IL17A and rheumatoid arthritis: Moreover, Luo et al. compared the mode of action of iguratimod with classic RA DMARDs, i.e., MTX and leflunomide, and their study also suggested that iguratimod has a varied mode of action compared with MTX and leflunomide.22 Iguratimod directly suppresses mRNA expression of the Act1 gene, leading to disturbances in IL-17 pathways and ultimately reducing inflammation, either directly or by affecting IL-17-associated proinflammatory factors (Fig. 2).