Proteins, which are the active ingredients of biopharmaceuticals, have large molecular weights and complex structures compared to chemical substances. Various physical and chemical changes of proteins occur in the process of manufacturing, storage, transportations and medical practice, which may lead to decrease of biological activity and aggregate formation, ultimately affecting the efficacy and safety of the products. Stability data are essential information for determining key elements of control strategies, such as molecular design, formulation design, primary packaging, and manufacturing processes, and are the basis for establishing product shelf-life. Developing next-generation antibodies with high medical importance and revolutionary properties tends to be required to shorten the development period. Thus, it is necessary to accumulate data on stability as early as possible in the development stage, and to understand possible physical and chemical changes quantitatively and qualitatively. However, the accumulation of stability data requires mush resources and time. Particularly it takes years to acquire stability data for setting the shelf-life, which is one of obstacles to rapid development. Therefore, it is highly expected that new technologies will be developed and utilized, such as methods for predicting stability of proteins using statistical analysis and predicting models from existing data and/or data obtained in a short period of time during accelerated tests. In this paper, we review the background, current situation, and general issues regarding stability evaluation of biopharmaceuticals, and discuss future issues.

In the production of biotechnological products, cell substrates established by introducing the expression construct into animal or microbial cells are used. Since the properties of cell substrates affect resultant product quality and safety, establishing an appropriate cell substrate for use in manufacturing is of quite importance for ensuring the quality of the final product. ICH Q5B and Q5D guidelines provide the basic concepts for the analysis of gene expression constructs and the establishment and characterization of cell banks. Since both guidelines were developed more than 20 years ago, there have been various technological innovation and accumulation of relevant knowledge. In this review, in order to contribute to the efficient development and manufacture of biotechnological products such as next-generation therapeutic antibodies, an overview of existing ICH guidelines for establishment, characterization, and control of cell substrates used in the production of biotechnological products is provided. In addition, methods for the evaluation and basic concepts for control of cell substrate clonality and product sequence variants are introduced based on the international trends and the discussion in AMED research group.