Biosimilars--global issues, national solutions.

Biotechnology derived medicinal products are presently the best characterized biologicals with considerable production and clinical experience, and have revolutionized the treatment of some of the most difficult-to-treat diseases, prolonging and improving the quality of life and patient care. They are also currently one of the fastest growing segments of the pharmaceutical industry market. The critical challenge that the biopharmaceutical industry is facing is the expiry of patents for the first generation of biopharmaceuticals, mainly recombinant DNA derived products, such as interferons, growth hormone and erythropoetin. The question that immediately arose was how should such copies of the originator products be licensed, bearing in mind that they are highly complex biological molecules produced by equally complex biological production processes with their inherent problem of biological variability. Copying biologicals is much more complex than copying small molecules and the critical issue was how to handle the licensing of products if relying in part on data from an innovator product. Since 2004 there has been considerable international consultation on how to deal with biosimilars and biological copy products. This has led to a better understanding of the challenges in the regulatory evaluation of the quality, safety and efficacy of "biosimilars", to the exchange of information between regulators, as well as to the identification of key issues. The aim of this article is to provide a brief overview of the scientific and regulatory challenges faced in developing and evaluating similar biotherapeutic products for global use. It is intended as an introduction to the series of articles in this special issue of Biologicals devoted to similar biotherapeutic products.