Considering new lessons about the use of IL-6 inhibitors in arthritis

Abstract

Interleukin (IL)−6 represents one of several possible targets for the treatment of rheumatoid arthritis. Drugs targeting IL-6 can be divided into monoclonal antibodies against IL-6 itself and monoclonal antibodies against the IL-6 receptor. Both types of agent inhibit both classical signalling through membrane-bound IL-6 receptor, and trans-signalling via formation of a complex between IL-6 and soluble IL-6 receptor. The IL-6 receptor blockers tocilizumab and sarilumab inhibit the low affinity binding of IL-6 to its receptor. The anti-IL-6 agents clazakizumab and vobarilizumab also block binding of IL-6 to the receptor, while olokizumab blocks the higher affinity interaction of the IL-6-receptor complex with gp130. The doses and dosing intervals of the biologics targeting different elements vary, but no major differences in efficacy or safety have yet been seen between the two approaches, although more studies are needed in this area. In addition to the different blocking actions of monoclonal antibodies, we consider therapeutic strategies including the timing of IL-6 blockade and the use of monotherapy versus the addition of methotrexate.