ABSTRACT
As more biologic products are going off patent protection, the development of follow-on biologics (biosimilars) products has received much attention from both biotechnology industry and the regulatory agencies. Unlike traditional small-molecule (chemical) drug products, the development of biologic products is very different and variable with respect to the manufacturing process and environment. The complexity and heterogeneity of the molecular structure; complicated manufacturing process; different analytical methods; and possibility of severe immunogenicity reactions make quantitative evaluation of follow-on biologics a great challenge to both the scientific community and regulatory agencies. In this chapter, an overview of current criteria, study design, and statistical methods for quantitative evaluation of bioequivalence for the traditional small molecule generic drug products and biosimilarity for biosimilars products is provided. In addition, a general approach for development of a biosimilarity index based on the concept of reproducibility probability for quantitative evaluation of bioequivalence/biosimilarity is proposed. Some scientific factors and practical issues are also discussed.
