Efficacy and safety of baricitinib treatment for moderate to severe atopic dermatitis in real‐world practice in Japan

The authors evaluated the efficacy and safety of baricitinib, a Janus kinase 1/2 inhibitor, for atopic dermatitis (AD) in real-world practice. From August 2021 to September 2022, 36 patients aged ≥15 years with moderate to severe AD were treated with oral baricitinib 4 mg/day plus topical corticosteroids. Baricitinib improved clinical indexes; the percent reduction at weeks 4 and 12 was a median of 69.19% and 69.98% for the Eczema Area and Severity Index (EASI), 84.52% and 76.33% for the Atopic Dermatitis Control Tool, and 76.39% and 64.58% for Peak Pruritus Numerical Rating Score, respectively. The achievement rate of EASI 75 was 38.89% and 33.33% at weeks 4 and 12, respectively. The percent reduction of EASI in the head and neck, upper limbs, lower limbs, and trunk was 56.9%, 68.3%, 80.7%, and 62.5% at week 12, respectively, with a significant difference between the head and neck versus the lower limbs. Baricitinib decreased thymus and activation-regulated chemokine, lactate dehydrogenase, and total eosinophil count at week 4. Baseline EASI of the head and neck negatively correlated with percent reduction of EASI at week 4, while baseline EASI of the lower limbs positively correlated with percent reduction of EASI at week 12. Treatment-emergent adverse events included elevation of creatine phosphokinase (11.1%), herpes labialis (5.6%), furuncle (8.3%), and exacerbation of AD (1%), without serious treatment-emergent adverse events. In this real-world study, baricitinib was well tolerated for patients with AD and achieved therapeutic effects comparable to those in clinical trials. High baseline EASI of the lower limbs might predict good treatment response at week 12, while high baseline EASI of the head and neck might predict poor treatment response at week 4 in baricitinib treatment for AD.