Janus kinase 1 and 1/2 inhibitors for treating 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) treatment, yet tapering is challenging due to the risk of relapse. In this retrospective single-centre case series, we evaluated the effectiveness and safety of selective Janus kinase (JAK) inhibitors in facilitating CS tapering in patients with moderate-to-severe refractory DRESS and in ameliorating pruritus. Six patients (median age 35 years, range 9-70, five female) received baricitinib or abrocitinib with CS between July 2023 and June 2024. All achieved rapid clinical improvement, with generalized lesion resolution and a reduction in pruritus by > 3 points on the Worst Itch Numerical Rating Scale. Successful initial CS tapering occurred within 7-12 days. Four patients discontinued CS completely within 28-62 days, while two continued with low-dose CS due to primary autoimmune disease. Serum cytokines, particularly interleukin-5, decreased markedly following JAK inhibition. No severe adverse events occurred, including in patients with pancytopenia or hepatic dysfunction. JAK inhibitors appear to be effective and well-tolerated for promoting CS tapering in patients with refractory DRESS. Larger, controlled studies would be useful to confirm these findings.