General characteristics of clinical trials for biosimilar drugs

Abstract

Biosimilar is a highly similar product to biological reference medicinal product. The development, licensing and clinical use of these products differ from the implementations of conventional drugs, which were shaped on the concept of equivalence, in various aspects. Negative attitudes towards generic drugs, many of which are thought to be based on lack of knowledge, are still substantial. There is concern that the problem may reach more critical levels in the use of biosimilars, which are known to be more complex compared to generics. Knowing the prominent critical aspects of the development process of the biosimilars may contribute to the solution of this problem that causes significant difficulties in practice. In all conventional and biological products, the innovative drug research consist of the preclinical phase followed by the successive phases I-IV. The first three phases are carried out before the licensing. The clinical trials required for licensing of generics are limited to bioequivalence studies. However, in biosimilars, this process is more complex due to the nature of biological products. Adequate quality, clinical efficacy and safety data are needed on the basis of comparability of the biosimilar with the reference product. Phase I and III are generally required for biosimilarity, although it may vary per product. Although, these phases are perceived as classical phase studies, they differ considerably from those in the development process of reference drug in terms of design, purpose, content and flexibility. Approaches that do not pay attention to these details sufficiently might cause many problems such as the advantages of biosimilars being limited, ineffective implementation of risk management, loss of trust, delay in product supply, unfair competition, etc. The general characteristics of clinical trials and the details of the subject specifically for biosimilars are mentioned in this review article.