles in therapeutic protein formulations. We describe the underlying theory, benefits, shortcomings, and illustrative examples for quantification techniques, as well as characterization techniques for particle shape, morphology, structure, and identity.
Understanding the effects of additives on therapeutic protein stability is of paramount importance for obtaining stable formulations. In this work, we apply several high- and medium-throughput ...methods to study the physical stability of a model monoclonal antibody at pH 5.0 and 6.5 in the presence of sucrose, arginine hydrochloride, and arginine glutamate. In low ionic strength buffer, the addition of salts reduces the antibody colloidal and thermal stability, attributed to screening of electrostatic interactions. The presence of glutamate ion in the arginine salt partially reduces the damaging effect of ionic strength increase. The addition of 280 mM sucrose shifts the thermal protein unfolding to a higher temperature. Arginine salts in the used concentration reduce the relative monomer yield after refolding from urea, whereas sucrose has a favorable effect on antibody refolding. In addition, we show 12-month long-term stability data and observe correlations between thermal protein stability, relative monomer yield after refolding, and monomer loss during storage. The monomer loss during storage is related to protein aggregation and formation of subvisible particles in some of the formulations. This study shows that the effect of commonly used additives on the long-term antibody physical stability can be predicted using orthogonal biophysical measurements.
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The development of a new protein drug typically starts with the design, expression and biophysical characterization of many different protein constructs. The initially high number of ...constructs is radically reduced to a few candidates that exhibit the desired biological and physicochemical properties. This process of protein expression and characterization to find the most promising molecules is both expensive and time-consuming. Consequently, many companies adopt and implement philosophies, e.g. platforms for protein expression and formulation, computational approaches, machine learning, to save resources and facilitate protein drug development. Inspired by this, we propose the use of interpretable artificial neuronal networks (ANNs) to predict biophysical properties of therapeutic monoclonal antibodies i.e. melting temperature Tm, aggregation onset temperature Tagg, interaction parameter kD as a function of pH and salt concentration from the amino acid composition. Our ANNs were trained with typical early-stage screening datasets achieving high prediction accuracy. By only using the amino acid composition, we could keep the ANNs simple which allows for high general applicability, robustness and interpretability. Finally, we propose a novel “knowledge transfer” approach, which can be readily applied due to the simple algorithm design, to understand how our ANNs come to their conclusions.
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