Thermal stability of human immunoglobulins with sorbitol. A critical evaluation

The Study of Protein-Cyclitol Interactions

Investigation of interactions between the target protein molecule and ligand allows for an understanding of the nature of the molecular recognition, functions, and biological activity of protein–ligand complexation. In the present work, non-specific interactions between a model protein (Bovine Serum Albumin) and four cyclitols were investigated. D-sorbitol and adonitol represent the group of linear-structure cyclitols, while shikimic acid and D-(–)-quinic acid have cyclic-structure molecules. Various analytical methods, including chromatographic analysis (HPLC-MS/MS), electrophoretic analysis (SDS-PAGE), spectroscopic analysis (spectrofluorimetry, Fourier transform infrared spectroscopy, and Raman spectroscopy), and isothermal titration calorimetry (ITC), were applied for the description of protein–cyclitol interactions. Additionally, computational calculations were performed to predict the possible binding places. Kinetic studies allowed us to clarify interaction mechanisms that may take place during BSA and cyclitol interaction. The results allow us, among other things, to evaluate the impact of the cyclitol’s structure on the character of its interactions with the protein.

Formulation strategies in immunotherapeutic pharmaceutical products

Development of immunologic-based biopharmaceutical products have strikingly increased in recent years and have made evident contributions to human health. Antibodies are the leading entity in immunotherapy, while chimeric antigen receptor T cells therapies are the advent of a novel strategy in this area. In order to enable antibody candidates or cells available as products, formulation is critical in terms of stabilize molecules or cells to achieve practical shelf life, storage and handling conditions. Here we provide a concise and contemporary review of ongoing formulation strategies and excipients used in approved antibodies and cellular therapeutic products. Excipients are categorized, and their function in formulations are discussed.

Kappa-on-Heavy (KoH) bodies are a distinct class of fully-human antibody-like therapeutic agents with antigen-binding properties

We describe a Kappa-on-Heavy (KoH) mouse that produces a class of highly diverse, fully human, antibody-like agents. This mouse was made by replacing the germline variable sequences of both the Ig heavy-chain (IgH) and Ig kappa (IgK) loci with the human IgK germline variable sequences, producing antibody-like molecules with an antigen binding site made up of 2 kappa variable domains. These molecules, named KoH bodies, structurally mimic naturally existing Bence-Jones light-chain dimers in their variable domains and remain wild-type in their antibody constant domains. Unlike artificially diversified, nonimmunoglobulin alternative scaffolds (e.g., DARPins), KoH bodies consist of a configuration of normal Ig scaffolds that undergo natural diversification in B cells. Monoclonal KoH bodies have properties similar to those of conventional antibodies but exhibit an enhanced ability to bind small molecules such as the endogenous cardiotonic steroid marinobufagenin (MBG) and nicotine. A comparison of crystal structures of MBG bound to a KoH Fab versus a conventional Fab showed that the KoH body has a much deeper binding pocket, allowing MBG to be held 4 Å further down into the combining site between the 2 variable domains.

Application of circular dichroism and magnetic circular dichroism for assessing biopharmaceuticals formulations photo-stability and small ligands binding properties

Synchrotron radiation circular dichroism (SRCD) is a powerful tool for photo-stability assessment of proteins. Recently our research has been interested in applying SRCD to develop screening methodologies for accelerated photo-stability assessment of monoclonal antibody formulations. Despite it was proven to be reliable and applicable within a wide range of salts and excipients containing solutions, the presence of far-UV (<260nm) strong absorbing species (e.g., sodium chloride, histidine, arginine) in common formulations completely prevent the analysis. Herein, we propose a new method based on CD coupled with magnetic CD (MCD) to address the problem and offer an additional versatile tool for monitoring the photo-stability. This is done by assessing the stability of the samples by looking at the near-UV band, as well as giving insights in the denaturation mechanism. We applied this method to four mAbs formulations and correlated the results with dynamic light scattering data. Finally, we applied MCD in ligand interaction to key proteins such as lysozyme, comparing the human with the hen enzyme in the binding of N,N',N''-triacetylchitotriose.

Interactions of formulation excipients with proteins in solution and in the dried state

A variety of excipients are used to stabilize proteins, suppress protein aggregation, reduce surface adsorption, or to simply provide physiological osmolality. The stabilizers encompass a wide variety of molecules including sugars, salts, polymers, surfactants, and amino acids, in particular arginine. The effects of these excipients on protein stability in solution are mainly caused by their interaction with the protein and the container surface, and most importantly with water. Some excipients stabilize proteins in solution by direct binding, while others use a number of fundamentally different mechanisms that involve indirect interactions. In the dry state, any effects that the excipients confer to proteins through their interactions with water are irrelevant, as water is no longer present. Rather, the excipients stabilize proteins through direct binding and their effects on the physical properties of the dried powder. This review will describe a number of mechanisms by which the excipients interact with proteins in solution and with various interfaces, and their effects on the physical properties of the dried protein structure, and explain how the various interaction forces are related to their observed effects on protein stability.

High-throughput measurement, correlation analysis, and machine-learning predictions for pH and thermal stabilities of Pfizer-generated antibodies

Generating stable antibodies is an important goal in the development of antibody-based drugs. Often, thermal stability is assumed predictive of overall stability. To test this, we used different internally created antibodies and first studied changes in antibody structure as a function of pH, using the dye ANS. Comparison of the pH(50) values, the midpoint of the transition from the high-pH to the low-pH conformation, allowed us for the first time to rank antibodies based on their pH stability. Next, thermal stability was probed by heating the protein in the presence of the dye Sypro Orange. A new data analysis method allowed extraction of all three antibody unfolding transitions and showed close correspondence to values obtained by differential scanning calorimetry. T(1%) , the temperature at which 1% of the protein is unfolded, was also determined. Importantly, no correlations could be found between thermal stability and pH(50) , suggesting that to accurately quantify antibody stability, different measures of protein stability are necessary. The experimental data were further analyzed using a machine-learning approach with a trained model that allowed the prediction of biophysical stability using primary sequence alone. The pH stability predictions proved most successful and were accurate to within pH ±0.2.

Use of Microcalorimetry and Its Correlation with Size Exclusion Chromatography for Rapid Screening of the Physical Stability of Large Pharmaceutical Proteins in Solution

The utility of microcalorimetry as a rapid screening tool for assessing the solution stability of high molecular weight pharmaceutical proteins was evaluated by using model recombinant antibodies, Protein I and Protein II. Changes in the transition midpoint, T(m), were monitored as a function of pH and/or in the presence of excipients, and results were compared with traditional accelerated stability data from samples that were analyzed by size exclusion chromatography (SEC). The data from microcalorimetry were well correlated with those from SEC for predicting both optimal solution pH as well as excipient effects on solution stability. These results indicate that microcalorimetry can be an efficient screening tool useful in identifying optimal pH conditions and excipients to stabilize pharmaceutical proteins in solution formulations.

The RNA continent

Recent progress in the analyses of the mouse transcriptome leads to unexpected discoveries. The mouse genomic sequences read by RNA polymerase II may be six times more than previously expected for human chromosomes. The transcript-abundant regions (named "transcription forests") occupy more than half of the genomic sequence and are divided by transcript-scarce regions (transcription deserts). Many of the coding mRNAs may have partially overlapping antisense RNAs. There are transcripts bridging several adjacent genes that were previously regarded as distinct ones. The transcription start sites appearing as cap analysis of gene expression (CAGE) tags are mapped on the mouse genomic sequences. Distributions of CAGE tags show that the shapes of mammalian gene promoters can be classified into four major categories. These shapes were conserved between mouse and human. Most of the gene has exonic transcription start sites, especially in the 3' untranslated region (3' UTR) sequences. The term "RNA continent" has been invented to express this unexpectedly complex and prodigious mouse transcriptome. More than a half of the RNA polymerase II transcripts are regarded as noncoding RNAs (ncRNAs). The great variety of ncRNAs in mammalian transcriptome implies that there are many functional ncRNAs in the cells. Especially, the evolutionarily conserved microRNAs play critical roles in mammalian development and other biological functions. Moreover, many other ncRNAs have also been shown to have biological significant functions, mainly in the regulation of gene expression. The functional survey of the RNA continent has just started. We will describe the state of the art of the RNA continent and its impact on the modern molecular biology, especially on the cancer research.

Thermodynamic stability and formation of aggregates of human immunoglobulin G characterised by differential scanning calorimetry and dynamic light scattering

The final process step of polyclonal human immunoglobulin G is formulation with agents such as sugars, polyols, amino acid and salts. Often the most stable formulations were empirically identified. Physicochemical methods, such as differential scanning calorimetry and dynamic light scattering, provide a deeper insight on the biophysical properties of such a protein solution. The combination of these methods proved to be sensitive enough to detect fine differences in the properties relevant for the development of stable protein solutions. The influence of additives, such as maltose and glycine in combination with water or low concentrations of salts, on human immunoglobulin preparations was analysed. Differential scanning calorimetry illustrated that 0.2 M glycine had better stabilising effects compared to 10% maltose. Dynamic light scattering and differential scanning calorimetry revealed that solutions preventing aggregation were not optimal in terms of thermodynamic stability. Aggregation was minimised with increasing ionic strength, shown by dynamic light scattering, whereas thermodynamic stability for heat sensitive parts of human immunoglobulin G, analysed with differential scanning calorimetry, was decreased.

Protein aggregation and its inhibition in biopharmaceutics

Protein aggregation is arguably the most common and troubling manifestation of protein instability, encountered in almost all stages of protein drug development. Protein aggregation, along with other physical and/or chemical instabilities of proteins, remains to be one of the major road barriers hindering rapid commercialization of potential protein drug candidates. Although a variety of methods have been used/designed to prevent/inhibit protein aggregation, the end results are often unsatisfactory for many proteins. The limited success is partly due to our lack of a clear understanding of the protein aggregation process. This article intends to discuss protein aggregation and its related mechanisms, methods characterizing protein aggregation, factors affecting protein aggregation, and possible venues in aggregation prevention/inhibition in various stages of protein drug development.

Human intravenous immunoglobulin preparation and virus inactivation by pasteurization and solvent detergent treatment

Human intravenous immunoglobulin (IVIG) solutions were prepared by two different methods and compared to each other. The crude immunoglobulin fraction obtained from Cohn-Oncley fractionation of plasma was further purified and subjected to virus inactivation, either by polyethylene glycol precipitation and pasteurization at 60 degrees C for 10 hours, or by ion exchange chromatography and solvent/detergent treatment. The final preparations, formulated in 5% immunoglobulin solutions were characterized by in vitro analyses of biochemical and biological properties and compared with the samples of other manufacturer's IVIG solution products. The critical properties evaluated in this study were purity, molecular intactness, and the biological functions such as Fc function and anticomplementary activity. Virus inactivation and removal by processing steps and by deliberate virucidal steps, as described above, were tested on various human pathogenic viruses, such as human immunodeficiency and experimental model viruses. The tested viruses were successfully inactivated and removed. We conclude that the intravenous immunoglobulins prepared by two different methods, as described above, provide an equivalent viral safety and quality.

Instability, stabilization, and formulation of liquid protein pharmaceuticals

One of the most challenging tasks in the development of protein pharmaceuticals is to deal with physical and chemical instabilities of proteins. Protein instability is one of the major reasons why protein pharmaceuticals are administered traditionally through injection rather than taken orally like most small chemical drugs. Protein pharmaceuticals usually have to be stored under cold conditions or freeze-dried to achieve an acceptable shelf life. To understand and maximize the stability of protein pharmaceuticals or any other usable proteins such as catalytic enzymes, many studies have been conducted, especially in the past two decades. These studies have covered many areas such as protein folding and unfolding/denaturation, mechanisms of chemical and physical instabilities of proteins, and various means of stabilizing proteins in aqueous or solid state and under various processing conditions such as freeze-thawing and drying. This article reviews these investigations and achievements in recent years and discusses the basic behavior of proteins, their instabilities, and stabilization in aqueous state in relation to the development of liquid protein pharmaceuticals.