Abstract: 【Abstract】 Objective To evaluate the clinical efficacy and safety of omalizumab in the treatment of chronic spontaneous urticaria （CSU）. Methods Clinical data were collected from 60 patients, who were diagnosed with CSU and received subcutaneous injections of omalizumab at a dose of 300 mg once every 4 weeks for 3 sessions in Hospital of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College from March 2020 to September 2020, and retrospectively analyzed. At weeks 0, 2, 4, 6, 8, 10 and 12, urticaria activity score over 7 days （UAS7） and chronic urticaria quality of life （CU-Q2oL） score were used to evaluate clinical symptoms and quality of life of patients. Changes in the use of other drugs were evaluated before and after the treatment with omalizumab. Paired t test was used to compare UAS7 or CU-Q2oL score before and after treatment. Results All the 60 CSU patients received 12 weeks of omalizumab treatment. The baseline UAS7 score was 22.37 ± 8.88 points; after one session of the treatment, the UAS7 score dropped to 2.01 ± 5.13 points, reaching the treatment plateau; at week 12, it dropped to 0.6 ± 2.63 points, and 0 point （complete control） in 93.3% of the patients, 1 - 6 points （favorable control） in 3.3%; the time required for UAS7 score to decrease to 0 point was 22.4 ± 3.2 days. The baseline CU-Q2oL score was 34.10 ± 15.01 points; after one session of the treatment, the CU-Q2oL score dropped to 2.41 ± 7.18 points, reaching the treatment plateau; at week 12, it was 0.56 ± 2.90 points; the time required for CU-Q2oL score to drop to 0 point was 21.15 ± 16.02 days. After the combination treatment with omalizumab, a gradual decrease in dosage or withdrawal of previous therapeutic drugs was realized. At week 12, 39 patients （65%） achieved complete control, and withdrew all therapeutic drugs except omalizumab. During the treatment and follow-up, omalizumab showed good safety, and no adverse reactions were observed. Conclusion Omalizumab at a dose of 300 mg once every 4 weeks is markedly effective and safe for the treatment of CSU, providing a new treatment option for CSU patients with poor response to traditional therapy.

Key words: Urticaria, Biological agents, Treatment outcome, Drug toxicity, Chronic spontaneous urticaria, Omalizumab