Biosimilars to recombinant human FSH medicines: comparable efficacy and safety to the original biologic

Two recombinant follicle-stimulating hormone (rFSH)-bearing similar biological medicines (biosimilars) have been authorized by the European Commission. Biosimilar is a regulatory concept alluding to the evidence-based high-standard comparability studies needed to demonstrate its equivalence to a reference original biologic. Because biosimilar development represents a shift from the long-lasting existing paradigms, a thorough understanding of the science behind it will contribute to helping prescribers make informed treatment choices. Contrary to chemically-synthesized medicines, biologics are subject to an inherent molecular variability. From the experience with original biologics, regulatory authorities have accumulated a wealth of knowledge as to what minor batch-to-batch physicochemical variations may be therapeutically acceptable in a given product. Furthermore, in spite of analytically detectable differences, the two original rFSH-bearing medicines currently on the market share fundamentally the same therapeutic profile. Unlike those original medicines, a biosimilar of an rFSH product and the corresponding reference biologic share essentially the same active pharmaceutical ingredient. They are also administered via the same route, at the same dose, and for the same indications. This article revises the background evidence over which the biosimilarity principle has been built, and highlights the therapeutic potential for follitropin biosimilars in order to reassure physicians on their benefit.