Clinical safety of biosimilar recombinant human granulocyte colony-stimulating factors.

INTRODUCTION: A 'biosimilar', or 'similar biological medicinal product', is a biologic agent that is similar in terms of quality, safety and efficacy to an authorized reference biological medicine. Since the expiration of the filgrastim patent in Europe, three agents have received marketing authorization from the EMA: Tevagrastim, Zarzio and Nivestim. Tevagrastim has also been approved as a biologic by the FDA as tbo-filgrastim. AREAS COVERED: Using the EMA dossiers (all three agents), the FDA dossier (Tevagrastim), and journal publications, this article reviews clinical safety data for these products with emphasis on serious/severe adverse events and special consideration of immunogenicity, bone pain, splenomegaly, allergic reactions, acute respiratory distress syndrome and mortality. EXPERT OPINION: All three agents have similar safety profiles. None were statistically higher on safety parameters to what is known about originator filgrastim (Neupogen). What is known about filgrastim in general regarding safety can be extended to biosimilar filgrastim. Safety profiles may become more differentiated once long-term product-specific safety data are available. Large-sample, long-term, observational studies of real-world practice will provide the heterogeneity and statistical power to demonstrate product-specific safety profiles. Current evidence indicates that statistically no one product is less and no one product is more safe.