Herpes Zoster in rheumatoid arthritis patients receiving tofacitinib, a single center experience from Taiwan

In clinical trials of tofacitinib for rheumatoid arthritis (RA), Japanese and Korean patients had higher incidence of herpes zoster (HZ) than subjects from elsewhere; however, post-market data from Asia are lacking. Hence, we investigated the incidence of HZ and its risk factors in Taiwanese RA patients receiving tofacitinib. At a medical center in Taichung, Taiwan, we enrolled patients with active RA treated with tofacitinib between January 4, 2015 and December 9, 2017, following unsuccessful methotrexate therapy and no tofacitinib exposure RA patients as a control group. Demographic characteristics, interferon-gamma levels, and lymphocyte counts were compared. Among 125 tofacitinib-treated RA patients, 7 developed HZ, an incidence rate of 3.6/100 person-years. Patients with HZ had shorter disease duration than those without, but higher frequency of prior HZ. Baseline interferon-gamma levels and HLA-DR(+) activated T cell counts were positively correlated and significantly lower in patients with HZ than without. Strikingly, 5/7 HZ cases occurred within 4 months of starting tofacitinib therapy. Incidence of HZ in tofacitinib-treated Taiwanese RA patients is lower than rates in Japan or Korea, and commensurate with the global average. HZ may occur soon after commencing tofacitinib therapy. The role of interferon-gamma and activated T cells in tofacitinib-related HZ deserves further investigation.