PURPOSE OF REVIEW: Abbreviated pathways for the approval of biosimilars have been established in the European Union (EU), the United States, and other countries. Biosimilar TNF inhibitors have been available in South Korea and the EU since 2012 and 2013, respectively, and the first biosimilar infliximab was introduced to the clinic in the United States in November 2016. Five TNF inhibitor biosimilars have now been approved, and many other biosimilars to treat rheumatoid arthritis and other inflammatory diseases are in development.

RECENT FINDINGS: Over the last 18 months, published results of randomized clinical trials (RCTs) have shown equivalent efficacy and comparable safety and immunogenicity of biosimilars with their reference products. 'Real world' experience with biosimilars in the EU continues to increase and provides evidence regarding the efficacy and safety of using biosimilars in the clinic and of switching from bio-originators to their biosimilars.

SUMMARY: Cost implications of using biosimilars and extrapolation of their use to treat diseases in which they were not tested in RCTs are of great interest. We review the results of RCTs and available experience with biosimilars in the clinic.