Abstract: 【Abstract】 Objective To evaluate the efficacy and safety of baricitinib in the treatment of moderate-to-severe atopic dermatitis （AD）. Methods From June 2020 to June 2021, patients with moderate-to-severe AD who were insensitive or intolerant to topical agents were enrolled from Department of Dermatology, Peking University First Hospital. Before treatment, the patients were evaluated by 4 scales, including the Investigator′s Global Assessment （IGA）, Eczema Area and Severity Index （EASI）, Itch Numeric Rating Scale （NRS）, and Dermatology Life Quality Index （DLQI）; meanwhile, photos of skin lesions were taken, routine blood test was performed, blood biochemical indices and total IgE levels were measured. After exclusion of contraindications, the patients were treated with oral baricitinib at a dose of 2 mg/d for 16 weeks. Regular follow-up was conducted at weeks 1, 2, 4, 8, 12, 16 and 20 after the start of treatment, clinical evaluation was carried out with the above 4 scales, and adverse events were recorded during the treatment. Results A total of 24 patients were enrolled in the study, and all completed 16-week oral treatment and 20-week follow-up. All the 4 scale scores showed a continuous downward trend within 20 weeks after the start of treatment. At week 20, the patients′ IGA, EASI, NRS, and DLQI scores significantly decreased from 4.13 ± 0.61, 37.59 ± 14.86, 6.83 ± 2.26 and 18.67 ± 8.64 points respectively at baseline to 1.12 ± 0.49, 4.53 ± 3.78, 0.72 ± 0.58 and 1.39 ± 0.85 points respectively （t = 22.70, 10.55, 10.69, 8.40, respectively, all P < 0.001）. During the follow-up period, no serious adverse reactions were observed; 3 patients experienced gastric discomfort at the start of oral treatment, but the symptoms disappeared after the treatment continued; 3 developed acute allergic manifestations （1 case of allergic conjunctivitis, 2 cases of acute urticaria）, which resolved rapidly after the use of antihistamines without recurrence. Conclusion Baricitinib can provide a safer and more effective treatment option for patients with moderate-to-severe AD, especially those who are insensitive or intolerant to topical agents and need systemic treatments.

Key words: Dermatitis, atopic, Janus kinases, Protein kinase inhibitors, Treatment outcome, Baricitinib