Asian Journal of Immunology

Iguratimod is a small novel compound considered as a disease-modifying anti-rheumatic drug (DMARD), which exhibits anti-inflammatory and immunomodulatory effects. Iguratimod acts directly on B cells by inhibiting the production of inflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-8, IL-17), thereby suppressing the production of immunoglobulin and inhibiting the activity of nuclear factor kappa-light chain enhancer of activated B cells. Preclinical studies demonstrate its positive impact on arthritis models in animals by reducing immunoglobulin production and various inflammatory cytokines. Iguratimod demonstrates its efficacy as well as tolerance when used as an additional therapy for rheumatoid arthritis patients who exhibit an insufficient response to both methotrexate and biological disease-modifying anti-rheumatic drugs. Additionally, iguratimod was found to possess an anabolic effect on bone metabolism, through both stimulations of osteoblastic differentiation and inhibition of osteoclastogenesis.

Further, the mechanism also involves suppressing nuclear factor kappa B (NF-κB) activation without blocking NF-κB inhibitor α (IκBα) degradation. Although the true target molecules of iguratimod have been unclear, it would be necessary to suppose the multiple mechanisms including suppression of NF-κB. Clinical trials of rheumatoid arthritis patients have shown more effectiveness and tolerability when compared to salazosulfapyridine, making iguratimod a promising DMARD with unique novel properties and positive clinical outcomes. Further research will determine its suitability as an alternative for patients unable to use biologics.