Abstract
Treatment for rheumatoid arthritis (RA) has dramatically developed by the usage of biologics. Better clinical efficacy can be achieved by setting a clear treatment goal with the usage of methotrexate as an anchor drug in combination with biologics. However, biologics requires parenteral administration and long-lasting treatment is necessary in most patients. Therefore an orally available anti-rheumatic drug with similar efficacy with biologics has been desired. Tofacitinib is an oral medicine as effect as biologics and was approved in Japan at March2013. Unsurprisingly, adverse events with a different profile from biologics have been observed in the clinical trials. Most of all,2～4fold increase compared to pre-existing biologics was observed in herpes zoster. Surprisingly, it was increased in Asian population especially in Japan and Korea. Incidence of malignancy was similar to biologics, however rare malignancy such as sarcoma has been observed. It is conceivable that suppressed lymphocytes such as CD4＋,CD8＋ and natural killer cells are involved in these events. Evaluation of patients in our department revealed that low CD8＋T cell count prior to treatment with tofacitinib was a risk factor for infectious adverse events. This indicates the possibility of patient selection suitable for treatment with tofacitinib. Therefore, the results from the post-marketing study will be important and we should keep an eye on it.
