The differential effects of upadacitinib treatment on skin rashes of four anatomical sites in patients with atopic dermatitis

Background Upadacitinib is an oral Janus kinase (JAK) 1 inhibitor approved in Japan for moderate-to-severe atopic dermatitis (AD), and it provides a high therapeutic efficacy. Objectives We compared the therapeutic effects of upadacitinib on skin rashes of individual anatomical sites, head and neck, upper limbs, lower limbs, and trunk in patients with AD. Methods From August 2021 to December 2022, 65 Japanese patients with moderate-to-severe AD (aged ≥ 12 years) were treated with oral once daily upadacitinib 15 mg plus twice daily topical corticosteroids of moderate-to-strongest classes. Results The eczema area and severity indexes (EASIs) of individual sites decreased significantly at weeks 4, 12, and 24 compared to those at week 0 in parallel to total (whole body) EASI. The achievement rates of EASI 75 at week 24 and of EASI 90 at week 12 of lower limbs were significantly higher than those of trunk. The percent reductions of EASI of lower limbs at weeks 12 and 24 were significantly higher than those of head and neck and of trunk. Conclusions Among the four anatomical sites, the treatment responsiveness to upadacitinib in lower limbs appeared the highest, while those in trunk and in head and neck appeared relatively lower.