Biosimilars: controversies as illustrated by rhGH

Abstract

Background and scope:Similar biological medicinal products, also called ‘biosimilars’, are copies of biopharmaceutical products whose patent has expired. Whether biosimilars are truly comparable and interchangeable with their reference biopharmaceutical products in terms of quality, efficacy and tolerability, is still a matter of debate. This review discusses the controversies related to the criteria for regulatory approval of biosimilars. These concerns are illustrated using recombinant human growth hormone (rhGH) biosimilars as an example.Methods:Publications on the regulatory approval of biosimilars in general and rhGH biosimilars in particular were searched in MEDLINE by exploding and combining the medical subject heading terms ‘human growth hormone’, ‘efficacy’ or ‘safety’ and the free-text words ‘biosimilar’, ‘biopharmaceutical’, ‘similar biological medicinal product’, ‘follow-up biologic’ or ‘biogeneric’. Searches were limited to full-text English-language articles. The websites from the European Medicines Agency (EMA) and from the American Food and Drug Administration were also consulted.Regulatory status:To obtain regulatory approval of a biosimilar product by EMA, demonstration of comparability with an approved reference biopharmaceutical product in terms of quality, efficacy and tolerability is needed. Thus, comparative quality studies, non-clinical and clinical efficacy and tolerability studies are required. However, in contrast to the reference product, comparative non-clinical pharmacokinetics, safety pharmacology, reproduction toxicology, mutagenicity and carcinogenicity studies are not mandatory to obtain approval of a biosimilar. In addition, comparable efficacy and tolerability only needs to be established by one study in a single population during a limited time interval (12 months) and often allows extrapolation to all other approved indications of the reference product. Consequently, for the currently approved rhGH biosimilars, long-term efficacy and tolerability in all indications has not been proven to the same degree as for the reference products.Conclusions:The validity of the current criteria for comparability and interchangeability of biosimilars and their reference products remains controversial. The authors conclude that long-term clinical investigations and systematic monitoring of the efficacy and tolerability of rhGH biosimilars in all indications are needed. In addition, the medico-economical environment should allow physicians to take a free and informed decision about the type of rhGH to be prescribed.