JAK1 or JAK1/2 inhibitors in Drug Reaction with Eosinophilia and Systemic Symptoms: A case series

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe drug-induced hypersensitivity reaction often requiring prolonged corticosteroid (CS) therapy, yet tapering is difficult due to relapse. This retrospective single-center case series evaluated the efficacy and safety of selective JAK inhibitors in facilitating CS tapering in moderate-to-severe, refractory DRESS, and in ameliorating pruritis. Six patients (median age 35 years; five females) received baricitinib or abrocitinib with CS between July 2023 and June 2024. All achieved rapid clinical improvement, with generalized lesion resolution and pruritus reduction by more than three WI-NRS points. Successful initial CS tapering occurred within 7∼12 days, and four patients discontinued CS completely within 28∼62 days, two stayed with low-dose CS due to primary autoimmune disease. Serum cytokines, particularly interleukin-5, decreased markedly after JAK inhibition. No severe adverse events occurred, including in patients with pancytopenia or hepatic dysfunction. JAK inhibitors appear effective and well-tolerated in promoting CS tapering in refractory DRESS, suggesting larger controlled studies are needed.