Safety of Janus Kinase Inhibitors: A Real-World Multicenter Retrospective Cohort Study

. Objective. Oral Janus kinase inhibitors (JAKis) represent an effective strategy for rheumatoid arthritis (RA) treatment. A previous study supported that tofacitinib (TOF) is associated with higher incidence of cardiovascular (CV) and neoplastic events compared to tumor necrosis factor inhibitors. Given the apparent discrepancy between these data and real-world experience, we aimed to investigate the safety and efficacy of the available JAKis in a multicenter cohort. Methods. We retrospectively evaluated patients with RA who ever received 1 JAKi (TOF, baricitinib [BAR], upadactinib [UPA], filgotinib [FIL]) from 4 tertiary care centers in Milan, Italy. Outcomes related to JAKi safety were recorded, particularly major CV events as well as adverse events of special interest (AESIs), which liver injury, malignancies, and deaths; retention rates were also calculated. Further analyses included patients fulfilling the risk factors suggested to influence TOF safety. Results. Six hundred eighty-five patients were included and received BAR (48%), TOF (31%), UPA (14%), or FIL (7%) as first-line innovative treatment prior to a biologic. Of a total of 1137 patient-years of observation, we recorded 1 stroke and 123 (18%) AESIs, including 3 deaths, all a result of severe infections. Among patients with a higher CV risk, we observed a higher frequency of AESIs (23%). Conclusion. Our real-world data confirm that JAKis are effective and carry a low risk of AESIs, especially in patients who do not display CV risk factors at baseline. Our study could not identify differences between JAKis. Different safety profiles should be defined in larger prospective cohorts.