IL-17 Inhibition in Axial Spondyloarthritis

Axial spondyloarthritis (axSpA) affects 0.5–1.5 % of western population. Although TNF inhibitor (TNFi) medications have dramatically improved the treatment of this disabling disease, there are almost 40 % of patients who do not respond or have intolerance to TNFi. Several genetic, animal model, translational, and clinical studies have confirmed the role of IL-23/IL-17 pathway in the pathogenesis of the axSpA. This axis could be targeted upstream by inhibiting either IL-23 or IL-23 receptor (IL-23R) or downstream by blocking IL-17 or IL-1RA receptor. Ustekinumab, a monoclonal antibody against p40 subunit of IL-12 and IL-23, and secukinumab, a monoclonal antibody against IL-17, have both demonstrated significant beneficial effect in controlling the disease activity, quality of life, and physical function as well as MRI scores in axSpA. Combined IL-17 and TNF-α blockade is a novel option for the patients with axSpA, which needs to be investigated further. We need prospective trials to evaluate the effect of IL-23/IL-17 axis manipulation on the radiographic progression and also on the extra-articular manifestations of axSpA.