Biosimilars for the treatment of psoriatic arthritis.

Introduction: In recent years, biosimilars of reference adalimumab (re-ADA), etanercept (re-ETN) and infliximab (re-IFX) have been licensed. In the absence of specific controlled studies, by the extrapolation principle, biosimilars have been approved for the treatment of psoriatic arthritis (PsA).Areas covered: To assess the efficacy and safety of biosimilars in PsA, the literature, present until 30 June 2019, was reviewed. The literature search was undertaken using the PubMed database to identify English-language papers focusing on biosimilar efficacy in PsA. No specific PsA study was found, and the results were retrieved from trials on different inflammatory rheumatic diseases that were also enrolling patients with PsA. Data on re-IFX biosimilar CT-P13 and re-ETN SB4 were found, but not on re-ADA biosimilars. The results showed a trend toward a reduced efficacy of biosimilars. However, considering the small number of PsA patients, the non-statistically-powered studies, and the inappropriate outcome measures, these results could have occurred by chance.Expert opinion: The few data do not allow to draw definitive conclusions, and emerging results suggest the need of specific trials, and of rigorous registries to evaluate the efficacy and safety of biosimilars in PsA.