Introduction: Biosimilars, as defined by the European Medicines Agency, have been used in Europe since 2006. The landscape was considerably expanded when the first biosimilar of a monoclonal was approved and introduced in the European market. CT-P13 was developed by Celltrion as an infliximab biosimilar in 2013, not without controversy. As these complex molecules cannot be completely identical, some experts, clinicians, and even patients were skeptical regarding the real bioequivalence of the drugs. Currently, several new infliximab and adalimumab biosimilars are available or will reach the market in a few months. Areas covered: Our goal is to review, mainly from a clinical perspective, the available evidence for bioequivalence of anti-TNF biosimilars. We aim to take into account not only preclinical studies, mostly done for regulatory issues, but also data from clinical studies. Expert opinion: We can conclude that bioequivalence with originator is well demonstrated in those drugs which have followed European Medicines Agency regulatory pathways. Switching from originator to biosimilar appears safe for all indications. However, there are few data available for switching from one biosimilar to another, or for complete interchangeability. Prospective studies and strict pharmacovigilance are recommended.
Keywords: Infliximab; adalimumab; anti-TNF; bioequivalence; biosimilar; switching.