Background/Purpose: Iguratimod is a new small-molecular drug for rheumatoid arthritis (RA), which was approved on June, 2012 in Japan. The agent inhibits the production of immunoglobulins and various inflammatory cytokines (interleukin-1, -6 and -8 and TNF), and exerts anabolic effects on bone metabolism by stimulating osteoblastic differentiation and inhibiting osteoclastogenesis in mice through inhibiting the nuclear transcription factor NF-κB, but not its inhibitor, IκBα. In addition this agent is very cheap (1.5$/25 mg tablet) , so 50 mg/day iguratimod therapy costs only 3$/day. In this study, We evaluate the efficacy and safety of iguratimod for RA patients. In addition, We examine NK cell counts compared with tofacitinib to evaluate the mechanism of the safety.

Methods: 62 patients who were administered iguratimod at a dosage of 25mg qd during the first month, then 50mg qd thereafter, and followed up for 24 weeks were enrolled. Efficacy and safety were evaluated utilizing clinical and laboratory findings. We also monitor the NK cell counts in peripheral blood from 20 RA patients before and 12 weeks after the commencement of Iguratimod by flow cytometery analysis.

Results: The mean age was 61.6 years and 75.8% of patients were female. MTX was used in 46.8%, the average dose was 8.6±2.9 mg/week. LOCF analysis revealed that DAS28-ESR and SDAI decreased significantly from 4.49±1.33 to 3.09±1.12 and from 18.5±10.9 to 7.44±7.11 in 24 weeks respectively (P<0.01). Remission and LDA rate in SDAI were 30.4% and 47.8%.  HAQ-DI score also decreased from 1.2±0.8 to 0.94±0.85.The difference between the efficacy of igurarimod with and without MTX was not significant. 29.0% of the patients discontinued iguratimod within 24 weeks. The reason of cessation consisted of adverse events (21.0%) and lack of efficacy (4.8%). Adverse events were digestive symptom (n=6), liver dysfunction (n=3), nasal hemorrhage (n=2) and so on. There’s no severe adverse event. Peripheral NK cell counts in 12 weeks had not been changed significantly. 

Conclusion: Iguratimod was well tolerable and may have a good cost effectiveness. So iguratimod be a new useful option as small molecule DMARDs for RA patients in a manner similar to tofacitinib.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-and-safety-of-iguratimod-for-rheumatoid-arthritis/