Antibody drugs have heterogeneity, and therefore, the evaluation of the physical properties of antibodies are required to obtain the accurate amount of the target protein as an active ingredient and its impurities for the control of drug substances. Furthermore, it is also important to investigate the physical properties of the antibody that affects the stability of the pharmaceutical product, such as the antibody characteristics that suppress the aggregation in the phase of the development of new antibody candidates. In this review, we will introduce several techniques to evaluate the physical properties of antibody, which is necessary for the quality control of the drug substance, namely, the protein concentration, viscosity, and its binding ability to antigens and receptors, as well as the physical properties of antibody that affect the stability of the biopharmaceutical products, namely, structural stability, colloidal stability, surface potential, and particle size, with brief introduction of the implication of each parameters.

View full abstract

Therapeutic monoclonal antibodies （mAbs） undergo several modifications including deamidation, isomerization, oxidation and glycosylation during cell culture, purification, formulation and storage. Some modifications are associated to biological activities, pharmacokinetics, and stability of mAbs. To ensure quality of mAbs it is important to establish control strategy ensuring that the structural properties, of which the change has potential impacts on efficacy or safety, are within an appropriate limit, range or distribution. Structural evaluation methods for mAbs using several chromatographic techniques have been successfully established to date. However, many of these conventional methods usually only evaluate a kind of quality attribute of mAbs, and therefore, complicated and time-consuming multiple tests have been required to perform for a comprehensive characterization of mAbs. Currently, integration and simplification of the multiple tests is in the spotlight in the biopharmaceutical industry. A quantitative characterization method called multi-attribute method （MAM） by peptide mapping technique using liquid chromatography/high resolution mass spectrometry is attracting attention in lieu of the conventional methods. MAM can provide detailed qualitative and quantitative information about the multiple structural aspects, and process and product-related impurities by only single measurement. Recently, several MAM solutions have been provided by mass spectrometer and software vendors, and is gradually becoming popular in regulatory authorities as well as the industry. This article provides brief review of common modifications of mAbs, overview and issues of MAM, and the current status of MAM analysis.

View full abstract

Dissociation of DNA into its respective oligonucleotides was analyzed using differential scanning calorimetry, and association of oligonucleotides to form DNA was analyzed using isothermal titration calorimetry. Both the melting temperature and calorimetric enthalpy change increased with increase in chain length. Under the different concentrations of NaCl, 20 mM, 140 mM, and 250 mM, the melting temperature increased with increase in ionic strength, possibly due to the decrease of electrostatic repulsion. At 25℃, the association of 10-base oligonucleotides largely depended on ionic strength, however, for oligonucleotides of 12-base and above, association was independent of ionic strength. Both binding enthalpy and entropy changes decreased with increase in chain length, providing similar binding affinity. The highest association constant was approximately 1×10⁹ M^–1. The binding enthalpy change gradually decreased with increase in temperature around 25℃, followed by increasing, close to the melting temperature. The temperature-dependent binding enthalpy change was apparently extrapolated to the calorimetric enthalpy change of DNA at the melting temperature. Effects of DNA and ionic strength on thermal stability of DNA-binding protein, c-Myb R2R3, were also evaluated. Both the melting temperature and calorimetric enthalpy change of R2R3 increased upon the DNA binding, indicating that the DNA binding strengthened the intramolecular interactions. The thermal stability of R2R3 increased with increasing NaCl concentrations. The DNA-binding affinity of R2R3 decreased both with an increase or decrease in NaCl concentration from the physiological levels. The decreased DNA-binding affinity under low NaCl concentrations was due to the unfavorable entropy change, which would closely correlate with the structural dynamics of molecules.

View full abstract

The prospect of developing novel oligonucleotide therapeutics through the practical use of mRNA vaccines during the COVID-19 pandemic are increasing rapidly. Because most of the proteins and nucleic acids that are targets of oligonucleotide therapeutics, such as antisense oligonucleotides, aptamers, and CpG oligodeoxynucleotides, localize inside cells, it is important to control the interaction between oligonucleotides and their target molecules in the intracellular environment to ensure proper function. The structural flexibility of oligonucleotides is higher than that of small chemical compounds and proteins; oligonucleotides change their structure and topology depending on the nucleotide sequence and surrounding conditions. The guanine quadruplex structure, formed by guanine-rich oligonucleotides, dynamically changes its structure in response to the surrounding conditions, and plays an important role in regulating cellular function. In this paper, we review the fundamental characteristics of the guanine quadruplex structure, and methods for analyzing the topology of oligonucleotides, and introduce the application of guanine quadruplex-based oligonucleotide to novel oligonucleotides therapeutics.

View full abstract

The manufacturing of regenerative medicine product consists of variety of processes in upstream, downstream, and outer-stream. Features inherent in cell processing cause the fluctuation of process and the instability of final product quality, requiring a novel doctrine. This article describes the features of cell processing as well as product quality and the importance of the design of cell manufacturability. In addition, the stability of the cells as final product is analyzed in the process of cell dispensing and freezing, determining the lot size of the product with simple indices for cell survival. This evidence confirms the importance of design and systematization of cell processing based on the cell manufacturability.

View full abstract

In addition to explaining the outline of quality control of regenerative medical products, in this article, the management of raw materials derived from humans and animals, the quality control items of final products, the stability evaluation, and the evaluation of impurities derived from the manufacturing process are discussed.

View full abstract

Antibody-drug conjugate（ADC） represents a promising class of pharmaceutical with a wide therapeutic index due to highly efficient and selective drug delivery. We have developed a novel drug-linker technology with a potent camptothecin derivative. Using this technology, we generated a new anti-HER2 ADC named trastuzumab deruxtecan（T-DXd）. We stably supply of this drug by performing high level quality control on complex constituents as antibody, drug-linker, and both by selecting formulation, forms, vials, and packing. T-DXd was approved for breast cancer and gastric cancer with HER2 expression, as a new treatment option. However, it is necessary to use it while carefully monitoring side effects such as interstitial lung disease and so on in clinical settings.

View full abstract