Room for more IL-6 blockade? Sarilumab for the treatment of rheumatoid arthritis

Introduction: Rheumatoid arthritis (RA) treatment has been revolutionized by the development of highly efficacious biotherapeutics. However, a significant subset of RA patients has persistently active disease and ongoing erosive joint damage despite the available therapies. Sarilumab targets interleukin-6, one of the main cytokines mediating inflammation in RA. Positive results with sarilumab in RA clinical trials support the licensing application currently under review with the US Food and Drug Administration. Areas covered: The rationale for IL-6 targeting in RA, the pharmacologic properties of sarilumab, and the clinical trial results are reviewed focusing on the pending application for the RA indication. Comparisons with other IL-6 targeting biologics as well as additional potential therapeutic directions are discussed. Expert opinion: Sarilumab is a highly active therapeutic in patients with RA. While pharmacologic data demonstrate that sarilumab has a higher affinity than tocilizumab for the target receptor, available clinical results suggest that efficacy and adverse event profiles are similar to this other IL-6 blocker, which is currently approved for the treatment of RA. Whether there are other distinct differences or advantages of sarilumab that will support the approval and successful marketing of this drug, over existing therapies, remains to be determined.