Janus kinase inhibitor—Tofacitinib associated with pemphigus: an analysis of the FDA adverse event reporting system data

To establish the association between the therapy of Janus kinase inhibitors and the adverse event of pemphigus in patients with rheumatologic and inflammatory disorders.A disproportionality analysis using multi-item gamma Poisson shrinker was conducted to identify signals between medication and adverse events within the FDA Adverse Event Reporting System.The spontaneous reporting system contained 3,032 pemphigus reports associated with two Janus kinase inhibitors, namely Tofacitinib and Upadacitinib. The year/reporter/geographic area/country/age/sex/indication with the highest number of cases were the year of 2021, physician, North America, Canada, age between 40-49, female and rheumatoid arthritis, respectively. A significant signal was detected in the Tofacitinib group.Pemphigus, a rare and potentially fatal adverse event, was found to occur more frequently in patients receiving Tofacitinib. High-risk individuals were identified as female, age between 40-49, or with rheumatoid arthritis. Medication, adverse events, and underlying disease conditions were identified as potential contributing factors. Rheumatology and dermatology specialists should exercise increased vigilance in clinical practice.What is already known on this topic – Orally administered Janus kinase inhibitors exhibit similar therapeutic efficacy and side effects as biologic agents.What this study adds – The association between the therapy of Janus kinase inhibitors and the adverse event of pemphigus in patients with rheumatologic and inflammatory disorders was confirmed through this study using real-world data.How this study might affect research, practice or policy. The absence of annotation regarding this topic in package inserts, guidelines, or expert consensus highlights the importance of clinical providers paying attention to high-risk patients. Early recognition and management may reduce the aggravation of the adverse event, benefitting these patients.